期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 736, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/736/1/L22
关键词
galaxies: abundances; galaxies: dwarf; galaxies: individual (WISEP J080103.93+264053.9, WISEP J170233.53+180306.4); galaxies: starburst
资金
- National Aeronautics and Space Administration
- W. M. Keck Foundation
We report two new low-metallicity blue compact dwarf galaxies (BCDs), WISEP J080103.93+264053.9 (hereafter W0801+26) and WISEP J170233.53+180306.4 (hereafter W1702+18), discovered using the Wide-field Infrared Survey Explorer (WISE). We identified these two BCDs from their extremely red colors at mid-infrared wavelengths and obtained follow-up optical spectroscopy using the Low Resolution Imaging Spectrometer on Keck I. The mid-infrared properties of these two sources are similar to the well-studied, extremely low metallicity galaxy SBS 0335-052E. We determine metallicities of 12+log (O/H) = 7.75 and 7.63 for W0801+26 and W1702+18, respectively, placing them among a very small group of very metal deficient galaxies (Z <= 1/10Z(circle dot)). Their >300 angstrom H beta equivalent widths, similar to SBS 0335-052E, imply the existence of young (<5Myr) star-forming regions. We measure star formation rates of 2.6 and 10.9M(circle dot) yr(-1) for W0801+26 and W1702+18, respectively. These BCDs, showing recent star formation activity in extremely low metallicity environments, provide new laboratories for studying star formation in extreme conditions and are low-redshift analogs of the first generation of galaxies to form in the universe. Using the all-sky WISE survey, we discuss a new method to identify similar star-forming, low-metallicity BCDs.
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