Distinguishing post-AGB impostors in a sample of pre-main sequence stars

Abstract

A sample of 27 sources, catalogued as pre-main sequence stars by the Pico dos Dias Survey (PDS), is analyzed to investigate a possible contamination by post-AGB stars. The far-infrared excess, due to dust present in the circumstellar envelope, is typical for both categories: young stars and objects that have already left the main sequence and are suffering a severe mass-loss. The presence of two known post-AGB stars in our sample inspired us to seek for other very likely or possible post-AGB objects among PDS sources previously suggested to be Herbig Ae/Be stars, by revisiting the observational database of this sample. In a comparative study with well known post-AGBs, several characteristics were evaluated: (i) parameters related to the circumstellar emission; (ii) spatial distribution to verify the background contribution from dark clouds; (iii) spectral features, and (iv) optical and infrared colors. These characteristics suggest that 7 objects of the studied sample are very likely post-AGBs, 5 are possible post-AGBs, 8 are unlikely post-AGBs, and the nature of 7 objects remains unclear.

12 pages, 9 figures

References in corpus (26)

• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• A spectroscopic atlas of post-AGB stars and planetary nebulae selected from the IRAS Point Source Catalogue
• Spitzer's view on aromatic and aliphatic hydrocarbon emission in Herbig Ae stars
• A Survey for New Members of Taurus with the Spitzer Space Telescope
• Characterisation of the magnetic field of the Herbig Be star HD 200775
• Spitzer IRS Spectra and Envelope Models of Class I Protostars in Taurus
• An evolutionary catalogue of Galactic post-AGB and related objects
• The Evolution of the Multiplicity of Embedded Protostars I: Sample Properties and Binary Detections
• Circumstellar disks around Herbig Be stars
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds.X. The Chamaeleon II Pre-Main Sequence Population as Observed With IRAC and MIPS
• The RMS Survey: Mid-Infrared Observations of Candidate Massive YSOs in the Southern Hemisphere
• The Formation and Evolution of Planetary Systems: Description of the Spitzer Legacy Science Database
• The RMS Survey: ${}^{13}$CO observations of candidate massive YSOs in the northern Galactic plane
• Infrared Nebulae Around Young Stellar Objects
• A survey for nanodiamond features in the 3 micron spectra of Herbig Ae/Be stars
• Echelle long-slit optical spectroscopy of evolved stars
• The TEXES Survey For H2 Emission From Protoplanetary Disks
• Spitzer IRAC Detection and Analysis of Shocked Molecular Hydrogen Emission
• A search for diffuse bands in the circumstellar envelopes of post-AGB stars
• HST/NICMOS Imaging Polarimetry of Proto-Planetary Nebulae II: Macro-morphology of the Dust Shell Structure via Polarized Light
• New detections of H2O masers in planetary nebulae and post-AGB stars using the Robledo-70m antenna
• MWC 297: a young high-mass star rotating at critical velocity
• AKARI's infrared view on nearby stars : Using AKARI Infrared Camera All-Sky Survey, 2MASS, and Hipparcos catalog
• Evidence for an Edge-On Disk around the Young Star MWC 778 from Infrared Imaging and Polarimetry
• Spectroscopic analysis of two peculiar emission line stars: RJHA 49 and SS73 21
• The Unusual Object IC 2144/MWC 778

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• The study of unclassified B[e] stars and candidates in the Galaxy and Magellanic Clouds
• Spectroscopy and Linear Spectropolarimetry of the early Herbig Be Stars PDS 27 and PDS 37
• Resolving the MYSO binaries PDS 27 and PDS 37 with VLTI/PIONIER
• Fullerenes in the circumstellar medium of Herbig Ae/Be stars: Insights from the Spitzer mid-infrared spectral catalog
• Variability in Proto-Planetary Nebulae: VIII. A New Sample of Southern Hemisphere Objects