Pulsations and planets at late stages of stellar evolution

Sonja Schuh1,2

1Eberhard-Karls-Universit¨at Tubingen¨ 2Georg-August-Universit¨at G¨ottingen

Kepler Kolloquium, November 6 2009

1 Asteroseismology 2 Subdwarf B stars 3 PG 1159 white dwarfs Pulsations and planets at late stages of stellar evolution

Sonja Schuh1,2

1Eberhard-Karls-Universit¨at Tubingen¨ 2Georg-August-Universit¨at G¨ottingen

Kepler Kolloquium, November 6 2009

1 Asteroseismology 2 Subdwarf B stars 3 PG 1159 white dwarfs Collaborators

I Georg-August-Universit¨at G¨ottingen Dreizler, Lutz, Stahn (now MPS), Kruspe, Beeck (now MPS), Traulsen, Loeptien, Glatzel, Huber

I Eberhard-Karls-Universit¨at Tubingen¨ Nagel, Werner PG 1159 white dwarfs

I Friedrich-Alexander-Universit¨at Erlangen-Nurnberg¨ Heber, Falter, Tillich subluminous B stars

I INAF – Istituto Nazionale di AstroFisica, Neapel/Turin Silvotti subluminous B stars

I University of Arizona, Tucson – Steward Observatory Green observations of sdBs

I Universit´ede Montr´eal Fontaine, Charpinet (at Toulouse), Randall (now ESO) pulsation theory of sdBs Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Stellar models

I self-gravitating fluid sphere described by stellar structure equations conservation of mass conservation of momentum conservation of energy transport of energy

I as well as properties of stellar matter equation of state energy production opacity

Sonja Schuh Pulsations and planets Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Probing stellar interiors

Asteroseismology: infer inner structure of stars from oscillatory eigenmodes

non-radial modes particularly useful

two limiting cases of gravo-acoustic modes:

Sonja Schuh Pulsations and planets Deviations from

Lamb frequency Brunt-V¨ais¨al¨a frequency p modes g modes

Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars the equilibrium solution temperature, pressure, density and chemical composition as a function of a spatial radial coordinate

Sonja Schuh Pulsations and planets Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Deviations from the equilibrium solution

temperature, pressure, density and chemical composition as a function of a spatial radial coordinate

Lamb frequency Brunt-V¨ais¨al¨a frequency p modes g modes

Sonja Schuh Pulsations and planets Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Helio- and asteroseismology

I comparison of full frequency spectrum νnlm to theoretical predictions (forward modelling) requires high frequency resolution, many modes, mode identification parameters for the models: stellar mass, Teff or L, chemical composition and stratification, rotation, magnetic field need appropriate theory for convection, equation of state, opacities allows to probe interior physics

Sonja Schuh Pulsations and planets Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Helio- and asteroseismology

Sonja Schuh Pulsations and planets Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Helio- and asteroseismology

Sonja Schuh Pulsations and planets Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Science with pulsating stars

Asteroseismology useful to study ...

I depth of the convection zone in solar-like stars

I Classical pulsators: driving, opacities, rotation, magnetic fields ...

I non-standard feeder channels for white dwarfs overshoot efficiency parameter in PG 1159 white dwarfs (GW Vir, born-again evolutionary scenario) clues about the evolutionary history of subdwarf B stars (sdB), diffusion secular evolution from P˙ measurements

Sonja Schuh Pulsations and planets Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Solar-like pulsators

← ground-based observations

Aerts, Christensen-Dalsgaard, CunhaSonja Schuh & KurtzPulsations 2008, SoPh and planets 251, 3 Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Science with pulsating stars

Asteroseismology useful to study ...

I depth of the convection zone in solar-like stars

I Classical pulsators: driving, opacities, rotation, magnetic fields ...

I non-standard feeder channels for white dwarfs overshoot efficiency parameter in PG 1159 white dwarfs (GW Vir, born-again evolutionary scenario) clues about the evolutionary history of subdwarf B stars (sdB), diffusion secular evolution from P˙ measurements

Sonja Schuh Pulsations and planets Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars Science with pulsating stars

Asteroseismology useful to study ...

I depth of the convection zone in solar-like stars

I Classical pulsators: driving, opacities, rotation, magnetic fields ...

