Zusammenfassung
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 amongst a very small
group of very metal deficient galaxies (Z < 1/10 Zsun). Their > 300 Angstrom
Hbeta equivalent widths, similar to SBS 0335-052E, imply the existence of young
(< 5 Myr) star forming regions. We measure star formation rates of 2.6 and 10.9
Msun/yr 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.
Beschreibung
[1106.4844] WISE Discovery of Low Metallicity Blue Compact Dwarf Galaxies
Links und Ressourcen
Tags