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The Journal of the American Association

JAAVSO Volume 40Number 22012of Variable Star Observers

49 Bay State RoadCambridge, MA 02138

U. S. A.

ε Aurigae Special Edition

Also in this issue...• BVRI photometry of SN 2011fe in M101

• The 1909 outburst of RT Ser

• Photometry and spectroscopy of P Cygni

• A W UMa system with complete eclipses

• MP Gem—an EB with a very long period?Complete table of contents inside...

Historic first: 1.6-m wavelength image of ε Aur, 2009 Nov. 2, as initially processed by John Monnier, based on four telescope beam combination data acquired by MIRC at the CHARA Array and showing the shadow of the disk crossing the face of ε Aur. see page 618

Image courtesy of John Monnier, Univ. Michigan

Editorial BoardGeoffrey C. ClaytonLouisiana State UniversityBaton Rouge, Louisiana

Edward F. GuinanVillanova UniversityVillanova, Pennsylvania

Pamela KilmartinUniversity of CanterburyChristchurch, New Zealand

Laszlo KissKonkoly ObservatoryBudapest, Hungary

Paula SzkodyUniversity of WashingtonSeattle, Washington

The Journal of the American Association of Variable Star Observers

The Council of the American Association of Variable Star Observers2011–2012

Director Arne A. Henden President Mario E. Motta Past President Jaime R. García 1st Vice President Jennifer Sokoloski Secretary Gary Walker Treasurer Gary W. Billings (term ended May 2012) Treasurer Timothy Hager

Councilors

Editor John R. Percy University of TorontoToronto, Ontario, Canada

Associate EditorElizabeth O. Waagen

Assistant Editor Matthew R. Templeton

Production EditorMichael Saladyga

Matthew R. TempletonAAVSO

Douglas L. WelchMcMaster UniversityHamilton, Ontario, Canada

David B. WilliamsWhitestown, Indiana

Thomas R. WilliamsHouston, Texas

Lee Anne WillsonIowa State UniversityAmes, Iowa

ISSN 0271-9053

Edward F. GuinanRoger S. KolmanChryssa KouveliotouArlo U. Landolt

John MartinDonn R. StarkeyRobert J. StineDavid G. Turner

JAAVSOThe Journal of

The American Associationof Variable Star Observers

49 Bay State RoadCambridge, MA 02138

U. S. A.

Volume 40 Number 2

2012

ISSN 0271-9053

ε Aurigae Special Edition

The Journal of the American Association of Variable Star Observers is a refereed scientific journal published by the American Association of Variable Star Observers, 49 Bay State Road, Cambridge, Massachusetts 02138, USA. The Journal is made available to all AAVSO members and subscribers.

In order to speed the dissemination of scientific results, selected papers that have been refereed and accepted for publication in the Journal will be posted on the internet at the eJAAVSO website as soon as they have been typeset and edited. These electronic representations of the JAAVSO articles are automatically indexed and included in the NASA Astrophysics Data System (ADS). eJAAVSO papers may be referenced as J. Amer. Assoc. Var. Star Obs., in press, until they appear in the concatonated electronic issue of JAAVSO. The Journal cannot supply reprints of papers.

Page Charges

Unsolicited papers by non-Members will be assessed a charge of $15 per published page.

Instructions for Submissions

The Journal welcomes papers from all persons concerned with the study of variable stars and topics specifically related to variability. All manuscripts should be written in a style designed to provide clear expositions of the topic. Contributors are strongly encouraged to submit digitized text in ms word, latex+postscript, or plain-text format. Manuscripts may be mailed electronically to [email protected] or submitted by postal mail to JAAVSO, 49 Bay State Road, Cambridge, MA 02138, USA.

Manuscripts must be submitted according to the following guidelines, or they will be returned to the author for correction: Manuscripts must be: 1) original, unpublished material; 2) written in English; 3) accompanied by an abstract of no more than 100 words. 4) not more than 2,500–3,000 words in length (10–12 pages double-spaced).

Figures for publication must: 1) be camera-ready or in a high-contrast, high-resolution, standard digitized image format; 2) have all coordinates labeled with division marks on all four sides;

3) be accompanied by a caption that clearly explains all symbols and significance, so that the reader can understand the figure without reference to the text.

Maximum published figure space is 4.5” by 7”. When submitting original figures, be sure to allow for reduction in size by making all symbols and letters sufficiently large.

Photographs and halftone images will be considered for publication if they directly illustrate the text. Tables should be: 1) provided separate from the main body of the text; 2) numbered sequentially and referred to by Arabic number in the text, e.g., Table 1.

References: 1) References should relate directly to the text.

2) References should be keyed into the text with the author’s last name and the year of publication, e.g., (Smith 1974; Jones 1974) or Smith (1974) and Jones (1974).

3) In the case of three or more joint authors, the text reference should be written as follows: (Smith et al. 1976).

4) All references must be listed at the end of the text in alphabetical order by the author’s last name and the year of publication, according to the following format:

Brown, J., and Green, E. B. 1974, Astrophys. J., 200, 765. Thomas, K. 1982, Phys. Report, 33, 96. 5) Abbreviations used in references should be based on recent issues of the Journal or the listing provided

at the beginning of Astronomy and Astrophysics Abstracts (Springer-Verlag).

Miscellaneous:1) Equations should be written on a separate line and given a sequential Arabic number in parentheses

near the right-hand margin. Equations should be referred to in the text as, e.g., equation (1).2) Magnitude will be assumed to be visual unless otherwise specified.3) Manuscripts may be submitted to referees for review without obligation of publication.

© 2012 The American Association of Variable Star Observers. All rights reserved.

Journal of the American Association of Variable Star ObserversVolume 40, Number 2, 2012

Table of Contents continued on following pages

e Aurigae Special Edition

Highlighting ε Aurigae and Citizen Sky John R. Percy 609

ε Aurigae Papers

The Origins and Future of the Citizen Sky Project Aaron Price, Rebecca Turner, Robert E. Stencel, Brian K. Kloppenborg, Arne A. Henden 614

ε Aurigae—an Overview of the 2009–2011 Eclipse Campaign Results Robert E. Stencel 618

The International ε Aurigae Campaign 2009 Photometry Report Jeffrey L. Hopkins 633

An Analysis of the Long-term Photometric Behavior of ε Aurigae Brian K. Kloppenborg, Jeffrey L. Hopkins, Robert E. Stencel 647

V-band Light Curve Analysis of ε Aurigae During the 2009–2011 Eclipse Thomas Karlsson 668

Report From the ε Aurigae Campaign in Greece Grigoris Maravelias, Emmanuel Kardasis, Iakovos-Marios Strikis, Byron Georgalas, Maria Koutoulaki 679

Photoelectric Photometry of ε Aurigae During the 2009–2011 Eclipse Season Frank J. Melillo 695

Small Telescope Infrared Photometry of the ε Aurigae Eclipse Thomas P. Rutherford 704

UV-Blue (CCD) and Historic (Photographic) Spectra of ε Aurigae—Summary R. Elizabeth Griffin, Robert E. Stencel 714

Ha Spectral Monitoring of ε Aurigae 2009–2011 Eclipse Benjamin Mauclaire, Christian Buil, Thierry Garrel, Robin Leadbeater, Alain Lopez 718

High Cadence Measurement of Neutral Sodium and Potassium Absorption During the 2009–2011 Eclipse of ε Aurigae Robin Leadbeater, Christian Buil, Thierry Garrel, Stanley A. Gorodenski, Torsten Hansen, Lothar Schanne, Robert E. Stencel, Berthold Stober, Olivier Thizy 729

Spectroscopic Results From Blue Hills Observatory of the 2009–2011 Eclipse of ε Aurigae Stanley A. Gorodenski 743

Eclipse Spectropolarimetry of the ε Aurigae System Kathleen M. Geise, Robert E. Stencel, Nadine Manset, David Harrington, Jeffrey Kuhn 767

Table of Contents continued on next page

Polarimetry of ε Aurigae, From November 2009 to January 2012 Gary M. Cole 787

Modeling the Disk in the ε Aurigae System: a Brief Review With Proposed Numerical Solutions Richard L. Pearson, III, Robert E. Stencel 802

A Demonstration of Accurate Wide-field V-band Photometry Using a Consumer-grade DSLR Camera Brian K. Kloppenborg, Roger Pieri, Heinz-Bernd Eggenstein, Grigoris Maravelias, Tom Pearson 815

Stellar Photometry With DSLR: Benchmark of Two Color Correction Techniques Toward Johnson's VJ and Tycho VT Roger Pieri 834

Algorithms + Observations = VStar David Benn 852

An Artist’s Note on Art in Science Nico Camargo 867

JAAVSO Volume 40, Number 2—other papers received

BVRI Photometry of SN 2011fe in M101 Michael W. Richmond, Horace A. Smith 872

New Light Curve for the 1909 Outburst of RT Serpentis Grant Luberda, Wayne Osborn 887

International Observing Campaign: Photometry and Spectroscopy of P Cygni Ernst Pollmann, Thilo Bauer 894

The Pulsation Period of the Hot Hydrogen-Deficient Star MV Sagittarii John R. Percy, Rong Fu 900

GEOS RR Lyrae Survey: Blazhko Period Measurement of Three RRab Stars— CX Lyrae, NU Aurigae, and VY Coronae Borealis Pierre de Ponthière, Jean–François Le Borgne, F. Fumagalli, Franz–Josef Hambsch, Tom Krajci, J–M. Llapasset, Kenneth Menzies, Marco Nobile, Richard Sabo 904

Recent Maxima of 55 Short Period Pulsating Stars Gerard Samolyk 923

The Ross Variable Stars Revisited. II Wayne Osborn, O. Frank Mills 929

GSC 4552-1643: a W UMa System With Complete Eclipses Dirk Terrell, John Gross 941

VSX J071108.7+695227: a Newly Discovered Short-period Eclipsing Binary Mario Damasso, Davide Cenadelli, Paolo Calcidese, Luca Borsato, Valentina Granata, Valerio Nascimbeni 945

Variability Type Determination and High Precision Ephemeris for NSVS 7606408 Riccardo Furgoni 955

Is MP Geminorum an Eclipsing Binary With a Very Long Period? Dietmar Böhme 973

Recent Minima of 150 Eclipsing Binary Stars Gerard Samolyk 975

The Variable Stars South Eclipsing Binary Database Tom Richards 983

A Note on the Variability of V538 Cassiopeiae Gustav Holmberg 986

A Practical Approach to Transforming Magnitudes onto a Standard Photometric System David Boyd 990

ROAD (Remote Observatory Atacama Desert): Intensive Observations of Variable Stars Franz-Josef Hambsch 1003

The AAVSO 2011 Demographic and Background Survey Aaron Price, Kevin B. Paxson 1010

The Citation of Manuscripts Which Have Appeared in JAAVSO Arlo U. Landolt 1032

Abstracts of Papers and Posters Presented at the Joint Meeting of the Society for Astronomical Sciences and the American Association of Variable Star Observers (AAVSO 101st Spring Meeting), Held in Big Bear Lake, California, May 22–24, 2012

Fast Spectrometer Construction and Testing John Menke 1037

Observations Using a Bespoke Medium Resolution Fast Spectrograph John Menke 1037

Enhancing the Educational Astronomical Experience of Non-Science Majors With the Use of an iPad and Telescope Robert M. Gill, Michael J. Burin 1037

The Rotational Period of the Sun Using the Doppler Shift of the Ha Spectral Line Robert M. Gill 1038

A Single Beam Polarimeter (Poster) Jerry D. Horne 1038

Index to Volume 40 1039

Percy, JAAVSO Volume 40, 2012 609

Highlighting ε Aurigae and Citizen Sky

John R. PercyDepartment of Astronomy and Astrophysics, University of Toronto, Toronto. ON M5S 3H4, Canada; [email protected]

