Bibcode
Nowak, G.; Niedzielski, A.; Wolszczan, A.
Bibliographical reference
American Astronomical Society, ESS meeting #2, #30.04
Advertised on:
9
2011
Citations
0
Refereed citations
0
Description
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.