The coolest isolated M dwarf and other 2MASS discoveries

被引:87
作者
Kirkpatrick, JD [1 ]
Beichman, CA [1 ]
Skrutskie, MF [1 ]
机构
[1] UNIV MASSACHUSETTS,DEPT PHYS & ASTRON,FIVE COLL,DEPT ASTRON,AMHERST,MA 01003
关键词
infrared; stars; late-type; low-mass; brown dwarfs; surveys;
D O I
10.1086/303613
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have obtained follow-up spectroscopy of eight late dwarf candidates discovered in a 105 deg(2) area observed with the 2MASS Prototype Camera during test runs between 1992 and 1994. These objects were chosen because of their red infrared colors (e.g., J - K-s greater than or equal to 1.10) and/or red OIR colors (e.g., R - K-s greater than or equal to 6.00). All eight are late M dwarfs, six of which have spectral types later than van Biesbroeck 8 (type M7 V). Despite the fact that we have only followed up a fraction of the reddest sources discovered, the number of known M dwarfs of type M7 and cooler has been increased by 30%. Extrapolation of these results alone shows that over 2000 dwarfs of similar spectral type and with K-s less than or equal to 14.0 will be imaged by 2MASS over the entire sky. One of these new discoveries is astonishingly cool and has a tentative type of greater than or equal to M10 V. This dwarf, one of the least luminous objects yet discovered, could itself be a high-mass brown dwarf, thus providing another empirical data point in a regime where few such objects are now recognized. Only the substellar suspect GD 165 B and the bona fide brown dwarf GL 229 B, both discovered as companions to known stars, are cooler. Thus, this 2MASS discovery becomes the coolest isolated object so far identified.
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页码:311 / &
页数:10
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