2MASS J0920+3517 (also called 2MASSW J0920122+351742) is a triple brown dwarf system. Alternatively it is a low-mass star orbiting a pair of brown dwarfs.[3]
 2MASS J0920+3517 resolved in 2007 with Keck NIRC2 Credit: Keck Observatory & Meli_thev | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lynx |
| Right ascension | 09h 20m 12.24s |
| Declination | +35° 17′ 42.97″ |
| Characteristics | |
| Evolutionary stage | brown dwarf |
| Spectral type | L5.5+L9[1] |
| Apparent magnitude (J) | 13.89 ±0.17[2] |
| Apparent magnitude (H) | 12.92 ±0.07[2] |
| Apparent magnitude (Ks) | 12.12 ±0.08[2] |
| Astrometry | |
| Proper motion (μ) | RA: -188.9 ±0.8 mas/yr[1] Dec.: -198.5 ±0.7 mas/yr[1] |
| Parallax (π) | 32.3 ± 0.6 mas[3] |
| Distance | 101 ± 2 ly (31.0 ± 0.6 pc) |
| Orbit | |
| Primary | 2MASS J0920+3517A |
| Companion | 2MASS J0920+3517B |
| Period (P) | 7.258 ±0.009[3] yr |
| Semi-major axis (a) | 0.069 ± 0.024[4]" (2.11 ±0.04 AU[3]) |
| Eccentricity (e) | 0.180+0.006 −0.007[3] |
| Inclination (i) | 88.6 ±2.4[4]° |
| Longitude of the node (Ω) | 69.0 ±1.5[4]° |
| Periastron epoch (T) | 2003.43 ±1.15[4] |
| Argument of periastron (ω) (secondary) | 317+43 −300[4]° |
| Details | |
| 2MASS J0920+3517A | |
| Mass | 71±5[3] MJup |
| Radius | 0.91+0.03 −0.01[2] RJup |
| Luminosity (bolometric) | 10-4.270 ±0.030[2] L☉ |
| Surface gravity (log g) | 5.32+0.03 −0.04[2] cgs |
| Temperature | 1621+32 −30[2] K |
| 2MASS J0920+3517B | |
| Mass | 116+7 −8[3] MJup |
| Radius | 0.91 ±0.04[2] RJup |
| Luminosity (bolometric) | 104.340 ±0.030[2] L☉ |
| Surface gravity (log g) | 5.24 ±0.10[2] cgs |
| Temperature | 1320 ±250[2] K |
| Age | 2.3+0.3 −0.4[3] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Discovery
edit2MASS J0920+3517 was first discovered in 2000 by J. Davy Kirkpatrick et al., using 2MASS photometry and Keck spectroscopy. The optical spectral type was measured to be L6.5 and the distance was estimated to be 21 parsec.[5] Shortly after the discovery, a paper by Ian Neill Reid et al. used Hubble WFPC2 to search binary L dwarfs and found that 2MASS J0902+3517 is extended in the F814W image, but not in the F606W image, showing that it has a red companion. The pair is separated by 70 milliarcseconds. Using the available distance at the time, this translated to a separation of 1.6 astronomical units.[6] In 2017 the dynamical mass was measured by Trent J. Dupuy and Michael C. Liu and showed that the binary is overly massive with 187±11 MJ and with the B component being more massive. This showed that the B component is in fact two brown dwarfs of equal masses. The A component could be either a low-mass star or a high-mass brown dwarf.[3]
Observations
editBefore the multiple status of 2MASS J0920+3517 was discovered, a team used the Subaru Telescope to measure the spectrum of this brown dwarf. This team found methane in the H- and K-band spectrum which is unusual for an L6.5 type dwarf. Methane is usually associated with T-dwarfs.[7] Later a team classified the infrared spectral type as T0pec, suspecting the binary to be composed of an L- and a T-dwarf.[8] After the binary was discovered with Hubble WFPC2,[6] VLT and Hubble observations did not resolve the binary, likely due to the highly inclined orbit and the low separation in this part of the orbit.[9] Keck adaptive optics observations were able to resolve the binary again. This showed that the binary was on a highly inclined orbit of 88.6 ±1.2° and had a chance of 6.8% of being an eclipsing binary. The orbital period was measured to be about 6.7 years.[4] A team estimated the component spectral types with the help of spectral deconvolution and found the primary to have a spectral type of L5.5±1 and the secondary to have a spectral type of L9±1.5.[1] The new dynamical mass measurement found masses of 71±5 MJ for 2MASS J0920+3517A and 116+7
−8 MJ for 2MASS J0920+3517B. This mass for component B is too large for an L9-dwarf and it was interpreted that it is composed of two components with an equal mass of 58+3
−4 MJ. Because the B component was never resolved, the pair must be on a tight orbit. The system age is estimated to be around 2 billion years.[3] The binary was observed with the Spitzer Infrared Spectrograph, which covers the mid-infrared and can observe silicate absorption features.[10] The primary was identified to have silicate-rich clouds. In this study 2MASS J020+3517 belongs to their old sample and therefore the silicates are made up of small ≤0.1μm grains made of amorphous enstatite or silicon monoxide.[11] Another study found the most abundant condensates in the top cloud layer of the primary to be 48% iron and 52% silicates. These silicates are enstatite, fosterite, periclase and quartz.[2]
See also
editOther triple brown dwarfs
References
edit- ^ a b c Dupuy, Trent J.; Liu, Michael C. (2012-08-01). "The Hawaii Infrared Parallax Program. I. Ultracool Binaries and the L/T Transition". The Astrophysical Journal Supplement Series. 201 (2): 19. arXiv:1201.2465. Bibcode:2012ApJS..201...19D. doi:10.1088/0067-0049/201/2/19. ISSN 0067-0049.
