HD 102365

HD 102365 (66 G. Centauri) is a binary star system that is located in the northeastern part of the Centaurus constellation, at a distance of about 30.4 light-years (9.3 parsecs) from the Solar System. The larger member of the system is a G-type star that is smaller than the Sun but of similar mass. It has a common proper motion companion that was discovered by W. J. Luyten in 1960.^[6] This M-type star appears to be in a wide orbit around the primary at a current separation of about 211 astronomical units (AU),^[6] (or 211 times the separation of the Earth from the Sun). By comparison, Neptune orbits at an average distance of 30 AU.

HD 102365

Observation data Epoch J2000      Equinox J2000
Constellation	Centaurus
HD 102365 A
Right ascension	11h 46m 31.07253s[1]
Declination	−40° 30′ 01.2859″[1]
Apparent magnitude (V)	4.88[2]
HD 102365 B
Right ascension	11h 46m 32.68988s[3]
Declination	−40° 29′ 47.6048″[3]
Apparent magnitude (V)	15[4]
Characteristics
Spectral type	G2V[5] + M4V[6]
U−B color index	0.10[2]
B−V color index	0.67[2]
Astrometry
HD 102365 A
Radial velocity (Rv)	16.94±0.12[1] km/s
Proper motion (μ)	RA: −1530.971 mas/yr[1] Dec.: +403.287 mas/yr[1]
Parallax (π)	107.3024 ± 0.0873 mas[1]
Distance	30.40 ± 0.02 ly (9.319 ± 0.008 pc)
Absolute magnitude (MV)	5.07[7]
HD 102365 B
Radial velocity (Rv)	17.23±0.27[3] km/s
Proper motion (μ)	RA: −1534.679 mas/yr[3] Dec.: +381.396 mas/yr[3]
Parallax (π)	107.4237 ± 0.0351 mas[3]
Distance	30.362 ± 0.010 ly (9.309 ± 0.003 pc)
Details
A
Mass	0.889[8] M☉
Radius	0.96[8] R☉
Luminosity	0.85[9] L☉
Surface gravity (log g)	4.51[5] cgs
Temperature	5,643[9] K
Metallicity [Fe/H]	−0.28[9] dex
Rotational velocity (v sin i)	0.5[10] km/s
Age	4.5–5.7[11] Gyr
Other designations
CD−39°7301, GJ 442, HD 102365, HIP 57443, HR 4523, SAO 223020, G 66 Centauri, LHS 311, LTT 4373[12]
Database references
SIMBAD	A
	B
ARICNS	data

Description

The stellar classification for the primary star in this system is G2V;^[5] the same as the Sun. That of the red dwarf companion is M4V.^[6] The primary star has an estimated 86%^[13] to 89% the mass of the Sun, 96% of the Sun's radius,^[8] and 85% of the Sun's luminosity.^[9] It is a slow rotator, with a projected rotational velocity of 0.5 km/s.^[10] Age estimates range from 4.5 to 5.7 billion years (Gyr)^[11] up to 7.1 Gyr^[7] or 9.48 Gyr.^[8] Compared to the Sun, it only has about 52%^[14] of the abundance of elements other than hydrogen and helium; what astronomers term the metallicity of a star.

This star system has a relatively large proper motion.^[12] The HR 4523 system is presently located within the Epsilon Indi Moving Group, although it gives itself away as an interloper, since the star is older and has a different composition than the group members.^[15] It has space velocity components [U, V, W] = [−67, −40, +4] km/s.^[16]

Planetary system

The primary star is believed to be orbited by a Neptune-like planet with a minimum mass 16 times that of the Earth. The orbital period of this planet is 122.1 days. No other planets have been discovered orbiting this star.^[17] While a 2013 study was unable to confirm this planet,^[18] it was confirmed by a 2023 study, with updated parameters.^[19]: 27

An examination of this system in the infrared did not reveal an excess emission that would otherwise suggest the presence of a circumstellar debris disk.^[20]

The HD 102365 planetary system^[17][19]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥9.34+1.52 −1.5 M🜨	0.46±0.04	121.3±0.25	0.28±0.15	—	—

In popular culture

The couch gag for Bart's Not Dead in the television series The Simpsons has an alien family sitting on a couch in this star system. The adult male alien asks why Homer sounds like Walter Matthau.

