Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf ·...

28
Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik (ESO, Santiago de Chile) Kerstin Geissler (MPIA, Heidelberg) Gael Chauvin (LAOG, Grenoble) Eric Pantin (CEA, Saclay) Wednesday, August 12, 2009

Transcript of Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf ·...

Page 1: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Mid-Infrared Variability in Binary Brown Dwarfs

Michael F. Sterzik (ESO, Santiago de Chile)Kerstin Geissler (MPIA, Heidelberg)

Gael Chauvin (LAOG, Grenoble)Eric Pantin (CEA, Saclay)

Wednesday, August 12, 2009

Page 2: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Ground-based MIR photometry of binary stars/b.d. systems

- spatial resolution < 2”

- precise relative photometry (<5%)

- good absolute photometry (<20%) constrain Teff and Lbol

- discriminate atmospheric models

Wednesday, August 12, 2009

Page 3: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

The case of ε Ind B

Roelling et al., 2004

- SPITZER IRS from Roelling, 2004:- Matches cloudless combo of Saumon, Marley, Lodders (2003)- TBb = 800K and TBa = 1200K- NH3 absorption @ 10.5 µm

BUT:

- McCaughrean et al., 2004, AO assisted H-band R=1000 spectroscopy: TBb = 835K … 875K and TBa = 1238K … 1312K (0.8…2Gyr) - Smith et al., 2003, combo R=50000, compared with Tsuji (2002) : TB ≈ 1500K - MIR model spectra differ: Allard/Burrows/Saumon/Helling …- TBa is a tough one! (L/T transition: settling?, cond?, non-equilibrium chem?)- if TBa hot, then problems with its radius …

Wednesday, August 12, 2009

Page 4: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

VISIR - VLT Imager and Spectrometer for mid-IR

- diffraction limited (0.3” resolution)

- high sensitivity N-band imaging (5mJy 10σ /hr)

- 11 narrow N band filters

- long slit R=350/3000/25000 spectroscopy

- queue (service) and visitor mode

- reduction pipeline

Wednesday, August 12, 2009

Page 5: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

The case of ε Ind B

Sterzik et al., 2004

Wednesday, August 12, 2009

Page 6: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

! Indi Bab and AMES-cond. models

8 9 10 11 12 13" [µm]

1

10

F# [m

Jy]

T = 1200K, 1300KT = 800K, 900K

Wednesday, August 12, 2009

Page 7: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

! Indi B and Burrows, Sudarsky, Hubeny (2006) models

8 9 10 11 12 13" [µm]

1

10

F# [m

Jy]

T = 1200K, 1300KT = 800K, 900K

Wednesday, August 12, 2009

Page 8: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

! Indi B and Burrows, Sudarsky, Hubeny (2006) models

8 9 10 11 12 13" [µm]

1

10

F# [m

Jy]

T = 1200K, 1300KT = 800K, 900K

Hubeny & Burrows (2007) models

8 9 10 11 12 13! [µm]

1

10

F" [m

Jy]

T = 1200K, 1300KT = 800K, 900K

Wednesday, August 12, 2009

Page 9: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

! Indi B and Burrows, Sudarsky, Hubeny (2006) models

8 9 10 11 12 13" [µm]

1

10

F# [m

Jy]

T = 1200K, 1300KT = 800K, 900K

Hubeny & Burrows (2007) models

8 9 10 11 12 13! [µm]

1

10

F" [m

Jy]

T = 1200K, 1300KT = 800K, 900K

indication for non-equilibrium atmosphereWednesday, August 12, 2009

Page 10: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Star - Brown Dwarf binaries (8.6μ)

GJ 229

HR 7329

HD 130948

dist ~ 6pcsep. 7”.7SpTy T7T~1000Kage 30-200 Myrs

dist ~ 18pcsep. 2”.6 + 0”.13SpTy L4+L4T~1900Kage 300-800 Myrs

dist ~ 50pcsep. 4”.2SpTy M7-M8T~2600Kage 12 Myrs

Geissler, Chauvin & Sterzik, 2008

Wednesday, August 12, 2009

Page 11: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Star - Brown Dwarf binaries (8.6μ)