- ^ a b c d e f g h i j k l Brock, Laci; Barman, Travis; Konopacky, Quinn M.; Stone, Jordan M. (2021-06-01). "Cloud Properties of Brown Dwarf Binaries across the L/T Transition". The Astrophysical Journal. 914 (2): 124. Bibcode:2021ApJ...914..124B. doi:10.3847/1538-4357/abfc46. ISSN 0004-637X.
- ^ a b c d e f g h i j Dupuy, Trent J.; Liu, Michael C. (2017-08-01). "Individual Dynamical Masses of Ultracool Dwarfs". The Astrophysical Journal Supplement Series. 231 (2): 15. arXiv:1703.05775. Bibcode:2017ApJS..231...15D. doi:10.3847/1538-4365/aa5e4c. ISSN 0067-0049.
- ^ a b c d e f Konopacky, Q. M.; Ghez, A. M.; Barman, T. S.; Rice, E. L.; Bailey, J. I., III; White, R. J.; McLean, I. S.; Duchêne, G. (2010-03-01). "High-precision Dynamical Masses of Very Low Mass Binaries". The Astrophysical Journal. 711 (2): 1087–1122. arXiv:1001.4800. Bibcode:2010ApJ...711.1087K. doi:10.1088/0004-637X/711/2/1087. ISSN 0004-637X.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Kirkpatrick, J. Davy; Reid, I. Neill; Liebert, James; Gizis, John E.; Burgasser, Adam J.; Monet, David G.; Dahn, Conard C.; Nelson, Brant; Williams, Rik J. (2000-07-01). "67 Additional L Dwarfs Discovered by the Two Micron All Sky Survey". The Astronomical Journal. 120 (1): 447–472. arXiv:astro-ph/0003317. Bibcode:2000AJ....120..447K. doi:10.1086/301427. ISSN 0004-6256.
- ^ a b Reid, I. Neill; Gizis, John E.; Kirkpatrick, J. Davy; Koerner, D. W. (2001-01-01). "A Search for L Dwarf Binary Systems". The Astronomical Journal. 121 (1): 489–502. arXiv:astro-ph/0010202. Bibcode:2001AJ....121..489R. doi:10.1086/318023. ISSN 0004-6256.
- ^ Nakajima, Tadashi; Tsuji, Takashi; Yanagisawa, Kenshi (2001-11-01). "H- and K-Band Methane Features in an L Dwarf, 2MASS 0920+35". The Astrophysical Journal. 561 (1): L119–L122. arXiv:astro-ph/0109370. Bibcode:2001ApJ...561L.119N. doi:10.1086/324440. ISSN 0004-637X.
- ^ Burgasser, Adam J.; Geballe, T. R.; Leggett, S. K.; Kirkpatrick, J. Davy; Golimowski, David A. (2006-02-01). "A Unified Near-Infrared Spectral Classification Scheme for T Dwarfs". The Astrophysical Journal. 637 (2): 1067–1093. arXiv:astro-ph/0510090. Bibcode:2006ApJ...637.1067B. doi:10.1086/498563. ISSN 0004-637X.
- ^ Bouy, H.; Martín, E. L.; Brandner, W.; Forveille, T.; Delfosse, X.; Huélamo, N.; Basri, G.; Girard, J.; Zapatero Osorio, M. -R.; Stumpf, M.; Ghez, A.; Valdivielso, L.; Marchis, F.; Burgasser, A. J.; Cruz, K. (2008-04-01). "Follow-up observations of binary ultra-cool dwarfs". Astronomy and Astrophysics. 481 (3): 757–767. arXiv:0801.4424. Bibcode:2008A&A...481..757B. doi:10.1051/0004-6361:20078803. ISSN 0004-6361.
- ^ Suárez, Genaro; Metchev, Stanimir (2022-07-01). "Ultracool dwarfs observed with the Spitzer infrared spectrograph - II. Emergence and sedimentation of silicate clouds in L dwarfs, and analysis of the full M5-T9 field dwarf spectroscopic sample". Monthly Notices of the Royal Astronomical Society. 513 (4): 5701–5726. arXiv:2205.00168. Bibcode:2022MNRAS.513.5701S. doi:10.1093/mnras/stac1205. ISSN 0035-8711.
- ^ Suárez, Genaro; Metchev, Stanimir (2023-08-01). "Ultracool dwarfs observed with the Spitzer Infrared Spectrograph - III. Dust grains in young L dwarf atmospheres are heavier". Monthly Notices of the Royal Astronomical Society. 523 (3): 4739–4747. arXiv:2306.01119. Bibcode:2023MNRAS.523.4739S. doi:10.1093/mnras/stad1711. ISSN 0035-8711.