83 Leonis

83 Leonis, abbreviated 83 Leo, is a binary star system approximately 59 light-years away in the constellation of Leo (the Lion). The primary star of the system is a cool orange subgiant star, while the secondary star is an orange dwarf star. The two stars are separated by at least 515 astronomical units from each other. Both stars are presumed to be cooler than the Sun.

83 Leonis

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Leo
83 Leonis A
Right ascension	11h 26m 45.32173s[1]
Declination	+03° 00′ 47.1566″[1]
Apparent magnitude (V)	6.49
83 Leonis B
Right ascension	11h 26m 46.27833s[2]
Declination	+03° 00′ 22.7567″[2]
Apparent magnitude (V)	7.58[3]
Characteristics
Spectral type	G9IV-V[4] / K2V[5]
U−B color index	1.024 (83 Leonis B)[6]
B−V color index	0.913 (83 Leonis B)[6]
Variable type	None
Astrometry
83 Leonis A
Radial velocity (Rv)	4.18±0.13[1] km/s
Proper motion (μ)	RA: −725.963(29) mas/yr[1] Dec.: 180.980(30) mas/yr[1]
Parallax (π)	55.0090 ± 0.0240 mas[1]
Distance	59.29 ± 0.03 ly (18.179 ± 0.008 pc)
83 Leonis B
Radial velocity (Rv)	3.63±0.13[2] km/s
Proper motion (μ)	RA: −728.131(34) mas/yr[2] Dec.: 188.554(27) mas/yr[2]
Parallax (π)	55.0618 ± 0.0304 mas[2]
Distance	59.23 ± 0.03 ly (18.16 ± 0.01 pc)
Details
83 Leonis A
Mass	0.95 ± 0.06[7] M☉
Radius	0.96+0.04 −0.02[8] R☉
Luminosity	0.74[7] L☉
Surface gravity (log g)	4.42[7] cgs
Temperature	5509 ± 8.6[9] K
Metallicity	0.30[7]
Age	8.09 ± 6.75[7] Gyr
83 Leonis B
Mass	0.85±0.02[3] M☉
Radius	0.78±0.02[3] R☉
Luminosity (bolometric)	0.418 ± 0.057[5] L☉
Surface gravity (log g)	4.57±0.06[3] cgs
Temperature	4929±44[3] K
Metallicity	0.3±0.03[3]
Rotation	40-45 days[10]
Rotational velocity (v sin i)	0.41±0.5[3] km/s
Age	4.8±4.1[3] Gyr
Other designations
BD+03° 2502/3, GJ 429, HD 99491/99492, HIP 55846, HR 4414, Wolf 393[11]
Database references
SIMBAD	HD 99491
	HD 99492

The primary star is also known as HD 99491 and the secondary star as HD 99492. In 2005, an exoplanet was confirmed to be orbiting the secondary star within the system.^[12]

Stellar system

The primary component, 83 Leonis A, is a 6th magnitude star. It is not visible to the unaided eye, but easily visible with small binoculars. The star is classified as a subgiant, meaning that it has ceased fusing hydrogen in its core and started to evolve towards red gianthood.

The secondary component, 83 Leonis B, is an 8th magnitude orange dwarf, somewhat less massive (0.88 M_Sun), smaller and cooler than the Sun.^[13] It is visible only with binoculars or better equipment. Components A and B share common proper motion, which confirms them as a physical pair. The projected separation between the stars is 515 AU, but the true separation may be much higher.^[14]

There is yet another, magnitude 14.4 component listed in the Washington Double Star Catalog. However, this star is moving into a different direction and is therefore not a true member of the 83 Leonis system.

