Volume 491, Number 2, November IV 2008
|Page(s)||515 - 523|
|Section||Stellar structure and evolution|
|Published online||01 October 2008|
Low-resolution spectroscopy and spectral energy distributions of selected sources towards σ Orionis
Dpto. de Astrofísica y Ciencias de la Atmósfera, Facultad de Física, Universidad Complutense de Madrid, 28040 Madrid, Spain e-mail: firstname.lastname@example.org
2 Instituto de Astrofísica de Canarias, Avenida Vía Láctea, 38200 La Laguna, Tenerife, Islas Canarias, Spain
3 University of Central Florida, Dept. of Physics, PO Box 162385, Orlando, FL 32816-2385, USA
Accepted: 2 September 2008
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 () of the nine targets with ALFOSC at the Nordic Optical Telescope. We also re-analysed -band photometry from MIPS/Spitzer and compiled the highest quality photometric dataset available at the passbands and the four IRAC/Spitzer channels, for constructing accurate spectral energy distributions between 0.55 and 24 μm.
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.
Key words: stars: emission-line, Be / stars: low-mass, brown dwarfs / stars: pre-main sequence / Galaxy: open clusters and associations: individual: σ Orionis / galaxies: quasars: emission lines
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.