VII Zw 403: H I STRUCTURE IN A BLUE COMPACT DWARF GALAXY
- Department of Physics, Florida International University, Miami, FL 33199 (United States)
- Lowell Observatory, Flagstaff, AZ 86001 (United States)
- Department of Physics, University of Redlands, Redlands, CA 92373 (United States)
- Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL 10 9AB (United Kingdom)
- IBM T. J. Watson Research Center, Yorktown Heights, NY 10598 (United States)
- Kitt Peak National Observatory, NOAO, Tucson, AZ 85726 (United States)
- Australia Telescope National Facility, CSIRO, Epping, NSW 1710 (Australia)
- Stockholm Observatory, Department of Astronomy, AlbaNova, SE-10691 Stockholm (Sweden)
- Department of Physics, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States)
We present optical (UBVJ), ultraviolet (FUV, NUV), and high-resolution atomic hydrogen (H I) observations of the nearby blue compact dwarf (BCD), VII Zw 403. We find that VII Zw 403 has a relatively high H I mass-to-light ratio for a BCD. The rotation velocity is nominally 10-15 km s{sup -1}, but rises to {approx}20 km s{sup -1} after correction for the {approx}8-10 km s{sup -1} random motions present in the gas. The velocity field is complex, including a variation in the position angle of the major axis going from the northeast to the southwest parts of the galaxy. Our high-resolution H I maps reveal structure in the central gas, including a large, low-density H I depression or hole between the southern and northern halves of the galaxy, coincident with an unresolved X-ray source. Although interactions have been proposed as the triggering mechanism for the vigorous star formation occurring in BCDs, VII Zw 403 does not seem to have been tidally triggered by an external interaction, as we have found no nearby possible perturbers. It also does not appear to fall in the set of galaxies that exhibit a strong central mass density concentration, as its optical scale length is large in comparison to similar systems. However, there are some features that are compatible with an accretion event: optical/H I axis misalignment, a change in position angle of the kinematic axis, and a complex velocity field.
- OSTI ID:
- 21582928
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 3 Vol. 142; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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