ROXs 42Bb is a directly imaged planetary-mass companion[1] to the binary M star ROXs 42B,[4] a likely member of the Rho Ophiuchi cloud complex. The companion was announced/discovered on October 17, 2013 by University of Toronto astronomer Thayne Currie.

ROXs 42Bb
ROXs42Bb image.jpeg
Discovery image for ROXs 42Bb.
Discovered byCurrie et al.[1]
Discovery siteKeck Telescope, Very Large Telescope, Subaru Telescope
Discovery dateOctober 17, 2013
Direct imaging
Orbital characteristics
StarROXs 42B
Physical characteristics
Mean radius
0.9 – 3[3] RJ
[3] MJ
3.8 ± 0.2[3] g
Temperature1,800-2,600 K[3]

The object has an estimated mass around 9 Jupiter masses, depending on the age of the star,[1] 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, formed by disk (gravitational) instability, or formed more like a binary star. Preliminary fits of the spectra and broadband photometry to atmospheric models imply an effective temperature of about 2,000 K for a radius of 2.43 ± 0.18 RJ or about 2150 K for a radius of 2.55 ± 0.20 RJ.[3] Like Beta Pictoris b, ROXs 42Bb's atmosphere is likely very cloudy and dusty.[3]

See alsoEdit


  1. ^ a b c Currie, Thayne; Daemgen, Sebastian; Debes, John; Lafreniere, David; Itoh, Yoichi; Jayawardhana, Ray; Ratzka, Thorsten; Correia, Serge (2014). "Direct Imaging and Spectroscopy of a Candidate Companion Below/Near the Deuterium-Burning Limit In The Young Binary Star System, ROXs 42B". The Astrophysical Journal Letters. 780 (2): 30. arXiv:1310.4825. Bibcode:2014ApJ...780L..30C. doi:10.1088/2041-8205/780/2/L30. S2CID 118464822.
  2. ^ "Exoplanet-catalog".
  3. ^ a b c d e f Currie, Thayne; Burrows, Adam; Daemgen, Sebastian (2014). "A First-Look Atmospheric Modeling Study of the Young Directly-Imaged Planet-Mass Companion, ROXs 42Bb". The Astrophysical Journal. 787 (2): 104. arXiv:1404.0131. Bibcode:2014ApJ...787..104C. doi:10.1088/0004-637X/787/2/104. S2CID 118376549.
  4. ^ Simon, Michael; Ghez, A. M.; Leinert, Ch.; Cassar, L.; Chen, W. P.; Howell, R. R.; Jameson, R. F.; Matthews, K.; Neugebauer, G.; Richichi, A. (1995). "A lunar occultation and direct imaging survey of multiplicity in the Ophiuchus and Taurus star-forming regions" (PDF). The Astrophysical Journal. 443: 625. Bibcode:1995ApJ...443..625S. doi:10.1086/175554. S2CID 122944079.