GJ 229

HR 7329

HD 130948

dist ~ 6pcsep. 7”.7SpTy T7T~1000Kage 30-200 Myrs

dist ~ 18pcsep. 2”.6 + 0”.13SpTy L4+L4T~1900Kage 300-800 Myrs

dist ~ 50pcsep. 4”.2SpTy M7-M8T~2600Kage 12 Myrs

Geissler, Chauvin & Sterzik, 2008

Wednesday, August 12, 2009

Page 12: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Star - Brown Dwarf binaries (8.6μ)

GJ 229

HR 7329

HD 130948

dist ~ 6pcsep. 7”.7SpTy T7T~1000Kage 30-200 Myrs

dist ~ 18pcsep. 2”.6 + 0”.13SpTy L4+L4T~1900Kage 300-800 Myrs

dist ~ 50pcsep. 4”.2SpTy M7-M8T~2600Kage 12 Myrs

λ

mJy

8.6μ 10.5μ 11.3μ

3.2(0.5) <3.2 <6.7

λ

mJy

8.6μ 10.5μ 11.3μ

3.2(2.3) <1.9 <2.9

Geissler, Chauvin & Sterzik, 2008

Wednesday, August 12, 2009

Page 13: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Star - Brown Dwarf binaries (8.6μ)

GJ 229

HR 7329

HD 130948

dist ~ 6pcsep. 7”.7SpTy T7T~1000Kage 30-200 Myrs

dist ~ 18pcsep. 2”.6 + 0”.13SpTy L4+L4T~1900Kage 300-800 Myrs

dist ~ 50pcsep. 4”.2SpTy M7-M8T~2600Kage 12 Myrs

λ

mJy

8.6μ 10.5μ 11.3μ

3.2(0.5) <3.2 <6.7

λ

mJy

8.6μ 10.5μ 11.3μ

3.2(2.3) <1.9 <2.9

λmJy

8.6μ 10.5μ 11.3μ

3.8(0.4) 5.7(0.4) <2.4

n.o. <3.2 n.o.

Geissler, Chauvin & Sterzik, 2008

Wednesday, August 12, 2009

Page 14: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Comparison w/ atm. models (GJ229)

GJ229BAMES - cond

T=900Kt=200Myr

L&T cloud freeT=900K

t=200Myr

PAH1 (3.2+-0.5 mJy)

Siv (<3.2 mJy)

PAH2 (<6.7mJy)

3.3 3.43.0 3.05.1 4.3

HD130948BCAMES - dusty

T=1900Kt=300Myr

L&T cloudyT=1900Kt=300Myr

PAH1 (1.9+-0.4 mJy)

Siv (2.9+-0.4 / < 1.6 mJy)

PAH2 (<1.2mJy)

2.1 1.51.6 1.31.4 1.2

Wednesday, August 12, 2009

Page 15: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Comparison w/ atm. models (GJ229)

GJ229BAMES - cond

T=900Kt=200Myr

L&T cloud freeT=900K

t=200Myr

PAH1 (3.2+-0.5 mJy)

Siv (<3.2 mJy)

PAH2 (<6.7mJy)

3.3 3.43.0 3.05.1 4.3

HD130948BCAMES - dusty

T=1900Kt=300Myr

L&T cloudyT=1900Kt=300Myr

PAH1 (1.9+-0.4 mJy)

Siv (2.9+-0.4 / < 1.6 mJy)

PAH2 (<1.2mJy)

2.1 1.51.6 1.31.4 1.2

Wednesday, August 12, 2009

Page 16: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Is HD 130948 variable @ 10.5μ?

5/Aug/06 3/Aug/06 simulated

5.7 ± 0.4 mJy <3.2 (b.l. + 3σ) mJy sim. source 4 mJy

Wednesday, August 12, 2009

Page 17: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Is HD 130948 variable @ 10.5μ?

