Post on 19-Dec-2015
research group ‘Solar and Stellar Seismology and Extrasolar
planet searches’
Interests in SONG:
* the Sun-as-a-star* solar-like stars* red giants* SdB stars* δ Sct, γ Dor* β Cep, SPB* OB supergiants* binaries with pulsating components
* follow-up of planet candidates
Seis
molo
gy
pla
nets
(7 staff, 2 PostDocs, 3 PhD)
Massive main-sequence pulsators
= γ Dor, δ Sct, SPB, β Cep
Problem: mode-ID does not rely on regularity of frequency spectrum
Seismic study requires identified (l,m) modes!
δ Sct HD50844
Mode-ID via line-profile analysis!
(l,m)* amplitude and phase
distribution across line-profile* velocity moments
GOAL: SONG RV time-seriesa)mode-identification!
b) test and improve seismic models
Sun-as-a-star: SONG and Mark-I
Mark-I * operational at Obs. Teide since 1976
* full-time monitoring since 1984
* RV of the Sun through potassium KI 769.9 nm line
* sampling rate: 2sec
GOAL: daytime solar spectra with SONG
a) compare simultaneous (same site!) Mark-I and SONG observations (resample to same sampling rate)
b) evaluate quality and sensitivity of SONG solar observations
Planet transits
See talk by Brandon!
Use SONG photometry to confirm transit candidates through color changes during transit
> 50 staff scientists
> 65 post-docs
> 35 PhD students
Interests in SONG from IAC research groups other than the
group on ‘Solar and Stellar Seismology and
Extrasolar planet searches’
twilight sky spectrumHET McDonald
observatory
* 1 yr solar orbitampl=0.507 km s-1
* 1 d Earth orbit(not well covered)
+ other deviations!
i. Wavelength variations in Solar spectral lines
ΔT = 1750 days
Origin of deviations?
* changes in granulation properties along solar cycle
* presence of planets e.g. Jupiter: 13 m s-1 over 12yr
GOAL: twilight sky spectra with SONG and I2 cell
a) investigate wavelength stability of the solar spectrum
b) demonstrate that deviations due to a Jupiter-size planet can unambigously be found
c) study stellar activity
* Compact Binaries (Porb~hrs), primary is compact object (neutron star, black hole).
* Roche-lobe overflow, matter accreted via accretion disk.
* Inner accretion disk gives rise to X-rays.
* optical emission due to Reprocessing of X-rays in outer accretion disk
* Different optical wavelengths probe different parts of the outer accretion disk
ii. Low mass X-ray binariesRémon Cornelisse
Large night to night changes in lightcurve morphology
Goal: ~1 week continuous multi-colour photometric monitoring with the SONG network
a) understand the origin of the lightcurve changes b) understand physics of the accretion disk
Origin? changes in accretion disk due to precession or the presence of a warp?
Nova = thermonuclear explosions on surface of white dwarf accreting mass in a close binary
questions:
* model that fits at all wavelengths ?
T Pyx, lightcurve
Mag
MJD - 2450000
* brightening (< V=10mag few weeks)
* FeII or He/N line absorption
* origin of absorption lines?
* mysterious absorption systems (THEA)
iii. Classical Novae at maximum light
Alessandro Ederoclite
T Pyx, FIES spectraTim
e
15.04.2011
30.05.2011
GOAL: few SONG spectra per day (without I2 cell) during max light of
novae
follow-up optical thick and thin phase
a) describe chemistry
b) describe dynamics of explosion
Well-detached EBs are best calibrators for models of stellar structure and evolution
accurate orbital parameters, M*, R* !
BUT! spectral chemical analysis is lacking!
GOAL: SONG spectra (without I2 cell) of well-known, bright, well-
detached EBs at max separation
a)derive metallicity and chemical abundances of binary componentsb)calibrate models stellar structure & evolution
iv. Chemical analysis of EBs
Carlos Allende Prieto
v. Multiple populations in globular clusters
Antonino Milone
Many globular clusters show multiple sequences!
GOAL: SONG spectra of bright stars in GCs
(filling program)
derive chemical and dynamical properties
and try to solve:
a)abundance anomalies
b) multiple sequences
c)horizontal branch morphology
CMD of NGC 2808 with isochrones
vi. macroturbulent broadening in OB supergiants
Sergio Simón Díaz
pilot study!signature of collective effect of pulsations?!
OB SGs show extra line broadening:
‘macrotubulence’
origin?
GOAL: time-series of SONG
spectra of bright OB supergiants
a) understand ‘macroturbulence’
b) improve atmosphere models of OB SGs
c) first seismic studies of OB SGs!
promising!