Optical spectroscopy of isolated planetary mass objects in the σ Orionis cluster

被引：53

作者：

Navascués, DBY

Osorio, MRZ

Béjar, VJS

Rebolo, R

Martín, EL

Mundt, R

Bailer-Jones, CAL

机构：

[1] Univ Autonoma Madrid, Dept Fis Teor, E-28049 Madrid, Spain

[2] Max Planck Inst Astron, D-69117 Heidelberg, Germany

[3] CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA

[4] Inst Astrofis Canarias, Tenerife 38205, Spain

[5] CSIC, Madrid, Spain

[6] Univ Hawaii Manoa, Inst Astron, Honolulu, HI 96822 USA

来源：

ASTRONOMY & ASTROPHYSICS | 2001年 / 377卷 / 02期

关键词：

giant planet formation; open clusters and associations : individual : sigma Orionis; stars : brown dwarfs;

D O I：

10.1051/0004-6361:20011152

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We have obtained low resolution optical spectra of 15 isolated planetary mass objects (IPMOs) in the sigma Orionis cluster, and derived spectral types by comparison with nearby M and L dwarfs. The spectral types are in the range late M - mid L, in agreement with our expectations based on colors and magnitudes for bona fide members. Therefore, most of these objects have masses below the deuterium burning limit. About 2/3 show H alpha in emission at our spectral resolution. From our spectroscopic and photometric data, we infer that three IPMOs in this sample may be binaries with components of similar masses. These results confirm that the substellar mass function of the sigma Orionis cluster, in the form dN/dM, keeps rising in the planetary domain.

引用

页码：L9 / L13

页数：5

共 28 条

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