IONIZED GAS KINEMATICS AT HIGH RESOLUTION. II. DISCOVERY OF A DOUBLE INFRARED CLUSTER IN II Zw 40
- School of Physics and Astronomy, Tel Aviv University, Ramat Aviv 69978 (Israel)
- Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 (United States)
- Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States)
- Southwest Research Institute, San Antonio, TX 78228-0510 (United States)
The nearby dwarf galaxy II Zw 40 hosts an intense starburst. At the center of the starburst is a bright compact radio and infrared source, thought to be a giant dense H II region containing Almost-Equal-To 14, 000 O stars. Radio continuum images suggest that the compact source is actually a collection of several smaller emission regions. We accordingly use the kinematics of the ionized gas to probe the structure of the radio-infrared emission region. With TEXES on the NASA-IRTF we measured the 10.5 {mu}m [S IV] emission line with effective spectral resolutions, including thermal broadening, of {approx}25 and {approx}3 km s{sup -1} and spatial resolution {approx}1''. The line profile shows two distinct, spatially coextensive, emission features. The stronger feature is at galactic velocity and has FWHM 47 km s{sup -1}. The second feature is {approx}44 km s{sup -1} redward of the first and has FWHM 32 km s{sup -1}. We argue that these are two giant embedded clusters, and estimate their masses to be Almost-Equal-To 3 Multiplication-Sign 10{sup 5} M{sub Sun} and Almost-Equal-To 1.5 Multiplication-Sign 10{sup 5} M{sub Sun }. The velocity shift is unexpectedly large for such a small spatial offset. We suggest that it may arise in a previously undetected kinematic feature remaining from the violent merger that formed the galaxy.
- OSTI ID:
- 22167403
- Journal Information:
- Astrophysical Journal, Vol. 767, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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