(Proposal ID) S11A-071

(PI) Sato, Bun'ei

(Proposal Title)
Precise Radial Velocity Measurements of Hyades A-type Stars

(Abstract)
Intermediate-mass A-type dwarfs have attracted increasing attention as 
promising sites for planet formation based on the discoveries of many giant 
planets by precise Doppler surveys of intermediate-mass giants and subgiants, 
which are "evolved counter parts of A-type dwarfs". On the other hand, planets 
around A-type dwarfs have not been extensively explored so far due to the poor 
measurement precision in radial velocity (RV) because of the paucity of 
spectral features and the rapid rotation. We here propose a simple but new 
idea for precise RV measurements of rapidly-rotating A-type dwarfs. We try to 
overcome the poor measurement precision by very high-S/N observations; we 
collect many high-S/N spectra in a short period of time (~30 min) taking 
advantage of the large aperture of Subaru to obtain a total S/N higher than 
1500, and then take average of the derived RVs. If the idea works well, we can 
achieve an RV precision better than 10 m s^-1 for rapidly-rotating A-type 
stars. We select three well-studied "Hyades A-type dwarfs" as our science 
targets. This project has an aspect of extension of the previous Doppler 
surveys of Hyades F-M dwarfs and intermediate-mass GK giants.