WelcometothisspecialissueoftheJournal of the American Association of Variable Star Observers,featuringpapersoneAurigaeandtheCitizenSkyproject (www.citizensky.org). As Price et al. explain in the opening paper,Citizen Sky grew out of International Year of Astronomy 2009, brilliantlypiggybackingontheinternationalcampaigntoobservethe2009–2011eclipseofabrightbutmysteriousstar.Itincorporatedthe“citizenastronomy”philosophyon which the AAVSO is founded—skilled volunteers participating in andadvancing astronomical research. Itwas a complexmultidisciplinaryprojectwhichrequiredcarefulorganization,facilitatedbyagenerousgrantfromtheNationalScienceFoundation.Thepapersinthisissuerepresenttheculminationoftheastronomicalresearchaspectsoftheprojectbut,asPriceet al.explain,thereweremanyotherpositiveoutcomesoftheprojectwhich,wehope,willcontinuetobearfruitinthefuture.Inparticular,itprovidesanexcellentmodelforhowtoorganizeandmanageacomplexproject,andevaluatetheresults—somethingwhichisrarelydone. I’ve been actively involved in astronomical research for exactly halfacentury,soIhaveexperienced threeeclipsesofeAurigae(if I include the1955–1957onewhichIreadaboutasagraduatestudent).Iwaseducatedinanastronomydepartment(attheUniversityofToronto)whichhadspecialexpertiseinvariableandbinarystars—ofwhicheAurigaeisaprominentexample.Ihaveaspecificinterestintheintrinsicvariabilityofthesupergiantcomponentofthesystemso,unlikemanyobservers,Idon’thavetowaitfortheeclipseseverytwenty-sevenyears.Whatfascinatesmeaboutthepapersinthisissue,andinCitizenSkyingeneral, ishowtheyillustratesomanydiverseandintriguingfacetsofvariablestarastronomy. Firstandforemost:eAurigaeisagenuineastronomicalmystery.Itconsistsof a pulsating blue supergiant and a secondary component, in a 9,896-day(27.09-year)orbit.Thesecondarycomponentissurroundedbyadonut-shapeddiskofgasanddust,whicheclipsestheprimarycomponentforalmostexactlytwoyearseachorbit.Itisstillnotclearwhethertheprimaryisanormalmassivesupergiant,inwhichcasethesecondaryismostlikelyapairofstarsincloseorbit(the“high-massmodel”),orwhethertheprimaryisalow-masssupergiant,and thesecondary isasinglestar (the“low-massmodel”).Wehope that thepapersinthisspecialissuewillhelptoresolvethismystery.ForanexcellentoverviewofeAurigaepriortothe2009–2011eclipse,seeTempleton(2008). Thisisfrontierastronomy.Disksofgasanddustarewidelystudied,becausetheyareubiquitous in theuniverse.Theyare foundaroundformingstars, in

Percy, JAAVSO Volume 40, 2012610

cataclysmicbinarysystems,andaroundsupermassiveblackholesatthenucleiof galaxies. Binary and multiple star evolution is poorly understood, eventhoughbinaryandmultiplestarsarethenorm,nottheexception.Itisatopicwhichisrelevanttosomeofthemostexcitingtopicsinastrophysicstoday.TheoriginofTypeIasupernovae,whicharethemostimportant“measuringsticks”inmoderncosmology,isoneexample. eAurigae has an apparentV magnitude of about 3.0—not much fainterthanthestarsintheBigDipper—soit isvisibleevenincitiessuchasmine.Beginningskywatcherstendtothinkthatallstarsarethesameso,atstarparties,Iliketotellthemabouttheparticularcharacteristicsofindividualbrightstars,especially bizarre stars such as eAurigae. Beginning skywatchers can thenbecomebeginningobservers;eAurigaeiseasytomeasurewiththeunaidedeye(thoughbinocularshelp). Indeed, thiswasthewholepointofCitizenSky; itbringsastronomyandastronomicalresearchtoanyone,ofanyage,anywhere. Asothershavepointedout,eacheclipseofeAurigaebringsanewgenerationofastronomers,andanewgenerationof technology.The1982–1984eclipsecoincidedwiththeblossomingofamateurphotoelectricphotometry(PEP).The2009–2011eclipsewasobservedwithCCDandDSLRcameras,aswellasPEPandvisualtechniques. Itwasalsoobservedwithspectroscopy,atechniquewhichisincreasinglyavailabletoamateurs,andwithpolarimetry—afrontiertechniqueforsuitably-equippedadvancedamateurs.Veryfewprofessionalobservatoriesarecarryingout long-termspectroscopicandpolarimetricobservations, so this isanareainwhichamateurscouldtakeuptheslackinthefuture.Thiseclipsewasalsoobservedwithanopticalinterferometer—GeorgiaStateUniversity’sCHARAarray—so,forthefirsttime,wecan“see”thismysterioussystem. Finally, this eclipse campaign benefitted from modern information andcommunication technology, including email, the Internet, and social media.These made the transfer, display, and storage of information efficient andeffective.Theyalsohelpedtoconnecttheinternationalnetworkofamateurandprofessionalobserversasneverbefore. Youwillnoticethattheauthorsofthepapersinthisissuecomefrommanycountries.Theobservationswhichamateursandprofessionalshavecontributedduring this eclipse campaign come from even more countries, so everycontributorispartofaninternationalcommunityofvariablestarobservers. Furthermore,thearchivaldataoneAurigaestretchbackforover160years.Thedata in theAAVSOInternationalDatabasecover the last seveneclipses(1847–1849,1874–1876,1901–1903,1928–1930,1955–1957,1982–1984,and2009–2011),includingobservationsbytheeminentFriedrichArgelanderofthefirstofthese.ThevariabilityofthestarwasfirstsuspectedbyJohannFritchin1821,duringthe1820–1822eclipse.The1847–1849eclipsewasobservedsystematically byArgelander and others. Hans Ludendorff (1904) suggestedthatthestarwasaneclipsingvariable.By1937,ithadengagedthemindsof

Percy, JAAVSO Volume 40, 2012 611

some of the foremost astronomers of the time: Gerard Kuiper, Otto Struve,andBengtStrömgren(1937)statedthat“thephotometricandthespectroscopicdataoneAurseemtoleadtocontradictionsunparalleledinthestudyofothereclipsing systems”. By the 1955–1957 eclipse, the situation was even morecritical, as stellar astrophysics had matured greatly. Various models wereproposed,includingthepossibility(sinceruledout)thatthesystemcontainedablackhole.Today’sobserversarethusconnected,acrosstime,withyesterday’sobservers and interpreters. The AAVSO centennial, the centennial history(WilliamsandSaladyga2011),andthehistoricalpapersinthecentennialissueofJAAVSO(volume40,number1)weretimelyvehiclesforhelpingtomakethesehistoricalconnections. CitizenSky,andthisspecialissue,wouldnothavebeenpossiblewithoutthesupportofmanyorganizationsandpeople:theNationalScienceFoundationforgrantsupport(DRL-0840188);theAAVSOanditsstaffwhoprovidedin-kindsupport; theCitizenSky team:AaronPrice,RebeccaTurner,RobertE.Stencel,BrianKloppenborg,andArneA.Henden;partnerorganizationsandindividualswhocontributedtopartsoftheprojectsuchastheworkshopsandtutorials;theauthorsofthepapersinthisissue;andalltheobserversandothervolunteerswhocontributedtothediversescientificandeducationalaspectsoftheproject.Special thanks,asalways, to the staffof thisJournal:AssociateEditorElizabethWaagen,AssistantEditorMatthewTempleton,andProductionEditorMichaelSaladyga.Wehopethatyouenjoythisissue!

References

Kuiper,G.,Struve,O.,andStrömgren,B.1937,Astrophys. J.,86,570.Ludendorff,H.1904,Astron. Nachr.,164,81.Templeton,M.2008,http://www.aavso.org/vsotsepsaurWilliams,T.R.,andSaladyga,M.2011,Advancing Variable Star Astronomy:

The Centennial History of the American Association of Variable Star Observers,CambridgeUniv.Press,Cambridge.

JAAVSO Volume 40, 2012612

JAAVSO Volume 40, 2012 613

ε Aurigae Papers

Price etal., JAAVSO Volume 40, 2012614

The Origins and Future of the Citizen Sky Project

Aaron PriceRebecca TurnerAAVSO Headquarters, 49 Bay State Road, Cambridge, MA 02138; address email correspondence to R. Turner, [email protected]

Robert E. StencelBrian K. KloppenborgUniversity of Denver, Department of Physics and Astronomy, 2112 E. Wesley Avenue, Denver, CO 80208; [email protected]; [email protected]

Arne A. HendenAAVSO Headquarters, 49 Bay State Road, Cambridge, MA 02138; [email protected]

Received June 12, 2012

CitizenSkyaroseasaproductofthe2009InternationalYearofAstronomy(IYA)project.AaronPricewasappointedtotheU.S.IYAProgramCommitteewhenitwasfirstconstitutedin2006.Afteraboutayearofplanning,thecommitteeestablishedaWorkingGroupforResearchExperiencesforStudents,Teachers,andCitizenScientistswithAaronas thechair.Thegoalwas touse the IYAinitiativetopromotecitizenscienceprojectstothegeneralpublic.ThegroupmetforthefirsttimeattheAstronomicalSocietyofthePacificmeetinginChicago—2007.At the meeting they decided to focus their efforts around one projectinsteadofpromotingaslateofprojects.Manyspecific ideaswerediscussedduringamorningmeeting,butnothingcaughttheexcitementoftheentiregroup. Intheafternoon,AaronhadahallwaydiscussionwithRickFienberg,theneditor-in-chief of Sky & Telescope magazine. Rick mentioned the upcomingeAurigaeeclipseasapossibletopic.Hehadpreviouslyco-presentedapaperonthetopicwithRobertStencel(“Dr.Bob”)atthe2006meetingoftheInternationalAstronomicalUnion.Itseemedlikeanidealproject.Andastheworkinggroupresearcheditmore,itbecamemoreandmoreenticing.eAurisbrightenoughtobeseenfromthecity,itseclipsehasanamplitudethatcanbedetectedwiththenakedeye,ithappensveryrarely,itisdifficultforprofessionalstomonitor(dueto limited large telescope time)and, aboveall, itwas still anenigma—evenafteroveracenturyofresearchandspeculation. U.S.IYAfundingwasaconstantissue.TheProgramCommitteeonlyhadenoughfundstosupportasmallstaffandafewprojects.TheWorkingGroupknewthatanyprojecttheycameupwithwouldbetargetedatanarrowaudienceandsowouldnotreceivethesamelevelofsupportfromtheProgramCommitteethat a more generalized topic—such as the Galileoscope—received. So theWorkingGroupcameupwithtwoplans.Onewasaimedatwhattheywould

