Wikipedia

Gliese 229

(Redirected fromGliese 229A)

Gliese 229(also written asGl 229orGJ 229) is a multiple system composed of ared dwarfand twobrown dwarfs,[3][11]located 18.8light yearsaway in theconstellationLepus.The primary component has 58% of themass of the Sun,[4]55% of theSun's radius,[7]and a very lowprojected rotation velocityof 1 km/s at the stellar equator.[10]

Gliese 229

Gliese 229 A and B
Observation data
EpochJ2000EquinoxJ2000
Constellation Lepus
Right ascension 06h10m34.61494s[1]
Declination −21° 51′ 52.6564″[1]
Apparent magnitude(V) 8.14
Characteristics
Evolutionary stage Main sequence/Brown dwarf
Spectral type M1Ve[2]+T7+T8[3]
U−Bcolor index +1.222[2]
B−Vcolor index +1.478[2]
Variable type Flare star
Astrometry
Radial velocity(Rv)4.23±0.12[1]km/s
Proper motion(μ)RA:−135.692(11)mas/yr[1]
Dec.:−719.178(17)mas/yr[1]
Parallax(π)173.5740 ± 0.0170mas[1]
Distance18.791 ± 0.002ly
(5.7612 ± 0.0006pc)
Absolute magnitude(MV)9.326[4]
Absolute bolometric
magnitude(Mbol)		7.96[5]
Orbit[4][6]
PrimaryGliese 229 A
CompanionGliese 229 B
Period(P)216.925+10.604
−10.352yr
Semi-major axis(a)28.933+1.008
−1.000AU
Eccentricity(e)0.853±0.002
Inclination(i)5.497+0.153
−0.162°
Longitude of the node(Ω)145.946+0.306
−0.294°
Periastronepoch(T)2466912+97
−63
Argument of periastron(ω)
(secondary)		358.285+0.836
−0.846°
Semi-amplitude(K1)
(primary)		0.081674+0.001688
−0.001680km/s
Orbit[3]
PrimaryGliese 229 Ba
CompanionGliese 229 Bb
Period(P)12.134±0.003d
Semi-major axis(a)0.0424±0.0004AU
Eccentricity(e)0.234±0.004
Inclination(i)31.4±0.3°
Longitude of the node(Ω)213±2°
Periastronepoch(T)2460378.38±0.04
Argument of periastron(ω)
(secondary)		0.7±1.2°
Details
A
Mass0.579[4]M☉
Radius0.549±0.043[7]R☉
Luminosity (bolometric)0.0430[4]L☉
Luminosity (visual, LV)0.0158[nb 1]L☉
Surface gravity(logg)4.695±0.035[7]cgs
Temperature3,700[5]K
Metallicity−0.02±0.06[8]
Rotation27.3±0.2d[9]
Rotational velocity(vsini)1[10]km/s
Ba
Mass38.1±1.0[3]MJup
Radius0.81+0.05
−0.12[8]RJup
Luminosity (bolometric)3.890+0.375
−0.342×10−6[3]L☉
Surface gravity(logg)5.15±0.04[8]cgs
Temperature900+78
−29[8]K
Metallicity0.00+0.04
−0.03[8]
Age2.45±0.20[3]Gyr
Bb
Mass34.4±1.5[3]MJup
Radius0.85+0.12
−0.05[8]RJup
Luminosity (bolometric)2.630+0.254
−0.231×10−6[3]L☉
Surface gravity(logg)5.07+0.04
−0.011[8]cgs
Temperature775+20
−33[8]K
Metallicity0.00+0.04
−0.03[8]
Age2.45±0.20[3]Gyr
Other designations
NSV2863,BD−21°1377,GJ229,HD42581,HIP29295,SAO171334,LHS1827,TYC5945-765-1
Database references
SIMBADA
B
Gliese 229 is located in the constellation Lepus
Gliese 229 is located in the constellation Lepus
Gliese 229
Location of Gliese 229 in the constellationLepus

Alight curvefor Gliese 229 showing a small flare, adapted from Byrneet al.(1985)[2]

The star is known to be a low activityflare star,which means it undergoes random increases in luminosity because ofmagnetic activityat the surface. The spectrum shows emission lines of calcium in theHandKbands. The emission ofX-rayshas been detected from thecoronaof this star.[12]These may be caused by magnetic loops interacting with the gas of the star's outer atmosphere. No large-scale star spot activity has been detected.[2]