I non-standard feeder channels for white dwarfs overshoot efficiency parameter in PG 1159 white dwarfs (GW Vir, born-again evolutionary scenario) clues about the evolutionary history of subdwarf B stars (sdB), diffusion secular evolution from P˙ measurements

Sonja Schuh Pulsations and planets HerwigDormanGreen, Fontaine, 2005, et al. ARAA 1993, Hyde ApJ43, et 435 419,al. 2008, 596 ASPC 392, 75 +++++ Østensen 2009, CoAst 159, 75

Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars

Sonja Schuh Pulsations and planets DormanGreen, Fontaine, et al. 1993, Hyde ApJ et 419,al. 2008, 596 ASPC 392, 75 +++++ Østensen 2009, CoAst 159, 75

Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars

Herwig 2005, ARAA 43, 435

Sonja Schuh Pulsations and planets HerwigGreen, Fontaine, 2005, ARAA Hyde 43, et 435 al. 2008, ASPC 392, 75 +++++ Østensen 2009, CoAst 159, 75

Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars

Dorman et al. 1993, ApJ 419, 596

Sonja Schuh Pulsations and planets HerwigDorman 2005, et al. ARAA 1993, ApJ43, 435 419, 596

Asteroseismology Stars as gravo-acoustic resonant cavities Subdwarf B stars and their planets Forward modelling PG 1159 white dwarfs: testing the models Evolved stars

Green, Fontaine, Hyde et al. 2008, ASPC 392, 75 +++++ Østensen 2009, CoAst 159, 75

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

short-period sdB variable stars

I short pulsations, periods of a few minutes

I driving: κ mechanism due to Z bump opacity accumulated by diffusion =⇒ coherent pulsations

Kilkenny et al. 1997, MNRAS 285, 640 Charpinet et al. 1996, ApJL, 471, 103 Dreizler, Schuh, Deetjen et al. 2002, A&A 386, 249

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

short-period sdB variable stars

I short pulsations, periods of a few minutes

I driving: κ mechanism due to Z bump opacity accumulated by diffusion =⇒ coherent pulsations

Randall, Fontaine, Brassard & Charpinet 2008, JPhCS 118, 2022 Han et al. 2003, MNRAS 341, 669

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

PG1716 stars (lpsdBVs)

I slower pulsations, periods of 30-80 min

I same κ mechanism, lower amplitudes

I & 30 objects known I g mode pulsators

Kilkenny et al. 1997, MNRAS 285, 640 Green, Fontaine, Reed, . . . , Schuh, . . . et al. 2003, ApJ Letters 583, 31

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

PG1716 stars (lpsdBVs)

I slower pulsations, periods of 30-80 min

I same κ mechanism, lower amplitudes

I & 30 objects known I g mode pulsators

Kilkenny et al. 1997, MNRAS 285, 640 Green, Fontaine, Reed, . . . , Schuh, . . . et al. 2003, ApJ Letters 583, 31

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

Kilkenny et al. 1997, MNRAS 285, 640 Green, Fontaine, Reed, . . . , Schuh, . . . et al. 2003, ApJ Letters 583, 31

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

Dreizler, Schuh, Deetjen et al. 2002, A&A 386, 2 49 Schuh, Huber, Dreizler et al. 2006, A&AL 4 45, 31

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

hybrid pulsators with p- and g-modes simultaneously great potential for asteroseismology

Schuh, Huber, Dreizler et al. 2006, A&AL 4 45, 31 Lutz, Schuh, Silvotti et al. 2009, A&A 496, 469

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars

hybrid pulsators with p- and g-modes simultaneously great potential for asteroseismology

Schuh, Huber, Dreizler et al. 2006, A&AL 4 45, 31 Lutz, Schuh, Silvotti et al. 2009, A&A 496, 469

Sonja Schuh Pulsations and planets additional constraint from degree l

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Mode identification – degree l

complex spectrum of frequencies ν −→ strong constraint for models (forward modelling)

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Mode identification – degree l

additional constraint from degree l

complex spectrum of frequencies ν −→ strong constraint for models (forward modelling)

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars l, ν diagram for stars

I pulsation frequency ν photometry I degree l of pulsation mode geometric consideration for mode identification complementary spectroscopic methods

brightness ∝ cosθ velocity ∝ cos2θ

cosθ area cosθ area × cosθ projected velocity light-to-velocity ratio differs for different degrees l

