Infrared spectroscopy of asymptotic giant branch stars in the Galactic bulge

S. S. Golriz; J. A.D.L. Blommaert; E. Vanhollebeke; M. A.T. Groenewegen; H. J. Habing; F. Kemper; M. Schultheis; A. G.G.M. Tielens; L. B.F.M. Waters; P. R. Wood; J. Cami

doi:10.1093/mnras/stu1317

Infrared spectroscopy of asymptotic giant branch stars in the Galactic bulge

S. S. Golriz^*, J. A.D.L. Blommaert, E. Vanhollebeke, M. A.T. Groenewegen, H. J. Habing, F. Kemper, M. Schultheis, A. G.G.M. Tielens, L. B.F.M. Waters, P. R. Wood, J. Cami

^*Corresponding author for this work

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Abstract

We have selected a homogeneous sample of asymptotic giant branch (AGB) stars in theGalactic bulge population from the ISOGAL survey. Our target stars cover a wide range of mass-loss rates (~10^-8-10^-4 M⊙ yr^-1) and differ primarily by their age on the AGB. This homogeneous sample is thus ideally suited to study the dust formation process as a function of age on the AGB. We observed our sample with Spitzer-Infrared Spectrograph, and studied the overall properties of the infrared spectra of these targets. The analysis is complicated by the presence of strong and variable background emission, and the extracted infrared AGB star spectra are affected by interstellar extinction. Several stars in our sample have no detectable dust emission, and we used these 'naked stars' to characterize the stellar and molecular contributions to the infrared spectra of our target stars. The resulting dust spectra of our targets do indeed show significant variety in their spectral appearance, pointing to differing dust compositions for the targets. We classify the spectra based on the shape of their 10-μm emission following the scheme by Sloan & Price.We find that the early silicate emission classes associated with oxide dust are generally under-represented in our sample due to extinction effects. We also find a weak 13-μm dust feature in two of our otherwise naked star spectra, suggesting that the carrier of this feature could potentially be the first condensate in the sequence of dust condensation.

Original language	English
Pages (from-to)	3402-3434
Number of pages	33
Journal	Monthly Notices of the Royal Astronomical Society
Volume	443
Issue number	4
DOIs	https://doi.org/10.1093/mnras/stu1317
Publication status	Published - 1 Oct 2014

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Golriz, S. S., Blommaert, J. A. D. L., Vanhollebeke, E., Groenewegen, M. A. T., Habing, H. J., Kemper, F., Schultheis, M., Tielens, A. G. G. M., Waters, L. B. F. M., Wood, P. R., & Cami, J. (2014). Infrared spectroscopy of asymptotic giant branch stars in the Galactic bulge. Monthly Notices of the Royal Astronomical Society, 443(4), 3402-3434. https://doi.org/10.1093/mnras/stu1317

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title = "Infrared spectroscopy of asymptotic giant branch stars in the Galactic bulge",

abstract = "We have selected a homogeneous sample of asymptotic giant branch (AGB) stars in theGalactic bulge population from the ISOGAL survey. Our target stars cover a wide range of mass-loss rates (~10-8-10-4 M⊙ yr-1) and differ primarily by their age on the AGB. This homogeneous sample is thus ideally suited to study the dust formation process as a function of age on the AGB. We observed our sample with Spitzer-Infrared Spectrograph, and studied the overall properties of the infrared spectra of these targets. The analysis is complicated by the presence of strong and variable background emission, and the extracted infrared AGB star spectra are affected by interstellar extinction. Several stars in our sample have no detectable dust emission, and we used these 'naked stars' to characterize the stellar and molecular contributions to the infrared spectra of our target stars. The resulting dust spectra of our targets do indeed show significant variety in their spectral appearance, pointing to differing dust compositions for the targets. We classify the spectra based on the shape of their 10-μm emission following the scheme by Sloan & Price.We find that the early silicate emission classes associated with oxide dust are generally under-represented in our sample due to extinction effects. We also find a weak 13-μm dust feature in two of our otherwise naked star spectra, suggesting that the carrier of this feature could potentially be the first condensate in the sequence of dust condensation.",

