Astronomy and Astrophysics – Astronomy
Scientific paper
Sep 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011ess.....2.3004n&link_type=abstract
American Astronomical Society, ESS meeting #2, #30.04
Astronomy and Astrophysics
Astronomy
Scientific paper
Evolved stars observed within the Penn State - Torun Center for Astronomy Planet Search (PTPS) conducted with the Hobby-Eberly Telescope are supposed to present various effects of activity. In addition to chromospheric activity and/or pulsations one may expect spots temporarily appearing on their surfaces and rotating with stars that mimic planetary companions in precise radial velocities (RV) by altering line profiles. Proper interpretation of the observed radial velocity variations in these stars requires therefore simultaneous to RV measurements monitoring of line profile variations at the precision level comparable to that in RV. The most efficient way of such a monitoring is bisector velocity span (BVS) and/or bisector curvature variation (BC) monitoring using exactly the same spectra as used in measurements of RV.
To achieve maximum possible atomization in simultaneous RV and BVS/BC measurement we developed an independent code. The main point in our approach is the combination of the iodine cell method (Marcy & Butler 1992) for RVs and the cross-correlation technique for BVS/BC (Queloz et al. 2001). Using the iodine cell method to measure RVs independently in 96-pixel long segments of our HET/HRS spectra we obtain information about imperfection in the initial Th-Ar dispersion curve and determine the instrumental profile. With these informations at hand we clean-up our spectra from the iodine lines and construct the cross-correlation function (CCF) from exactly the same parts of the spectra from which we measure RVs.
Here we present examples of application of our code. We show BVS variations in HD 166435, present new spectroscopic binaries detected within PTPS with the CCF technique, and demonstrate precision of the RV code for stars of various spectral types. We also present the calibration of the vsin(i) of our stars based on the width of the CCFs obtained from our template spectra.
Niedzielski Andrzej
Nowak Grzegorz
Wolszczan Alex
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