Price etal., JAAVSO Volume 40, 2012 615

dowithzerofunding—whateachmemberofthegroupcouldcontributegratisand/orcandoaspartoftheirregularjob.FortheAAVSO,thismeantissuinganAlert Noticeonthetopic,makingcharts,andrunningaregularcampaign,butnotmuchmore.Theyalsocameupwithaprogramtoimplementiftheycouldraise substantial levelsof support.After these twoplanswere inplace, theylookedforfunding. The National Science Foundation (NSF) seemed like a natural fit.Theyfund citizen science, have a nice history with theAAVSO, and the workinggrouphadsomeexperiencewritingproposalsforthem.However,strongNSFproposalsarenoteasytoassemble.IttookalmostsixmonthstowritetheCitizenSkyproposal.Aaronwroteadraft,circulateditamongsttheWorkingGroup,andthentheyheldconferencecallstodiscussrevisions.Theprocesswentverysmoothly,buttookalotoftime. AAVSO Director Arne Henden was chosen as the project’s principalinvestigator(PI)becauseAarondidnotyethaveaPh.D.(hewasingraduateschoolat thetime).Allof theco-PIscontributedtotheproposal.InadditiontoAaron, they were Lucy Fortson, Jordan Raddick, and Bob Stencel. RyanWyatt also contributed to the proposal and was a member of the advisoryboard along with Chris DuPree, Suzanne Jacoby, Hee-Sun Lee, and DavidAnderson.TheproposalitselfwasoriginallycalledSTARS—ScienceThroughtheAstronomicalResearchofStars.ItwasafterfundingthatitwaschangedtoCitizenSky,anamefirstproposedbyRebeccaTurner. RobertStencelservedasscientificadvisor fromtheverybeginning.Theoriginal idea to involve web cams and DSLR cameras began with him. Heprovidedmuchneededscientificadviceandalsoawelcomesenseofhumorwhenthingsgottightanddeadlinesloomed.Healsorecruitedagraduatestudentofhis,BrianKloppenborg,intotheproject. By the time we submitted the proposal to the NSF’s Informal ScienceEducation (ISE) program, which funds their citizen science projects, thebudget had increased to about $796,000 for a three-year project. It was aninterdisciplinary project with funding for modeling software, workshops, ahigh-endplanetariumshow,journalpublication,ScienceOlympiadmaterials,andmuchmore.ThescientificgoaloftheprojectwastocollectdatatohelpresearchersuncoverwhatiscausingtheeAureclipse.Theeducationalgoalwastoinvolvethepublicinallaspectsofascientificproject.Insteadoffocusingsolelyondatacollection,theprojectaimedtotrainparticipantstoanalyzedata,pose their own research questions, and write up results for a peer-reviewedjournal.Thishadnotbeendonebeforeinalargescalecitizenscienceproject,and theAAVSO was in a unique position to do so thanks to our history ofhavinganengagedmembership.ThegoalwithCitizenSkywas toput it alltogetherinonepackageandmakeitaccessibletonoviceamateurastronomerswiththebeliefthatparticipantswillgetabetterunderstandingofthescientificmethodiftheyaremoreengagedwithitateverystepoftheway.

Price etal., JAAVSO Volume 40, 2012616

TheproposalwassubmittedinJune2008.InNovember2008wereceivedthewordthatithadbeenfavorablyreviewedbytheNSF.OverthenextfewmonthsweansweredquestionsandrespondedtosuggestionsfromtheNSFtostrengthentheproject.Inmid-April2009wefinallyreceivedofficialnotificationthattheprojectwouldbefullyfunded.However,wewerenewtotheNSFsothereweresubstantialadministrative tasks tocompletebefore fundingcouldbegin.Thisadditionaldelaycausedaproblembecause,asweallknow,theskywaitsfornoone.Theeclipsewaspredictedtobegininthelatterhalfoftheyearandweneededpre-eclipseobservations.Intheoriginalproposalweplannedtohavealmostayeartobuildtheproject,materials,andsoon,beforetheeclipsebegan.Nowwehadtodoayear’sworkinafewmonths. Rebecca Turner was assigned the position of Project Manager, meaningshe was responsible for overall implementation of the project. Dr. Bob wasthescientificadvisor.BrianKloppenborgwashiredasastaffmembertoassistRebecca.Thefirstauthorwasfundedtoconductanevaluationoftheproject,whicheventuallymorphedintohisdissertationatTuftsUniversity.TheMorrisonPlanetariumattheCaliforniaAcademyofSciences,actingunderRyanWyatt,was contracted to produce an eight-minute planetarium film for the project.TheAdlerPlanetariumandAstronomyMuseum,actingunderMarkSubbaRao,washiredtodevelopaninteractiveeclipsingbinarymodelingsoftware.JordanRaddickatJohnsHopkinswashiredtoconsultonwebsitedevelopment,whichwasmostlydonebyKateDavis,theAAVSOwebmasteratthetime. Thefirstyearof theprojectwasdedicated tobuilding infrastructureanddatacollection.ThewebsitewasofficiallylaunchedinJune2009.Itconsistedof simplified versions of WebObs, the light curve generator, and the QuickLookfile,tutorialsonobservingandreadinglightcurves,onlineforums,andablogmaintainedbythestaffandDr.Bob.ThefirstCitizenSkyworkshopwasheldinSeptember2009attheAdlerPlanetariuminChicago.Thefocusoftheworkshopwasondatacollection(visual,photoelectric,andspectra)andonthesciencebehindthesystem. Thesecondyearoftheprojectwasdedicatedtobuildingteamsandtrainingindataanalysis.Thenon-observingaspectofCitizenSkywasdesignedaroundtheconceptof teamsofparticipantsworkingtogether.Itwasinspiredbythesuccess of the chart and comparison star database teams that were active intheAAVSO in thepreviousdecade.Asecondworkshopwasheld inAugust2010attheCaliforniaAcademyofSciencesinSanFrancisco.Thefocusofthatworkshopwasondataanalysisandwritingscientificpapers. Thethirdyearoftheprojectwasdedicatedtoobservingtheendoftheeclipseandwritingpapersfor theJournal of the AAVSO (JAAVSO).Thiswasa lesspubliclyactiveperiodastheteamsworkedontheirpapers,mostofwhicharepublishedinthiseditionofJAAVSO, abouteAur,CitizenSky,andrelatedtopics. SowhatishappeningnextwithCitizenSky?Oneofthelessonswelearnedin thisproject is that teamscanindeeddogreatwork.Evidenceof that is in

Price etal., JAAVSO Volume 40, 2012 617

thisJAAVSO issue.However, some teamsdidnotachieve theirgoals.Therearemanyreasonsforthis,butinourviewtherewasoneoveralllessontolearn:project staff cannot appoint leaders of teams; theyhave togroworganicallyfromamongtheparticipants.Themostsuccessfulteamsweremostlytheonesthathadself-nominatedleaders.Theteamswhichhadstaff-invitedleaderswerelesssuccessful,withafewnotableexceptions. AttheendofthethirdyearoftheCitizenSkyProjecttheAAVSOreceivedasupplementalNSFgranttofundathirdworkshop.ThisworkshopwillfocusongeneratingamanualforDSLRPhotometry.Applicationswillbeacceptedinlate2012andearly2013.ItwilltakeplaceMarch22–24,2013,atAAVSOHeadquarters in Cambridge, Massachusetts. The program will comprise amixof1)talksbyexperiencedDSLRphotometristsand2)breakoutsessionsduringwhichsmallgroupsofparticipants(eachwithadesignatedleader)willdeveloppreassignedsectionsofthemanual.Thesegroupswillbedeterminedwellinadvanceandwillbebasedonparticipantinterest,experience,andskills.NopriorDSLRexperienceisrequired,but therewillbesomepre-workshopreadingandpreparationrequired.Theworkshopwillproduceaneasytouse,introductory manual that will help the AAVSO support observers who areinterestedingivingDSLRphotometryatry. WiththeconclusionoftheeAureclipseandnewsoftheDSLRworkshop,theAAVSOhasgivenCitizenSkyanewmission:tobethenewhomeoftheAAVSO’sbrightvariablestaractivities. Initially, theCitizenSkyareaof theAAVSOwebsitewillhosttheAAVSOBinocularObservingProgramandtheDSLR Photometry Program.Additional bright object programs/projects willbe added to the Citizen Sky pages as they develop. Important Citizen SkymaterialswillbemovedfromitsexistingwebsitetotheCitizenSkysectionoftheAAVSOwebsite.TheoriginalCitizenSkywebsitewillbefrozenin2013butwillstayonlineasanarchive. Asforstaff,theyhavealsobuiltonwhattheyhavelearnedaspartofthisproject.Dr.BrianKloppenborg,whoreceivedhisPh.D.atUniv.ofDenverinspring2012,isnowavisitingscientistattheMaxPlanckInstituteforRadioAstronomy in Bonn, Germany, working on interferometry. He continues toinvolveamateurastronomersinhisresearch.Dr.AaronPriceisnowManagerofResearchandEvaluationattheMuseumofScienceandIndustryinChicago,whereheisapplyingthesocialscienceresearchskillshelearnedthroughhisdissertationonCitizenSky’simpactonthescientificbeliefsofitsparticipants.Rebecca Turner has been promoted to Operations Director at the AAVSO,whereshe isapplyingmanyof theprojectandpersonnelmanagement skillsshe learnedasProjectManagerof theCitizenSkyproject.Dr.ArneHendencontinues asDirectorof theAAVSO, andDr.RobertStencel continues as aprofessorattheUniversityofDenver,andisnowplanningobservationsforthenexteclipseofeAurin2036!

Stencel, JAAVSO Volume 40, 2012618

e Aurigae—an Overview of the 2009–2011 Eclipse Campaign Results

Robert E. StencelUniversity of Denver, Department of Physics and Astronomy, 2112 E. Wesley Avenue, Denver, CO 80208;[email protected]

Received March 19, 2012; revised May 30, 2012; accepted June 19, 2012

Abstract Evidenceisprovidedfromthearrayofobservationsamassedduringthe2009–2011eclipse,thatdefinestheenigmaticbinaryeAurigaeascomprisedof an unstable F0-1 Iab star in orbit around a comparable mass upper mainsequencestar(orstars)enshroudedinadiskresultingfromFstarmassloss.Inthispicture,theFstarmaybeundergoingrapidevolutionarychanges,andtherecent67-dayprimaryquasi-periodmaymakeitsuitableforasteroseismicstudies.Thehiddenstar(s)mayhavegainedmassfromtheFstar,andthediskitselfprovidesopportunitiesforstudyofaccretion,dustevolution,anddynamics.

1. Introduction

Duringthe20thcentury,thebrightstareAurigaeconfoundedastronomersbecause the visible member of this single-lined spectroscopic binary starappearedtobeamassive,F-typesupergiantstar,withanequally-massivebutinvisible companion (Guinan and deWarf 2002). Unimpeachable evidencefor the eclipsing object, a disk in transit, was obtained with interferometricimagingduringthe2009–2010eclipse(Kloppenborget al.2010),buildingontheinfrareddetectionofsamebyBackmanet al.(1984).Hoardet al.(2010),and previous authors, argued that the F star is in a volatile, reduced mass,post-AsymptoticGiantBranch(AGB)evoutionaryphase,withthecompanionbeingadisk-enshroudedB-typemainsequencestar—possiblynowthemoremassiveobjectinthesystem.Resolutionofthemassesandevolutionarystateofstarsinthissystemisaprimarymotivatorfortherecenteclipsecampaign,resultsofwhicharesummarizedinthispaper.ThisarticleispartofagroupofarticlescollectedintheJournal of the AAVSO,intendedtodocumentresultsofaninternationalefforttocollecthighqualityobservationsoftheeAursystemduring its 2009–2011 eclipse. Those reports provide details for each facet,butherewesummarizesomeoftheimportantfindings,inrelationtofindingsrecognizedasaresultofthestudiesofpreviouseclipses.

