Open AccessDiscovery of an Extended Ultraviolet Disk in the Nearby Galaxy NGC 4625
Author(s) -
A. Gil de Paz,
B. F. Madore,
S. Boissier,
R. A. Swaters,
C. C. Popescu,
R. J. Tuffs,
Kartik Sheth,
Robert C. Kennicutt,
L. Bianchi,
David A. Thilker,
D. Christopher Martin
Publication year - 2005
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/432054
Subject(s) - physics , astrophysics , galaxy , milky way , spiral galaxy , astronomy , stars , interacting galaxy , star formation , lenticular galaxy , galaxy formation and evolution , galaxy merger , barred spiral galaxy
Recent far-UV (FUV) and near-UV (NUV) observations of the nearby galaxyNGC4625 made by the Galaxy Evolution Explorer (GALEX) show the presence of anextended UV disk reaching 4 times the optical radius of the galaxy. TheUV-to-optical colors suggest that the bulk of the stars in the disk of NGC4625are currently being formed, providing a unique opportunity to study today thephysics of star formation under conditions similar to those when the normaldisks of spiral galaxies like the Milky Way first formed. In the case ofNGC4625, the star formation in the extended disk is likely to be triggered byinteraction with NGC4618 and possibly also with the newly discovered galaxyNGC4625A. The positions of the FUV complexes in the extended disk coincide withpeaks in the H I distribution. The masses of these complexes are in the range10^3-10^4 Msun with their Halpha emission (when present) being dominated byionization from single stars.Comment: 12 pages, 4 figures, accepted for publication in ApJ
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