HI Envelopes Around Low Luminosity Galaxies

van Zee, L., Haynes, M.P., & Giovanelli, R. 1995, AJ, 109, 990.

Abstract

HI mapping observations of a sample of isolated low luminosity galaxies were undertaken with the Arecibo 305m telescope in order to determine the extent of their HI distribution. The sample included both compact emission-line galaxies (BCD's) and galaxies with hydrogen mass to blue luminosity ratios, M_H/L_B, greater than five. Of 78 targeted galaxies, 49 were found to have extended HI envelopes. Whereas most (25 of 41) of the BCD's are compact in both optical light and in HI, 29 of the 33 high M_H/L_B galaxies had some evidence of extended hydrogen. As a class, the high M_H/L_B galaxies are low luminosity, low optical surface brightness, gas-rich dwarfs. Their extreme values of M_H/L_B and large HI extent make them similar to HI 1225+01 and I Zw 18, but the possibility that the high M_H/L_B galaxies are BCD's in a quiescent phase is still unresolved.

ADS abstract