Sonja Schuh Pulsations and planets =⇒ simultaneous measurement of light (brightness change) and velocity (radial velocity change) for PG 1605+072

Falter, Heber, Dreizler, Schuh et al. 2003, A&A 401, 289 O’Toole, Heber, Jeffery, . . . , Schuh, . . . et al. 2005, A&A 440,667 Stahn 2005, Diplomarbeit, Georg-August-Universit¨at G¨ottingen Tillich, Heber, O’Toole, . . . , Schuh, . . . et al. 2007, A&A 473, 219

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars l, ν diagram for stars

light-to-velocity ratio differs for different degrees l

wavelength dependency of amplitude differs for different degrees l

BUSCA Sonja Schuh Pulsations and planets =⇒ simultaneous measurement of light (brightness change) and velocity (radial velocity change) for PG 1605+072

Falter, Heber, Dreizler, Schuh et al. 2003, A&A 401, 289 O’Toole, Heber, Jeffery, . . . , Schuh, . . . et al. 2005, A&A 440,667 Stahn 2005, Diplomarbeit, Georg-August-Universit¨at G¨ottingen Tillich, Heber, O’Toole, . . . , Schuh, . . . et al. 2007, A&A 473, 219

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars l, ν diagram for stars

light-to-velocity ratio differs for different degrees l

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars l, ν diagram for stars

light-to-velocity ratio differs for different degrees l

=⇒ simultaneous measurement of light (brightness change) and velocity (radial velocity change) for PG 1605+072

Falter, Heber, Dreizler, Schuh et al. 2003, A&A 401, 289 O’Toole, Heber, Jeffery, . . . , Schuh, . . . et al. 2005, A&A 440,667 Stahn 2005, Diplomarbeit, Georg-August-Universit¨at G¨ottingen Tillich, Heber, O’Toole, . . . , Schuh, . . . et al. 2007, A&A 473, 219

Sonja Schuh Pulsations and planets – phase relations

I phase relations radial velocity versus temperature variation: π/3 check: radial velocity versus log g variation: π/2 I points to non-adiabatic pulsational behaviour I further result: strongest pulsation corresponds to l=1 instead of l=0

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Time series of optical spectra

I deviations from mean spectral line profile

Tillich, Heber, O’Toole, . . . , Schuh, . . . et al. 2007, A&A 473, 219 Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Time series of optical spectra – phase relations

I deviations from mean spectral line profile I phase relations radial velocity versus temperature variation: π/3 check: radial velocity versus log g variation: π/2 I points to non-adiabatic pulsational behaviour I further result: strongest pulsation corresponds to l=1 instead of l=0 Tillich, Heber, O’Toole, . . . , Schuh, . . . et al. 2007, A&A 473, 219 Sonja Schuh Pulsations and planets will need E-ELT

subdwarf B stars are hot, but compact and hence faint objects

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Pulsational radial velocity variation

upper limits for line profile variations in V391 Pegasi

Kruspe 2009, Diplomarbeit, Georg-August-Universit¨at G¨ottingen

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Pulsational radial velocity variation

upper limits for line profile variations in V391 Pegasi

will need E-ELT

Kruspe 2009, Diplomarbeit, Georg-August-Universit¨at G¨ottingen

subdwarf B stars are hot, but compact and hence faint objects

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Timing method - P˙ as constraint for models

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Timing method - P˙ as constraint for models

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Timing method - P˙ as constraint for models

Sonja Schuh Pulsations and planets → ... coherent pulsations provide a regular time signal

I clock slows down or accelerates due to secular evolution

I previously measured secular P˙ for pulsating sdBs:

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagrams

I example: pulsations as regular clock

Sonja Schuh Pulsations and planets → ... coherent pulsations provide a regular time signal

I clock slows down or accelerates due to secular evolution

I previously measured secular P˙ for pulsating sdBs:

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagrams

I example: pulsations as regular clock

Sonja Schuh Pulsations and planets → ... coherent pulsations provide a regular time signal

I previously measured secular P˙ for pulsating sdBs:

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagrams

I example: pulsations as regular clock

I clock slows down or accelerates due to secular evolution

Sonja Schuh Pulsations and planets → ... coherent pulsations provide a regular time signal

