HI observations of SA 68-6597: The faintest blue compact dwarf galaxy

作者：Pisano DJ^*; Koo DC; Willmer CNA; Noeske KG; Phillips AC

来源：Astrophysical Journal, 2005, 630(1): L25-L28.

DOI：10.1086/491645

• galaxies : dwarf
• galaxies : evolution
• galaxies : formation
• galaxies : fundamental parameters
• galaxies : ISM

Blue compact dwarf galaxies ( BCDs) are faint (M-B <= -17 mag), compact (R < 1 kpc), and at least qualitatively very blue galaxies, due to active star formation, and have low metallicities. Found serendipitously as part of a redshift survey of faint galaxies with the Keck Telescope ( DEEP), SA 68- 6597 is at a distance of 80 Mpc, and is one of the faintest ( - 12.4 mag), lowest metallicity (similar to 0.05 Z(circle dot),) BCDs known. Its H beta line width of sigma = 27 km s (-1) and small size,R-eff similar to 190 pc, suggest that it is an extremely low mass galaxy. We have used the Arecibo telescope to measure R similar to 190 the H (I) properties of SA 68- 6597 in order to better constrain its total mass and its potential for future star formation. SA 68- 6597 has a M-HI =(1.4 +/- 0.4) x 10(7) M-circle dot and H I FWHM line width of 33 (+60)(-12) Combining the H (I) width with an estimate of the size of H (I) disk, we derive M-dyn greater than or similar to 3 x 10(7) M circle dot. The values M-HI /L-B = 1.0 +/- 0.3 M-circle dot/L-circle dot, M-dyn /L-B > 2 M-circle dot/ L-circle dot and M-HI/M-dyn <= 0.47 are typical for BCDs. Combining the measured star formation 0.3M(circle dot) yr(-1)with the H (I) mass, we derive a gas depletion timescale of 5 +/- 2 Gyr. While SA 68-6597 is a fainter, lower mass, higher metalicity counterpart to other BCDs like I Zw 18 and SBS 0335-052, its H (I) properties suggest that it will not evolve dramaticaly in the near future. Given the limits on its gaseous and dynamical masses, SA 68-6597 may be able to evolve into a moderately massive dwarf spheroidal galaxy.

• 出版日期2005-9-1