Mon. Not. R. Astron. Soc., 454, 1468-1502 (2015/December-1)
Optically visible post-AGB stars, post-RGB stars and young stellar objects in the Large Magellanic Cloud.
KAMATH D., WOOD P.R. and VAN WINCKEL H.
Abstract (from CDS):
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 (logg), 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 logg, 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, logg, [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 logg 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.
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
techniques: photometric - techniques: spectroscopic - stars: AGB and post-AGB - stars: fundamental parameters - planetary nebulae: general - Magellanic Clouds
VizieR on-line data:
<Available at CDS (J/MNRAS/454/1468): table2.dat table4.dat table5.dat table6.dat tablea1.dat tablea2.dat tablea3.dat tableb1.dat refs.dat fig/* sed/*>
Table 2: [KWV2015] JHHMMSS.ss+DDMMSS.s N=2106.
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