2. Results

AsdiscussedbyJeffHopkins(2012),photometricV-bandtimingsof thelatesteclipseareasfollows:

Stencel, JAAVSO Volume 40, 2012 619

Firstcontact: RJD55070 2009August16

“Second”contact: RJD55250 2010February22

Mid-eclipse: RJD55400 2010July22

“Third”contact: RJD55620 2011February27

Fourthcontact: RJD55800 2011August26

whereRJD=JD–2,400,000andtheuncertainty in timings isat leastone totwoweeks.Thenotionofcontacttimeshistoricallyreferstotangentcrossingsbetweenobjectsthatappearcircularinprojection,butwithaellipsoidaldiskshapeinvolved,thenormalmeaningsofsecondandthirdcontactsarechanged.Also,thesetimingsarecomplicatedbypersistent~0.1magnitudelightvariationsonaquasi-periodof67days(Kim2008).Spectroscopicevidencesuggeststhatdiskmaterialencroachedonthelineofsightmonthspriortophotometricfirstcontact(forexample,inKI7699A—seeLeadbeateret al.,thisissue),orevenyearsprior(Ha,seeChadimaet al.2011).SpectroscopicfourthcontactwasrecentlyannouncedbyobserverThierryGarrell,whoreportedexcessblue-shiftedHaandNaD-lineabsorptiondisappearedcircaRJD55950(2012January25). Theeclipsingobject isa large,550Kflattenedstructure,basedonrecentinfrared photometry and imaging. Although speculated to be a “swarm ofmeteors”byHansLudendorffearlyinthe20thcentury,thefirstphotometricevidencefortheeclipsingobjectwasprovidedbyMitchell(1964)withnine-colorphotometry,whoclaimeda500Kexcess,withaprojectedlinearsizeof50AU!Later,Backmanet al. (1984)observedeAurenteringeclipseandconfirmedthe result, reporting a 500K blackbody, with an apparent size of 8×10–16ster-radians.At thereferencedistanceof650pc, this translates toanareaof14AUsquared,orequivalenttoarectangularshape1AUtalland14AUlong. The eclipsing object is disk shaped as seen in the near-IR. Thanks toremarkableprogressininterferometricimagingoverthepastdecade,itwaspossible in autumn 2009, during ingress, to detect the shadow of the diskcrossing the faceof theF star (Figure1),using theMIRCbeamcombinerat the Center for HighAngular ResolutionAstronomy (CHARA)Array oftelescopesatopMt.Wilson,California(Kloppenborget al.2010).Moreaboutthisbelow. Theneutralpotassiumlineat7699Åreappearedandshowedvelocityshiftsthatassociateitwiththediskanditsrotation.OriginallyreportedbyLambertandSawyer(1986),extensivemonitoringbyRobinLeadbeater(reportedinthisissue) showed a repeat of the phenomenon, demonstrating disk rotation andshowingstepwisechangesintheaddedequivalentwidthoftheline,suggestiveof disk substructure (Leadbeater and Stencel 2010). Subsequent study ofspectrarevealsanumberoflineswiththisbehavior(seeLeadbeateret al.2012;Schanneet al.2012;GriffinandStencel2012).


TheonlymoleculedetectedineAur,sofar,istransientcarbonmonoxide.ThiswasoriginallyreportedbyHinkleandSimon(1987),andshownbyStencelet al.(2011)toreappearagainaftermid-eclipse,usingbothmoderateresolutionIRTF+SpeXandhighdispersionGeminiNorthNear-IRSpectrometer(GNIRS)spectra. The data do not clearly confirm the low isotopic 12C/13C ratio ~10(comparedtothesolarvalue,89).TheoverlapofaPfundserieslineofhydrogenatop the 13CO bandhead demands post-eclipse observations where the COcontributionisremoved,allowingdisentanglementoftherelativecontribution.SeeFigures2aand2b.Alessextreme12C/13CratioreducestheevidencefortheFstarbeingalowermass,post-AGBstar. For the first time, transient HeI 10830Å absorption was detected, andit strengthened around mid-eclipse (Stencel et al. 2011), using NASA’sIRTF+SpeXinstrument;seeFigure3.Thislinearisesfroma19.8eVlevelandsuggestsahightemperaturecentralregioninthedisk.ThisisconsistentwithaccretionontoaB0-B5centralstar(Pequetteet al.2011). InfraredmonitoringconfirmedthepredictionbyTakeuti(1986)thatthesideofthediskfacingtheFstarisheatedto1100K(Hoardet al.2012),incontrasttothe550KsidefacingawayfromtheFstar.Amongtheimplicationsofthisarethatthebinaryseparationmightbeevaluated,independentoftheuncertaindistance,andthisdegreeofheatingisrelatedtothematerialpropertiesofthedustinthedisk. Aseriesofthreein-eclipseobservationsofthethefar-ultravioletspectrumofeAurwereobtainedwiththeCosmicOriginsSpectrograph(COS)onHubbleSpaceTelescope (Howell et al. 2011), and it was found that the continuumoutputissomewhateclipsed.Thefar-UVemissionlinesshowevidenceforaPCygni-likeoutflow(Figure4).Bothfactspoint tosurfaceactivityof theFstar,althoughcontributionsfromthediskcentralregionscannotberuledout. Attemptstoobservesolidstatespectralfeatures(ices,PAHs,or10-micronsilicates)failedtodetectany.InstrumentsinvolvedincludedSpeXandBASSatNASA’sIRTF,plusMIRACatMountHopkins(seeStencelet al.2011).Thebroadbandinfraredexcess,combinedwithlackofspectralfeatures,arguesthatthedustiscomprisedoflargeparticles(greaterthan~1micronsize).Kopal(1954)concluded similarlywhenstudying the similarityofeclipsedepthatmanyopticalwavelengths—theeclipse is“gray”due to largeparticlesizes,muchgreater than thewavelengths involved.Asnotedabove,eclipsedepthdeparturefromgrayness isseenatwavelengths longer thanseveralmicronsandintheultraviolet,andthesemayprovideusefulconstraintsonparticlesizeandtype. Photometric monitoring shows persistence of ~0.1 magnitude variationswithaquasi-periodof~67days(Kim2008),bothinandoutofeclipse(Figure5,andseeHopkins(2012)).ThesehavebeenassociatedwithFstaroscillationsandperhapswindevents(seeGriffinandStencel2012).


3. System parameters

Among the generally agreed system parameters are the eclipse period,9890±2days,and themassfunction in thissingle linespectroscopicbinary,f(M) =2.51±0.12 (Stefaniket al. 2010).System inclination seems securelyestablishedatverycloseto90degrees,basedoninterferometricimagesshowingthediskeclipsingtheprimarystar(Kloppenborg2010).Giventheseparameters,possiblesolutionsforthemassratio(q)includethe“highmass”case,q~1.1(sumofmasses,M+m~25M

Ä,andsemi-majoraxis,a~25AU)andthe“low

mass”case,q~0.5(M+m~9MÄ

,a~18AU),whereMistheFstarmass,andmreferstothemassofthesecondaryobject–assumedtobeastarinsidethedisk,andwhereaisthesemi-majoraxisoftheorbit.Astrometricsolutionsforbothextremeshavebeenpublished(Strand1959;vandeKamp1978).Workisunderwaytoincludeinterferometricresultsasanewconstraintoncombinedastrometricandphotometricsolutions(Kloppenborg2012),whichfavors thehighermasssolution. What constraints do we have on the mass (M) of the primary star?Classically, the spectral type of the primary star has been classified as anF0Iastar(7500K).Yellowsupergiantstarshavecatalogedmassesof12M

Ä

andabsolutemagnitude,MV=–6.6 (see, for example,StraizysandKuriliene1981). The historic q=1 solution for this single lined spectroscopic binaryimmediately called into question how a high mass companion could remaininvisibleoutsideoftheeclipsesitcauses(StruveandElvey1930).Usingtheapparentmagnitude,V=3.05andthereddening,AV=0.3,theimplieddistanceis740pc(about20%larger thanthatusedbyKloppenborg(2010)basedonthefirstHipparcosparallax).Fromthis,theimpliedluminosityis3.7×104L

Ä,

andtheimpliedradiusis115RÄ

—largerthanmostCepheids!At740pc,theangular diameterwould be 1.5 milli-arcsec (hereafter, mas), at least 0.5massmallerthanrecentinterferometricdeterminations(2.27mas,K-band,Stencelet al.2008).This requires thestar toeitherhaveunusual limbdarkening,orperhapsnotbeasdistantas740pc.Formally,a2.1masV-banduniformdiskdiameterindicatesadistanceof650pc. AninterestingconstraintonbinaryseparationcanbededucedfromrecentthermalIRdata,whichshowsthattheportionofthedisknearesttheFstarrisesto~1100K(Stencelet al.2011;Hoardet al.2012).Thisequilibriumtemperaturefordustparticles,withlowalbedo(0.3tozero),impliesaseparationfromthe7500KF0starof9to12AU.Foradiskradiusof4to5AU(seeKloppenborg2010),theimpliedbinaryseparationis13to17AU,whichismoreconsistentwiththeq=0.5solution.Thesumofmassesinthiscaserangesfrom3to7M

Ä.

However,adistanceof1kpcdistance,forexample,requiresawiderseparation(25AU)toyieldthesamedisktemperature,inaq=1binarywherethesumofmasseswouldbe25M

Ä.


In terms of resolving the ambiguity in distance and masses, twodevelopmentsdeservemention.DissertationworkbyBrianKloppenborg,attheUniversityofDenverat the timeof thiswriting,combinedastrometric,spectroscopic, and interferometric constraints on the orbit absolutedimensions. This resulted in a solution that places the system at 737±67pc, with a separation of 25AU and masses of M=13 and m=11M

Ä.The

interferometricallyconstraineddiskdiameterof7.31±0.66AUreferstotheoptically thickest portions and hence a minimum disk size, relative to thelargersizesimpliedbyspectroscopicconstraints. Whatotherconstraintsarepossibleonthemass(m)ofthesecondarystar?Diskrotationcurvesmaybeobtainedfromtheopticallythinneutralpotassiumlinesat7699Å(LambertandSawyer1986;Leadbeateret al.2012),seenonlyduringeclipsephases,andarguablyarisingfromextremeouterportionsofthedisk.Theirmeasureddiskrotationspeedis~35±–5km/sec.Rotationcurvesfromopticallythickermetalliclines(forexample,TiII4028Å)indicatethediskrotationspeedis42±–2km/sec(Saitoet al.1987).Then,withadiskradiusvalue,wecandetermineaKeplerianrotationperiodatthesespeeds.InterferometricimageswerefittedbyKloppenborg(2010)witha3.8AUellipticalsemi-majoraxis, assuming a 625pc distance. Said rotation speeds (35,42km/sec) haveimplied circumferential rotation rates of 3.25 and 2.70 years, respectively,implying a central mass of 5.2 to 7.5 M

Ä. Saito et al. (1987), using eclipse

timing arguments, deduced that m < 5.3 MÄ

, whereas Lambert and Sawyer(1986)deducedm=3to6M

Ä fromtheirneutralpotassiumlinevelocityas

ameasureofdisk rotation.These resultsstronglysuggest thesecondarystarmass,m,iscloseto4to6M

Ä,comparabletothatofamainsequence,B-type

star.However,withalargerdistance(737pc)andusinganopticallythindiskradius(10AU),theseorbitalspeedsareconsistentwithalargersecondarymass(m=11M

Ä).

Another constraint on the mass of the secondary can be inferred fromobserved disk dust and gas scale heights. As shown by VEGA+CHARAobservations (Mourardet al.2012), theeclipse inHa is total incomparisonto the partial eclipse seen in the near-IR with the Michigan InfraRed beamCombiner(MIRC)atCHARA—thatis,thehydrogengasextendsatleastafullFstardiameteraboveandbelowthediskplane.Forstrictlythermaldispersionofmaterial,thescaleheight(H)todiskradius(RD)ratioequalsthesoundspeed-to-orbitalvelocityratio,whichis:

[H/RD] = [(γkT / m)/(Gm/RD)]1/2 (1)

(seeLissaueret al. 1996), where γ is the ratio of specific heats (5/3 for ideal gases),mistheatomicmass,andmisthecentralstarmass.TablesandFiguresinLissaueret al.illustratethattheobservedthicknessisseveraltimesthescaleheight.TheobservedratiooftheminimumVEGA-observedthicknessofgas


disk(2.1milli-arcsec,mas)relativetotheestimatedopticallythickdiskradius(8.92mas–Kloppenborg2012),is0.24,suggestingascaleheighttodiskradiusratioof0.12to0.08.FortheHipparcosreferencedistanceof650pc,theimpliedopticallythickdiskradiusis5.8AU.Giventherangeofdisktemperatures,550to1100K,thethermalspeedofhydrogenatomsrangesfrom2.8to3.9km/sec,andwededucethequantity(Gm/R)1/2tobelessthanorequalto35km/sec,orimplyingagainthatthesecondarystarmass,m,islessthanorequalto10.7M

Ä.

