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The Substellar Mass Function in Σ Orionis
| Content Provider | Semantic Scholar |
|---|---|
| Author | Béjar, Vı́ctor J. S. Mart́in, Eduardo L. Osorio, M. R. Zapatero Rebolo, R. Barrado, David Navascués Bailer-Jones, Coryn A. L. Mundt, Reinhard Baraffe, Isabelle Chabrier, Christian Allardécole, F. |
| Copyright Year | 2001 |
| Abstract | We combine results from imaging searches for substellar objects in the σ Orionis cluster and follow-up photometric and spectroscopic observations to derive a census of the brown dwarf population in a region of 847 arcmin 2. We identify 64 very low-mass cluster member candidates in this region. We – 2 – have available three color (IZ and J) photometry for all of them, spectra for 9 objects, and K photometry for 27 % of our sample. These data provide a well defined sequence in the I versus I − J, I − K color magnitude diagrams, and indicate that the cluster is affected by little reddening despite its young age (∼5 Myr). Using state-of-the-art evolutionary models, we derive a mass function from the low-mass stars (0.2 M ⊙) across the complete brown dwarf domain (0.075 M ⊙ to 0.013 M ⊙), and into the realm of free-floating planetary-mass objects (≤ 0.013 M ⊙). We find that the mass spectrum (dN/dm) ∝ m −α increases toward lower masses with an exponent α = 0.8 ± 0.4. Our results suggest that planetary-mass isolated objects could be as common as brown dwarfs; both kinds of objects together would be as numerous as stars in the cluster. If the distribution of stellar and substellar masses in σ Orionis is representative of the Galactic disk, older and much lower luminosity free-floating planetary-mass objects with masses down to about 0.005 M ⊙ should be abundant in the solar vicinity, with a density similar to M-type stars. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://arxiv.org/pdf/astro-ph/0104097v1.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | ABRA gene Accumulation Ratio Cmin Censuses DWARF Diagram Mass Spectrometry Orionis eximius Photometry Physical object Planetary scanner Stars, Celestial Stellar (payment network) |
| Content Type | Text |
| Resource Type | Article |