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. Feinstein, A. (1966), "Photoelectric observations of Southern late-type stars", The Information Bulletin for the Southern Hemisphere, 8: 30, Bibcode:1966IBSH....8...30F
3. 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.
4. Poveda, A.; et al. (April 1994), "Statistical studies of visual double and multiple stars. II. A catalogue of nearby wide binary and multiple systems", Revista Mexicana de Astronomía y Astrofísica, 28 (1): 43–89, Bibcode:1994RMxAA..28...43P
5. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992
6. Raghavan, Deepak; et al. (September 2010), "A Survey of Stellar Families: Multiplicity of Solar-type Stars", The Astrophysical Journal Supplement, 190 (1): 1–42, arXiv:1007.0414, Bibcode:2010ApJS..190....1R, doi:10.1088/0067-0049/190/1/1, S2CID 368553 For the adopted physical separation, see Table 11 in the appendix.
7. Holmberg, J.; Nordström, B.; Andersen, J. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511
8. Takeda, Genya; et al. (February 2007), "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog", The Astrophysical Journal Supplement Series, 168 (2): 297–318, arXiv:astro-ph/0607235, Bibcode:2007ApJS..168..297T, doi:10.1086/509763, S2CID 18775378
9. Porto de Mello, G.; del Peloso, E. F.; Ghezzi, L. (2006), "Astrobiologically Interesting Stars Within 10 Parsecs of the Sun", Astrobiology, 6 (2): 308–331, arXiv:astro-ph/0511180, Bibcode:2006AsBio...6..308P, doi:10.1089/ast.2006.6.308, PMID 16689649, S2CID 119459291
10. Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377^{[permanent dead link‍]}
11. 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, arXiv:0807.1686, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785, S2CID 27151456
12. "HD 102365". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2011-10-11.
13. O'Toole, S. J.; et al. (August 2009), "The Frequency of Low-Mass Exoplanets", The Astrophysical Journal, 701 (2): 1732–1741, arXiv:0906.4619, Bibcode:2009ApJ...701.1732O, doi:10.1088/0004-637X/701/2/1732, S2CID 18041021
14. For a metallicity of [Fe/H] = −0.28 dex, the proportion of metals is given by 10^−0.28, or 52%.
15. Kovacs, N.; Foy, R. (1978), "A detailed analysis of three stars in the Eggen's Epsilon INDI moving group", Astronomy and Astrophysics, 68 (1–2): 27–31, Bibcode:1978A&A....68...27K
16. Gliese, W. (1969), "Catalogue of Nearby Stars. Edition 1969", Veröffentlichungen des Astronomischen Rechen-Instituts Heidelberg, vol. 22, Karlsruhe, p. 1, Bibcode:1969VeARI..22....1G{{citation}}: CS1 maint: location missing publisher (link)
17. Tinney, C. G.; et al. (2011), "The Anglo-Australian Planet Search. XX. A Solitary Ice-giant Planet Orbiting HD 102365" (PDF), The Astrophysical Journal, 727 (2): 103, Bibcode:2011ApJ...727..103T, doi:10.1088/0004-637X/727/2/103, S2CID 54984338
18. Zechmeister, M.; Kürster, M.; et al. (April 2013). "The planet search programme at the ESO CES and HARPS. IV. The search for Jupiter analogues around solar-like stars". Astronomy & Astrophysics. 552: A78. arXiv:1211.7263. Bibcode:2013A&A...552A..78Z. doi:10.1051/0004-6361/201116551. S2CID 53694238.
19. Laliotis, Katherine; Burt, Jennifer A.; et al. (February 2023). "Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions". The Astronomical Journal. 165 (4): 176. arXiv:2302.10310. Bibcode:2023AJ....165..176L. doi:10.3847/1538-3881/acc067.
20. Beichman, C. A.; et al. (December 2006), "New Debris Disks around Nearby Main-Sequence Stars: Impact on the Direct Detection of Planets", The Astrophysical Journal, 652 (2): 1674–1693, arXiv:astro-ph/0611682, Bibcode:2006ApJ...652.1674B, doi:10.1086/508449, S2CID 14207148

External links

• HR 4523 AB, SolStation, retrieved 2011-10-11