Title

Low-Resolution Spectroscopy And Spectral Energy Distributions Of Selected Sources Towards Σ Orionis

Keywords

Galaxies: quasars: emission lines; Galaxy: open clusters and associations: individual: σ Orionis; Stars: emission-line, Be; Stars: low-mass, brown dwarfs; Stars: pre-main sequence

Abstract

Aims. We study in detail nine sources in the direction of the young σ Orionis cluster, which is considered to be a unique site for studying stellar and substellar formation. The nine sources were selected because of their peculiar properties, such as extremely-red infrared colours or excessively strong Hα emission for their blue optical colours.Methods. We acquired high-quality, low-resolution spectroscopy (R ∼ 500) of the nine targets with ALFOSC at the Nordic Optical Telescope. We also re-analysed [24]-band photometry from MIPS/Spitzer and compiled the highest quality photometric dataset available at the ViJHKs passbands and the four IRAC/Spitzer channels, for constructing accurate spectral energy distributions between 0.55 and 24μm.Results. The nine targets were classified into: one Herbig Ae/Be star with a scattering edge-on disc; two G-type stars; one X-ray flaring, early-M, young star with chromospheric Hα emission; one very low-mass, accreting, young spectroscopic binary; two young objects at the brown-dwarf boundary with the characteristics of classical T Tauri stars; and two emission-line galaxies, one undergoing star formation, and another whose spectral energy distribution is dominated by an active galactic nucleus. We also discovered three infrared sources associated with overdensities in a cold cloud of the cluster centre.Conclusions. Low-resolution spectroscopy and spectral energy distributions are a vital tool for measuring the physical properties and evolution of young stars and candidates in the σ Orionis cluster. © 2008 ESO.

Publication Date

11-1-2008

Publication Title

Astronomy and Astrophysics

Volume

491

Issue

2

Number of Pages

515-523

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1051/0004-6361:200810616

Socpus ID

57049159997 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/57049159997

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