Thespace velocitycomponents of this star are U = +12, V = –11 and W = –12 km/s.[13]The orbit of this star through theMilky Waygalaxy has aneccentricityof 0.07 and an orbitalinclinationof 0.005.[2]

Companions

edit

Brown dwarf

edit

Asubstellar companionwas discovered in 1994 by Caltech astronomers Kulkarni, Tadashi Nakajima, Keith Matthews, andRebecca Oppenheimer,and Johns Hopkins scientists Sam Durrance and David Golimowski. It was confirmed in 1995 as Gliese 229B,[14][15]It was one of the first two brown dwarfs to be confirmed. Although too small to sustainhydrogen-burningnuclear fusionas in amain sequencestar, with a mass of around 40 to 60 times that ofJupiter(0.06 solar masses),[6][16]it is still too massive to be aplanet.As a brown dwarf, its core temperature is high enough to initiate the fusion ofdeuteriumwith a proton to formhelium-3,but it is thought that it used up all its deuterium fuel long ago.[17]This object has a surface temperature of 950 K.[18]

Gliese 229B is the prototype of theT-dwarfs,due to the detection ofmethanein its spectrum.[19]It also shows other molecules in its atmosphere, namelywater vapor,[20]carbon monoxide[21]andammonia.[22][8]Atomic absorption lines ofcaesium,[23]sodiumandpotassiumare also detected.[24]

The most recent parameters for Gliese 229 B as of 2022 come from a combination of data fromradial velocity,astrometry,and imaging, showing that it is about 60.4 times the mass of Jupiter, and on aneccentricorbit with asemi-major axisof about 28.9AUand an orbital period of about 217 years.[6]

Inconsistencies between the measured mass and luminosity of Gliese 229 B suggested that it may in fact be an unresolved binary brown dwarf.[4][25]Further evidence that Gliese 229B is an equal-mass binary comes from high-resolution spectroscopy from theSubaru Telescope.[26]The binary was resolved in 2024 withVLT/GRAVITYandVLT/CRIRES+. The components are called Gliese 229 Ba (38.1±1.0MJ) and Gliese 229 Bb (34.4±1.5MJ). The pair is a tight binary with an orbital period of 12.1 days and a semi-major axis of 0.042astronomical units(about 16 Earth-Moon distances). The changes inradial velocityextracted from CRIRES+ helped to resolve the orbit of Gliese 229B. The binary has aninclinationof 31.4 ±0.3° and aneccentricityof 0.234 ±0.004. The inclination of the binary is misaligned by37+7
−10° in respect to the orbit of Gliese 229B around Gliese 229A.[3]Additional radial velocity changes between two epochs were detected in Gliese 229B withKeckNIRSPEC. This team independently discovered the binarity of Gliese 229B.[11]

Gliese 229B was observed with JWSTMIRIlow resolution spectroscopy. Previous works showed a difference in abundances between host star and companion in Gliese 229 from near-infrared spectra. This new study using mid-infrared data showed that the pair has abundances consistent with the host star. The metallicities were measured to be C/O = 0.65 ±0.05 and [M/H]=0.00+0.04
−0.03and are equal for each brown dwarf in the pair. The host star has C/O = 0.68 ± 0.12 and [M/H] = −0.02 ± 0.06.[8]

Planetary system

edit

In March 2014, asuper-Neptunemass planet candidate was announced in a much closer-in orbit around GJ 229.[27]Given the proximity of the Gliese 229 system to the Sun, the orbit of GJ 229 Ab might be fully characterized by theGaiaspace-astrometry mission or via direct imaging. In 2020, asuper-Earthmass planet was discovered around GJ 229. GJ 229 Ac orbits the star closer in than GJ 229 Ab, located towards the outer edge but still well inside the star'shabitable zoneand in that sense similar toMarsin our ownSolar System.While considering GJ 229 Ab unconfirmed, the study estimated a significantly lowerminimum massfor it.[28]As of 2022,most sources consider both planets to be confirmed.[6][29][30][31]

The Gliese 229 A planetary system[28]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
c ≥7.268±1.256M🜨 0.339±0.011 121.995±0.161 0.19±0.08 — —
b ≥8.478±2.033M🜨 0.898±0.031 526.115±4.300 0.10±0.06 — —

If the planets Gliese 229 Ab & c orbit in the same plane as the brown dwarf Gliese 229 B, their true masses would be significantly greater than theirminimum masses,making them both nearly as massive asSaturn.[nb 2]

