Title: A search for young companions to Vega-type stars
Author(s):Ayako Ono, Yoichi Itoh
Abstract:
Many objects form multiple systems; about half of solar-type stars are binary stars and many planetary systems have been discovered. On the other hand, the very limited number of brown dwarfs are discovered as companions. It is known as the "brown dwarf desert" problem. This scarcity may be attributed to the formation process. To investigate the formation process of brown dwarfs, we surveyed companions of nearby Vega-type stars. We analyzed near-infrared images of 85 Vega-type stars taken with the Infrared Camera on the AKARI satellite and detected 105 faint objects around 62 stars. To exclude background stars, we estimated temperatures and distances of 14 faint objects around 12 stars by constructing their spectral energy distributions from broad-band photometries. As a result, we identified a companion candidate at 82" away from an F-type star, HIP 18170.The temperature of the candidate is estimated to be between 2500 to 3150 K from its SED, corresponding to the spectral type of L0-M4. This object may be a brown dwarf companion to a Vega-type star.