1999/06/18 by Ray Jayawardhana, Lee Hartmann, Giovanni Fazio +7 · 5 citations
Chemistry · Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Binary number #Chemistry #Circumstellar disk #Flux (metallurgy) #Infrared #Infrared excess #Physics #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/312200
10 pages and 1 PostScript figure, accepted for publication in The Astrophysical Journal Letters
arxiv created 1999/06/18 · openalex publication_date 1999/08/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
A group of young, active stars in the vicinity of TW Hydrae has recently been identified as a possible physical association with a common origin. Given its proximity (~50 pc), age (~10 Myr), and abundance of binary systems, the TW Hya association is ideally suited to studies of the diversity and evolution of circumstellar disks. Here we present mid-infrared observations of 15 candidate members of the group, 11 of which have no previous flux measurements at wavelengths longer than 2 μm. We report the discovery of a possible 10 μm excess in CD -33°7795, which may be due to a circumstellar disk or a faint and as yet undetected binary companion. Of the other stars, only TW Hya, HD 98800, Hen 3-600A, and HR 4796A—all of which were detected by IRAS —show excess thermal emission. Our 10 μm flux measurements for the remaining members of the association are consistent with photospheric emission, allowing us to rule out dusty inner disks. In light of these findings, we discuss the origin and age of the TW Hya association as well as the implications for disk evolution timescales.