I previously measured secular P˙ for pulsating sdBs:

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagrams

I example: pulsations as regular clock

I clock slows down or accelerates due to secular evolution

Sonja Schuh Pulsations and planets → ... coherent pulsations provide a regular time signal

I previously measured secular P˙ for pulsating sdBs:

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagrams

I example: pulsations as regular clock

I clock slows down or accelerates due to secular evolution

Sonja Schuh Pulsations and planets → ... coherent pulsations provide a regular time signal

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagrams

I example: pulsations as regular clock

I clock slows down or accelerates due to secular evolution

I previously measured secular P˙ for pulsating sdBs:

Sonja Schuh Pulsations and planets f2=2824.1 µHz

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagram for V391 Pegasi

f1=2860.94µHz

Silvotti, Janulis, Schuh et al. 2002, A&A 389, 180 Silvotti, Schuh, Janulis et al. 2007, Nature 449, 189

Sonja Schuh Pulsations and planets f2=2824.1 µHz

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagram for V391 Pegasi

f1=2860.94µHz

Silvotti, Janulis, Schuh et al. 2002, A&A 389, 180 Silvotti, Schuh, Janulis et al. 2007, Nature 449, 189

Sonja Schuh Pulsations and planets f2=2824.1 µHz

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagram for V391 Pegasi

f1=2860.94µHz

Silvotti, Janulis, Schuh et al. 2002, A&A 389, 180 Silvotti, Schuh, Janulis et al. 2007, Nature 449, 189

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars O−C diagram for V391 Pegasi

f1=2860.94µHz f2=2824.1 µHz

Silvotti, Janulis, Schuh et al. 2002, A&A 389, 180 Silvotti, Schuh, Janulis et al. 2007, Nature 449, 189

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Coherent pulsations as timing signal

Data points+++++ compared to mean model

Sonja Schuh Pulsations and planets time delay of ±5.3 s ˆ=projected semi-major axis of 5.3 light seconds

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanets: radial velocity versus timing

Sonja Schuh Pulsations and planets time delay of ±5.3 s ˆ=projected semi-major axis of 5.3 light seconds

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanets: radial velocity versus timing

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanets: radial velocity versus timing time delay of ±5.3 s ˆ=projected semi-major axis of 5.3 light seconds

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanets: radial velocity versus timing time delay of ±5.3 s ˆ=projected semi-major axis of 5.3 light seconds

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanets: radial velocity/ pulsation timing time delay of ±5.3 s ˆ=projected semi-major axis of 5.3 light seconds

Sonja Schuh Pulsations and planets Wolszczan A. & Frail D., 1992, Nature, 355 , 145

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Pulsar planets

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Pulsar planets

Wolszczan A. & Frail D., 1992, Nature, 355 , 145

Sonja Schuh Pulsations and planets goal Find more planets like V 391 Pegasi b method Long-term monitoring of pulsations in subdwarf B stars advantage Timing method can fill gap: sensitive to planets in wide orbits applicable to evolved stars follow-up Characterisation of target stars monitored I mode splitting I chromatic amplitudes I time-dependent spectroscopy

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanet search with the timing method

Sonja Schuh Pulsations and planets two posters in the splinter session ”Exoplanets, stellar activity, and the star-planet connection” Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanet search with the timing method

goal Find more planets like V 391 Pegasi b method Long-term monitoring of pulsations in subdwarf B stars advantage Timing method can fill gap: sensitive to planets in wide orbits applicable to evolved stars follow-up Characterisation of target stars monitored I mode splitting I chromatic amplitudes I time-dependent spectroscopy

Sonja Schuh Pulsations and planets two posters in the splinter session ”Exoplanets, stellar activity, and the star-planet connection” Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanet search with the timing method

goal Find more planets like V 391 Pegasi b method Long-term monitoring of pulsations in subdwarf B stars advantage Timing method can fill gap: sensitive to planets in wide orbits applicable to evolved stars follow-up Characterisation of target stars monitored I mode splitting I chromatic amplitudes I time-dependent spectroscopy

Sonja Schuh Pulsations and planets two posters in the splinter session ”Exoplanets, stellar activity, and the star-planet connection” HS0702+6043: Lutz, PhD thesis, on-going

