Carnegie: When It Comes to Brown Dwarfs, "How Far?" Is a Key Question

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Carnegie: When It Comes to Brown Dwarfs, "How Far?" Is a Key Question

Post by bystander » Tue Jun 28, 2016 3:32 pm

When It Comes to Brown Dwarfs, "How Far?" Is a Key Question
Carnegie Institution for Science | 2016 June 27

Brown dwarfs are sometimes called failed stars. They’re stars’ dim, low-mass siblings and they fade in brightness over time. They’re fascinating to astronomers for a variety of reasons, but much about them remains unknown. New work from a Carnegie-led team reports the distances of a number of brown dwarfs, as well as low-mass stars, in The Astronomical Journal.

Brown dwarfs are too small to sustain the hydrogen fusion process that powers stars. Their temperatures can range from nearly as hot as a star to as cool as a planet, and their masses also range between star-like and giant planet-like. They are of particular interest to scientists because they can offer clues to star-formation processes.

The intrinsic brightness of brown dwarfs, particularly cool brown dwarfs, is poorly known, but this key parameter can only be determined once an object’s distance has been measured. Intrinsic brightness is a determination of how bright an object would be if observed at a common distance, eliminating the fact that a bright star can seem dimmer if it is far away and a dim star can seem brighter if it is close.

An ongoing planet-hunting survey run by Carnegie co-authors Alycia Weinberger, Alan Boss, Ian Thompson, Sandy Keiser, and others has yielded the distances to 134 low mass stars and brown dwarfs, of which 38 had not been previously measured. ...

Trigonometric Parallaxes and Proper Motions of 134 Southern Late M, L, and T Dwarfs
from the Carnegie Astrometric Planet Search Program
- Alycia J. Weinberger et al
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