First Imaged Planet around a White Dwarf (WD 0806-661)

EPE page: http://exoplanet.eu/star.php?st=WD+0806-661

Discovery paper: Discovery of a candidate for the coolest known brown dwarf

Quote :

We have used multi-epoch images from the Infrared Array Camera on board the Spitzer Space Telescope to search for substellar companions to stars in the solar neighborhood based on common proper motions. Through this work, we have discovered a faint companion to the white dwarf WD 0806-661. The comoving source has a projected separation of 130'', corresponding to 2500 AU at the distance of the primary (19.2 pc). If it is physically associated, then its absolute magnitude at 4.5 μm is ~1 mag fainter than the faintest known T dwarfs, making it a strong candidate for the coolest known brown dwarf. The combination of M 4.5 and the age of the primary (1.5 Gyr) implies an effective temperature of ~300 K and a mass of ~7 M Jup according to theoretical evolutionary models. The white dwarf's progenitor likely had a mass of ~2 M_Sun , and thus could have been born with a circumstellar disk that was sufficiently massive to produce a companion with this mass. Therefore, the companion could be either a brown dwarf that formed like a binary star or a giant planet that was born within a disk and has been dynamically scattered to a larger orbit

300 kelvin? Wow. If the spectral type sequence is useful below letter T, I guess this object should indicate this. As they say, the wide separation might indicate that this is a low-mass brown dwarf though...

It's on arXiv now.
http://arxiv.org/abs/1102.5411

Hi

http://iopscience.iop.org/2041-8205/730/1/L9

Quote :

We have used multi-epoch images from the Infrared Array Camera on board the Spitzer Space Telescope to search for substellar companions to stars in the solar neighborhood based on common proper motions. Through this work, we have discovered a faint companion to the white dwarf WD 0806-661. The comoving source has a projected separation of 130'', corresponding to 2500 AU at the distance of the primary (19.2 pc). If it is physically associated, then its absolute magnitude at 4.5 μm is ~1 mag fainter than the faintest known T dwarfs, making it a strong candidate for the coolest known brown dwarf. The combination of M 4.5 and the age of the primary (1.5 Gyr) implies an effective temperature of ~300 K and a mass of ~7 M Jup according to theoretical evolutionary models. The white dwarf's progenitor likely had a mass of ~2 M , and thus could have been born with a circumstellar disk that was sufficiently massive to produce a companion with this mass. Therefore, the companion could be either a brown dwarf that formed like a binary star or a giant planet that was born within a disk and has been dynamically scattered to a larger orbit.

http://www.theweatherspace.com/news/TWS-3_13_2011_browndwarf.html

http://news.discovery.com/space/ultra-cold-brown-dwarf-new-record-breaker-110312.html

http://www.newscientist.com/article/mg20928034.600-newly-found-brown-dwarf-is-ultracool.html

Merging this thread with the one already discussing this discovery. Added star name to thread title.

I'm sorry

Stalker wrote:

I'm sorry

Not a problem, just keeping things organised.

The Ultra Cool Brown Dwarf WD 0806-661B: Age, Mass, and Formation Mechanism
They find a mass of < 10 - 13 M_J and a temperature < 400 K.

The discussion of formation mechanisms is a worthwhile read, yet more arguments against the IAU definition of the distinction between planets and brown dwarfs.

Wasn't aware of the evidence against planet-planet scattering for forming these wide-separation objects either.

Exoplanetary physics just keep us surprising

Confirmation of One of the Coldest Known Brown Dwarfs

Apparently WD 08061-661B is a contender for the coolest currently-known brown dwarf with the Y dwarf WISEP J1828+2650, and may itself be a Y dwarf. Updated mass range 6-9 Jupiter masses, so at the low end of the brown dwarf mass range.

Near-infrared Detection of WD 0806-661 B with the Hubble Space Telescope
http://arxiv.org/abs/1409.5897