WD 0806−661 (L 97-3, GJ 3483), formally named Maru,[1] is a DQ white dwarf with an extremely cold Y-type substellar companion (designated "B"), located in the constellation Volans at 62.7 light-years (19.2 parsecs) from Earth. The companion was discovered in 2011, and is the only known Y-type companion to a star or stellar remnant. At the time of its discovery WD 0806-661 B had the largest actual (2500 AU) and apparent separation (more than 2 arcminutes) of any known planetary-mass object, as well as being the coldest directly imaged substellar object then known.

WD 0806-661 B

Main article: WD 0806−661 B

Component WD 0806-661 B was discovered in 2011 with the Spitzer Space Telescope. Its discovery was announced in the paper Luhman et al., 2011. The secondary has a mass between 7 and 9 and a temperature between 325 and 350 K C F.[2] At the time of its discovery, WD 0806−661 B was the coldest "brown dwarf" that has ever been found.[3] The object is too faint to acquire a spectrum even with the Hubble Space Telescope, however the spectral type of this object was estimated to be Y1 based on its detection in Hubble images at near-infrared wavelengths.[4] The photometric colors of this object suggest that it is metal-poor. The metal-poor composition of the companion could explain the DQ spectral type of the primary white dwarf.[2] Hydrogen-deficient AGB stars might evolve into DB white dwarfs and then into DQ white dwarfs as they cool down.[5]

In August 2022, WD 0806-661 and its planetary-mass companion were included among 20 systems to be named by the third NameExoWorlds project.[6] The approved names, proposed by a team from South Korea, were announced in June 2023. WD 0806-661 and its companion are named after the Korean words Maru () and Ahra ().[1]

See also

References

  1. ^ "2022 Approved Names". nameexoworlds.iau.org. IAU. Retrieved 7 June 2023.
  2. ^ Leggett, S. K.; Tremblin, P.; Esplin, T. L.; Luhman, K. L.; Morley, Caroline V. (June 2017). "The Y-type Brown Dwarfs: Estimates of Mass and Age from New Astrometry, Homogenized Photometry, and Near-infrared Spectroscopy". The Astrophysical Journal. 842 (2): 118. arXiv:1704.03573. Bibcode:2017ApJ...842..118L. doi:10.3847/1538-4357/aa6fb5. ISSN 0004-637X. S2CID 119249195
  3. ^ Luhman, K. L.; Burgasser, Adam J.; Bochanski, J. J. (2011). "Discovery of a Candidate for the Coolest Known Brown Dwarf". The Astrophysical Journal Letters. 730 (1): L9. arXiv:1102.5411. Bibcode:2011ApJ...730L...9L. doi:10.1088/2041-8205/730/1/L9. S2CID 54666396
  4. ^ Leggett, S. K.; Morley, Caroline V.; Marley, M. S.; Saumon, D. (January 2015). "Near-infrared Photometry of Y Dwarfs: Low Ammonia Abundance and the Onset of Water Clouds". The Astrophysical Journal. 799 (1): 37. arXiv:1411.2020. Bibcode:2015ApJ...799...37L. doi:10.1088/0004-637X/799/1/37. ISSN 0004-637X. S2CID 118530454
  5. ^ Althaus, L. G.; Serenelli, A. M.; Panei, J. A.; Córsico, A. H.; García-Berro, E.; Scóccola, C. G. (May 2005). "The formation and evolution of hydrogen-deficient post-AGB white dwarfs: The emerging chemical profile and the expectations for the PG 1159-DB-DQ evolutionary connection". Astronomy and Astrophysics. 435 (2): 631–648. arXiv:astro-ph/0502005. Bibcode:2005A&A...435..631A. doi:10.1051/0004-6361:20041965. ISSN 0004-6361
  6. ^ "List of ExoWorlds 2022". nameexoworlds.iau.org. IAU. 8 August 2022. Retrieved 27 August 2022.