5/Aug/06 3/Aug/06 simulated

5.7 ± 0.4 mJy <3.2 (b.l. + 3σ) mJy sim. source 4 mJy

Wednesday, August 12, 2009

Page 18: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Variability in B.D.s

The Quest for Weather: Silicates, Methane, Ammonia, COL/T transition: cloudy/clear...

A SENSITIVE SEARCH FOR VARIABILITY IN LATE L DWARFS: THE QUEST FOR WEATHER

M. Morales-Calderon,1,2 J. R. Stauffer,3 J. Davy Kirkpatrick,4 S. Carey,3 C. R. Gelino,3

D. Barrado y Navascues,1 L. Rebull,3 P. Lowrance,3 M. S. Marley,5

D. Charbonneau,6,7 B. M. Patten,6 S. T. Megeath,6 and D. Buzasi8

Received 2006 June 2; accepted 2006 July 21

ABSTRACT

We have conducted a photometric monitoring program of three field late L brown dwarfs (DENIS-P J0255!4700,2MASS J0908+5032, and 2MASS J2244+2043) looking for evidence of nonaxisymmetric structure or temporalvariability in their photospheres. The observations were performed using Spitzer IRAC 4.5 and 8 !m bandpasses andwere designed to cover at least one rotational period of each object; 1" rms uncertainties of less than 3 mmag at 4.5!mand around 9mmag at 8!mwere achieved. Two out of the three objects studied exhibit somemodulation in their lightcurves at 4.5 !m—but not 8 !m—with periods of 7.4 hr (DENIS 0255) and 4.6 hr (2MA 2244) and peak-to-peakamplitudes of 10 and 8 mmag. Although the lack of detectable 8 !m variation suggests an instrumental originfor the detected variations, the data may nevertheless still be consistent with intrinsic variability, since the shorterwavelength IRAC bandpasses probemore deeply into late L dwarf atmospheres than the longer wavelengths. A cloudfeature occupying a small percentage (1%Y2%) of the visible hemisphere could account for the observed amplitudeof variation. If, instead, the variability is indeed instrumental in origin, then our nonvariable L dwarfs could be eithercompletely covered with clouds or objects whose clouds are smaller and uniformly distributed. Such scenarios wouldlead to very small photometric variations. Follow-up IRAC photometry at 3.6 and 5.8 !m bandpasses should dis-tinguish between the two cases. In any event, the present observations provide the most sensitive search to date forstructure in the photospheres of late L dwarfs at mid-IR wavelengths, and our photometry provides stringent upperlimits to the extent to which the photospheres of these transition L dwarfs are structured.

Subject headinggs: stars: individual (DENIS-P J0255!4700, 2MASS J0908+5032, 2MASS J2244+2043) —stars: low-mass, brown dwarfs — stars: variables: other

1. INTRODUCTION

The onslaught of L and T dwarf discoveries within in the last10 years has enabled direct comparisons between observationsand modeling of brown dwarf cooling tracks. The transition re-gion from the late L dwarfs to the early T dwarfs has always beenproblematic for brown dwarf atmosphere modelers. First amongthe unanswered questions relates to the fact that early T dwarfstend to have absolute J magnitudes brighter than later L dwarfs,the so-called J-band bump (Vrba et al. 2004). Further problemsarise from the large dispersion of certain colors as a function ofspectral type (Knapp et al. 2004) as well as the discrepanciesbetween the optical and near-IR derived spectral types of sometransition objects (Kirkpatrick 2005). Although some of theseissues can be answered with unresolved binaries (Liu 2006), it isalso likely true that the mechanism for dust clearing is intimatelyinvolved in the explanation of all of these observables. At leastthree mechanisms for dust clearing have been proposed: (1) thecloud deck thins and sinks, eventually dropping below the pho-tosphere (Tsuji & Nakajima 2003); (2) the cloud deck breaks up

