NOAO >   Observing Info >   Approved Programs >   2009B-0142

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Proposal Information for 2009B-0142


PI: Andreas Seifahrt, University of Goettingen, seifahrt@astro.physik.uni-goettingen.de
Address: Institute for Astrophysics, Friedrich-Hund-Platz 1, Goettingen 37073, Germany

CoI: Jacob Bean, University of Goettingen
CoI: Todd Henry, Georgia State University

Title: Rotation periods and activity of low mass stars: supporting a large near- infrared radial velocity campaign

Abstract: We have been granted a large programme (33 nights over four semesters) with CRIRES to conduct a radial velocity search programme on about 40 mid- to late M dwarfs. We developed an absorption cell for CRIRES which allows us to achieve detection limits of about 5 m/s, precise enough to find Neptune mass planets around most of these stars. We propose here for supporting photometric observations addressing two important points: (1) We need to measure the rotational periods of all targets of our RV programme to (a) estimate the inclination angle of the stars (which is likely the same for the orbital inclination of their planets) and (b) to distinguish between a RV signal induced by a planet and a 'false' RV signal due to star spots. (2) It is commonly believed that due to the reduced contrast between stellar spots and photosphere in the nIR, photometric and RV signatures from stellar activity are notably reduced at longer wavelength. However, empirical results supporting this assumption are still preliminary. We thus propose to monitor the activity level of our targets with simultaneous photometry in the optical and in the near infrared in parallel to our VLT/CRIRES observations. Variability in the photometric signal is a direct result of the activity of the stars and the ratio in amplitude between the optical and near infrared allows us to determine the spot temperatures and surface area, as well as the lifetimes of these features.


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