Young, red, low mass brown dwarf PSO J318.5-22 from Pan-STARRS

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Image credit: N. Metcalfe & Pan-STARRS PS1 Science Consortium. The new discovery in arXiv a week ago is now the subject of a press release from the Institute for Astronomy (IfA) at Honolulu, as well as wider publicity. The estimated six Jupiter masses for the object rely on its membership of the beta Pictoris moving group with an age of 12 Myr, but a new estimate today (Binks A.S. & Jeffries R.D., arXiv) of that age is 21 Myr, requiring an upward revision of the mass probably to the deuterium burning limit. nelson2The problem is well illustrated even by very old evolutionary tracks for brown dwarfs and low mass stars (left). Consider an object thought to have age 10 Myr and a luminosity 0.00001 solar; its mass by inspection of these models might be 0.005 solar (a), but if actually nearer 60 Myr old (b) it might have twice the mass. This is quite apart from uncertainty in the luminosity itself due to uncertain distance. Some previous discoveries in the same age/luminosity space are plotted with much more modern models (below, right) in a figure taken from the discovery paper of a recent dusty young L dwarf companion to an M dwarf. apj480297f5_lr

The precise mass apart, the important realisation here is that the infrared spectrum is similar to that of the HR 8799 planets and other young low mass objects such as 2M1207b. From the preprint:

Altogether, PSO J318-22 is the first free-floating object with the colors, magnitudes, spectrum, luminosity, and mass that overlap the young dusty planets around HR 8799 and 2MASS J1207-39.

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One Response to “Young, red, low mass brown dwarf PSO J318.5-22 from Pan-STARRS”

  1. […] credit: N. Metcalfe & Pan-STARRS PS1 Science Consortium. An update on this object from New Scientist: the paper by Beth A. Biller et al., (2015) “Variability in a Young, L/T […]

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