into discrete (patchy) clouds, and eventually those clouds eithershrink or sink below the visible photosphere (Burgasser et al.2002); and (3) a ‘‘sudden downpour’’ (rapid sedimentation period)occurs, rapidly removing grains from the visible photosphere(Knapp et al. 2004).Photometric variability is one observable that may be able to

provide constraints on which of these mechanisms, if any, is thedominant process occurring in very cool atmospheres. The atmo-spheres of these objects are too cool and neutral to support starspots (Mohanty & Basri 2003; Gelino et al. 2002), so if vari-ability exists, it is most likely caused by nonuniform structures inthe cloud deck. If the objects are not variable, then either thevariability is below the limits of detection, or the cloud decks areuniformly distributed over the entire atmosphere, leaving no fea-tures to produce brightness variations.Numerous attempts have been made to search for photometric

variability in L and T dwarfs. These searches for ‘‘weather’’ havebeen performed largely in the optical regime (Tinney & Tolley1999; Bailer-Jones & Mundt 1999, 2001; Clarke et al. 2002a,2002b; Gelino 2002; Gelino et al. 2002; Koen 2003, 2005; Maitiet al. 2005) and the near-IR (Bailer-Jones 2002; Gelino 2002;Bailer-Jones & Lamm 2003; Enoch et al. 2003; Koen et al. 2004,2005). The results of these surveys indicate that the photometricvariability of these objects falls under one of three categories:nonvariable, periodic variable, and nonperiodic variable. Objectsthat show no variations generally have limits of a few percent.Those that show nonperiodic variations have rms amplitudes ofa few percent and vary on timescales too short to be correlatedwith a rotation period (Bailer-Jones &Mundt 2001; Gelino et al.2002; Bailer-Jones 2004). The small fraction that appear to showperiodic modulation of their light curves have typical amplitudes

1 Laboratorio de Astrofısica Espacial y Fısica Fundamental (LAEFF-INTA),P.O. Box 50727, E-28080 Madrid, Spain; [email protected].

2 Visiting Graduate Student Fellow at the Spitzer Science Center, CaliforniaInstitute of Technology, Pasadena, CA 91125.

3 Spitzer Science Center, California Institute of Technology, Pasadena, CA91125.

4 Infrared Processing and Analysis Center, California Institute of Technology,Pasadena, CA 91125.

5 NASA Ames Research Center, Moffett Field, CA 94035.6 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138.7 Alfred P. Sloan Research Fellow.8 US Air Force Academy, Colorado Springs, CO 80840.

1454

The Astrophysical Journal, 653:1454Y1463, 2006 December 20Copyright is not claimed for this article. Printed in U.S.A.

A&A 487, 277–292 (2008)DOI: 10.1051/0004-6361:20065075c! ESO 2008

Astronomy&

Astrophysics

CLOUDS search for variability in brown dwarf atmospheres

Infrared spectroscopic time series of L/T transition brown dwarfs!

B. Goldman1,2, M. C. Cushing3 ,!!, M. S. Marley4, É. Artigau5, K. S. Baliyan6, V. J. S. Béjar7, J. A. Caballero2,8,N. Chanover1, M. Connelley9, R. Doyon10, T. Forveille11,12, S. Ganesh6, C. R. Gelino1,13, H. B. Hammel14,J. Holtzman1, S. Joshi15, U. C. Joshi6, S. K. Leggett16, M. C. Liu9, E. L. Martín8, V. Mohan17, D. Nadeau10,

R. Sagar15, and D. Stephens18

1 Department of Astronomy, New Mexico State University, Las Cruces, NM 88003, USA2 M.P.I.A., Königstuhl 17, 69117 Heidelberg, Germany

e-mail: [email protected] Steward Observatory, University of Arizona, Tucson, AZ 85721, USA4 NASA Ames Research Center, Mo!ett Field, CA 94035, USA5 Gemini Observatory, Southern Operations Center, A.U.R.A., Inc., Casilla 603, La Serena, Chile6 Astronomy & Astrophysics Division, Physical Research Laboratory, Navarangpura, Ahmedabad 380 009, India7 GTC project. Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain8 Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain9 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA

