SPITZER/INFRARED SPECTROGRAPH INVESTIGATION OF MIPSGAL 24 {mu}m COMPACT BUBBLES
- Spitzer Science Center, California Institute of Technology, 1200 East California Boulevard, MC 220-6, Pasadena, CA 91125 (United States)
- NASA Herschel Science Center, California Institute of Technology, 770 S. Wilson Ave, MS 100-22, Pasadena, CA 91125 (United States)
The MIPSGAL 24 {mu}m Galactic Plane Survey has revealed more than 400 compact-extended objects. Less than 15% of these MIPSGAL bubbles (MBs) are known and identified as evolved stars. We present Spitzer observations of four MBs obtained with the InfraRed Spectrograph to determine the origin of the mid-IR emission. We model the mid-IR gas lines and the dust emission to infer physical conditions within the MBs and consequently their nature. Two MBs show a dust-poor spectrum dominated by highly ionized gas lines of [O IV], [Ne III], [Ne V], [S III], and [S IV]. We identify them as planetary nebulae with a density of a few 10{sup 3} cm{sup -3} and a central white dwarf of {approx}>200,000 K. The mid-IR emission of the two other MBs is dominated by a dust continuum and lower-excitation lines. Both of them show a central source in the near-IR (Two Micron All Sky Survey and IRAC) broadband images. The first dust-rich MB matches a Wolf-Rayet star of {approx}60,000 K at 7.5 kpc with dust components of {approx}170 and {approx}1750 K. Its mass is about 10{sup -3} M{sub sun} and its mass loss is about 10{sup -6} M{sub sun} yr{sup -1}. The second dust-rich MB has recently been suggested as a Be/B[e]/luminous blue variable candidate. The gas lines of [Fe II] as well as hot continuum components ({approx}300 and {approx}1250 K) arise from the inside of the MB while its outer shell emits a colder dust component ({approx}75 K). The distance to the MB remains highly uncertain. Its mass is about 10{sup -3} M{sub sun} and its mass loss is about 10{sup -5} M{sub sun} yr{sup -1}.
- OSTI ID:
- 21587324
- Journal Information:
- Astrophysical Journal, Vol. 741, Issue 1; Other Information: DOI: 10.1088/0004-637X/741/1/4; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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