AAS 205th Meeting, 9-13 January 2005
Session 128 The Buildup of Galaxy Disks - Star Formation History
Oral, Wednesday, January 12, 2005, 2:00-3:30pm, California

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[128.01] Witnessing the Formation of a Extended Galactic Disk in the Nearby Spiral Galaxy NGC 4625

B. F. Madore, A. Gil de Paz, S. Boissier (Carnegie Observatories), GALEX Science Team

Recent UV observations of the nearby spiral galaxy NGC 4625 made by GALEX in the course of undertaking the Nearby Galaxies Survey have led to the discovery of a UV-bright disk extending more than four times beyond the optical radius of its host. The UV disk is found to spatially correlate with an extended low-density HI halo seen at 21cm. The ubiquity of the UV emission in the extended disk of this galaxy and its extremely low surface brightness at optical wavelengths indicates this disk is forming most of its stars at the current epoch. This galaxy provides us with a unique opportunity to study the on-going formation of stellar galactic disks which may give valuable insights into the formation of spiral galaxies at high redshift.

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.