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars EXOTIME preliminary results

Timing method - long-term stability of the pulsations in HS 0444+0458

Loeptien 2009, Bachelorarbeit, Georg-August-Universit¨at G¨ottingen

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars EXOTIME preliminary results

Timing method - long-term stability of the pulsations in HS 0444+0458

Loeptien 2009, Bachelorarbeit, Georg-August-Universit¨at G¨ottingen HS0702+6043: Lutz, PhD thesis, on-going

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Exoplanets: radial velocity / eclipse timing time delay of ±5.3 s ˆ=projected semi-major axis of 5.3 light seconds

Sonja Schuh Pulsations and planets Kruspe, Schuh & Traulsen 2007, IBVS 5796, 1

Drechsel, Heber, Napiwotzki, . . . , Schuh, . . . et al. 2001, A&A 379, 893

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Timing of binary eclipses

Lee et al. 2009, AJ 137, 3181 discovery of two planetary-mass objects around HW Vir

Sonja Schuh Pulsations and planets Kruspe, Schuh & Traulsen 2007, IBVS 5796, 1

Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Timing of binary eclipses

Qian et al. 2009, ApJ Letters 695, 163 discovery of a brown dwarf around HS 0705+6700 Drechsel, Heber, Napiwotzki, . . . , Schuh, . . . et al. 2001, A&A 379, 893

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Timing of binary eclipses

Kruspe, Schuh & Traulsen 2007, IBVS 5796, 1 Qian et al. 2009, ApJ Letters 695, 163 discovery of a brown dwarf around HS 0705+6700 Drechsel, Heber, Napiwotzki, . . . , Schuh, . . . et al. 2001, A&A 379, 893

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Beyond ”extrasolar planet science”

I fate of planetary systems: first or second generation planets? pulsation timing (V 391 Peg) eclipse timing (HW Vir, HS 0705+6700) radial velocity planet around the subdwarf B star HD 149382: Geier, Edelmann, Heber & Morales-Rueda 2009, ApJL, 702, 96

I origin of subdwarf B stars binarity decisive influence of low-mass companions on RGB evolution complementary to insights from asteroseimology and P˙ KEPLER/KASC program; target list small due to limited field Silvotti, Handler, Schuh et al. 2009, CoAst 159, 97 ground-based observations remain important

I morphology of blue horizontal branch

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Renaissance of an old idea

suggested second parameter influencing the (blue) horizontal branch morphology in globular clusters and elliptical galaxies

I Age of the globular cluster

I Deep helium mixing and radiative levitation

I Large He abundance or fast rotation

I Stellar density in the cluster

I Planets enhancing mass loss on the Red Giant Branch Soker 1998, AJ 116, 1308

Sonja Schuh Pulsations and planets Asteroseismology Pulsations in sdBs and mode identification techniques Subdwarf B stars and their planets Long-term monitoring PG 1159 white dwarfs: testing the models Planets, low-mass companions and origin of sdB stars Renaissance of an old idea

suggested second parameter influencing the (blue) horizontal branch morphology in globular clusters and elliptical galaxies

I Age of the globular cluster

I Deep helium mixing and radiative levitation

I Large He abundance or fast rotation

I Stellar density in the cluster

I Planets enhancing mass loss on the Red Giant Branch Soker 1998, AJ 116, 1308

Sonja Schuh Pulsations and planets Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation Hot hydrogen-deficient white dwarfs GW Vir pulsators

Sonja Schuh Pulsations and planets HerwigDormanGreen, Fontaine, 2005, et al. ARAA 1993, Hyde ApJ43, et 435 419,al. 2008, 596 ASPC 392, 75 +++++ Østensen 2009, CoAst 159, 75

Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation

Sonja Schuh Pulsations and planets HerwigDormanGreen, Fontaine, 2005, et al. ARAA 1993, Hyde ApJ43, et 435 419,al. 2008, 596 ASPC 392, 75 +++++ Østensen 2009, CoAst 159, 75

Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation

Sonja Schuh Pulsations and planets HerwigDormanGreen, Fontaine, 2005, et al. ARAA 1993, Hyde ApJ43, et 435 419,al. 2008, 596 ASPC 392, 75 +++++ Østensen 2009, CoAst 159, 75

Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation

Sonja Schuh Pulsations and planets Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation Mass determinations with different methods

frequencies ν Teff, log g (stellar atmosphere modelling) → pulsation models → evolutionary models

asteroseismic and spectroscopic masses differ by up to 10%

Sonja Schuh Pulsations and planets Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation SDSS2125: a PG 1159 close binary system

consistency check with simple physics, no complicated assumptions

Sonja Schuh Pulsations and planets Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation SDSS2125: a PG 1159 close binary system

hot white dwarf and late-type main sequence companion

reflection effect −→ periodic brightness variation Nagel, Schuh, Kusterer et al. 2006, A&A Letters 448, 25 Schuh, Traulsen, Nagel et al. 2008, AN 329, 376

Sonja Schuh Pulsations and planets Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation SDSS2125: a PG 1159 close binary system

hot white dwarf and late-type main sequence companion

reflection effect −→ periodic brightness variation Nagel, Schuh, Kusterer et al. 2006, A&A Letters 448, 25 Schuh, Traulsen, Nagel et al. 2008, AN 329, 376

Sonja Schuh Pulsations and planets Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation SDSS2125: a PG 1159 close binary system

radial velocity curves; inclination a priori unknown Beeck 2009, Diplomarbeit, Georg-August-Universit¨at G¨ottingen −→ inclination from light curve modelling

Sonja Schuh Pulsations and planets in the only definite PG 1159 close binary system independent check of the results through measurement of the predicted gravitational redshift in the white dwarfs’ potential well

Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation Results I: hot hydrogen-deficient white dwarfs (PG 1159)

DONE Frequency spectra of GW Vir pulsators, asteroseismic mass determination

TODO alternative mass determination

ESO: VLT Sonja Schuh Pulsations and planets independent check of the results through measurement of the predicted gravitational redshift in the white dwarfs’ potential well

Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation Results I: hot hydrogen-deficient white dwarfs (PG 1159)

DONE Frequency spectra of GW Vir pulsators, asteroseismic mass determination

TODO alternative mass determination in the only definite PG 1159 close binary system

ESO: VLT Sonja Schuh Pulsations and planets Asteroseismology Born-again scenario Subdwarf B stars and their planets Dynamic mass determination PG 1159 white dwarfs: testing the models Mass-radius relation Results I: hot hydrogen-deficient white dwarfs (PG 1159)

DONE Frequency spectra of GW Vir pulsators, asteroseismic mass determination

TODO alternative mass determination in the only definite PG 1159 close binary system independent check of the results through measurement of the predicted gravitational redshift in the white dwarfs’ potential well

ESO: VLT Sonja Schuh Pulsations and planets Sun: observation of g modes not confirmed yet white dwarfs: observation of p modes not successful yet

direct observation of stellar evolution

empirical constraints for theoretical evolutionary scenarios

Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY Results II: subdwarf B stars (sdB)

Search for rapidly pulsating subdwarf B stars discovery of g modes in subdwarf B stars discovery of hybrid pulsators (p+g modes) in subdwarf B stars

from long-term monitoring of the pulsations in V391 Pegasi: slow changes in the two main frequencies due to expansion of −12 −12 the star: P˙1=(1.46±0.07)×10 P˙2=(2.05±0.26)×10

discovery of a massive gas giant planet (M sin i=3.2MJupiter) in a 1.7×AU orbit, orbit period 3.2a planet survived the red giant phase of its host star measured frequency spectra, frequency changes, and discovery of stellar, sub-stellar and planetary sdB companions:

Sonja Schuh Pulsations and planets direct observation of stellar evolution

empirical constraints for theoretical evolutionary scenarios

Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY Results II: subdwarf B stars (sdB)

Search for rapidly pulsating subdwarf B stars discovery of g modes in subdwarf B stars discovery of hybrid pulsators (p+g modes) in subdwarf B stars Sun: observation of g modes not confirmed yet white dwarfs: observation of p modes not successful yet from long-term monitoring of the pulsations in V391 Pegasi: slow changes in the two main frequencies due to expansion of −12 −12 the star: P˙1=(1.46±0.07)×10 P˙2=(2.05±0.26)×10

discovery of a massive gas giant planet (M sin i=3.2MJupiter) in a 1.7×AU orbit, orbit period 3.2a planet survived the red giant phase of its host star measured frequency spectra, frequency changes, and discovery of stellar, sub-stellar and planetary sdB companions:

