The HI dominated Low Surface Brightness Galaxy KKR17
  We present new narrow-band (H$\alpha$ and [OIII]) imagings and optical
spectrophotometry of HII regions for a gas-rich low surface brightness
irregular galaxy, KKR 17. The central surface brightness of the galaxy is
$\mu_0(B)$ = 24.15 $\pm$0.03 mag~sec$^{-2}$. The galaxy was detected by
\emph{Arecibo Legacy Fast ALFA survey} (ALFALFA), and its mass is dominated by
neutral hydrogen (HI) gas. In contrast, both the stellar masses of the bright
HII and diffuse stellar regions are small. In addition, the fit to the spectral
energy distribution to each region shows the stellar populations of HII and
diffuse regions are different. The bright HII region contains a large fraction
of O-type stars, revealing the recent strong star formation, whereas the
diffuse region is dominated by median age stars, which has a typical age of
$\sim$ 600 Myrs. Using the McGaugh's abundance model, we found that the average
metallicity of KKR 17 is 12 + (O/H) = 8.0 $\pm$ 0.1. The star formation rate of
KKR 17 is 0.21$\pm$0.04 M$_{\odot}$/yr, which is $\sim$1/5 of our Milky Way's.
Based on the analysis results to young stellar clusters in HII region, it is
found that the bright HII region showed two sub-components with different
velocities and metallicities. This may be caused by the outflow of massive
stars or merging events. However, the mechanism of triggering star formation in
the HII region is still uncertain.