See also

edit

Notes

edit
  1. ^Using the absolute visual magnitude of Gliese 229 Aand the absolute visual magnitude of the Sun,the visual luminosity can be calculated by
  2. ^7.268ME/sin(5.497°) = 75.87ME
    8.478ME/sin(5.497°) = 88.50ME

References

edit
  1. ^abcdeVallenari, A.; et al. (Gaia collaboration) (2023)."GaiaData Release 3. Summary of the content and survey properties ".Astronomy and Astrophysics.674:A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID244398875. Gaia DR3 record for this sourceatVizieR.
  2. ^abcdefByrne, P. B.; Doyle, J. G.; Menzies, J. W. (May 1, 1985)."Optical photometry and spectroscopy of the flare star Gliese 229 (=HD42581)".Monthly Notices of the Royal Astronomical Society.214(2): 119–130.Bibcode:1985MNRAS.214..119B.doi:10.1093/mnras/214.2.119.
  3. ^abcdefghijXuan, Jerry W.; Mérand, A.; Thompson, W.; Zhang, Y.; Lacour, S.; Blakely, D.; Mawet, D.; Oppenheimer, R.; Kammerer, J.; Batygin, K.; Sanghi, A.; Wang, J.; Ruffio, J.-B.; Liu, M. C.; Knutson, H. (2024-10-16)."The cool brown dwarf Gliese 229 B is a close binary".Nature:1–5.arXiv:2410.11953.doi:10.1038/s41586-024-08064-x.ISSN1476-4687.PMID39415016.
  4. ^abcdefBrandt, G. Mirek; Dupuy, Trent J.; Li, Yiting; Chen, Minghan; Brandt, Timothy D.; Wong, Tin Long Sunny; Currie, Thayne; Bowler, Brendan P.; Liu, Michael C.; Best, William M. J.; Phillips, Mark W. (2021)."Improved Dynamical Masses for Six Brown Dwarf Companions Using Hipparcos and Gaia EDR3".The Astronomical Journal.162(6): 301.arXiv:2109.07525.Bibcode:2021AJ....162..301B.doi:10.3847/1538-3881/ac273e.S2CID237532125.
  5. ^abMorales, J. C.; Ribas, I.; Jordi, C. (February 2008). "The effect of activity on stellar temperatures and radii".Astronomy and Astrophysics.478(2): 507–512.arXiv:0711.3523.Bibcode:2008A&A...478..507M.doi:10.1051/0004-6361:20078324.S2CID16238033.Data from CDS table J/A+A/478/507Archived2016-10-06 at theWayback Machine.
  6. ^abcdFeng, Fabo; Butler, R. Paul; et al. (August 2022)."3D Selection of 167 Substellar Companions to Nearby Stars".The Astrophysical Journal Supplement Series.262(21): 21.arXiv:2208.12720.Bibcode:2022ApJS..262...21F.doi:10.3847/1538-4365/ac7e57.S2CID251864022.
  7. ^abcStassun, Keivan G.; Oelkers, Ryan J.; Paegert, Martin; Torres, Guillermo; Pepper, Joshua; De Lee, Nathan; Collins, Kevin; Latham, David W.; Muirhead, Philip S.; Chittidi, Jay; Rojas-Ayala, Bárbara; Fleming, Scott W.; Rose, Mark E.; Tenenbaum, Peter; Ting, Eric B. (2019-10-01)."The Revised TESS Input Catalog and Candidate Target List".The Astronomical Journal.158(4): 138.arXiv:1905.10694.Bibcode:2019AJ....158..138S.doi:10.3847/1538-3881/ab3467.ISSN0004-6256.
  8. ^abcdefghijkXuan, Jerry W.; Perrin, Marshall D.; Mawet, Dimitri; Knutson, Heather A.; Mukherjee, Sagnick; Zhang, Yapeng; Hoch, Kielan K.; Wang, Jason J.; Inglis, Julie (2024-11-15). "Atmospheric abundances and bulk properties of the binary brown dwarf Gliese 229 Bab from JWST/MIRI spectroscopy".arXiv:2411.10571.
  9. ^Díez Alonso, E.; Caballero, J. A.; Montes, D.; De Cos Juez, F. J.; Dreizler, S.; Dubois, F.; Jeffers, S. V.; Lalitha, S.; Naves, R.; Reiners, A.; Ribas, I.; Vanaverbeke, S.; Amado, P. J.; Béjar, V. J. S.; Cortés-Contreras, M.; Herrero, E.; Hidalgo, D.; Kürster, M.; Logie, L.; Quirrenbach, A.; Rau, S.; Seifert, W.; Schöfer, P.; Tal-Or, L. (2019). "CARMENES input catalogue of M dwarfs. IV. New rotation periods from photometric time series".Astronomy and Astrophysics.621:A126.arXiv:1810.03338.Bibcode:2019A&A...621A.126D.doi:10.1051/0004-6361/201833316.S2CID111386691.
