Optically visible post-AGB stars, post-RGB stars and young stellar objects in the Large Magellanic Cloud

D. Kamath*, P. R. Wood, H. Van Winckel

*Corresponding author for this work

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

We have carried out a search for optically visible post-asymptotic giant branch (post-AGB) stars in the Large Magellanic Cloud (LMC). First, we selected candidates with a mid-IR excess and then obtained their optical spectra. We disentangled contaminants with unique spectra such as M stars, C stars, planetary nebulae, quasi-stellar objects and background galaxies. Subsequently, we performed a detailed spectroscopic analysis of the remaining candidates to estimate their stellar parameters such as effective temperature, surface gravity (log g), metallicity ([Fe/H]), reddening and their luminosities. This resulted in a sample of 35 likely post-AGB candidates with late-G to late-A spectral types, low log g, and [Fe/H] < -0.5. Furthermore, our study confirmed the existence of the dusty post-red giant branch (post-RGB) stars, discovered previously in our Small Magellanic Cloud survey, by revealing 119 such objects in the LMC. These objects have mid-IR excesses and stellar parameters (Teff, log g, [Fe/H]) similar to those of post-AGB stars except that their luminosities (< 2500 L), and hence masses and radii, are lower. These post-RGB stars are likely to be products of binary interaction on the RGB. The post-AGB and post-RGB objects show spectral energy distribution properties similar to the Galactic post-AGB stars, where some have a surrounding circumstellar shell, while some others have a surrounding stable disc similar to the Galactic post-AGB binaries. This study also resulted in a new sample of 162 young stellar objects, identified based on a robust log g criterion. Other interesting outcomes include objects with an UV continuum and an emission line spectrum; luminous supergiants; hot main-sequence stars; and 15 B[e] star candidates, 12 of which are newly discovered in this study.

Original languageEnglish
Pages (from-to)1468-1502
Number of pages35
JournalMonthly Notices of the Royal Astronomical Society
Volume454
Issue number2
DOIs
Publication statusPublished - 1 Dec 2015
Externally publishedYes

Keywords

  • Magellanic Clouds
  • Planetary nebulae: general
  • Stars: AGB and post-AGB
  • Stars: fundamental parameters
  • Techniques: photometric
  • Techniques: spectroscopic

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