An Astronomy GradNet Tech Talk: Searching for Eclipsing Binary Stars Jonathan Devor, Ph.D. October 20, 2008

Stellar structure: understanding how stars work

Why Eclipsing Binaries? Eclipsing binaries provide the most direct and accurate method of measuring both the masses and radii of stars. We need to know both the masses and radii of stars to constrain their structure. This is especially needed to understand low- mass stars, which don’t conform well to currently stellar models.

What are Eclipsing Binary Stars? Primary eclipse Secondary eclipse Out-of-eclipse “plateau” Animation from Wikipedia Light curve EB = eclipsing binary LC = light curve

Circular and Eccentric Orbits a Circular orbit Eccentric orbit

Outline 1.Where the data comes from- The multi-epoch photometric surveys 2.How I analyzed the data- The automated DEBiL/MECI pipeline 3.Results- Discovery of low-mass eclipsing binaries Testing tidal circularization theory Finding “abnormal” eclipsing binaries

OGLE: The Optical Gravitational Lensing Experiment The Warsaw Telescope Las Campanas Observatory, Chile OGLE website Located at Las Campanas Observatory, Chile 1.3m physical aperture I-band photometric observations Magnitude limit I < 19 ~200 observations per LC, compiled over three years ( ) Analyzed 49 bulge fields, totaling 218,699 LCs Specs:

“It is a common situation nowadays that the ability to generate data far exceeds the ability to process it, and even more so, to comprehend it.” (Wozniak et al. 2002) Release all the data to the public Many discoveries, most of which had nothing to do with the original survey motivations (e.g. pulsating stars, transiting exoplanets, population statistics, irregular variables, eclipsing binaries, etc.)

TrES/Sleuth – a robotic telescope TrES = Trans-atlantic Exoplanet Survey Sleuth is one of three robotic telescopes in the TrES network. Located at Palomar Obs., CA 10 cm physical aperture 30“ photometric aperture radius r - band photometric observations Magnitude limit r < 15 Effective 9-minute cadence (5 x 90sec) ~2000 observations per LC Analyzed 10 fields, totaling 185,445 LCs Specs: Large field / bright targets  easier to follow-up

(Devor 2005)

“Abnormal” Eclipsing Binaries P = days P = days P = daysP = days P = days (Devor et al. 2008)

A Binary with Large Eclipse Timing Variations

The Orbital Period Distribution (Devor 2005)

The MECI Flow-Chart (Devor & Charbonneau 2006) (Yi et al. 2001) The Yonsei-Yale theoretical isochrones Main- sequence Log Luminosity Log Temperature

(Devor & Charbonneau 2006)

Testing MECI with Known Systems (Lacy et al. 2002)(Lacy et al. 2003) (Devor & Charbonneau 2006)

Binary Mass-Mass Plot (Devor et al. 2008)

TrES/PSST (LC) Lowell Obs., AZ TrES/Slueth (LC) Palomar Obs., CA NIRSPEC (RV) Mauna Kea, HI TRES (RV) FLWO, AZ HATNet (LC) Mauna Kea, HI & FLWO, AZ IAC80 (LC) Observatorio del Teide Canary Islands Markus Rabus Gaspar Bakos Georgi Mandushev Dave Charbonneau Francis O'Donovan Dave Charbonneau John Bailey Cullen Blake Dave Charbonneau Russel White Gabor Furesz Doug Mink Andy Szentgyorgyi Bill Wyatt MECI + DEBiL pipeline

T-Lyr : A long-period low-mass EB [J. Devor, D. Charbonneau, G. Torres, C. H. Blake, R. White, M. Rabus, F. T. O'Donovan, G. Mandushev, G. Bakos, & A. Szentgyorgyi The Astrophysical Journal] P = ± days (Devor et al., in press)