  10. ^abReiners, Ansgar (May 2007). "The narrowest M-dwarf line profiles and the rotation-activity connection at very slow rotation".Astronomy and Astrophysics.467(1): 259–268.arXiv:astro-ph/0702634.Bibcode:2007A&A...467..259R.doi:10.1051/0004-6361:20066991.S2CID8672566.
  11. ^abWhitebook, Samuel; Brandt, Timothy D.; Brandt, G. Mirek; Martin, Emily C. (2024-10-06)."Discovery of the Binarity of Gliese 229B, and Constraints on the System's Properties".The Astrophysical Journal Letters.974(2): L30.arXiv:2410.11999.doi:10.3847/2041-8213/ad7714.ISSN2041-8205.
  12. ^Schmitt JHMM; Fleming TA; Giampapa MS (September 1995)."The X-Ray View of the Low-Mass Stars in the Solar Neighborhood".Astrophys. J.450(9): 392–400.Bibcode:1995ApJ...450..392S.doi:10.1086/176149.
  13. ^Gliese, W. (1969). "Catalogue of Nearby Stars".Veröffentlichungen des Astronomischen Rechen-Instituts Heidelberg.22:1.Bibcode:1969VeARI..22....1G.
  14. ^"Astronomers Announce First Clear Evidence of a Brown Dwarf".Space Telescope Science Institutenews release STScI-1995-48. November 29, 1995.Archivedfrom the original on 9 July 2008.Retrieved24 September2013.
  15. ^Oppenheimer, Ben R. (2014),"Companions of Stars: From Other Stars to Brown Dwarfs to Planets and the Discovery of the First Methane Brown Dwarf",in Joergens, Viki (ed.),50 Years of Brown Dwarfs - From Prediction to Discovery to Forefront of Research,Astrophysics and Space Science Library, vol. 401, Springer, pp. 81–111,arXiv:1404.4430,doi:10.1007/978-3-319-01162-2_6,ISBN978-3-319-01162-2,S2CID118304613,archivedfrom the original on 2015-02-19,retrieved2017-08-29
  16. ^Howe, Alex R.; McElwain, Michael W.; Mandell, Avi M. (2022)."GJ 229B: Solving the Puzzle of the First Known T Dwarf with the APOLLO Retrieval Code".The Astrophysical Journal.935(2): 107.arXiv:2203.11706.Bibcode:2022ApJ...935..107H.doi:10.3847/1538-4357/ac5590.S2CID247597251.
  17. ^J. Kelly Beatty; Carolyn Collins Petersen; Andrew Chaikin (1999).The New Solar System.Cambridge University Press.
  18. ^Geißler, K.; Chauvin, G.; Sterzik, M. F. (March 2008). "Mid-infrared imaging of brown dwarfs in binary systems".Astronomy and Astrophysics.480(1): 193–198.arXiv:0712.1887.Bibcode:2008A&A...480..193G.doi:10.1051/0004-6361:20078229.S2CID9331798.
  19. ^Oppenheimer, B. R.; Kulkarni, S. R.; Matthews, K.; Nakajima, T. (1995-12-01)."Infrared Spectrum of the Cool Brown Dwarf Gl 229B".Science.270(5241): 1478–1479.Bibcode:1995Sci...270.1478O.doi:10.1126/science.270.5241.1478.ISSN0036-8075.PMID7491492.
  20. ^Geballe, T. R.; Kulkarni, S. R.; Woodward, Charles E.; Sloan, G. C. (1996-08-01)."The Near-Infrared Spectrum of the Brown Dwarf Gliese 229B".The Astrophysical Journal.467(2): L101–L104.arXiv:astro-ph/9606056.Bibcode:1996ApJ...467L.101G.doi:10.1086/310203.ISSN0004-637X.
  21. ^Oppenheimer, B. R.; Kulkarni, S. R.; Matthews, K.; van Kerkwijk, M. H. (1998-08-01)."The Spectrum of the Brown Dwarf Gliese 229B".The Astrophysical Journal.502(2): 932–943.arXiv:astro-ph/9802299.Bibcode:1998ApJ...502..932O.doi:10.1086/305928.ISSN0004-637X.