Forthelargerdistanceestimate,1kpc,theimplieddiskradiusbecomes8.9AUandthedisktemperaturesresultinamaximummassof16.5M

Ä.Intheabsence

ofdynamicalstirring,thesemassesareanupperlimit,asthedisk’shydrogenatmosphere could be thicker. Higher gas temperatures and/or a thicker diskscaleheightbothpoint to a lower secondarymass. If theoptically thindiskradiusislargerthanimpliedbythephotometriceclipseduration,theresultantmasscouldbelarger. Arethereanyadditionaldistance-independentdiscriminators?OnemightbetheEddingtonlimitonluminosity,whichisclassicallycomputedtobe:

LEdd/LÄ=3.8×104M/M

Ä. (2)

Forthetwosolutionsoffered,m=3to4andm=15to25MÄ

,therespectiveEddingtonluminositiesare1.1–1.5×105L

Äversus5-9.5×105L

Ä.Bothranges

exceed the upper estimates for L/LÄ

. Other distance-independent means ofestablishingbinarystarparametersareneeded.

3.1.Natureofthedisk Kloppenborget al.(2010)estimatedthatthedisk-fittedsemi-majoraxisis6.10mas,meaningthefullmajoraxisis12.2mas,or~5.8timesFstardiameter(2.1mas).Giventhereported0.62masE-Wmotionpermonthduringingress(plusaN-Scomponent0.34mas/month,foranetmotionof0.72mas/month),anda2.1masuniformdiskdiameterstar,itshouldtake~2.9monthsforagivenpointinthedisktomoveacrosstheFstardisk,assuminguniformmotion,and~18monthstohavetheentirediskmovepast,whichisclosetotheobservedfirsttothirdcontacteclipseduration.Theellipsemodeldevisedduringingresswas poorly constrained, dictated mainly by the expected length of eclipse.Afterwards,weobtainedthecompletelightcurve(Figure5)andthefirst tofourthcontact lengthindaysisoforderRJD5800–5060=740days,or~24months,and largerstill inspectroscopic terms,suggesting thedisk is largerthanoriginallyestimatedand/or therelativevelocitiesarevarying(slowing,post-periastron). Evidenceexiststhatthediskisstructuredandasymmetric.Therehasbeenoutstanding spectroscopic monitoring of Ha by Mauclaire et al. (2012) andofKI7699ÅbyLeadbeateret al.(2012)andbluespectroscopicfeaturesbyGriffinandStencel(2012),reportedinthisissueandelsewhere,indicatingan


extended,asymmetricspectroscopicsignatureofthedisk.TheHaequivalentwidthchangesversustimesuggestacompactringmaycontributetolatephasesofingress(RJD55150–55250),whilethediskmainbodyisseenduringtotality(withapossiblemid-eclipsedeclinecircaRJD55450,perhapsduetoionizationrelatedtotheappearanceofHeI10830Å(Stencelet al.2011)).Amorediffusefollowingringassociateswithegress,butlastingpastnominalfourthcontact(RJD55800)withexcessHaabsorptionstillpresentinearly2012,agood150dayspastfourthcontact.Similarly,theneutralpotassiummonitoringhasbeeninterpretedtoshowstepwisechangesinequivalentwidthrelatedtointernalringstructure(LeadbeaterandStencel2010).ThesewerelabeledasringsAthroughF.RingsDandEmightcontributetothelateingressHabehavior,whileringsD-A associate with egress phenomena.As reported elsewhere, however, therelationshipbetweenthedustandgascomponentsisonlyjustbeingrevealedbyspectro-interferometryobtainedwiththeVEGAinstrumentattheCHARAArray(Mourardet al.2012). AdditionalsuggestionsofanionizingphotoninducedshockintheingresssideofthediskhasbeenmadebySaitoet al.(1987).Similarly,amattertransferstreamimpactingtheegresssideofthediskhadbeenadvancedbyStruveandcolleaguesearlyon,andsomethingtothiseffectwasseenagaininblueregionspectra reported by Griffin and Stencel (2012). Finally, the out-of-eclipsephotometricvariationsareconsistentwithsurfacephenomena-drivenmasslossepisodesfromtheFstarthatcontributetoastellarwind,asymmetricallyshapedtoward thecenterofmassand ionizedbyUV light scatteredaway from thesourceinternaltothedisk(Figure6).

3.2.Dustscattering Thecompositionof thedisk isof interestbecausedeterminingdust sizewould provide evidence for the age of the object and the degree to whichplanetessimal formationmay have occurred in the disk. Kopal (1954) notedthewavelength-independenceofeclipsedepthsandconcludedthatlargegrainsmustbepresentwithmulti-micronsizes,muchgreaterthanopticalwavelengths.However,observationstodatehavenotdetectedanytypicalspectroscopicbandsdue tosolids,suchas ice(3microns),PAHs,or10-micronsilicates(Stencelet al.2011).Anestimatefordiskmasscanbemade,basedonthefarIR/sub-mmfluxesreportedbyHoardet al.(2012):

M(dust)=Fnl2d2/(2kTdustkn) (3)

whereFn(250microns)=57mJy=3×10–22W/cm2/micron.Using650pcasthe distance, a dust temperature of 550K and a mass absorption coefficient,kn=3cm2/gm (Juraet al. 2001),wededuce a dustmassof 1.2×1031 gmor

nearly6Jupitermasses.Thisseemstoolargeifthegastodustratiois~100,because the disk mass would be dynamically significant in the system.


Disk volume (Kloppenborg et al. 2010) and deduced densities (Hinkle andSimon1987)argueforalowerdustmass,roughlyanEarth-mass.Dustopacitybasedonsub-mmdiskstudiessuggeststhatmassabsorptioncoefficientsarenotwelldetermined.FurtherworkisneededtobettercharacterizethematerialintheeAurigaedisk(seePearsonandStencel2012). Another avenue for exploring the disk content involves polarimetry.BroadbandpolarimetricstudieshavebeenreportedbyKempet al.(1986)andbyCole (2012).These showanoutofeclipsebaselinevalue inphotometricVbandof2.0percent,presumed tobe interstellar,butgrowingandvaryingduringeclipseto2.4percent.ThesubstructureofV-bandpolarizationduringeclipsedoesnotsimplycorrelatewithphotometricchanges.Kempet al.(1986)correctlydeducedthepositionangleoftheeclipsingdiskdecadespriortotheinterferometricimagingofit.Recently,linepolarizationmonitoringhasbecomepossible,greatlyincreasinginsightintodiskandstarphenomena,andgreatlycomplicatingtheanalysis(seeGeiseet al.2012). Onemore lineofevidence tobeexplored involvesadifferencebetweeneclipsebehavioramongredwavelengthlineslikeHaandKI7699Å,andbluewavelengthlineslikeFeI3920Åandothers.Theformershowequivalentwidthvariation due to the eclipse, but remain substantially enhanced around mid-eclipse,whilethebluerlineshaveequivalentwidthexcessthatnearlyvanishesatmid-eclipseandthenreturnsstronglyduringlateeclipse.Thisistosaythatthelinedepthchangesarelessintheblueregionscomparedtotheredregions,suggestiveofparticlesizesdominatedbythegreater-than-micronscale.

4. Archives

Table1listsobservationsthatthisauthorproposedandconducted,manyof which will appear in public data archives maintained by the institutionsinvolved.TheAAVSOprovidesacomprehensivephotometryarchive.Thereareanumberofspectroscopicdatasourcesthatmightnotbefullyreflectedinthisreport,butwellworththemention.InadditiontothecarefuldigitizationbyElizabethGriffinofMt.WilsonandDAOphotographicspectra(plusnewdigitalobservations),additionalmodernhighdispersiondigitalspectrawereobtainedregularly during eclipse by Hideyuki Izumiura at Okayama Observatory, byWilliamKetzebackandcollaboratorsatApachePointObservatory(seeBarentineet al. 2012),byNadineManset andcollaborators atCFHT (seeGeiseet al.2012),byJohnMartinattheUniversityofIllinois,Springfield,Observatory,byNancyMorrisonattheUniversityofToledoRitterObservatory,byUlisseMunari and collaborators atAsiago Observatory, by Klaus Strassmeier andcollaborators (Astronomical InstituteatPotsdam)STELLA telescopeat IAC(seeSchanneet al.2012),andseveralothers.Ideally,thesedataarchivescanbemaintainedbytheiroriginatorsandmadeavailabletointerestedresearchers.Thisauthorwouldbehappytotrytohelpcoordinateanalysisefforts.


5. Conclusions

ClarificationofthenatureoftheeclipsingobjectineAurwillstandasoneofthemajorachievementsofthiseclipsecycle.WhiletheeclipsehasbroughtattentiontothestudyofeAuranditsmysteries,wenowhaveenteredthelonginter-eclipseperiod,prior to the startof thenexteclipsecirca2036.Currentorbitalelements(Stefaniket al.2010)predictkeytimesthatshouldbeofinteresttoobservers:theFstarreachesmaximumblueshiftcircaautumn2017(anditreachedmaximumredshiftduringautumn2006).EclipseofthediskbytheFstar is anticipatedduring2020and this shouldbedetectable in the infrared,insofarastheobservationalcapabilityexiststhen.Thereismeritinphotometricmonitoringofout-of-eclipsebehavior,althoughthecharacteristicbehavior(67-dayquasi-periodplusovertonesandevolution)seemsestablished(forexample,Kim(2008)andKloppenborg(2012)).TheAAVSO’sphotometricdataarchive(www.aavso.org) provides an excellent resource. Nonetheless, with robotictelescopesanddedicatedpersons,theslowchangesinthissystemcanyetbefollowedduringthisnewestorbitalcycle.

6. Acknowledgements

Therearemany,manypeopletothankforhelpinthisoveralleffort,makingcoverageoftherecenteclipsethemostcompleteinhumanhistory.WithoutJeffHopkins’andLouBoyd’sdedicationtolongtermphotometry,wewouldhaveamuchsparserdataset.MythankstoHalMcAlisterforacceptingmyproposalstousetheCHARAArrayforinterferometricstudyoftheeclipse,andtoJohnMonnierforaccess to theMIRCinstrument thatmade the imagingpossible.ManyfacetsoftheworkpresentedherewerefacilitatedbyBrianKloppenborgandhisamazingcomputerskills.IamgratefultoAaronPrice,RebeccaTurner,andArne Henden atAAVSO for their efforts with the Citizen Sky observercampaignthatenrichedthedataarchiveswiththousandsofnewmeasures,allcarefully archived. Additional spectroscopic monitoring was contributed byRobinLeadbeater,ThierryGarrel,ChristianBuil,ElizabethGriffin,andmanyothers. Key collaborators on HST COS and Spitzer/IRAC data acquisitionincludedSteveHowellandDonaldHoard,withexcellentadvicereceivedfromCOSteammembersStephaneBeland,JimGreen,StevenPenton,andothers.Collaborators obtaining and reducing Gemini North GNIRS data were TomGeballeandRachelMason.Helpfulcommentsonthispaperfromananonymousrefereeareappreciated.MyparticipationwassupportedinpartbythebequestofWilliamHerschelWombleinsupportofAstronomyattheUniversityofDenver,forwhichIamextremelygrateful(astheprojectwouldnothavebeenpossibleotherwise),alongwithanNSF-RAPIDgrant,AST10-16678,totheUniversityofDenver,organizedbytheprescientprogramdirectorDonaldTerndrup,whodeservespublicthanksforrecognizingthesingularopportunityaffordedbyeAur.