Planetary system

Planet 83 Leonis Bb was discovered in Jan 2005 by the California and Carnegie Planet Search team, who use the radial velocity method to detect planets. The planet's minimum mass is less than half of the mass of Saturn. It orbits very close to the star, completing one orbit in about 17 days.^[12]

In 2010, a second planet, 83 Leonis Bc, was claimed,^[5] but was found to be a false positive in 2016.^[3] However, in 2023 a different second planet was discovered, also given the designation "c".^[10]

The 83 Leonis B planetary system^[3][10]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥25.5±0.6 M🜨	0.123±0.001	17.0503±0.0016	0.034+0.025 −0.021	—	—
c	≥17.9±1.3 M🜨	—	95.233+0.098 −0.096	0.063+0.060 −0.040	—	—

See also

• 16 Cygni
• 30 Arietis
• List of stars in Leo

References

1. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
3. Kane, Stephen R.; Thirumalachari, Badrinath; Henry, Gregory W.; Hinkel, Natalie R.; Jensen, Eric L. N.; Boyajian, Tabetha S.; Fischer, Debra A.; Howard, Andrew W.; Isaacson, Howard T.; Wright, Jason T. (2016). "Stellar Activity and Exclusion of the Outer Planet in the Hd 99492 System". The Astrophysical Journal. 820 (1): L5. arXiv:1603.00487. Bibcode:2016ApJ...820L...5K. doi:10.3847/2041-8205/820/1/L5. S2CID 16443458.
4. Abt, H. A. (1986). "The Ages and Dimensions of Trapezium Systems". Astrophysical Journal. 304: 688. Bibcode:1986ApJ...304..688A. doi:10.1086/164207.
5. Meschiari, Stefano; et al. (2011). "The Lick-Carnegie Survey: Four New Exoplanet Candidates". The Astrophysical Journal. 727 (2). 117. arXiv:1011.4068. Bibcode:2011ApJ...727..117M. doi:10.1088/0004-637X/727/2/117. S2CID 59065004.
6. Koen, C.; Kilkenny, D.; van Wyk, F.; Marang, F. (2010). "UBV(RI)_C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society. 403 (4): 1949–1968. Bibcode:2010MNRAS.403.1949K. doi:10.1111/j.1365-2966.2009.16182.x.
7. Luck, R. Earle (2017). "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants". The Astronomical Journal. 153 (1): 19. arXiv:1611.02897. Bibcode:2017AJ....153...21L. doi:10.3847/1538-3881/153/1/21. 21.
8. 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.
9. Kovtyukh, V. V.; et al. (2003). "High precision effective temperatures for 181 F-K dwarfs from line-depth ratios". Astronomy and Astrophysics. 411 (3): 559–564. arXiv:astro-ph/0308429. Bibcode:2003A&A...411..559K. doi:10.1051/0004-6361:20031378. S2CID 18478960.
10. Stalport, M.; Cretignier, M.; et al. (August 2023). "A review of planetary systems around HD 99492, HD 147379 and HD 190007 with HARPS-N". Astronomy & Astrophysics. 678: A90. arXiv:2308.05669. Bibcode:2023A&A...678A..90S. doi:10.1051/0004-6361/202346887. S2CID 260775534.
11. "83 Leo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 15 February 2018.
12. Marcy, Geoffrey W.; et al. (2005). "Five New Extrasolar Planets" (PDF). The Astrophysical Journal. 619 (1): 570–584. Bibcode:2005ApJ...619..570M. doi:10.1086/426384. S2CID 5803173.
13. "The Planet Around HD 99492". California & Carnegie Planet Search. Archived from the original on 2005-12-16. Retrieved 2006-05-09.
14. Raghavan, Deepak; et al. (2006). "Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems". The Astrophysical Journal. 646 (1): 523–542. arXiv:astro-ph/0603836. Bibcode:2006ApJ...646..523R. doi:10.1086/504823. S2CID 5669768.

External links

• "83 Leonis AB". SolStation. Archived from the original on 25 July 2008. Retrieved 2008-06-20.
• "Notes for star HD 99492". Extrasolar Planets Encyclopaedia. Archived from the original on 1 June 2008. Retrieved 2008-06-20.