SCYON Abstract

Received on May 22 2002

Remnants of the Sagittarius Dwarf Spheroidal Galaxy around the young globular cluster Palomar 12

AuthorsD. Martínez-Delgado1, R. Zinn2, R. Carrera1, C. Gallart1
Affiliation1Instituto de Astrofísica de Canarias, E38200 La Laguna, Tenerife, Canary Islands, Spain,
2 Yale University, Department of Astronomy, P.O. Box 208101, New Haven, CT 06520-8101
Submitted toApJ Letters


Photometry of a large field around the young globular cluster Palomar 12 has revealed the main-sequence of a low surface-brightness stellar system. This main-sequence is indicative of a stellar population that varies significantly in metallicity and/or age, but in the mean is more metal poor than Pal 12. Under different assumptions for the properties of this population, we find distances from the Sun in the range 17-24 kpc, which encompasses the distance to Pal 12, 19.0 ± 0.9 kpc. The stellar system is also detected in a field 2° North of Pal 12, which indicates it has a minimum diameter of ~0.9 kpc. The orbit of Pal 12 (Dinescu et al. 2000), the color-magnitude diagram of the stellar system, their positions on the sky, and their distances suggest that they are debris from the tidal disruption of the Sgr dSph galaxy. We discuss briefly the implications for the evolution of Sgr and the Galactic halo.