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55084 2009Sep10 IRTF/SpeX 1–5-micronmed-resspectra55139 2009Nov2–4 CHARA+MIRC 1.6-microninterferometricimaging55140 2009Nov3 IRTF/SpeX 1–5-micronmed-resspectra55169 2009Dec2–4 CHARA+MIRC 1.6-microninterferometricimaging55197 2010Jan1 MMTO/MIRAC 10-micronphotometry/spectra55245 2010Feb18 CHARA+MIRC 1.6-microninterferometricimaging55250 2010Feb23 IRTF/SpeX 1–5-micronmed-resspectra55428 2010Aug19–21 CHARA+MIRC 1.6-microninterferometricimaging55432 2010Aug24 IRTF/SpeX 1–5-micronmed-resspectra55441 2010Sep1 HST/COS far-UVspectra55462 2010Sep22–23 CHARA+MIRC 1.6-microninterferometricimaging55467 2010Sep27 IRTF/SpeX 1–5-micronmed-resspectra55494 2010Oct24 MMTO/CLIO JHKLMphotometry55495 2010Oct25–26 CHARA+MIRC 1.6-microninterferometricimaging55499 2010Oct29 IRTF/SpeX 1–5-micronmed-resspectra55500 2010Oct29 Spitzer/IRAC 3.6and4.6-micronphotometry55513 2010Nov12 IRTF/SpeX 1–5-micronmed-resspectra55523 2010Nov22 Spitzer/IRAC 3.6and4.6-micronphotometry55537 2010Dec6 IRTF/SpeX 1–5-micronmed-resspectra55540 2010Dec9–10 CHARA+MIRC 1.6-microninterferometricimaging55540 2010Dec9 HST/COS 2ndfar-UVspectrum55553 2010Dec22 MMTO/MIRAC 10-micronphotometry/spectra55559 2010Dec28/9 GNIRSSV 2.3-micronhigh-resCOspectra55565 2011Jan04 GeminiN+GNIRS 2.3-micronhigh-resspectra55567 2011Jan06 IRTF/SpeX 1–5-micronmed-resspectra55582 2011Jan19 CHARA+MIRC4T 1.6-microninterferometricimaging55567 2011Mar3/4 IRTF+SpeX attempt,1–5-micronmed-resspectra55637 2011Mar17 HST+COS 1150–1800Åspectra(3rdepoch)55637 2011Mar17/18 CHARA+CLIMB 3Tinterferometry55649 2011Mar29 IRTF+SpeX JTR,1–5-micronmed-resspectra

Table1.SelectednewobservationsofeAurduringeclipse,2009–2011. RJD* Calendar Date Telescope Mode

Table continued on next page


55650 2011Mar30 GeminiN+GNIRS 2.3-micronhigh-resspectra55651 2011Apr1–5 CHARA+CLIMB 3Tinterferometry55663 2011Apr12 IRAC 3.5and4.5-micronphotometry55663 2011Apr12 GeminiN+GNIRS 2.3-micronhigh-resspectra55663 2011Apr12 Spitzer/IRAC 3.6and4.6-micronphotometry55678 2011Apr25 IRTF+MIRSI 10-micronphotometry55680 2011Apr29 Spitzer/IRAC 3.6and4.6-micronphotometry55814 2011Sep10 HSO–PACS 70,110,160-micronphotometry55824 2011Sep18 CHARA+MIRC6T 1.6-microninterferometricimaging55826 2011Sep21 HSO–SPIRE 250,350,500-micronphotometry55830 2011Sep24 CHARA+MIRC6T 1.6-microninterferometricimaging55830 2011Sep24 IRTF+SpeX 1–5-micronmed-resspectra55846 2011Oct10 CHARA+MIRC6T 1.6-microninterferometricimaging55869 2011Nov03 CHARA+MIRC6T 1.6-microninterferometricimaging55871 2011Nov05 MMT+MIRAC4 cloudedout55884 2011Nov17 Spitzer/IRAC 3.6and4.6-micronphotometry55894 2011Nov27 IRTF+SpeX 1–5-micronmed-resspectra55899 2011Dec02 Spitzer/IRAC 3.6and4.6-micronphotometry55913 2011Dec16 CHARA+MIRC cloudedout55915 2011Dec18 IRTF+SpeX 1–5-micronmed-resspectra*RJD = JD– 2400000.

Table1.SelectednewobservationsofeAurduringeclipse,2009–2011,cont. RJD1 Calendar Date Telescope2 Mode

Figure1.Historicfirst:the1.6-micronwavelengthimageofeAur2009November2asinitiallyprocessedbyJohnMonnier,basedonfourtelescopebeamcombinationdataacquiredbyMIRCattheCHARAArray,andshowingtheshadowofthediskcrossingthefaceofeAur.Thescalesareinmilli-arcsecondunits.Image courtesy of John Monnier, Univ. Michigan.


Figure2a.AportionoftheGeminiNorthGNIRSspectrumofeAurspanningthe12CO(2-0)bandheadat4360cm-1region(2.293microns)showingspectrallinesof12CO(2-0up)and12CO(2-0down), illustratingtheGNIRSresolutioncapable of separating these contributions. The lines show a –25 km/secsystematicblueshift,characteristicofthediskatthisepoch.

Figure2b.AportionoftheGeminiNorthGNIRSspectrumofeAurspanningthe13CO(2-0)bandheadat4265cm-1region(2.344microns)showingspectrallinepositionsof13CO(2-0),12CO(2-0),12CO(3-1)linesandhydrogenPfundlines.RedshiftedPfundlineabsorptionmayaccountforsome,orall,ofthepreviouslyreported13CObandheadnear2.345microns.

Figure3.TimeseriesofIRTF+SpeXdatashowingmid-eclipseappearanceofHe10830Å.


Figure4a.HST/COSspectraofeAur.ThestrongUVMgIIdoubletat1240Å(1239.925, 1240.395) but lack of N V (1238.821, 1242.804). The line near1243.3couldbeNI.

Figure4b.CIIprofilesshowingclearPCygnioutflow,unaffectedbyeclipsephase.


Figure5.Vmagnituderecordofthe2009–2011eclipseofeAurasrecordedbyavarietyofobservers.SeeStencelet al.(2011)fordetails.

Figure 6. Schematic model of eAur that incorporates F star wind focusingand ionizationeffectsdue toscatteringofUVphotonsoriginating inside thedarkdisk.Thismodelaccountsformanyofthenewlyobservedspectroscopicand radial velocity details reported here and in related papers, and providespredictionsforadvancedhigh-resolutionimaginginthefuture.

Hopkins, JAAVSO Volume 40, 2012 633

The International e Aurigae Campaign 2009 Photometry Report

Jeffrey L. HopkinsHopkins Phoenix Observatory, 7812 West Clayton Drive, Phoenix, AZ 85033; [email protected]

Received February 23, 2012; revised April 25, 2012, and June 29, 2012; accepted July 3, 2012

Abstract An International Campaign and Web site were started in Mayof 2006 for the 2009–2011 eclipse of the mysterious star systemeAurigae.Photometric and spectroscopic observations of the eclipse were coordinatedandreported.Theeclipsestarted in thesummerof2009and lasteduntil thespringof2011.Duringthecampaigntwenty-fournewsletterswerepublishedon theweb site andmadeavailable free as .pdf files to read anddownload.Twenty-sixobserversfromfourteendifferentcountriessubmittedphotometricdata in theUBVRIbands.Over3,600high-qualityphotometricobservationsweresubmittedwithnearly2,000observationsinjusttheVband.ThispaperdiscussestheCampaignandreporttheresults.

1. Introduction

Priortotheeclipse,datafrompreviouseclipsesandfrombetweeneclipseswereconsolidated in the formofabook (seeHopkinsandStencel2008).Apaperwasgiven at theSociety forAstronomicalSciences2010Symposiumthatdiscussedtheingressofthelatesteclipse(Hopkinset al.2010).Mostofthephotometricdataforthe2009–2011eclipsewereobtainedintheVband.Thelargestphotometricchangeswereintheintheshorterwavelengths,however.TheUband,whichwasonlyobservedwiththePMT-basedsystems,providedthelargestchanges. Some people thought that during the late spring and early summer thestarsystemwentbehindtheSunandwasnotobservable.Thisisnottrue.ThedeclinationofthestarsystemishighabovetheplaneofthesolarsystemanditnevergoesbehindtheSun.Theproblemisthatatlowerlatitudesitgetsveryclose to thehorizonduring thedarkhoursand thus the lightpasses throughvery high air mass. Extinction becomes a very significant problem. Thoseobserversathigherlatitudescouldobservethesystematlowerairmasses,butasonegoesfarthernorththenumberofdarkhoursdecreasestothepointofthemidnightSun.Someof thehigher-latitudeobserversdidheroicworkduringthesepoorobserving times.Even then thedataaresomewhatconfusingandnoisy.Themid-eclipsebrighteningperiodwasatoneofthesepoortimes.Somedataindicatethebrighteningandsomeindicatenobrightening.Also,midway

Hopkins, JAAVSO Volume 40, 2012634

duringegresswasapoor timeandsomething interestinghappened then too.Thereseemstobeaknee in theegressphotometricplots.Perhapsmoreandbetterdataduringthesetimescanbeobtainedduringthenexteclipsein2036. A Campaign was formed during the 1982–1984 eclipse and thirteennewsletters published. The current Campaign’s web site has some of thesenewslettersavailableonline.Forthe2009–2011eclipsethereweretwenty-fournewsletters published by the Hopkins Phoenix Observatory.All of these areavailableas .pdfsontheCampaignwebsitealongwithagreatdealofotherpertinentdataoneAur.Inadditiontothe2009Campaign’swebsiteathttp://www.hposoft.com/Campaign09.html, a Campaign Yahoo forum was startedandcanbeaccessedat:http://tech.groups.yahoo.com/EpsilonAurigae/

2. Observations summary

AsofDecember26,2011,wehadnearly3,700totalobservationsreportedduring the eclipse, with the visual band having by far the most at nearly2,000observations.Twenty-sixobservers fromaround theworldcontributedobservationaldata.Table1isasummaryoftheobserverscontributions.

