Astronomy:20 Leonis Minoris

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Short description: Star in the constellation Leo Minor
20 Leonis Minoris
Location of 20 Leonis Minoris (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Leo Minor
Right ascension  10h 01m 00.65688s[1]
Declination +31° 55′ 25.2130″[1]
Apparent magnitude (V) +5.40[2]
Characteristics
Spectral type G3 Va Hδ1[3] + M7 V[4]
U−B color index +0.27[5]
B−V color index +0.65[5]
Astrometry
Radial velocity (Rv)+55.96±0.09[6] km/s
Proper motion (μ) RA: −528.871(92)[1] mas/yr
Dec.: −429.376(74)[1] mas/yr
Parallax (π)66.9958 ± 0.0921[1] mas
Distance48.68 ± 0.07 ly
(14.93 ± 0.02 pc)
Absolute magnitude (MV)4.46[7]
Details
20 LMi A
Mass0.967±0.010[8] M☉
Radius1.237±0.019[8] R☉
Luminosity1.365±0.014[8] L☉
Surface gravity (log g)4.25±0.02[8] cgs
Temperature5,735±5.6[9] K
Metallicity [Fe/H]0.20±0.02[8] dex
Rotation10.64±0.14 d[2]
Rotational velocity (v sin i)2.4±0.5[8] km/s
Age6.2–7.7[10] Gyr
20 LMi B
Mass0.11[11] M☉
Temperature3,106(54)[12] K
Rotation19.2687 d[4]
Other designations
20 LMi, BD+32°1964, FK5 1258, GJ 376, HD 86728, HIP 49081, HR 3951, SAO 61808, LHS 2216, LTT 12671[13]
Database references
SIMBADA
B
Exoplanet Archivedata

20 Leonis Minoris is a binary star system in the northern constellation of Leo Minor. It is faintly visible to the naked eye, having an apparent visual magnitude of +5.4.[2] Based upon an annual parallax shift of 66.996 mas, it is located 48.7 light-years from the Sun. The star has a relatively high proper motion[3] and is moving away from the Sun with a radial velocity of +56 km/s.[6] The system made its closest approach about 150,000 years ago when it came within 32.2 ly (9.86 pc).[14]

The primary member of this system is a G-type main-sequence star with a stellar classification of G3 Va Hδ1.[3] It has 12% more mass and a 25% larger radius than the Sun. The star is about seven[10] billion years old and is spinning with a rotation period of 10.6 days.[2] The small companion is an active red dwarf star that has a relatively high metallicity.[15] The two stars are currently separated by 14.5 arc seconds,[citation needed] corresponding to a projected separation of 2016 AU.[11]

Planetary system

Artist's impression of 20 Leonis Minoris b orbiting its star.[16]

A candidate exoplanet orbiting 20 Leonis Minoris A (HD 86728) was first detected in 2020,[17] and confirmed in 2024 as the first discovery of the NEID Earth Twin Survey (NETS). With a minimum mass of 9.2 M⊕ and an orbital period of 31 days, this is most likely a hot Neptune-type planet.[8]

The 20 Leonis Minoris A planetary system[8]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥9.16+0.55
−0.56 M⊕ 		0.1916+0.00065
−0.00066 		31.1503+0.0062
−0.0066 		0.064+0.065
−0.044 		— —

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 2.2 2.3 Hempelmann, A. et al. (February 2016), "Measuring rotation periods of solar-like stars using TIGRE. A study of periodic CaII H+K S-index variability", Astronomy & Astrophysics 586: 19, doi:10.1051/0004-6361/201526972, A14, Bibcode: 2016A&A...586A..14H, https://orbi.uliege.be/bitstream/2268/192396/1/aa26972-15.pdf. 
  3. ↑ 3.0 3.1 3.2 Keenan, P.; McNeil, R. (October 1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series 71: 245–266, doi:10.1086/191373, Bibcode: 1989ApJS...71..245K. 
  4. ↑ 4.0 4.1 West, Andrew A. et al. (October 2015), "An Activity-Rotation Relationship and Kinematic Analysis of Nearby Mid-to-Late-Type M Dwarfs", The Astrophysical Journal 812 (1): 12, doi:10.1088/0004-637X/812/1/3, 3, Bibcode: 2015ApJ...812....3W. 
  5. ↑ 5.0 5.1 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode: 1986EgUBV........0M. 
  6. ↑ 6.0 6.1 Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G. 
  7. ↑ Holmberg, J. et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics 501 (3): 941–947, doi:10.1051/0004-6361/200811191, Bibcode: 2009A&A...501..941H. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 Gupta, Arvind F. et al. (2025-01-01). "The NEID Earth Twin Survey. I. Confirmation of a 31 Day Planet Orbiting HD 86728". The Astronomical Journal 169 (1). doi:10.3847/1538-3881/ad89bf. Bibcode: 2025AJ....169....1G. 
  9. ↑ Kovtyukh; Soubiran, C.; Belik, S. I.; Gorlova, N. I. (2003), "High precision effective temperatures for 181 F-K dwarfs from line-depth ratios", Astronomy and Astrophysics 411 (3): 559–564, doi:10.1051/0004-6361:20031378, Bibcode: 2003A&A...411..559K 
  10. ↑ 10.0 10.1 Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal 687 (2): 1264–1293, doi:10.1086/591785, Bibcode: 2008ApJ...687.1264M 
  11. ↑ 11.0 11.1 Tokovinin, A.; Kiyaeva, O. (February 2016), "Eccentricity distribution of wide binaries", Monthly Notices of the Royal Astronomical Society 456 (2): 2070−2079, doi:10.1093/mnras/stv2825, Bibcode: 2016MNRAS.456.2070T. 
  12. ↑ Jahandar, Farbod et al. (2025-01-01). "Chemical Fingerprints of M Dwarfs: High-resolution Spectroscopy on 31 M Dwarfs with SPIRou". The Astrophysical Journal 978 (2). doi:10.3847/1538-4357/ad91a0. Bibcode: 2025ApJ...978..154J. 
  13. ↑ "HD 86728". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+86728. 
  14. ↑ Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics 575: 13, doi:10.1051/0004-6361/201425221, A35, Bibcode: 2015A&A...575A..35B. 
  15. ↑ Gizis, J. E. et al. (2000), "Two Nearby M Dwarf Binaries from 2MASS", Monthly Notices of the Royal Astronomical Society 311 (2): 385, doi:10.1046/j.1365-8711.2000.03060.x, Bibcode: 2000MNRAS.311..385G, https://authors.library.caltech.edu/27948/1/GIZmnras00.pdf 
  16. ↑ "NEID Earth Twin Survey Delivers On Its Goal to Push the Limits of Exoplanet Discovery" (Press release). NOIRLab. 2024-11-21. Retrieved 2025-05-31.
  17. ↑ Hirsch, Lea A. et al. (2021), "Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc", The Astronomical Journal 161 (3): 134, doi:10.3847/1538-3881/abd639, Bibcode: 2021AJ....161..134H. 



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