Poster Abstracts - Kepler - NASA

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POSTER ABSTRACTSP0703. POSTER SESSION IIROTATION OF CLUSTER DWARFS AND SPECTROSCOPIC DIAGNOSTICS. Andrea K. Dupree, 1 ElisabethR. Adams 1 , and Andy Szentgyorgyi 1, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge,MA 02138; (dupree@cfa.harvard.edu, eadams@cfa.harvard.edu, aszentgyorgyi@cfa.havard.edu)Optical spectroscopic diagnostics (Ca II H and K,H-α, Ca IRT, Li I) are widely used to infer stellarproperties such as age, magnetic activity, and windsfrom cool stars. Rotation of a cool star affects thestrength of a magnetic dynamo which in turn determinesthe strength of magnetically associated spectraldiagnostics.We calibrate these diagnostics against rotation periodsfrom Kepler using spectra from the multi-objectspectrograph Hectochelle on the MMT [1]. Hectochelleprovides echelle resolution (~35,000) for selectedwavelength regions spanning ~150Ǻ.NGC 6811, an open cluster of age 1 Gyr in theKepler field has stellar rotation periods derived forsingle dwarf stars [2] from Q1-Q4 of Kepler photometry.Here, we compare these rotation periods to severaldiagnostics from the optical spectra to establish therelations generally applied to individual stars in thefield and evaluate their consistency. This cluster is partof a study of a larger sample of open clusters studiedwith Hectochelle spanning ages of 450 Myr (Melotte111) to 4.4 Gyr (NGC 6791, also in the Kepler field) .References: [1] Szentgyorgi, A. et al. 2011, PASP,in press [2] Meibom. S. et al. 2011, Ap.J., 733, L91862011 Kepler Science Conference - NASA Ames Research Center
POSTER ABSTRACTSP0704. POSTER SESSION IICycle 1 Observations of Low Mass Stars: New Eclipsing Binaries, Single Star Rotation Rates, and the Natureand Frequency of Starspots Thomas E Harrison 1, , J. L. Coughlin 1 , Nick M. Ule 1 , and Mercedes Lopez-Morales 2 ,1Astronomy Department, New Mexico State University, Las Cruces, NM 88003, tharriso@nmsu.edu, jlcough@nmsu.edu,nmule@nmsu.edu, 2 Institut de Ciencies de L'Espai (CSIC-IEEC), mlopez@ieec.uab.esIntroduction: We have analyzed Kepler lightcurves for 849 stars with T eff ≤ 5200 K from our Cycle1 Guest Observer program. We identify six new eclipsingbinaries, one of which has an orbital period of29.91 d, and two of which are probable W UMa variables.In addition, we identify a candidate “warmJupiter” exoplanet. We further examine a subset of 670sources for variability. Of these objects, 265 starsclearly show periodic variability that we assign to rotationof the low-mass star. At the photometric precisionlevel provided by Kepler, 251 of our objects showed noevidence for variability. We were unable to determineperiods for 154 variable objects. We find that 79\% ofstars with T eff ≤ 5200 K are variable. The rotation periodswe derive for the periodic variables span the range0.31 ≤ P rot ≤ 126.5 d. A considerable number of starswith rotation periods similar to the solar value showactivity levels that are 100 times higher than the Sun.This is consistent with results for solar-like field stars.As has been found in previous studies, stars with shorterrotation periods generally exhibit larger modulations.This trend flattens beyond P rot = 25 d, demonstratingthat even long period binaries may still have componentswith high levels of activity and investigatingwhether the masses and radii of the stellar componentsin these systems are consistent with stellar models couldremain problematic. Surprisingly, our modeling of thelight curves suggests that the active regions on thesecool stars are either preferentially located near the rotationalpoles, or that there are two spot groups located atlower latitudes, but in opposing hemispheres.2011 Kepler Science Conference - NASA Ames Research Center 187
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Poster Abstracts - Kepler - NASA

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