Astronomy:42 Leonis Minoris

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Short description: Star in the constellation Leo Minor
42 Leonis Minoris
Location of 42 Leo Minoris (circled)
Observation data
Equinox J2000.0]] (ICRS)
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
Evolutionary stage main sequence[3]
Spectral type B9 V[4]
U−B color index −0.16[5]
B−V color index −0.06[5]
Astrometry
Radial velocity (Rv)12±3.7[6] km/s
Proper motion (μ) RA: −20.344[1] mas/yr
Dec.: −38.234[1] mas/yr
Parallax (π)7.915 ± 0.0813 mas
Distance412 ± 4 ly
(126 ± 1 pc)
Absolute magnitude (MV)+0.02[7]
Details
Mass2.77±0.36[8] M☉
Radius3.29±0.11[8] R☉
Luminosity107[9] L☉
Surface gravity (log g)4±0.2[10] cgs
Temperature10,703±206[8] K
Rotational velocity (v sin i)145[11] km/s
Age69+199−59[10] Myr
Other designations
42 LMi, BD+31°2180, FK5 407, GC 14798, HD 93152, HIP 52638, HR 4203, SAO 62236
Database references
SIMBADdata

42 Leonis Minoris (42 LMi) is a solitary,[12] 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,[6] indicating that it is drifting away from the Solar System.

42 LMi has a general stellar classification of B9 V,[4] indicating that it is an ordinary B-type main-sequence star. However, Cowley et al. (1969) gave a slightly cooler class of A1 Vn,[13] 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☉.[8] It radiates at 107 times the luminosity of the Sun[9] from its photosphere at an effective temperature of 10,703 K.[8] 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.[11]

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°.[14] An 8th magnitude companion has been detected at a distance of over 400 arcseconds along a position angle of 92°.[14] 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.[15]

References

  1. ↑ 1.0 1.1 1.2 1.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ Zari, E.; Hashemi, H.; Brown, A. G. A.; Jardine, K.; De Zeeuw, P. T. (2018). "3D mapping of young stars in the solar neighbourhood with Gaia DR2". Astronomy and Astrophysics 620: A172. doi:10.1051/0004-6361/201834150. Bibcode: 2018A&A...620A.172Z. 
  4. ↑ 4.0 4.1 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. doi:10.1086/146706. ISSN 0004-637X. Bibcode: 1959ApJ...130..159O. 
  5. ↑ 5.0 5.1 Crawford, D. L. (February 1963). "U, b, v, and Hβ Photometry for the Bright B8- and B9-TYPE Stars.". The Astrophysical Journal 137: 530. doi:10.1086/147526. ISSN 0004-637X. Bibcode: 1963ApJ...137..530C. 
  6. ↑ 6.0 6.1 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. doi:10.1002/asna.200710776. ISSN 0004-6337. Bibcode: 2007AN....328..889K. 
  7. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S. 
  9. ↑ 9.0 9.1 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. doi:10.1093/mnras/stx1433. ISSN 0035-8711. Bibcode: 2017MNRAS.471..770M. 
  10. ↑ 10.0 10.1 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. doi:10.3847/0004-6256/152/2/40. Bibcode: 2016AJ....152...40G. 
  11. ↑ 11.0 11.1 Dworetsky, Michael M. (November 1974). "Rotational Velocities of A0 Stars". The Astrophysical Journal Supplement Series 28: 101. doi:10.1086/190312. ISSN 0067-0049. Bibcode: 1974ApJS...28..101D. 
  12. ↑ 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. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Bibcode: 2008MNRAS.389..869E. 
  13. ↑ 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. doi:10.1086/110819. ISSN 0004-6256. Bibcode: 1969AJ.....74..375C. 
  14. ↑ 14.0 14.1 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. doi:10.1086/323920. ISSN 0004-6256. Bibcode: 2001AJ....122.3466M. 
  15. ↑ Schröder, C.; Schmitt, J. H. M. M. (24 September 2007). "X-ray emission from A-type stars". Astronomy & Astrophysics 475 (2): 677–684. doi:10.1051/0004-6361:20077429. ISSN 0004-6361. Bibcode: 2007A&A...475..677S. 



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