Direct Imaging and Spectroscopy of Substellar Companions Next to Young Nearby Stars in TWA

Ralph Neuhäuser, Eike Guenther, Wolfgang Brandner, Nuria Húelamo, Thomas Ott, João Alves, Fernando Cómeron, Jean-Gabriel Cuby, Andreas Eckart

Direct imaging of substellar companions is possible since several years

around nearby stars (e.g. Gl 229) and young stars (e.g. TWA-5). We are

searching for brown dwarfs and giant planets as companions to stars

which are both very young (up to 100 Myrs) and relatively nearby (up to

100 pc), using ground-based facilities on La Silla, Cerro Paranal, Mauna

Kea, and Calar Alto with infrared imaging including speckle and adaptive

optics. The young nearby association of co-moving T Tauri stars around

TW Hya, called the TW Hya Association (TWA), is a prime target of our

observations. We will present imaging detections of substellar companion

candidates around three TWA stars and their H-band spectra, showing that

they are background stars. Given all the available ground-based and

space-based (HST NICMOS) data obtained so far for the TWA stars, we will

discuss the frequency of young brown dwarf companions, to be compared to

the frequency of old brown dwarf companions, both wide pairs from

imaging surveys as well as close pairs from radial velocity surveys. We

find no indications for young brown dwarf secondaries to be

overabundant, so that there is no evidence that many of them get ejected

during young ages.

Department of Astrophysics
External organisation(s)
Thüringer Landessternwarte Tautenburg, European Southern Observatory (Germany), Max-Planck-Institut für extraterrestrische Physik, Universität zu Köln, University of Hawaii at Manoa
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