keywords = "Circumstellar matter, Infrared: stars, Stars: AGB and post-AGB, Stars: mass-loss",

author = "Golriz, {S. S.} and Blommaert, {J. A.D.L.} and E. Vanhollebeke and Groenewegen, {M. A.T.} and Habing, {H. J.} and F. Kemper and M. Schultheis and Tielens, {A. G.G.M.} and Waters, {L. B.F.M.} and Wood, {P. R.} and J. Cami",

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AU - Golriz, S. S.

AU - Blommaert, J. A.D.L.

AU - Vanhollebeke, E.

AU - Groenewegen, M. A.T.

AU - Habing, H. J.

AU - Kemper, F.

AU - Schultheis, M.

AU - Tielens, A. G.G.M.

AU - Waters, L. B.F.M.

AU - Wood, P. R.

AU - Cami, J.

PY - 2014/10/1

Y1 - 2014/10/1

N2 - We have selected a homogeneous sample of asymptotic giant branch (AGB) stars in theGalactic bulge population from the ISOGAL survey. Our target stars cover a wide range of mass-loss rates (~10-8-10-4 M⊙ yr-1) and differ primarily by their age on the AGB. This homogeneous sample is thus ideally suited to study the dust formation process as a function of age on the AGB. We observed our sample with Spitzer-Infrared Spectrograph, and studied the overall properties of the infrared spectra of these targets. The analysis is complicated by the presence of strong and variable background emission, and the extracted infrared AGB star spectra are affected by interstellar extinction. Several stars in our sample have no detectable dust emission, and we used these 'naked stars' to characterize the stellar and molecular contributions to the infrared spectra of our target stars. The resulting dust spectra of our targets do indeed show significant variety in their spectral appearance, pointing to differing dust compositions for the targets. We classify the spectra based on the shape of their 10-μm emission following the scheme by Sloan & Price.We find that the early silicate emission classes associated with oxide dust are generally under-represented in our sample due to extinction effects. We also find a weak 13-μm dust feature in two of our otherwise naked star spectra, suggesting that the carrier of this feature could potentially be the first condensate in the sequence of dust condensation.

AB - We have selected a homogeneous sample of asymptotic giant branch (AGB) stars in theGalactic bulge population from the ISOGAL survey. Our target stars cover a wide range of mass-loss rates (~10-8-10-4 M⊙ yr-1) and differ primarily by their age on the AGB. This homogeneous sample is thus ideally suited to study the dust formation process as a function of age on the AGB. We observed our sample with Spitzer-Infrared Spectrograph, and studied the overall properties of the infrared spectra of these targets. The analysis is complicated by the presence of strong and variable background emission, and the extracted infrared AGB star spectra are affected by interstellar extinction. Several stars in our sample have no detectable dust emission, and we used these 'naked stars' to characterize the stellar and molecular contributions to the infrared spectra of our target stars. The resulting dust spectra of our targets do indeed show significant variety in their spectral appearance, pointing to differing dust compositions for the targets. We classify the spectra based on the shape of their 10-μm emission following the scheme by Sloan & Price.We find that the early silicate emission classes associated with oxide dust are generally under-represented in our sample due to extinction effects. We also find a weak 13-μm dust feature in two of our otherwise naked star spectra, suggesting that the carrier of this feature could potentially be the first condensate in the sequence of dust condensation.

KW - Circumstellar matter

KW - Infrared: stars

KW - Stars: AGB and post-AGB

KW - Stars: mass-loss

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DO - 10.1093/mnras/stu1317

M3 - Article

SN - 0035-8711

VL - 443

SP - 3402

EP - 3434

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 4

ER -

Infrared spectroscopy of asymptotic giant branch stars in the Galactic bulge

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