PSO J318.5−22 is a
rogue planet, an
extrasolar object of
planetary mass that does not orbit a parent star.[5][6] It is approximately 80 light-years away and belongs to the
Beta Pictoris moving group.[7] The object was discovered in 2013 in images taken by the
Pan-STARRS PS1 wide-field telescope. PSO J318.5-22's age is inferred to be 12 million years, the same age as the Beta Pictoris group.[8] Based on its calculated temperature and age, it is classified under the
brown dwarfspectral type L7.[9]
The team leader,
Michael Liu of the
Institute for Astronomy at the
University of Hawaii, stated, "We have never before seen an object free-floating in space that looks like this. It has all the characteristics of young planets found around other stars, but it is drifting out there all alone."[10] Current theories about such objects include the possibility that
gravitational perturbations may have kicked them out of their planetary systems soon after they formed through
planetaryaccretion, or they may have been formed by some other means.[11] Estimated temperatures inside its clouds exceed 1,100 K (800 °C). The clouds, made of hot dust and molten iron, show how widespread clouds are in planets and planet-like objects.[12] However, by 2020, modeling showed that the brightness variability could not be unambiguously attributed to clouds.[4]
^
abSanghi, Aniket; Liu, Michael C.; Best, William M.; Dupuy, Trent J.; Siverd, Robert J.; Zhang, Zhoujian; Hurt, Spencer A.; Magnier, Eugene A.; Aller, Kimberly M.; Deacon, Niall R. (6 September 2023). "The Hawaii Infrared Parallax Program. VI. The Fundamental Properties of 1000+ Ultracool Dwarfs and Planetary-mass Objects Using Optical to Mid-IR SEDs and Comparison to BT-Settl and ATMO 2020 Model Atmospheres". ApJ: 51.
arXiv:2309.03082.
^
abSanghi, Aniket; Liu, Michael C.; Best, William M.; Dupuy, Trent J.; Siverd, Robert J.; Zhang, Zhoujian; Hurt, Spencer A.; Magnier, Eugene A.; Aller, Kimberly M.; Deacon, Niall R. (7 September 2023).
"Table of Ultracool Fundamental Properties". Zenodo: 1.
^
abTremblin, P.; Phillips, M. W.; Emery, A.; Baraffe, I.; Lew, B. W. P.; Apai, D.; Biller, B. A.; Bonnefoy, M. (2020), "Rotational spectral modulation of cloudless atmospheres for L/T brown dwarfs and extrasolar giant planets", Astronomy & Astrophysics, 643: A23,
arXiv:2009.06269,
doi:
10.1051/0004-6361/202038771,
S2CID221655776
^
Michael C. Liu; Eugene A. Magnier; Niall R. Deacon; Katelyn N. Allers; et al. (1 October 2013). "The Extremely Red, Young L Dwarf PSO J318-22: A Free-Floating Planetary-Mass Analog to Directly Imaged Young Gas-Giant Planets". Astrophysical Journal Letters. 777.
arXiv:1310.0457.
Bibcode:
2013ApJ...777L..20L.
doi:
10.1088/2041-8205/777/2/L20.
S2CID54007072.