SIMBAD references

2007A&A...470..903C - Astronomy and Astrophysics, volume 470, 903-918 (2007/8-2)

The substellar mass function in σ Orionis. II. Optical, near-infrared and IRAC/Spitzer photometry of young cluster brown dwarfs and planetary-mass objects.

CABALLERO J.A., BEJAR V.J.S., REBOLO R., EISLOEFFEL J., ZAPATERO OSORIO M.R., MUNDT R., BARRADO Y NAVASCUES D., BIHAIN G., BAILER-JONES C.A.L., FORVEILLE T. and MARTIN E.L.

Abstract (from CDS):

We investigate the mass function in the substellar domain down to a few Jupiter masses in the young σ Orionis open cluster (3±2Ma, d=360+70–60pc). We have performed a deep IJ-band search, covering an area of 790arcmin2 close to the cluster centre. This survey was complemented with an infrared follow-up in the HKs- and Spitzer 3.6-8.0µm-bands. Using colour-magnitude diagrams, we have selected 49 candidate cluster members in the magnitude interval 16.1mag < I < 23.0mag. Accounting for flux excesses at 8.0µm and previously known spectral features of youth, we identify 30 objects as bona fide cluster members. Four are first identified from our optical-near infrared data. Eleven have most probable masses below the deuterium burning limit which we therefore classify as candidate planetary-mass objects. The slope of the substellar mass spectrum (ΔN/ΔM≃aM–α) in the mass interval 0.11M<M<0.006M is α=+0.6±0.2. Any mass limit to formation via opacity-limited fragmentation must lie below 0.006M. The frequency of σ Orionis brown dwarfs with circumsubstellar discs is 47±9%. The continuity in the mass function and in the frequency of discs suggests that very low-mass stars and substellar objects, even below the deuterium-burning mass limit, share the same formation mechanism.

Abstract Copyright:

Journal keyword(s): stars: low mass, brown dwarfs - Galaxy: open clusters and associations: individual: σ Orionis - stars: planetary systems: protoplanetary discs

Nomenclature: Table 3: [BMZ2001] S Ori JHHMMSS.s+DDMMSS N=4 added.

Status at CDS:  

Simbad objects: 77

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2020.06.01-04:57:30

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