10 Observatoire du Mont Mégantic et Département de Physique, Université de Montréal, H3C 3J7, C.P. 6128, Montréal, Canada11 Canada-France-Hawaii Telescope Corporation, 65-1238 Mamalahoa Highway, Kamuela, HI 96743, Hawaii, USA12 Observatoire de Grenoble, 414 rue de la Piscine, Domaine Universitaire de St. Martin d’Hères, 38041 Grenoble, France13 Spitzer Science Center, MC 220-6, California Institute of Technology, Pasadena, CA 91125, USA14 Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA15 Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital-263129, Uttaranchal, India16 Joint Astronomy Centre, 660 North A’ohoku Place, Hilo, HI 96720, USA17 Inter-University Centre for Astronomy and Astrophysics (IUCAA), Post Bag 4, Ganeshkhind, Pune 411007, India18 Department of Physics and Astronomy, Brigham Young University, Provo, UT 84602, USA

Received 23 February 2006 / Accepted 24 February 2008

ABSTRACT

Context. L-type ultra-cool dwarfs and brown dwarfs have cloudy atmospheres that could host weather-like phenomena. The detectionof photometric or spectral variability would provide insight into unresolved atmospheric heterogeneities, such as holes in a globalcloud deck. Indeed, a number of ultra-cool dwarfs have been reported to vary. Additional time-resolved spectral observations ofbrown dwarfs o!er the opportunity for further constraining and characterising atmospheric variability.Aims. It has been proposed that growth of heterogeneities in the global cloud deck may account for the L- to T-type transition whenbrown dwarf photospheres evolve from cloudy to clear conditions. Such a mechanism is compatible with variability. We searched forvariability in the spectra of five L6 to T6 brown dwarfs to test this hypothesis.Methods. We obtained spectroscopic time series using the near-infrared spectrographs ISAAC on VLT–ANTU, over 0.99"1.13 µm,and SpeX on the Infrared Telescope Facility for two of our targets in the J, H, and K bands. We searched for statistically variablelines and for a correlation between those.Results. High spectral-frequency variations are seen in some objects, but these detections are marginal and need to be confirmed.We find no evidence of large-amplitude variations in spectral morphology and we place firm upper limits of 2 to 3% on broad-bandvariability, depending on the targets and wavelengths, on the time scale of a few hours. In contrast to the rest of the sample, theT2 transition brown dwarf SDSS J1254"0122 shows numerous variable features, but a secure variability diagnosis would requirefurther observations.Conclusions. Assuming that any variability arises from the rotation of patterns of large-scale clear and cloudy regions across thesurface, we find that the typical physical scale of cloud-cover disruption should be smaller than 5"8% of the disk area for four of ourtargets, using simplistic heterogeneous atmospheric models. The possible variations seen in SDSS J1254"0122 are not strong enoughto allow us to confirm the cloud-breaking hypothesis.

Key words. stars: low-mass, brown dwarfs – stars: atmospheres – techniques: spectroscopic – stars: general

! Based on observations obtained at the European Observatory,Paranal, Chile, under programme 71.C-0559.!! Visiting Astronomer at the Infrared Telescope Facility, which is op-erated by the University of Hawaii under Cooperative Agreement No.NCC 5-538 with NASA, O"ce of Space Science, Planetary AstronomyProgram.

1. Introduction

The L/T transition brown dwarfs are an informal class of sub-stellar objects comprising the latest L-type and the earliestT-type dwarfs (roughly L8 to T4). Their near-infrared spec-tra may exhibit both CO and CH4 absorption, and they haveJ " K colours intermediate between those of the red late-type

Article published by EDP Sciences

Wednesday, August 12, 2009

Page 19: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Variability in B.D.s @ 10.5μL/T transition: cloudy/clear...non-equilibrium chemistry / vertical mixingheterogenity of cloud patterns: Silicates, Ammonia, CO

11

Hubeny & Burrows, 2007, ApJ669

Saumon, Marley & Lodders, 2003

Wednesday, August 12, 2009

Page 20: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Systematic Monitoring of HD 130948

Cha

pter

2B

row

nD

war

fsin

the

Mid

-IR

Page

28

Figu

re2.

