Low-resolution spectroscopy and spectral energy distributions of selected sources towards sigma Orionis

    Authors

    J. A. Caballero; L. Valdivielso; E. L. Martin; D. Montes; S. Pascual;P. G. Perez-Gonzalez

    Comments

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    Abbreviated Journal Title

    Astron. Astrophys.

    Keywords

    stars: emission-line, Be; stars: low-mass, brown dwarfs; stars: pre-main; sequence; Galaxy: open clusters and associations: individual: sigma; Orionis; galaxies: quasars: emission lines; LOW-MASS STARS; ALPHA EMISSION STARS; XMM-NEWTON OBSERVATIONS; YOUNG; BROWN DWARFS; T-TAURI STARS; H-ALPHA; MAIN-SEQUENCE; ORI CLUSTER; OPTICAL SPECTROSCOPY; CANDIDATE MEMBERS; Astronomy & Astrophysics

    Abstract

    Aims. We study in detail nine sources in the direction of the young sigma 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 H alpha emission for their blue optical colours. Methods. We acquired high-quality, low-resolution spectroscopy (R similar to 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 ViJHK(s) passbands and the four IRAC/Spitzer channels, for constructing accurate spectral energy distributions between 0.55 and 24 mu m. 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 H alpha 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 s Orionis cluster.

    Journal Title

    Astronomy & Astrophysics

    Volume

    491

    Issue/Number

    2

    Publication Date

    1-1-2008

    Document Type

    Article

    Language

    English

    First Page

    515

    Last Page

    523

    WOS Identifier

    WOS:000260761100028

    ISSN

    0004-6361

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