Spitzer SAGE-Spec: Near infrared spectroscopy, dust shells, and cool envelopes in extreme Large Magellanic Cloud asymptotic giant branch stars

Journal Article · Sat Nov 01 00:00:00 EDT 2014 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/148/5/86· OSTI ID:22342104

Blum, R. D. ^[1]; Srinivasan, S.; Kemper, F.; Ling, B. ^[2]; Volk, K. ^[3]

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1. NOAO, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
2. Academia Sinica, Institute of Astronomy and Astrophysics, 11F of Astronomy-Mathematics Building, NTU/AS, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China)
3. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

K-band spectra are presented for a sample of 39 Spitzer Infrared Spectrograph (IRS) SAGE-Spec sources in the Large Magellanic Cloud. The spectra exhibit characteristics in very good agreement with their positions in the near-infrared—Spitzer color-magnitude diagrams and their properties as deduced from the Spitzer IRS spectra. Specifically, the near-infrared spectra show strong atomic and molecular features representative of oxygen-rich and carbon-rich asymptotic giant branch stars, respectively. A small subset of stars was chosen from the luminous and red extreme ''tip'' of the color-magnitude diagram. These objects have properties consistent with dusty envelopes but also cool, carbon-rich ''stellar'' cores. Modest amounts of dust mass loss combine with the stellar spectral energy distribution to make these objects appear extreme in their near-infrared and mid-infrared colors. One object in our sample, HV 915, a known post-asymptotic giant branch star of the RV Tau type, exhibits CO 2.3 μm band head emission consistent with previous work that demonstrates that the object has a circumstellar disk.

• OSTI ID: 22342104
• Journal Information: Astronomical Journal (New York, N.Y. Online), Vol. 148, Issue 5; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABSORPTION SPECTROSCOPY
ASYMPTOTIC SOLUTIONS
CARBON
CARBON MONOXIDE
COLOR
DUSTS
EMISSION
ENERGY SPECTRA
INFRARED SPECTRA
MAGELLANIC CLOUDS
MASS TRANSFER
NEAR INFRARED RADIATION
OXYGEN
STARS
STELLAR WINDS