Sonja Schuh Pulsations and planets empirical constraints for theoretical evolutionary scenarios

Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY Results II: subdwarf B stars (sdB)

Search for rapidly pulsating subdwarf B stars discovery of g modes in subdwarf B stars discovery of hybrid pulsators (p+g modes) in subdwarf B stars Sun: observation of g modes not confirmed yet white dwarfs: observation of p modes not successful yet from long-term monitoring of the pulsations in V391 Pegasi: slow changes in the two main frequencies due to expansion of −12 −12 the star: P˙1=(1.46±0.07)×10 P˙2=(2.05±0.26)×10 direct observation of stellar evolution discovery of a massive gas giant planet (M sin i=3.2MJupiter) in a 1.7×AU orbit, orbit period 3.2a planet survived the red giant phase of its host star measured frequency spectra, frequency changes, and discovery of stellar, sub-stellar and planetary sdB companions:

Sonja Schuh Pulsations and planets Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY Results II: subdwarf B stars (sdB)

Search for rapidly pulsating subdwarf B stars discovery of g modes in subdwarf B stars discovery of hybrid pulsators (p+g modes) in subdwarf B stars Sun: observation of g modes not confirmed yet white dwarfs: observation of p modes not successful yet from long-term monitoring of the pulsations in V391 Pegasi: slow changes in the two main frequencies due to expansion of −12 −12 the star: P˙1=(1.46±0.07)×10 P˙2=(2.05±0.26)×10 direct observation of stellar evolution discovery of a massive gas giant planet (M sin i=3.2MJupiter) in a 1.7×AU orbit, orbit period 3.2a planet survived the red giant phase of its host star measured frequency spectra, frequency changes, and discovery of stellar, sub-stellar and planetary sdB companions: empirical constraints for theoretical evolutionary scenarios

Sonja Schuh Pulsations and planets Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY Results II: subdwarf B stars (sdB)

Search for rapidly pulsating subdwarf B stars discovery of g modes in subdwarf B stars discovery of hybrid pulsators (p+g modes) in subdwarf B stars Sun: observation of g modes not confirmed yet white dwarfs: observation of p modes not successful yet from long-term monitoring of the pulsations slow changes in the two main frequencies due to expansion of −12 −12 the star: P˙1=(1.46±0.07)×10 P˙2=(2.05±0.26)×10 direct observation of stellar evolution discovery of a massive gas giant planet (M sin i=3.2MJupiter) in a 1.7×AU orbit, orbit period 3.2a planet survived the red giant phase of its host star measured frequency spectra, frequency changes, and discovery of stellar, sub-stellar and planetary sdB companions: empirical constraints for theoretical evolutionary scenarios

Sonja Schuh Pulsations and planets Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY KEPLER mission:

useful tool to do asteroseismology; KEPLER/KASC programs

main objective is exoplanet search with transit method young stars and main sequence bias

Sonja Schuh Pulsations and planets Kepler’s Optical Phase Curve of the Exoplanet HAT-P-7b Borucki, Koch, Jenkins et al. 2009, Science 325, 709

Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY KEPLER mission: transits, transits, transits ... !

Sonja Schuh Pulsations and planets Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY KEPLER mission: transits, transits, transits ... !

Kepler’s Optical Phase Curve of the Exoplanet HAT-P-7b Borucki, Koch, Jenkins et al. 2009, Science 325, 709

Sonja Schuh Pulsations and planets Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY Convergence of instrumentation

Sonja Schuh Pulsations and planets Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY Convergence of instrumentation

Sonja Schuh Pulsations and planets Asteroseismology RESULTS Subdwarf B stars and their planets OUTLOOK PG 1159 white dwarfs: testing the models SUMMARY Investigation of stellar and planetary systems

Asteroseismology-exoplanet-connection for solar-like pulsators

I accurate radii for (solar-like) host stars of transiting exoplanets

Asteroseismology-exoplanet-connection for post-RGB stars

I fate of planetary systems known planets around extreme horizontal branch stars: first or second generation?

I origin of subdwarf B stars

I second parameter for HB in GC

Characterisation of post-AGB stars

Sonja Schuh Pulsations and planets