HIGH-PRECISION PHOTOMETRY OF ECLIPSING BINARY STARSJohn Southworth + Hans Bruntt + Pierre Maxted + many others

Eclipsing binary stars: why bother?

Eclipsing binary stars: why bother?Light curve and radial velocity analysis: get masses and radii of two stars to 1% where else could we get this from?

Eclipsing binary stars: why bother?Light curve and radial velocity analysis: get masses and radii of two stars to 1% where else could we get this from?Accurate mass, radius, Teff, luminosityuse as high-precision distance indicatorscheck that theoretical models work

Eclipsing binary stars: why bother?Light curve and radial velocity analysis: get masses and radii of two stars to 1% where else could we get this from?Accurate mass, radius, Teff, luminosityuse as high-precision distance indicatorscheck that theoretical models workComparison with theoretical modelsget metal abundance and ageinvestigate overshooting, mixing length, helium abundance, diffusion

Eclipsing binary stars: how?WW Aurigae Southworth et al. (2005)

Eclipsing binary stars: how?Light curve analysis gives:rA rB radii as fraction of orbital separatione orbital eccentricity and periastron longitudeP i orbital period and inclination

Eclipsing binary stars: how?WW Aurigae Southworth et al. (2005)

Eclipsing binary stars: how?Light curve analysis gives: rA rB e P iRadial velocity analysis gives:P e MA sin3 iminimum mass of star AMB sin3 iminimum mass of star Ba sin iprojected orbital separation

Eclipsing binary stars: how?Light curve analysis gives: rA rB e P iRadial velocity analysis gives:MA sin3 i MB sin3 i a sin i P e Combine quantities:MA MB RA RB log gA log gBget the masses and radii of both stars

Eclipsing binary stars: how?Light curve analysis gives: rA rB e P iRadial velocity analysis gives:MA sin3 i MB sin3 i a sin i P e Combine quantities:MA MB RA RB log gA log gBget the masses and radii of both stars Spectral modelling or photometric colours:get effective temperatures get luminosities get distance

The WIRE satelliteLaunched in 1999 for an IR galaxy surveyelectronics problem caused loss of coolant

The WIRE satelliteLaunched in 1999 for an IR galaxy surveyelectronics problem caused loss of coolant

Star tracker used since 1999 as a high-speed photometeraperture: 5 cmcadence: 2 Hz5 targets at once

Eclipsing binaries with WIRE. I. CentauriV = 4.0 spectral type = B9 V + A2 VKnown spectroscopic binaryWIRE light curve: 41 000 points with 2 mmag scatter

Interlude 1: JKTEBOPBased on EBOP model (Paul Etzel, 1975)stars treated as biaxial spheroidsnumerical integration includes LD and GD

Interlude 1: JKTEBOPBased on EBOP model (Paul Etzel, 1975)stars treated as biaxial spheroidsnumerical integration includes LD and GDJKTEBOP retains original modelnew input / outputLevenberg-Marquardt optimisation algorithmbootstrapping and Monte Carlo simulations to find parameter uncertaintieshttp://www.astro.keele.ac.uk/~jkt/codes.htmlFORTRAN77

Eclipsing binaries with WIRE. I. CentauriJKTEBOP fit to the eclipses

Eclipsing binaries with WIRE. I. CentauriBest fit and Monte Carlo simulation results:rA = 0.043984 0.000045 rB = 0.021877 0.000032 e = 0.55408 0.00024 P = 38.81252 0.00029 And limb darkening too: uA = 0.256 0.009 uB = 0.362 0.041

Eclipsing binaries with WIRE. I. CentauriBest fit and Monte Carlo simulation results:rA = 0.043984 0.000045 rB = 0.021877 0.000032 e = 0.55408 0.00024 P = 38.81252 0.00029 And limb darkening too: uA = 0.256 0.009 uB = 0.362 0.041 See Bruntt et al. (2006, A&A, 456, 651)We are currently working on new spectroscopy

P = 6.07 days B4 V + A6 V V = 4.9variation at primary star rotation periodseveral pulsation frequenciesEclipsing binaries with WIRE. II. AR Cas

V = 1.9 P = 3.960 days A1m + A1mFirst known double-lined binary: 1889 (Maury)First known double-lined eclipsing binary: Stebbins (1911)WIRE light curve: 30 000 points; 0.3 mmag scatterEclipsing binaries with WIRE. III. Aurigae

