G 107-69/70

G 107-69/70 is a quadruple system, consisting of the astrometric binary G 107-69 and the resolved binary G 107-70.[2] The system is 36.76 light years (11.27 parsecs) from Earth.[1] G 107-69 and G 107-70 are separated by 103.2 arcseconds, or 1163 astronomical units (AU).[2]

G 107-69/70

KPNO 4.0 meter Mayall telescope image of the quadruple system G 107-69/70
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lynx
G 107-69
Right ascension 07h 30m 42.7784s[1]
Declination +48° 11′ 58.5889″[1]
Apparent magnitude (V) 13.2[2]
G 107-70
Right ascension 07h 30m 46.9572s[1]
Declination +48° 10′ 06.2765″[1]
Apparent magnitude (V) 15.00[3]
Characteristics
Spectral type M4.5+DA+DA
Astrometry
G 107-69
Radial velocity (Rv)−56.486±0.0035[4] km/s
Proper motion (μ) RA: −201.282±0.027 mas/yr[1]
Dec.: −1,272.162±0.020 mas/yr[1]
Parallax (π)88.7231 ± 0.0298 mas[1]
Distance36.76 ± 0.01 ly
(11.271 ± 0.004 pc)
Details
G 107-69A
Mass0.17[2] M☉
Radius0.21[5] R☉
Luminosity0.003[6] L☉
Surface gravity (log g)5.0±0.13[7] cgs
Temperature3,200±25[7] K
Metallicity [Fe/H]−0.15±0.09[7] dex
G 107-69B
Mass0.08[2] M☉
G 107-70A
Mass0.634±0.01[3] M☉
G 107-70B
Mass0.599±0.01[3] M☉
Other designations
WDS J07307+4813, 2MASS J07304735+4810275, 2MASS J07304280+4811599 GJ 275.2, LHS 229, LHS 230, EGGR 52, WD 0727+482
Database references
SIMBADG 107-69
G 107-70
Hubble WFPC2 observation show part of the orbital motion of G 107-70 between 1997 and 1999.

G 107-69A is a red dwarf star with a spectral type of M4.5[7] and a mass of about 0.17 M☉. G 107-69B has a mass of about 0.08 M☉ or 84 MJ. The binary has a period of 0.94 years and a predicted separation of about 50 mas.[2] From its mass G 107-69B could be either a low-mass red dwarf star or a brown dwarf.

G 107-70 (also called WD 0727+482) is a pair of white dwarfs, with both having similar mass, brightness and atmospheric composition.[3][8] The binary was first partially resolved in 1976.[9] Later Nelan et al. fully resolved the orbit of this binary with Hubble's Fine Guidance Sensor and found an orbital period of 18.84±0.02 years and a semi-major axis of 663.62±0.79 mas.[3] At a distance of 11.27 parsecs the semi-major axis is about 7.5 AU.

By resolving the orbit of the G 107-70 system Nelan et al. were able to calculate the dynamical mass of each component: G 107-70A has a mass of 0.634±0.01 M☉ and G 107-70B has a mass of 0.599±0.01 M☉.[3] Both white dwarfs have a spectral type of DA, which indicates an atmosphere dominated by hydrogen.[8]

See also
  • Gliese 318, suspected to be the closest double white dwarf, which would make G 107-70 the second closest double white dwarf[10]
  • Capella, is another nearby quadruple system

References
  1. Gaia Collaboration (2022-05-01). "VizieR Online Data Catalog: Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)". VizieR Online Data Catalog: I/355. Bibcode:2022yCat.1355....0G.
  2. Harrington, R. S.; Christy, J. W.; Strand, K. A. (1981-06-01). "The nearby quadruple system G 107-69/70". The Astronomical Journal. 86: 909–911. Bibcode:1981AJ.....86..909H. doi:10.1086/112967. ISSN 0004-6256.
  3. Nelan, Edmund P.; Bond, Howard E.; Schaefer, Gail (2015-06-01). "Dynamical Masses of Cool White Dwarfs in Double Degenerate Binary Systems". 19Th European Workshop on White Dwarfs. 493: 501. Bibcode:2015ASPC..493..501N.
  4. Soubiran, C.; Jasniewicz, G.; Chemin, L.; Zurbach, C.; Brouillet, N.; Panuzzo, P.; Sartoretti, P.; Katz, D.; Le Campion, J. -F.; Marchal, O.; Hestroffer, D.; Thévenin, F.; Crifo, F.; Udry, S.; Cropper, M. (2018-08-01). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics. 616: A7. arXiv:1804.09370. Bibcode:2018A&A...616A...7S. doi:10.1051/0004-6361/201832795. ISSN 0004-6361.
  5. Sebastian, D.; Gillon, M.; Ducrot, E.; Pozuelos, F. J.; Garcia, L. J.; Günther, M. N.; Delrez, L.; Queloz, D.; Demory, B. O.; Triaud, A. H. M. J.; Burgasser, A.; De Wit, J.; Burdanov, A.; Dransfield, G.; Jehin, E.; McCormac, J.; Murray, C. A.; Niraula, P.; Pedersen, P. P.; Rackham, B. V.; Sohy, S.; Thompson, S.; Van Grootel, V. (2021). "SPECULOOS: Ultracool dwarf transit survey. Target list and strategy". Astronomy and Astrophysics. 645: 645. arXiv:2011.02069. Bibcode:2021A&A...645A.100S. doi:10.1051/0004-6361/202038827. S2CID 226245978.
  6. Reiners, Ansgar; Zechmeister, Mathias (2020). "Radial velocity photon limits for the dwarf stars of spectral classes F--M". The Astrophysical Journal Supplement Series. 247 (1): 11. arXiv:1912.04120. Bibcode:2020ApJS..247...11R. doi:10.3847/1538-4365/ab609f.
  7. Hejazi, Neda; Lépine, Sébastien; Homeier, Derek; Rich, R. Michael; Shara, Michael M. (2020-01-01). "Chemical Properties of the Local Galactic Disk and Halo. I. Fundamental Properties of 1544 Nearby, High Proper-motion M Dwarfs and Subdwarfs". The Astronomical Journal. 159 (1): 30. arXiv:1911.04612. Bibcode:2020AJ....159...30H. doi:10.3847/1538-3881/ab563c. ISSN 0004-6256. S2CID 207863707.
  8. Limoges, M. -M.; Bergeron, P.; Lépine, S. (2015-08-01). "Physical Properties of the Current Census of Northern White Dwarfs within 40 pc of the Sun". The Astrophysical Journal Supplement Series. 219 (2): 19. arXiv:1505.02297. Bibcode:2015ApJS..219...19L. doi:10.1088/0067-0049/219/2/19. ISSN 0067-0049. S2CID 118494290.
  9. Strand, K. A.; Dahn, C. C.; Liebert, J. W. (1976-09-01). "G107-70: A Partially Resolved Pair of Cool Degenerate Stars". Bulletin of the American Astronomical Society. 8: 506. Bibcode:1976BAAS....8..506S.
  10. Toonen, S.; Hollands, M.; Gänsicke, B. T.; Boekholt, T. (2017-06-01). "The binarity of the local white dwarf population". Astronomy and Astrophysics. 602: A16. arXiv:1703.06893. Bibcode:2017A&A...602A..16T. doi:10.1051/0004-6361/201629978. ISSN 0004-6361. S2CID 12367523.
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