  22. ^Saumon, D.; Geballe, T. R.; Leggett, S. K.; Marley, M. S.; Freedman, R. S.; Lodders, K.; Fegley, B., Jr.; Sengupta, S. K. (2000-09-01)."Molecular Abundances in the Atmosphere of the T Dwarf GL 229B".The Astrophysical Journal.541(1): 374–389.arXiv:astro-ph/0003353.Bibcode:2000ApJ...541..374S.doi:10.1086/309410.ISSN0004-637X.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  23. ^Schultz, A. B.; Allard, F.; Clampin, M.; McGrath, M.; Bruhweiler, F. C.; Valenti, J. A.; Plait, P.; Hulbert, S.; Baum, S.; Woodgate, B. E.; Bowers, C. W.; Kimble, R. A.; Maran, S. P.; Moos, H. W.; Roesler, F. (1998-01-01)."First Results from the Space Telescope Imaging Spectrograph: Optical Spectra of Gliese 229B".The Astrophysical Journal.492(2): L181–L184.Bibcode:1998ApJ...492L.181S.doi:10.1086/311103.ISSN0004-637X.
  24. ^Calamari, Emily; Faherty, Jacqueline K.; Burningham, Ben; Gonzales, Eileen; Bardalez-Gagliuffi, Daniella; Vos, Johanna M.; Gemma, Marina; Whiteford, Niall; Gaarn, Josefine (2022-12-01)."An Atmospheric Retrieval of the Brown Dwarf Gliese 229B".The Astrophysical Journal.940(2): 164.arXiv:2210.13614.Bibcode:2022ApJ...940..164C.doi:10.3847/1538-4357/ac9cc9.ISSN0004-637X.
  25. ^Howe, Alex R.; Mandell, Avi M.; McElwain, Michael W. (June 2023)."Investigating Possible Binarity for GJ 229B".The Astrophysical Journal Letters.951(2): L25.arXiv:2306.08450.Bibcode:2023ApJ...951L..25H.doi:10.3847/2041-8213/acdd76.
  26. ^Kawashima, Yui; Kawahara, Hajime; Kasagi, Yui; Ishikawa, Hiroyuki Tako; Masuda, Kento; Kotani, Takayuki; Kudo, Tamoyuki; Hirano, Teruyuki; Kuzuhara, Masayuki (2024-10-15). "Atmospheric retrieval of Subaru/IRD high-resolution spectrum of the archetype T-type brown dwarf Gl 229 B".arXiv:2410.11561[astro-ph].
  27. ^Tuomi, Mikko; et al. (2014)."Bayesian search for low-mass planets around nearby M dwarfs – Estimates for occurrence rate based on global detectability statistics".Monthly Notices of the Royal Astronomical Society.441(2): 1545.arXiv:1403.0430.Bibcode:2014MNRAS.441.1545T.doi:10.1093/mnras/stu358.S2CID32965505.
  28. ^abFeng, Fabo; Butler, R. Paul; Shectman, Stephen A.; Crane, Jeffrey D.; Vogt, Steve; Chambers, John; Jones, Hugh R. A.; Wang, Sharon Xuesong; Teske, Johanna K.; Burt, Jenn; Díaz, Matías R.; Thompson, Ian B. (2020)."Search for Nearby Earth Analogs. II. Detection of Five New Planets, Eight Planet Candidates, and Confirmation of Three Planets around Nine Nearby M Dwarfs".The Astrophysical Journal Supplement Series.246(1): 11.arXiv:2001.02577.Bibcode:2020ApJS..246...11F.doi:10.3847/1538-4365/ab5e7c.S2CID210064560.
  29. ^"Planet GJ 229 A b".Extrasolar Planets Encyclopaedia.1995.Retrieved7 September2022.
  30. ^"GJ 229".NASA Exoplanet Archive.Archivedfrom the original on 4 December 2023.Retrieved7 September2022.
  31. ^Reylé, Céline; Jardine, Kevin; Fouqué, Pascal; Caballero, Jose A.; Smart, Richard L.; Sozzetti, Alessandro (30 April 2021). "The 10 parsec sample in the Gaia era".Astronomy & Astrophysics.650:A201.arXiv:2104.14972.Bibcode:2021A&A...650A.201R.doi:10.1051/0004-6361/202140985.S2CID233476431.Data available athttps://gruze.org/10pc/Archived2023-03-12 at theWayback Machine
edit
Wikimedia Commons has media related toGliese 229.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Gliese_229&oldid=1259121677"