Lambda1 Tucanae

Lambda1 Tucanae is the Bayer designation for a pair of stars sharing a common proper motion[8] through space, which lie within the southern constellation of Tucana. As of 2013, the pair had an angular separation of 20.0 arc seconds along a position angle of 82°.[2] Together, they are barely visible to the naked eye with a combined apparent visual magnitude of 6.21.[5] Based upon an annual parallax shift for both stars of approximately 16.5[1][3] mas as seen from Earth, this system is located roughly 198 light years from the Sun.

This article is about Lambda1 Tucanae. For other stars with this Bayer designation, see Lambda Tucanae.
Lambda1 Tucanae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Tucana
λ1 Tuc A
Right ascension  00h 52m 24.5198s[1]
Declination −69° 30′ 13.5440″[1]
Apparent magnitude (V) 6.70[2]
λ1 Tuc B
Right ascension  00h 52m 28.3487s[3]
Declination −69° 30′ 10.3819″[3]
Apparent magnitude (V) 7.35[2]
Characteristics
Spectral type F7 IV-V[4]
U−B color index +0.07[5]
B−V color index +0.55[5]
Astrometry
λ1 Tuc A
Radial velocity (Rv)+29.4±0.2[6] km/s
Proper motion (μ) RA: 3.849±0.050[1] mas/yr
Dec.: −67.462±0.040[1] mas/yr
Parallax (π)16.4907 ± 0.0293[1] mas
Distance197.8 ± 0.4 ly
(60.6 ± 0.1 pc)
Absolute magnitude (MV)+2.68[7]
λ1 Tuc B
Proper motion (μ) RA: 9.966±0.062[3] mas/yr
Dec.: −79.096±0.052[3] mas/yr
Parallax (π)16.5242 ± 0.0361[3] mas
Distance197.4 ± 0.4 ly
(60.5 ± 0.1 pc)
Details
λ1 Tuc A
Mass1.55[8] M☉
Luminosity7[9] L☉
Surface gravity (log g)3.90[10] cgs
Temperature6,325[10] K
Metallicity [Fe/H]+0.09[10] dex
Age2.6[10] Gyr
λ1 Tuc B
Mass1.38[8] M☉
Other designations
DUN 2, λ1 Tuc, CCDM J00524-6930AB, WDS J00524-6930AB[11]
λ1 Tuc A: λ1 Tucanae A, CPD−70 37, HD 5190, HIP 4084, HR 252, SAO 248269, WDS J00524-6930A[11]
λ1 Tuc B: λ1 Tucanae B, CPD−70 38, HD 5208, HIP 4088, SAO 248271, WDS J00524-6930B[11]
Database references
SIMBADdata

The brighter member, component A, is a magnitude 6.70[2] F-type star with a stellar classification of F7 IV-V.[4] The luminosity class may indicate that, at the age of 2.6 billion years,[10] it is beginning to evolve away from the main sequence. It has an estimated 1.55[8] times the mass of the Sun and is radiating 7[9] times the solar luminosity from its photosphere at an effective temperature of 6,325 K.[10] The magnitude 7.35[2] companion, component B, has 1.38[8] times the mass of the Sun. If the pair are gravitationally bound, then their estimated orbital period is 27,000 years.[8]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  3. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  4. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  5. Cousins, A. W. J.; Lagerweij, H. C. (1971), "UBV Observations of Variable Stars", Monthly Notes of the Astronomical Society of Southern Africa, 30: 12, Bibcode:1971MNSSA..30...12C.
  6. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  7. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  8. Tokovinin, Andrei (2014), "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs", The Astronomical Journal, 147 (4): 14, arXiv:1401.6827, Bibcode:2014AJ....147...87T, doi:10.1088/0004-6256/147/4/87, 87.
  9. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  10. Casagrande, L.; et al. (2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy & Astrophysics, 530 (A138): 21, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276.
  11. "Lambda1 Tucanae". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-11-26.
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