3. Data quality

eAurisbrightenoughtobevisuallyseeneasilyeveninmostlightpollutedareas.Onecanevennoticethedimmingoftheeclipsevisually.Whiletheuseofvisualobservationsforplottingchangesinthebrightnessofstarsworkswellwithsomestars,theeclipseofeAurwasnotagoodprojectforvisualwork.Tobeofvaluemagnitudesestimatesmustbeofaresolutionof0.05magnitudeor better. This is an order of magnitude less than what even experiencedvisualobserverscanproduceunderthebestofconditions.ForthisreasontheInternationalCampaigndidnotuseanyvisualmagnitudeestimates. Photometricdatasubmittedtothecampaignhadaveragestandarddeviationsforthreeormoredatapointsofmagnitude0.01.Manyobservationsapproachedastandarddeviationofmagnitude0.001.Thestandarddeviationisusedasanindicationofthequalityofthedatabyrepresentingadataspreadofthreeormore data points.The photometric plots do not have error bars because thestandard deviations, which would be used for the error bars, are too smallinrelation to theplotscale.Mostsubmitteddatahavebeentransformedandcorrectedfornightlyextinction.TheHopkinsPhoenixObservatory(HPO)usedahigh-precisionUBV1P21-basedphotoncountingsystem.AllHPOdataweredeadtimecorrected,transformationcoefficientsdeterminedforeachband,andnightlyextinctioncoefficientsdeterminedforeachband.DatareductionwasdoneusingtheHardieequations.MagnitudesweredeterminedforbothlAurandeAurandthendifferentialcalculationsdoneandnormalizedtothestandardvaluesforlAur’smagnitudes.Nightlysessionsconsistedofthreecomparison


starmeasurementsineachband,threeadjacentskymeasurementsineachband,followedbythesameroutinefortheprogramstar.Therewerethreesetsofthesemeasurementsmadewiththeprogramstarbracketedbythecomparisonstar.Thedatawerealltransformedandextinctioncorrected.Threemagnitudesweredeterminedforeachband,astandarddeviationcalculated,andthemagnitudeaverageforeachbandreportedtofourplaces. TherehasbeensomeconcernabouttheUandBmagnitudesfromtheHopkinsPhoenixObservatory.First,therearenostandardUandBmagnitudesforeAur.Thestarsystemvariessignificantlyandrandomlyout-of-eclipse.ThevariationisgreatestintheUandBbands.Ifoneweretosuggestout-of-eclipsemagnitudes then theaverageofseveralseasonsofout-of-eclipsemagnitudescouldbe specified,but awarningwouldbeneeded indicating that these areaverages.Fromdata takenout-of-eclipsebetweenMarch1986andFebruary2008,thefollowingaremaximum,minimum,andaveragemagnitudesfortheUBVbands:

Vavg=3.04 Vmin=3.16 Vmax=2.94 Bavg=3.61 Bmin=3.53 Bmax=3.69 Uavg=3.73 Umin=3.60 Umax=3.92

Oneofthegreatthingsaboutacampaignlikethisisthatonegetsachancetocomparetheirphotometricdatatakenatapproximatelythesametimeagainstothers.Photometriclightcurvesforthecampaignwereupdatedandpublishedonthewebaroundonceamonth.Observerscouldidentifytheirdataandseehowwelltheycomparedtoothers.Noisydataareobvious.Iftheobserverwasinterested, he or she could investigate the differences and improvements intechniqueanddatareduction.

4. Comparison star

ThereareavastnumberofobservationsofeAurcoveringmanydecadesthatuselAurasacomparisonstar.BecauseduringthistimelAurhasbeenfoundtobeverystableoverseveraldecades,nocheckstarisneeded.TheUBVmagnitudesarethoseusedintheprevioustwoeclipses.ThelongerwavelengthmagnitudeswereobtainedfromtheAAVSO. Thedatausedforthecomparisonstarare:

Comparisonstar: lAurOtheridentification: SAO40233,HR1729,HD34411Position: R.A.(2000)05h19m08.4s,Dec.(2000)+40°05'57"Magnitudes: U=5.46,B=5.34,V=4.71,Ij=3.88,Ic=4.00,Rj=4.19, Rc=4.30,J=3.62,H=3.33


5. Equipment

Therewerefourtypesofinstrumentationusedtoacquiredataforthe2009Campaign:DigitalSingleLensReflex(DSLR)cameras,CCDcameras,PinDiode photometers (SSP-3 and SSP-4), and photon counting photometers(PMT-based). The photon counting provided highest quality UBV datafollowedbytheSSP-3forBVdata.ObtainingCCDdatawasmoredifficultas thebrightnesscausedproblems.CCDprovidedBVRIdata.Thelastandnewest equipment for photometry were the DSLR cameras. The DSLRprovidedV-banddatabyusingthegreenchanneloftheRGBimages.WiththeexceptionofacoupleDSLRobserversthedatasubmittedwereverynoisy.However,DSLRcamerasofferanexcellentintroductiontophotometry.OnceanobserverisconfidentwithdoingphotometrywithaDSLR,anentrylevelmonochromeCCDcamerawithBVRIphotometric filterswouldbeagreatwaytostartdoingprofessionalphotometry.

6. Results

6.1.HopkinsPhoenixObservatorydata The Hopkins Phoenix Observatory data were taken with a high-precision UBV photon counting system.All data were transformed, deadtimecorrected,andnightlyextinctiondeterminedandcorrected.Detailsofthe photometric work at the Hopkins Phoenix Observatory is reported inHopkinset al.(2007). When out-of-eclipse the star system has presented tantalizing data(Figure 1).The light is not constant, but varies at a pseudo-periodic rate inall thephotometricbands.Theperiod isnot stable,andvariesunpredictablybetween50and70days.Inadditiontotheperiodvariationstheamplitudesvaryunpredictably.Periodanalysiswasdoneusingperansoperiodanalysissoftware(Vanmunster2007),butnoperiodcouldbedetermined.DetailsofthisworkarereportedinHopkinsandStencel(2007)andHopkinset al.(2008). While not photometry, in an attempt to shed light on the out-of-eclipsevariations high-resolution out-of-eclipse spectroscopy of the star system’sHa region was done at Hopkins Phoenix. The main Ha absorption line isbracketedbyemissionlines(horns)thatgoupanddown,sometimestogetherandsometimescompletelyindependently(seeFigure2).Theysometimesreacha large peak and at other times disappear completely. This is known as the“HydrogenAlphaHornDance.”Noconnectionwas foundbetween theout-of eclipse Ha spectroscopic variations and the out-of-eclipse photometricvariations.Theemissionhornsdidseemtodecreaseandevengoawayforawhile during the eclipse, however. Details of the spectroscopic observationsatHopkinsPhoenixObservatoryarereportedinHopkinsandStencel(2009a,2009b)andHopkins(2012).


6.2.Campaigndata HighdataproducersfortheeAurcampaignwereasfollows:

DSLR:DesLoughney,Edinburgh,Scotland—238V-bandobservations.CCD:GerardSamolyk,Greenfield,Wisconsin—721BVRcIcobservations.SSP:PaulJ.Beckmann,JimBeckmannObservatory,MendotaHeights, Minnesota—89BVRjIjobservations;Photoncounting:JeffHopkins,HopkinsPhoenixObservatory,Phoenix, Arizona—565UBVobservations.

Observation techniques varied among observers. Details of each observerare presented on the 2009 Campaign’s web site at http://www.hposoft.com/Campaign09.html.

6.3.Campaignlightcurves SeeFigures3through7.UBVRIJHphotometricdatafrom1982to2012arearchivedandavailableinmultipleformatsathttp://www.hposoft.com/Eaur09/Data/UBVRIJHData.html.

7. Analysis

Therehasbeensomeconcernexpressedbyarmchairphotometristsaboutthecontact times.Thefollowingmayhelpunderstandthecomplexityofthissystemandthemethodologyusedtodeterminethecontactpoints. TheeAurstarsystemisverydifferentfrommosteclipsingbinarysystems.Fortheanalysisofthecontactpointstheclassicalmethodwasused.Inadditiontothenon-classicaleclipsingbody,complicatingtheanalysisarethepseudo-periodicout-of-eclipse(OOE)variations(seeFigure8). Figure9showstheprocedurefordeterminingthecurrenteclipsecontactpoints.Theaverageingressandegressslopeswereusedtofindtheintersectionwiththeaveragetotalityandout-of-eclipsemagnitudes. An archive of UBVRIJH photometric data is available to the public at http://www.hposoft.com/EAur09/Photometry.html and http://www.hposoft.com/EAur09/Data/UBVRIJHData.html. A summary of the data is given in Table 2.

8. Predictions for the 2036–2038 eclipse

While I am unlikely to be around for the next eclipse in 2036 it is stillinterestingtoofferphotometricpredictionsaboutit.OnlytheV-bandcontactpointsareincluded.Thereisstillcontroversyaboutthesecondandthirdcontactpoints.Thesedateswerecalculatedbyadding9,898daystothefirstcontact,mid-eclipse,andfourthcontactofthe2009–2011contacttimes.


TheV-bandpredictionsare:

firstcontact:JD2464964±12days,September27,2036;mid-eclipse:JD2465283±9.5days,August12,2037;fourthcontact:JD2465601±7days,June26,2038.

9. Conclusion

EacheclipseofeAurseesanewbreedofequipmentandobservers.Whilemorewaslearnedfromthislatesteclipse,thestarsystemisnotgivingupitssecretseasily.Itseemstobetauntingus.Duringsomeofthemostinterestingtimes,thesystemwasextremelydifficulttoobserve.Theeclipsemaybeoverforanothertwenty-sevenyears,butthestarsystemstillpresentssomeinterestingchallenges. Monitoring and understanding the out-of-eclipse variationswillbeamajorobjective.This is followedby thestrangeHahorndance.Acontinuedfollowingofthestarsystemwithbothphotometricandspectroscopicobservationsissuggested.Thismayprovidesomeadditionalinsightsintothesemysteries.Oneofthenicethingsaboutobservingout-of-eclipseisthetimesofhighairmasscanusuallybeavoided.Observingcanbedoneduringfavorabletimes,suchasintheearlyfall,duringwinter,andinearlyspring.Asindicatedearlier, the most active regions for photometry are the shorter wavelengths.Uband is a especially important band in which to make observations. Thesystemalsooffers excellent spectroscopic learning for thehydrogenBalmerlinesaswellasthesodiumDlines.

10. Acknowledgements

I would like to thank all the observers who contributed data to theCampaign. Inparticular Iwant to thankDr.RobertStencel (“Dr.Bob”)andBrianKloppenborgfor theirhelp,encouragement,and thehonorofworkingwiththembothwiththeCampaignandespeciallywiththeobservingsessionsatCHARAonMountWilsoninCalifornia,andtheMMTonMountHopkinsinsouthernArizona.Thosearetreasuredexperiencesandmemories.

References

Hopkins, J. L. 2012, Small Telescope Astronomical Spectroscopy, HopkinsPhoenixObservatory,Phoenix,AZ.

Hopkins, J. L., Schanne, L., and Stencel R. E. 2008, in The Society for Astronomical Sciences 27th Annual Symposium on Telescope Science,SocietyforAstronomicalSciences,RanchoCucamonga,CA,67.

Hopkins,J.L.,andStencel,R.E.2007,inThe Society for Astronomical Sciences 26th Annual Symposium on Telescope Science,Society forAstronomicalSciences,RanchoCucamonga,CA,37.


Hopkins, J., and Stencel, R. E. 2008, Epsilon Aurigae: A Mysterious Star System,HopkinsPhoenixObservatory,Phoenix,AZ.

Hopkins,J.L.,andStencel,R.E.2009a,eAurigaeHydrogen-aEmissionLineVariations:TheHornDance,J. Amer. Assoc. Variable Star Obs.,37,213.

Hopkins,J.L.,andStencelR.E.2009b,inTheSociety for Astronomical Sciences 28th Annual Symposium on Telescope Science,Society forAstronomicalSciences,RanchoCucamonga,CA,157.

Hopkins,J.L.,et al.2010,inThe Society for Astronomical Sciences 29th Annual Symposium on Telescope Science, Society for Astronomical Sciences,RanchoCucamonga,CA,13.

Vanmunster,T.2007,peransoperiodanalysissoftware,http://www.peranso.com.

