ROXs 42Bb

ROXs 42Bb is a directly imaged planetary-mass companion^[1] to the binary M star ROXs 42B,^[5] a likely member of the Rho Ophiuchi cloud complex. The companion was independently discovered in December, 2013, by astronomers from University of Texas at Austin & University of Toronto.^[1][2]

ROXs 42Bb

ROXs 42B and its companion (small red object on the right) with VLT MUSE
Discovery
Discovered by	Currie et al.[1] & Kraus et al.[2]
Discovery site	Keck Telescope, Very Large Telescope, Subaru Telescope
Discovery date	December, 2013
Detection method	Direct imaging
Orbital characteristics
Orbital period (sidereal)	1968.3 years[3]
Star	ROXs 42B
Physical characteristics
Mean radius	2.10±0.35[4] RJ
Mass	13±5[4] MJ
Surface gravity	3.2 - 12.8[4] g
Temperature	2240±150[4] K

The object has a best estimated mass around 9 to 10 Jupiter masses, depending on the age of the star,^[1][2] similar to the masses of directly imaged planets around HR 8799 and beta Pictoris. However, it is unclear whether ROXs 42Bb formed like these planets via core accretion, by disk (gravitational) instability, or more like a binary star. Preliminary fits of the spectra and broadband photometry to atmospheric models imply a radius of 2.43 ± 0.18 R_J for an effective temperature of about 2,000 K or a radius of 2.55 ± 0.20 R_J for about 1950 K.^[6] Like Beta Pictoris b, ROXs 42Bb's atmosphere is likely very cloudy and dusty.^[6]

The object is located in the constellation Ophiuchus, near the border with Scorpius.

See also

• List of largest exoplanets