Wikipedia

42 Leonis Minoris

42 Leonis Minoris (42 LMi) is a solitary,[11] bluish-white hued star located in the northern constellation Leo Minor. It has a visual apparent magnitude of 5.35,[2] allowing it to be faintly seen with the naked eye. Parallax measurements place it at a distance of 412 light years.[1] The object has a heliocentric radial velocity of 12 km/s,[5] indicating that it is drifting away from the Solar System.

42 Leonis Minoris
Location of 42 Leo Minoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Leo Minor
Right ascension 10h 45m 51.8947s[1]
Declination +30° 40′ 56.307″[1]
Apparent magnitude (V) 5.35±0.01[2]
Characteristics
Spectral type B9 V[3]
U−B color index −0.16[4]
B−V color index −0.06[4]
Astrometry
Radial velocity (Rv)12±3.7[5] km/s
Proper motion (μ) RA: −20.344 mas/yr[1]
Dec.: −38.234 mas/yr[1]
Parallax (π)7.915 ± 0.0813 mas
Distance412 ± 4 ly
(126 ± 1 pc)
Absolute magnitude (MV)+0.02[6]
Details
Mass2.77±0.36[7] M☉
Radius3.29±0.11[7] R☉
Luminosity107[8] L☉
Surface gravity (log g)4±0.2[9] cgs
Temperature10,703±206[7] K
Rotational velocity (v sin i)145[10] km/s
Age69+199
−59[9] Myr
Other designations
42 LMi, AG+30°1079, BD+31°2180, FK5 407, GC 14798, HD 93152, HIP 52638, HR 4203, SAO 62236
Database references
SIMBADdata

42 LMi has a general stellar classification of B9 V,[3] indicating that it is an ordinary B-type main-sequence star. However, Cowley et al. (1969) gave a slightly cooler class of A1 Vn,[12] indicating that it is instead an A-type main-sequence star with 'nebulous' (broad) absorption lines due to rapid rotation. Nevertheless, it has 2.77 times the mass of the Sun and a radius of 3.3 R☉.[7] It radiates at 107 times the luminosity of the Sun[8] from its photosphere at an effective temperature of 10,703 K.[7] Its high luminosity and slightly enlarged diameter suggests that the object might be evolved. Like most hot stars, 42 LMi spins rapidly with a projected rotational velocity of 145 km/s.[10]

There are two optical companions located near this star. BD+31°2181 is a 7th magnitude K2 giant star separated 146″ away along a position angle of 174°.[13] An 8th magnitude companion has been detected at a distance of over 400 arcseconds along a position angle of 92°.[13] Both have no relation to 42 LMi and is just moving with it by coincidence.

An X-ray emission with a luminosity of 278.2×1020 W has been detected around the object. A-type stars are not expected to emmit X-rays, so it must be coming from an unseen companion.[14]

References

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  1. ^ a b c d Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
  3. ^ a b Osawa, Kiyoteru (July 1959). "Spectral Classification of 533 B8-A2 Stars and the Mean Absolute Magnitude of a0 V Stars". The Astrophysical Journal. 130: 159. Bibcode:1959ApJ...130..159O. doi:10.1086/146706. eISSN 1538-4357. ISSN 0004-637X.
  4. ^ a b Crawford, D. L. (February 1963). "U, b, v, and Hβ Photometry for the Bright B8- and B9-TYPE Stars". The Astrophysical Journal. 137: 530. Bibcode:1963ApJ...137..530C. doi:10.1086/147526. eISSN 1538-4357. ISSN 0004-637X.
  5. ^ a b Kharchenko, N.V.; Scholz, R.-D.; Piskunov, A.E.; Röser, S.; Schilbach, E. (November 2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889–896. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. ISSN 0004-6337.
  6. ^ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
  7. ^ a b c d e Stassun, Keivan G.; et al. (9 September 2019). "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. eISSN 1538-3881.
  8. ^ a b McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. eISSN 1365-2966. ISSN 0035-8711.
  9. ^ a b Gullikson, Kevin; Kraus, Adam; Dodson-Robinson, Sarah (25 July 2016). "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars". The Astronomical Journal. 152 (2): 40. arXiv:1604.06456. Bibcode:2016AJ....152...40G. doi:10.3847/0004-6256/152/2/40. eISSN 1538-3881.
  10. ^ a b Dworetsky, Michael M. (November 1974). "Rotational Velocities of A0 Stars". The Astrophysical Journal Supplement Series. 28: 101. Bibcode:1974ApJS...28..101D. doi:10.1086/190312. eISSN 1538-4365. ISSN 0067-0049.
  11. ^ Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. eISSN 1365-2966. ISSN 0035-8711.
  12. ^ Cowley, A.; Cowley, C.; Jaschek, M.; Jaschek, C. (April 1969). "A study of the bright stars. I. A catalogue of spectral classifications". The Astronomical Journal. 74: 375. Bibcode:1969AJ.....74..375C. doi:10.1086/110819. ISSN 0004-6256.
  13. ^ a b Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. ISSN 0004-6256.
  14. ^ Schröder, C.; Schmitt, J. H. M. M. (24 September 2007). "X-ray emission from A-type stars". Astronomy & Astrophysics. 475 (2): 677–684. Bibcode:2007A&A...475..677S. doi:10.1051/0004-6361:20077429. eISSN 1432-0746. ISSN 0004-6361.
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