WD 0806−661 B
 JWST image of WD 0806−661 B and its white dwarf star | |
| Discovery[1] | |
|---|---|
| Discovered by | Luhman et al. |
| Discovery date | 2011 |
| Direct imaging | |
| Designations | |
| Ahra, GJ 3483 B | |
| Orbital characteristics | |
| 2,500 AU | |
| Star | WD 0806−661 |
| Physical characteristics | |
| 1.12RJ | |
| Mass | 7-9MJ |
| 16.17 g (Estimate) | |
| Temperature | 325-350 K |
WD 0806-661 B,formally namedAhra,is a planetary-mass companion of thewhite dwarfstarWD 0806−661,or Maru.
This object was discovered in 2011 by theSpitzer Space Telescope.It has a mass of between 7-9MJ,putting it as a gas giant planet. At the time of its discovery, WD 0806-661 b was the coldest brown dwarf ever discovered, with a temperature of 325-350 Kelvin (52-77 °C or 125-170 °F)[2]and also had the largest separation from its star at about 2,500AUat the time of its discovery. The photometric colors of the object suggest it is metal-poor.[3]
As of 2021, WD 0806-661 b is a potential target for study from theJames Webb Space Telescope.[4]
Host star
[edit]WD 0806−661, or Maru, is awhite dwarfstar of the spectral type DQ. The metal-poor composition of its planetary-mass companion could explain its spectral type, as it is theorized that hydrogen-deficient stars of theasymptotic giant branchcould evolve into white dwarfs of spectral type DB and then DQ as they cool down.[5]WD 0806-661 is estimated to be 1.5-2.7 billion years old,[6]and likely used to be anA-type main sequence starof 2.1 ± 0.3solar massesbefore reaching the end of its life and becoming a white dwarf.[7]WD 0806-661 B may have formed closer to the star, but migrated further away as it reached the end of its life.
Characteristics
[edit]Because it orbits very far away from its star, WD 0806−661 B is likely very dark, receiving almost no light from its star. However, due to the object's high mass, internal heat keeps the temperature hotter than that of Earth.[2]The object's radius is estimated to be 12% larger than that of Jupiter,[8]and is likely the same age as the star. Despite having temperatures comparable to that of Earth, WD 0806−661 B is a poor candidate for extraterrestrial life due to high surface gravity and lack of starlight. Because of its large mass and distance from its star, WD 0806−661 B could host many largeexomoons.
The WD 0806−661 system is planned to be studied by theJames Webb Space Telescope,which will probe theatmosphereof the object, as well as search for other planetary-mass bodies in the system.
Type of object
[edit]There is no consensus as to whether WD 0806-661 b should be considered anexoplanetor asub-brown dwarf.Based on its large distance from the white dwarf, this object likely formed like a star rather than in aprotoplanetary disk,and it is generally described as a brown dwarf in the scientific literature.[9]However, theIAUconsiders objects below the~13MJlimiting mass fordeuterium fusionthat orbit stars (or stellar remnants) to be planets, no matter how they formed.[10]Additionally, WD 0806-661 b has been named Ahra through the IAU'sNameExoWorldsexoplanet naming campaign,[11]and is included in databases such as theNASA Exoplanet Archive.[12]
See also
[edit]- WD 0806−661
- COCONUTS-2b- Another planetary-mass companion with a large separation from its star
- List of Y-dwarfs
References
[edit]- ^Luhman, K. L.; Burgasser, A. J.; Bochanski, J. J. (March 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.ISSN2041-8205.
- ^abLeggett, S. K.; Tremblin, P.; Esplin, T. L.; Luhman, K. L.; Morley, Caroline V. (2017-06-21)."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.doi:10.3847/1538-4357/aa6fb5.ISSN1538-4357.
- ^"_13428"._13428.doi:10.5270/esa-4bo1j7l.Retrieved2023-09-09.
- ^"1276 - Spectroscopic Observations of WD 0806-661B"(PDF).
- ^Camisassa, María E.; Althaus, Leandro G.; Rohrmann, René D.; García-Berro, Enrique; Torres, Santiago; Córsico, Alejandro H.; Wachlin, Felipe C. (April 2017)."Updated Evolutionary Sequences for Hydrogen-deficient White Dwarfs".The Astrophysical Journal.839(1): 11.doi:10.3847/1538-4357/aa6797.hdl:11336/63304.ISSN0004-637X.
- ^"The Extrasolar Planet Encyclopaedia — WD 0806-661 B b".Extrasolar Planets Encyclopaedia.Retrieved2023-09-09.
- ^Luhman, Kevin; Burgasser, Adam; Bochanski, John (2011-01-01)."Confirmation of a Candidate for the Coolest Known Brown Dwarf".Spitzer Proposal:70203.Bibcode:2011sptz.prop70203L.
- ^"Exoplanet-catalog".Exoplanet Exploration: Planets Beyond our Solar System.Retrieved2023-09-09.
- ^Rodriguez, David R.; Zuckerman, B.; Melis, Carl; Song, Inseok (May 2011). "The Ultra Cool Brown Dwarf Companion of WD 0806-661B: Age, Mass, and Formation Mechanism".The Astrophysical Journal Letters.732(2): L29.arXiv:1103.3544.Bibcode:2011ApJ...732L..29R.doi:10.1088/2041-8205/732/2/L29.
- ^Lecavelier des Etangs, A.; Lissauer, Jack J. (June 2022). "The IAU working definition of an exoplanet".New Astronomy Reviews.94:101641.arXiv:2203.09520.Bibcode:2022NewAR..9401641L.doi:10.1016/j.newar.2022.101641.IAU website link
- ^"2022 Approved Names".nameexoworlds.iau.org.IAU.Retrieved7 June2023.
- ^"WD 0806-661".NASA Exoplanet Archive.Retrieved22 January2024.
