Spitzer Space Telescope spectra of post-AGB stars in the large magellanic Cloud-polycyclic aromatic hydrocarbons at low metallicities

Mikako Matsuura, Jeronimo Bernard-Salas, T. Lloyd Evans, Kevin M. Volk, Bruce J. Hrivnak, G. C. Sloan, You Hua Chu, Robert Gruendl, Kathleen E. Kraemer, Els Peeters, R. Szczerba, P. R. Wood, Albert A. Zijlstra, S. Hony, Yoshifusa Ita, Devika Kamath, Eric Lagadec, Quentin A. Parker, Warren A. Reid, Takashi ShimonishiH. Van Winckel, Paul M. Woods, F. Kemper, Margaret Meixner, M. Otsuka, R. Sahai, B. A. Sargent, J. L. Hora, Iain McDonald

Research output: Contribution to journalArticle

Abstract

This paper reports variations of polycyclic aromatic hydrocarbons (PAHs) features that were found in Spitzer Space Telescope spectra of carbon-rich post-asymptotic giant branch (post-AGB) stars in the Large Magellanic Cloud (LMC). The paper consists of two parts. The first part describes our Spitzer spectral observing programme of 24 stars including post-AGB candidates. The latter half of this paper presents the analysis of PAH features in 20 carbon-rich post-AGB stars in the LMC, assembled from the Spitzer archive as well as from our own programme.We found that five post-AGB stars showed a broad feature with a peak at 7.7 μm, that had not been classified before. Further, the 10-13 μm PAH spectra were classified into four classes, one of which has three broad peaks at 11.3, 12.3 and 13.3 μm rather than two distinct sharp peaks at 11.3 and 12.7 μm, as commonly found in HII regions. Our studies suggest that PAHs are gradually processed while the central stars evolve from post-AGB phase to planetary nebulae, changing their composition before PAHs are incorporated into the interstellar medium. Although some metallicity dependence of PAH spectra exists, the evolutionary state of an object is more significant than its metallicity in determining the spectral characteristics of PAHs for LMC and Galactic post-AGB stars.

Original languageEnglish (US)
Pages (from-to)1472-1493
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Volume439
Issue number2
DOIs
StatePublished - Apr 2014

Keywords

  • AGB and post-AGB
  • Circumstellar matter
  • Galaxies
  • Individual
  • Infrared
  • Large magellanic cloud
  • Stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Matsuura, M., Bernard-Salas, J., Evans, T. L., Volk, K. M., Hrivnak, B. J., Sloan, G. C., Chu, Y. H., Gruendl, R., Kraemer, K. E., Peeters, E., Szczerba, R., Wood, P. R., Zijlstra, A. A., Hony, S., Ita, Y., Kamath, D., Lagadec, E., Parker, Q. A., Reid, W. A., ... McDonald, I. (2014). Spitzer Space Telescope spectra of post-AGB stars in the large magellanic Cloud-polycyclic aromatic hydrocarbons at low metallicities. Monthly Notices of the Royal Astronomical Society, 439(2), 1472-1493. https://doi.org/10.1093/mnras/stt2495