13:S

eque

nce

ofth

eM

arch

2008

obse

rvat

ions

ofH

D13

0948

BC

inPA

H1

and

SIV.

SIVPA

H1

Wednesday, August 12, 2009

Page 21: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Systematic Monitoring of HD 130948

Cha

pter

2B

row

nD

war

fsin

the

Mid

-IR

Page

28

Figu

re2.

13:S

eque

nce

ofth

eM

arch

2008

obse

rvat

ions

ofH

D13

0948

BC

inPA

H1

and

SIV.

0

2

4

6

10-07-06 03-08-06 05-08-06 25-03-08T05 25-03-08T06 25-03-08T07 26-03-08T05 26-03-08T07 26-03-08T08 26-03-08T09 27-03-08T05 27-03-08T07 27-03-08T08 27-03-08T09

SIVPA

H1

Wednesday, August 12, 2009

Page 22: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Variability Analysis

Geissler et al., Cool Stars

Χ2 P η

HD 130948PAH1

HD 130948SIV

1.8 0.99 0.4

5.5 0.59 0.7

- Χ2 analysis (Morales-Calderon et al.)- η (Enoch et al. 2003, statistically more robust)

Wednesday, August 12, 2009

Page 23: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Variability Analysis

Geissler et al., Cool Stars

Χ2 P η

HD 130948PAH1

HD 130948SIV

1.8 0.99 0.4

5.5 0.59 0.7 HD 130948 likely not variable in PAH1 and SIV!

- Χ2 analysis (Morales-Calderon et al.)- η (Enoch et al. 2003, statistically more robust)

Wednesday, August 12, 2009

Page 24: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Systematic Monitoring of ε Ind B2/Oct/04 25/Aug/05 9/Sep/05

folded

convol.wavelet

Photometric errors systematically measured through simulated sources

Photometric errors systematically measured through simulated sources

incl time series data from 2007

Wednesday, August 12, 2009

Page 25: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Systematic Monitoring of ε Ind B

13-Nov-2007 14-Nov-2007 15-Nov-2007 16-Nov-2007

0

2

4

6

8

10

12

14 F

lux [

mJy]

!Ind Ba (PAH2) !Ind Ba (SIV) !Ind Bb(PAH2) !Ind Bb(SIV)

Wednesday, August 12, 2009

Page 26: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Variability Analysis

Χ2 P ηε Ind BaPAH2

ε Ind BaSIV

ε Ind BbPAH2

ε Ind BbSIV

40 10-7 3.1

20 10-3 2.1

15 10-2 1.8

9 10-1 1.4

Wednesday, August 12, 2009

Page 27: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Variability Analysis

Χ2 P ηε Ind BaPAH2

ε Ind BaSIV

ε Ind BbPAH2

ε Ind BbSIV

40 10-7 3.1

20 10-3 2.1

15 10-2 1.8

9 10-1 1.4 ε Ind Bb unlikely variable in PAH2 and SIV.

Wednesday, August 12, 2009

Page 28: Mid-Infrared Variability in Binary Brown Dwarfs - ESOmsterzik/IAU09/SpS07_s1_20_Sterzik.pdf · Mid-Infrared Variability in Binary Brown Dwarfs Michael F. Sterzik ... Marley, Lodders

Variability Analysis

Sterzik et al., in prep.

Χ2 P ηε Ind BaPAH2

ε Ind BaSIV

ε Ind BbPAH2

ε Ind BbSIV

40 10-7 3.1

20 10-3 2.1

15 10-2 1.8

9 10-1 1.4

ε Ind Ba *maybe* variable in PAH2 and SIV,

tentatively attributed to variable NH3 absorption.

ε Ind Bb unlikely variable in PAH2 and SIV.

Wednesday, August 12, 2009