Brown Dwarf Stars with Arctic temperatures between -48 to -13 degrees Celsius

There could be a whole category of nearby, cool stellar objects which could be referred to as ‘Luhman objects’ A Brown Dwarf object that is thought to be between -48 to -13 degrees Celsius, colder than previous record holders, which were found to be close to room temperature. WISE imagery from 2010 was confirmed by two additional images taken by Spitzer in 2013 and 2014, with further observations at the Gemini South telescope on Cerro Pachon in Chile. The WISE and Spitzer data were used to measure the distance to the object via parallax. It turns out to be 7.2 light years away, fitting nicely into the chart below, which shows the Sun’s immediate neighborhood.

(H/T Centauri Dreams)

This diagram illustrates the locations of the star systems closest to the sun. The year when the distance to each system was determined is listed after the system’s name. NASA’s Wide-field Infrared Survey Explorer, or WISE, found two of the four closest systems: the binary brown dwarf WISE 1049-5319 and the brown dwarf WISE J085510.83-071442.5. NASA’s Spitzer Space Telescope helped pin down the location of the latter object. The closest system to the sun is a trio of stars that consists of Alpha Centauri, a close companion to it and the more distant companion Proxima Centauri. Credit: NASA/Penn State University.

Arxiv – Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun (8 pages)

Luhman has found that:

* The number ratio of brown dwarfs to stars is ~1/6. Large variations in this ratio are not present among the nearest star-forming regions.

* The IMF (Initial Mass Function) extends down to at least ~0.005-10 MSun (5-10 MJup) in Taurus and Chamaeleon, which is lower than the values predicted by some theories of star formation. Definitive measurement of the minimum mass of the IMF will require deeper observations, which are ongoing by myself and others.

* The IMF in Taurus reaches a maximum at 0.8 MSun whereas the mass functions of other star-forming regions peak at 0.1-0.2 MSun. This observation is the clearest example of a variation among the IMFs of nearby star-forming regions and may reflect a difference in the average Jeans masses.

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