CH 143 — — — — — — 143 DSLR CO 3 — — — — — — 3 CCD CQJ 100 100 — — — 95 — 295 CCD DES 242 — — — — — — 238 DSLR EAO 68 — — — — — — 68 CCD EGO 81 — — — — — — 81 DSLR EUO 1 39 9 — 40 — — 89 PMT FJM 65 — — — — — — 65 SSP-3 GHO 165 — — — — 160 — 325 CCD GO 22 — — 20 — — — 42 CCD GS 179 178 — 183 — 181 — 721 CCD GVO 13 8 — — 13 — 13 47 SSP-3 HPO 147 209 209 — — — — 565 PMT JBO 16 41 — — 16 — 16 89 SSP-3 JESO 34 — — — — — — 34 CCD KO 111 — — — — — — 111 CCD LO 87 — — — — — — 87 SSP-3 MSO 3 3 — — — — — 6 CCD NKO 38 — — — — — — 38 DSLR NPO — — — — 18 — 18 36 SSP-3 RES 56 — — — — — — 56 DSLR RLO 29 — — — — — — 29 DSLR SGGO 67 17 — 59 — — — 143 CCD TP 86 — — — — — — 86 DSLR VO 193 — — — — — — 193 DSLR WWC 50 42 — — — — — 92 DSLR

Total 1999 637 218 262 87 436 47 3686

Table1.2009eAurcampaignphotometricobservercount.

Observer1 V B U Rc Rj Ic Ij Total Equipment2



Table1.2009eAurcampaignphotometricobservercount,cont.1 Observers (AAVSO observer initials are given in parentheses): CH (HEN), Colin Henshaw, Tabuk, Saudi ArabiaCO (OSC), Steve Orlando, Custer Observatory, East Northport, NYCQJ (CQJ), John Centala, Eastern IowaDES (LDS), Des Loughney, Edinburgh, Scotland, UKEAO (SIAK), Iakovos Marios Strikis, Elizabeth Observatory of Athens, Haldrf (Athens), GreeceEGO, Charles Hofferber, East Greenwood Observatory, East Grand Forks, MNEUO, Serdar Evren, Ege University Observatory, Izmir, TurkeyFJM (MFR), Frank J. Melillo, Holtsville, NYGHO (MXL), Richard Miles, Golden Hill Observatory, Dorset, EnglandGO (CLZ), Laurent Corp, Garden Observatory, Rodez, FranceGS (SAH), Gerard Samolyk, Greenfield, WIGVO (MBE), Brian E. McCandless, Grand View Observatory, Elkton, MDHPO (HPO), Jeff Hopkins, Hopkins Phoenix Observatory, Phoenix, AZJBO (BPJ), Paul J. Beckmann, Jim Beckmann Observatory, Mendota Heights, MN JESO, Dr. Mukund Kurtadikar, Jalna Education Society Observatory, Maharashtra, IndiaKO (LHG), Hans-Goran Lindberg, Kaerrbo Observatory, Skultuna, SwedenLO (GSN), Snaevarr Gudmundsson, Lindarberg Observatory, Hafnarfjordur, IcelandMSO, Arvind Paranjpye, MVS IUCAA Observatory, Ganeshkhind Pune, IndiaNKO, Nils Karlsen, Nils Karlsen Observatory, Umea, SwedenNPO, Gary Frey, North Pines Observatory, Mayer, AZRES (SVR), Dr. Robert E. Stencel, University of Denver, Denver, CORLO (HHU), Hubert Hautecler, Roosbeek Lake Observatory, Boutersem Brabant, BelgiumSGGO (CTIO), Tiziano Colombo, S. Giovanni Gatano al Observatory, Pisa, ItalyTP, Tom Pearson, Virginia Beach, VAVO (KTHA), Thomas Karlsson, Varberg Observatory, Varberg, SwedenWWC (CDK), Donald Collins, Warren Wilson College, Ashville, NC2 Equipment key: CCD, CCD Camera and telescope; DSLR, Digital Single Lens Reflex Camera, unguided; SSP-3, PIN Diode photometer with telescope; PMT, Photomultiplier Tube, photon counting with telescope.

U bandOOEMag. 3.725Mag. 3.73Mag.(1982–1984) D0.230Mag.1stContact RJD=55,062 ±21days RJD=55,0652ndContact RJD=55,193 ±21days RJD=55,237Ingress 131days ±26.5days 120days(1982–1984)Mid-Eclipse RJD=55,377 ±14daysTotality AverageMag. 4.525Mag. 4.57Mag.(1982–1984) AverageDepth 0.800Mag. Duration 438days ±10days 455days(1982–1984)3rdContact RJD=55,631 ±09days

Table2.2009eAurcampaigndatasummary. Parameter Observed Error Predicted1 RJD = JD–2400000 RJD = JD–2400000

Table continued on following pages


Table continued on following pages

4thContact RJD=55,693 ±09daysEgress 62days ±37.5days 55days(1982–1984)Eclipse Duration 631days ±14days 630days(1982–1984) AverageDepth 0.800Mag. 0.84Mag. Period 9,882days ±21days 9,885days

B bandOOEMag. 3.605Mag. 3.61Mag.(1982–1984) D0.150Mag.1stContact RJD=55,089 ±12days RJD=55,0542ndContact RJD=55,202 ±12days RJD=55,214Ingress 113days ±12days 135days(1982–1984)Mid-Eclipse RJD=55,391 ±19.5daysTotality AverageMag. 4.325 4.32Mag.(1982–1984) AverageDepth 0.720Mag. Duration 432days ±09.5days 437days(1982–1984)3rdContact RJD=55,634 ±07days4thContact RJD=55,693 ±07daysEgress 59days ±07days 71days(1982–1984)Eclipse Duration 604days ±19.5days 643days(1982–1984) AverageDepth 0.720Mag. 0.71Mag. Period 9,919days ±12days 9,884days

V band2OOEMag. 3.035Mag. 3.03Mag.(1982–1984) D0.130Mag.1stContact RJD=55,066 ±12days RJD=55,0562ndContact RJD=55,199 ±12days RJD=55,213Ingress 133days ±12days 142days(1982–1984)Mid-Eclipse RJD=55,384.5 ±09.5daysTotality AverageMag. 3.710Mag. 3.73Mag.(1982–1984) AverageDepth 0.675Mag. 0.70Mag.(1982–1984) Duration 430days ±09.5days 447days(1982–1984)3rdContact RJD=55,629 ±07days4thContact RJD=55,703 ±07daysEgress 74days ±07days 65days(1982–1984)Eclipse Duration 637days ±09.5days 654days(1982–1984)

Table2.2009eAurcampaigndatasummary,cont. Parameter Observed Error Predicted1 RJD = JD–2400000 RJD = JD–2400000



AverageDepth 0.675Mag. 0.70Mag. Period 9,898days ±12days 9,908days

Rc bandOOEMag. 2.745Mag. D0.630Mag.1stContact RJD=55,073 ±67days2ndContact RJD=55,217 ±67daysIngress 144days ±67daysMid-Eclipse RJD=55,333 ±45.5daysTotality AverageMag. 3.415Mag. AverageDepth 0.670Mag. Duration 406days ±17.5days3rdContact RJD=55,623 ±34days4thContact RJD=55,695 ±34daysEgress 72days ±34daysEclipse Duration 622days ±45.5days AverageDepth 0.670Mag. Period —

Ic bandOOEMag. 2.255Mag. D0.410Mag.1stContact RJD=55,054 ±42days2ndContact RJD=55,202 ±42daysIngress 148days ±42daysMid-Eclipse RJD=55,414 ±32.5daysTotality AverageMag. 2.985Mag. AverageDepth 0.720Mag. Duration 424days ±32.5days3rdContact RJD=55,626 ±23days4thContact RJD=55,707 ±23daysEgress 81days ±23daysEclipse Duration 625.3days ±37.5days AverageDepth 0.730Mag. Period —



J bandOOEMag. 1.840Mag. D0.160Mag.1stContact RJD=55,060 ±30days2ndContact RJD=55,210 ±30daysIngress 150days ±30daysMid-Eclipse RJD=55,391 ±18daysTotality AverageMag. 2.480Mag. AverageDepth 0.640Mag. Duration 404days ±18days3rdContact RJD=55,614 ±14days4thContact RJD=55,722 ±14daysEgress 108days ±14daysEclipse Duration 662days ±18days AverageDepth 0.640Mag. Period —

H bandOOEMag. 1.605Mag. D0.645Mag.1stContact RJD=55,057 ±15days2ndContact RJD=55,202 ±15daysIngress 145days ±15daysMid-Eclipse RJD=55,395 ±15.5daysTotality AverageMag. 2.050Mag. AverageDepth 0.645Mag. Duration 388days ±15.5days3rdContact RJD=55,590 ±14days4thContact RJD=55,733 ±14daysEgress 143days ±14daysEclipse Duration 676days ±09.5days AverageDepth 0.645Mag. Period —1 The predicted times were calculated by adding the previous eclipse times to the previous determined periods. 2 There were no predictions for the longer wavelengths in the V band.



Figure 3. e Aur lightcurve, September 1982–May 1984: top, V band;middle, B band; bottom,Uband.HopkinsPhoenixObservatorydata.

Figure 4. e Aur lightcurve,August2009–April2009:top,Vband;middle,B band; bottom, Uband. Hopkins PhoenixObservatorydata.

Figure2.eAurHaspectrum.

Figure1.eAurout-of-eclipselightcurves:top,Vmagnitude;middle,Bmagnitude;bottom,Umagnitude.


Figure5.eAurcampaignVdata.SeeTable1forkeytoobserveridentification.

Figure6.eAurcampaignUandBdata.SeeTable1forkeytoobserveridentification.

Figure7.eAurcampaignRandIdata.SeeTable1forkeytoobserveridentification.


Figure8.Classicalcontactpoints(top)andeAurnewcontactpoints(bottom).

Figure9.Contactpointdeterminationmethodology.

Kloppenborgetal., JAAVSO Volume 40, 2012 647

An Analysis of the Long-term Photometric Behavior of e Aurigae

Brian K. KloppenborgDepartment of Physics and Astronomy, University of Denver, 2112 East Wesley Avenue, Denver, CO 80208; [email protected]

Jeffrey L. HopkinsHopkins Phoenix Observatory, 7812 West Clayton Drive, Phoenix, AZ 85033; [email protected]

Robert E. StencelUniversity of Denver, Department of Physics and Astronomy, 2112 E. Wesley Avenue, Denver, CO 80208;[email protected]

Received June 1, 2012; revised October 4, 2012; accepted October 4, 2012

Abstract

Thelureofa50%reductioninlighthasbroughtamultitudeofobserversandresearcherstoeAureverytwenty-sevenyears,butfewhavepaidattentiontothesystemoutsideofeclipse.Asearlyasthelate1800s,itwasclearthatthesystemundergoessomeformofquasi-periodicvariationoutsideoftotality,butfewconsideredthiseffectintheirresearchuntilthemid-1950s.Inthisworkwefocusexclusivelyontheout-of-eclipse(OOE)variationsseeninthissystem.Wehavedigitizedtwenty-sevensourcesofhistoricphotometryfromeighty-onedifferentobservers.Twoofthesesourcesprovidetwenty-sevenyearsofinter-eclipseUBVphotometrywhichwehaveanalyzedusingmodernperiodfindingtechniques.WehavediscoveredtheF-starvariationsaremulti-periodicwithatleasttwoperiodsthatevolveintimeatDP ≈ –1.5 day/year. These periods are detectedwhentheymanifestasnear-sinusoidalvariationsat3,200-dayintervals.We discuss our work in an evolutionary context by comparing the behaviorfoundineAurwithbona-fidesupergiantandpost-AGBstarsofsimilarspectraltype.Baseduponourqualitativecomparison,wefindthephotometricbehaviorof the F-star in the eAur system is more indicative of supergiant behavior.Thereforethestarismorelikelytobea“traditionalsupergiant’’thanapost-AGBobject.Weencouragecontinuedphotometricmonitoringofthissystemtotestourpredictions.

1. Introduction

eAurigaeisa27.1-yearsinglelineeclipsingspectroscopicbinarythathaslong been wrapped in an enigma. Ever since a dimming of the system was

Kloppenborgetal., JAAVSO Volume 40, 2012648

discoveredbyFritsch(1824),andit

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