The Great Austral Nearby Young Association 1

• Main Authors: Ray Jayawardhana, Thomas Greene, C. A. O. Torres, G. R. Quast, C. H. F. Melo
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2001
• Subjects: Austral; Hora; South Pole; South pole
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.315.3948; http://arxiv.org/pdf/astro-ph/0105291v1.pdf

Abstract. Observing ROSAT sources in an area covering ∼30 % of the Southern Hemisphere, we found evidences for a great nearby association (GAYA), comprising the proposed associations of Horologium (HorA) and the eastern part of Tucana (TucA), formed by at least 44 Post-T Tauri stars. The stars of the GAYA have similar space velocity components relative to the Sun (U, V, W) =(−9.8 ± 1.2, −21.7 ± 1.1, −2.0 ± 2.2) km/s and their Li line intensities are between those of the classical T Tauri stars and the ones of the Local Association stars. The distances of the members of the GAYA cover an interval of ∼70 pc, compatible with the angular size of ∼ 60 ◦ and in agreement with an initial velocity dispersion of ∼1.5 km/s and its evolutive age. We found many other young stars, not members of the GAYA. We also observed a control region near the equator, covering 700 square degrees, where we found only four young stars. The overabundance of young stars near the South Pole (by a factor of five) seems to show that there may be other young associations not yet characterized. 1.