The Great Austral Nearby Young Association

• Main Authors: Torres, C. A. O., Quast, G. R., de la Reza, R., da Silva, L., Melo, C. H. F.
• Format: Report
• Language: unknown
• Published: arXiv 2001
• Subjects: Astrophysics astro-ph; FOS Physical sciences; Austral; Greene; Hora; South Pole; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.astro-ph/0105291; https://arxiv.org/abs/astro-ph/0105291

Observing ROSAT sources in an area covering $\sim$30% of the Southern Hemisphere, we found evidences for a great nearby association (GAYA), comprising the proposed associations of Horologium (HorA) and the eastern part of Tucana (TucA), formed by at least 44 Post-T Tauri stars. The stars of the GAYA have similar space velocity components relative to the Sun (U, V, W) = ($-9.8 \pm 1.2, -21.7 \pm 1.1, -2.0 \pm 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 $\sim$70 pc, compatible with the angular size of $\sim60°$ and in agreement with an initial velocity dispersion of $\sim$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. : latex file, 5 pages, 3 figures, conference: Young Stars Near Earth: Progress and Prospects, ASP Conference Series ed:Ray Jayawardhana and Thomas Greene