HR 4177

HR 4177, also called t² Carinae (t² Car), is a double star[2] in the southern constellation of Carina. It is faintly visible to the naked eye with a combined apparent visual magnitude of +4.77.[2] The two components are HD 92397 and HD 92398. The primary component is located at a distance of approximately 1,600 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +11 km/s.[3] It has a peculiar velocity of 24.3+9.9
−16.1 km/s and may be a runaway star.[4] The star is a member of the BH 99 cluster.[7]

This article is about t2 Carinae. For t1 Carinae, see HD 92063.
HR 4177
Observation data
Epoch J2000      Equinox J2000
Constellation Carina
Right ascension  10h 38m 44.99524s[1]
Declination −59° 10′ 58.7927″[1]
Apparent magnitude (V) 4.77 (4.85 + 7.67)[2]
Characteristics
A
Spectral type K4.5Ib-II[3]
B−V color index 1.562±0.015[3]
B
Spectral type B9II/III[3]
B−V color index 0.100±0.020[3]
Astrometry
A
Radial velocity (Rv)+11.0±0.8[3] km/s
Proper motion (μ) RA: −14.284±0.338[1] mas/yr
Dec.: +1.117±0.329[1] mas/yr
Parallax (π)2.0056 ± 0.1809[1] mas
Distance1,600 ± 100 ly
(500 ± 40 pc)
Absolute magnitude (MV)−3.66[3]
B
Proper motion (μ) RA: −14.380±0.089[1] mas/yr
Dec.: +0.932±0.085[1] mas/yr
Parallax (π)2.1854 ± 0.0512[1] mas
Distance1,490 ± 30 ly
(460 ± 10 pc)
Details
A
Mass11.9±0.2[4] M☉
Radius202+5
−6[1] R☉
Luminosity8,478±875[1] L☉
Temperature3,900+63
−48[1] K
Age16.4±1.0[4] Myr
B
Temperature8,316+1,256
−1,389[1] K
Other designations
t2 Car, CPD−58°2460, HR 4177, CCDM J10388-5911, WDS J10387-5911[5]
A: GC 14647, HD 92397, HIP 52102, SAO 238295[5]
B: GC 14649, HD 92398, HIP 52106, SAO 238297[6]
Database references
SIMBADA
B

The magnitude 4.85[2] primary, component A, is a massive K-type supergiant or bright giant with a stellar classification of K4.5Ib-II.[3] Houk (1978) instead listed it with a class of K4/5III: but with some uncertainty about the classification.[8] It has 12[4] times the mass of the Sun and has expanded to 202[1] times the Sun's radius. The star is radiating 8,478[1] times the luminosity of the Sun from its bloated photosphere at an effective temperature of 3,900 K.[1]

The magnitude 7.48 companion star, component B, was discovered by J. Dunlop in 1829. As of 2015, it was located at an angular separation of 14.60″ along a position angle of 21°, relative to the primary.[9] It is a B-type giant/bright giant star with a class of B9II/III.[3] The pair show a common proper motion and roughly similar parallax measurements,[1] but it remains unclear whether they form a gravitationally-bound pair.[2]

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.
  2. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  3. 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.
  4. Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
  5. "HD 92397". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-13.
  6. "HD 92398". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-13.
  7. Cantat-Gaudin, T.; et al. (October 2018), "A Gaia DR2 view of the open cluster population in the Milky Way", Astronomy & Astrophysics, 618: 16, arXiv:1805.08726, Bibcode:2018A&A...618A..93C, doi:10.1051/0004-6361/201833476, A93.
  8. Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1975mcts.book.....H.
  9. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22

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