Spitzer/IRS investigation of MIPSGAL 24 microns compact bubbles
Nov, 2011Citations per year
Abstract: (arXiv)
The MIPSGAL 24 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 4 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 [\ion{O}{4}], [\ion{Ne}{3}], [\ion{Ne}{5}], [\ion{S}{3}] and [\ion{S}{4}]. We identify them as planetary nebulae with a density of a few 10 and a central white dwarf of 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 (2MASS and IRAC) broadband images. The first dust-rich MB matches a Wolf-Rayet star of K at 7.5 kpc with dust components of and K. Its mass is about and its mass loss is about . The second dust-rich MB has recently been suggested as a Be/B[e]/LBV candidate. The gas lines of [\ion{Fe}{2}] as well as hot continuum components ( and K) arise from the inside of the MB while its outer shell emits a colder dust component ( K). The distance to the MB remains highly uncertain. Its mass is about and its mass loss is about .Note:
- accepted for publication in ApJ
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