Interlude 2: more JKTEBOPProblem: linear limb darkening law too simpleSolution: add log, sqrt, quad, cubic LD laws

Interlude 2: more JKTEBOPProblem: linear limb darkening law too simpleSolution: add log, sqrt, quad, cubic LD lawsProblem: ratio of the radii poorly determinedSolution: allow spectroscopic light ratio to be included directly as another observationhttp://www.astro.keele.ac.uk/~jkt/codes.htmlFORTRAN77

Interlude 2: more JKTEBOPProblem: linear limb darkening law too simpleSolution: add log, sqrt, quad, cubic LD lawsProblem: ratio of the radii poorly determinedSolution: allow spectroscopic light ratio to be included directly as another observationProblem: difficult to get good times of minimum light from the WIRE dataSolution: include old times of minimum light directly as additional observationshttp://www.astro.keele.ac.uk/~jkt/codes.htmlFORTRAN77

rA = 0.1569 0.0008P = 3.96004673 (17)rB = 0.1460 0.0008e = 0.0018 0.0004Eclipsing binaries with WIRE. III. Aurigae

Combine light curve result with spectroscopic orbit of Smith (1948):MA = 2.376 0.027 MMB = 2.291 0.027 MRA = 2.762 0.017 RRB = 2.568 0.017 R

Eclipsing binaries with WIRE. III. Aurigae

Combine light curve result with spectroscopic orbit of Smith (1948):MA = 2.376 0.027 MMB = 2.291 0.027 MRA = 2.762 0.017 RRB = 2.568 0.017 RDistance to system:Hipparcos parallax:25.2 0.5 pcOrbital parallax:24.8 0.8 pcSurface brightness:25.0 0.4 pcBolometric corrections:24.8 0.3 pcSouthworth, Bruntt & Buzasi (2007, A&A, 467, 1215)Eclipsing binaries with WIRE. III. Aurigae

Eclipsing binaries: why bother?Get mass and radius to 1%accurate distance indicatorscompare to theoretical models: get precise age and metal abundance

Eclipsing binaries: why bother?Get mass and radius to 1%accurate distance indicatorscompare to theoretical models: get precise age and metal abundanceNow apply to EBs in open clustersget accurate distance get precise age and metallicityno need for MS fitting

Eclipsing binaries: why bother?Get mass and radius to 1%accurate distance indicatorscompare to theoretical models: get precise age and metal abundanceNow apply to EBs in open clustersget accurate distance get precise age and metallicityno need for MS fitting Combined study of cluster and binarystronger test of theoretical models

Eclipsing binaries in open clusters. I. V615 and V618 PerBoth members of the young h Per clusterhave same age and chemical compositioncompare all four stars to models using a mass-radius diagram

h Per has low metal abundance: Z = 0.01

Eclipsing binaries in open clusters. II. V453 CygMember of sparse young cluster NGC 6871Comparison to theoretical models:age = 10.0 0.2 Myrmetal abundance Z 0.01 (half solar maybe)

Eclipsing binaries in open clusters. III. The distance to the PleiadesSurface brightness method gives good resultsUse zeroth-magnitude angular diameter (m=0)Kervella et al (2004) give (m=0) - Teff calibrationsJust need RA and RB and apparent magnitudesSee Southworth, Maxted & Smalley (2005, A&A, 429, 645)

Eclipsing binaries in open clusters. III. HD 23642 in the PleiadesV = 6.8 P = 2.46 AO Vp (Si) + AmLight curves from Munari et al. (2004)We find distance = 139.1 3.5 pc

Eclipsing binaries in open clusters: what next?V1481 Cyg and V2263 Cyg in NGC 712814 nights of INT / WFC photometry7 nights of INT / IDS spectroscopywatch this space

JKTEBOP and HD 209458JKTEBOP very good for transiting exoplanetsfast and accuratelots of different limb darkening laws

JKTEBOP and HD 209458JKTEBOP very good for transiting exoplanetsfast and accuratelots of different limb darkening laws

Results for HD 209458rA = 0.11405 0.00042rB = 0.01377 0.00008gB = 9.28 0.15 m s-2Southworth et al. (2007, MNRAS, 379, L)

Extrasolar planet surface gravityThe known transiting extrasolar planets have a significant correlation between orbital period and suface gravitythe closer planets are more bloatedSouthworth et al. (2007, MNRAS, 379, L)

John Southworth jkt@astro.keele.ac.uk University of Warwick, UK