Alpha Reticuli

Alpha Reticuli
Location of α Reticuli (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Reticulum
Right ascension 04h 14m 25.47s
Declination −62° 28′ 25.7″
Apparent magnitude (V) 3.315
Characteristics
Spectral type G8 II-III
U−B color index +0.63
B−V color index +0.922
R−I color index +0.659
Astrometry
Radial velocity (Rv)+35.5 km/s
Proper motion (μ) RA: +45.069 mas/yr
Dec.: +42.948 mas/yr
Parallax (π)20.3431±0.1859 mas
Distance160 ± 1 ly
(49.2 ± 0.4 pc)
Absolute magnitude (MV)−0.104±0.041
Details
Mass3.12±0.03 M☉
Radius13.5±0.3 R☉
Luminosity91.6±5.8 L☉
Surface gravity (log g)2.977±0.087 cgs
Temperature4,775±100 K
Metallicity [Fe/H]+0.191±0.039 dex
Rotational velocity (v sin i)4.67±0.36 km/s
Age330±10 Myr
Other designations
Rhombus, α Ret, Alpha Ret, CPD−62 332, FK5 156, GC 5164, HD 27256, HIP 19780, HR 1336, SAO 248969, PPM 353975, CCDM J04144-6228, WDS 04144-6228A
Database references
SIMBADdata

Alpha Reticuli, Latinized from α Reticuli, also named Rhombus, is the brightest star in the southern circumpolar constellation of Reticulum, with an apparent visual magnitude of 3.3. This appears to be a solitary star located at a distance of 160 light-years from Earth. Although it is bright enough to be seen with the naked eye, the declination of this star means that it is best viewed from the southern hemisphere and is only readily visible south of the Tropic of Cancer.

Characteristics

This star has about three times the mass of the Sun and is about 300 million years old. The spectrum of this star matches a stellar classification of G8 II-III, with the luminosity class notation 'II-III' indicating it shows some traits of both a giant star and a bright giant. At this evolutionary stage, the surface has expanded to 13 times the radius of the Sun and the outer envelope has an effective temperature of 4,800 K. X-ray emission has been detected from this star, with an estimated luminosity of 3 × 1029 erg s−1.

Alpha Reticuli has a 12th-magnitude visual companion, CCDM J04144-6228B, at an angular separation of 48 arcseconds away along a position angle of 355°. Since the two stars share a common proper motion across the celestial sphere, it is possible that Alpha Reticuli, rather than being solitary, may instead be the primary component of a binary star system with a projected separation of 2400 au and an orbital period of, at least, 60,000 years. They have a 94% possibility to be related.

Naming

In Chinese, caused by adaptation of the European southern hemisphere constellations into the Chinese system, 夾白 (Jiá Bái), means White Patches Attached, and it refers to an asterism consisting of α Reticuli and θ Doradus. Consequently, α Reticuli itself is known as 夾白二 (Jiá Bái èr, English: the Second Star of White Patches Attached.)

The IAU Working Group on Star Names approved the name Rhombus for the primary component Alpha Reticuli A on 19 September 2024, after an obsolete name for the constellation Reticulum, and it is now so entered in the IAU Catalog of Star Names.

References

  1. 1 2 3 4 5 6 7 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. 1 2 3 4 Gutierrez-Moreno, Adelina; et al. (1966). "A System of photometric standards". Publications of the Department of Astronomy University of Chile. 1. Publicaciones Universidad de Chile, Department de Astronomy: 1–17. Bibcode:1966PDAUC...1....1G.
  3. 1 2 Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 1. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode:1975mcts.book.....H.
  4. ↑ HR 1336, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 4, 2008.
  5. ↑ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and Their Applications, Proceedings from IAU Symposium No. 30, 30, University of Toronto: International Astronomical Union: 57, Bibcode:1967IAUS...30...57E
  6. 1 2 3 Ottoni, G.; Udry, S.; Ségransan, D.; Buldgen, G.; Lovis, C.; Eggenberger, P.; Pezzotti, C.; Adibekyan, V.; Marmier, M.; Mayor, M.; Santos, N. C.; Sousa, S. G.; Lagarde, N.; Charbonnel, C. (2022-01-01). "CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars". Astronomy and Astrophysics. 657: A87. arXiv:2201.01528. Bibcode:2022A&A...657A..87O. doi:10.1051/0004-6361/202040078. ISSN 0004-6361. Alpha Reticuli's database entry at VizieR.
  7. 1 2 3 4 Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015-02-01). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy and Astrophysics. 574: A50. arXiv:1410.6422. Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. ISSN 0004-6361. Alpha Reticuli's database entry at VizieR.
  8. 1 2 3 Cruzalèbes, P; Jorissen, A; Rabbia, Y; Sacuto, S; Chiavassa, A; Pasquato, E; Plez, B; Eriksson, K; Spang, A; Chesneau, O (2013). "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER". Monthly Notices of the Royal Astronomical Society. 434 (1): 437–450. arXiv:1306.3288. Bibcode:2013MNRAS.434..437C. doi:10.1093/mnras/stt1037. S2CID 49573767.
  9. ↑ Cusano, F.; Paladini, C.; Richichi, A.; Guenther, E. W.; Aringer, B.; Biazzo, K.; Molinaro, R.; Pasquini, L.; Hatzes, A. P. (2012-03-01). "AMBER/VLTI observations of five giant stars". Astronomy & Astrophysics. 539: A58. arXiv:1112.5043. Bibcode:2012A&A...539A..58C. doi:10.1051/0004-6361/201116731. ISSN 0004-6361.
  10. ↑ * alf Ret -- Star in double system, database entry, SIMBAD. Accessed on line September 4, 2008.
  11. 1 2 Entry 04144-6228, The Washington Double Star Catalog Archived 2008-04-12 at the Wayback Machine, United States Naval Observatory. Accessed on line September 4, 2008.
  12. 1 2 "IAU Catalog of Star Names". Retrieved 22 February 2025.
  13. 1 2 3 Alpha Ret Archived 2008-12-04 at the Wayback Machine, Jim Kaler, Stars. Accessed on line September 4, 2008.
  14. ↑ Eggleton, P. P.; Tokovinin, A. A. (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. S2CID 14878976.
  15. ↑ Micela, G.; Favata, F.; Sciortino, S. (October 1997). "HIPPARCOS distances of X-ray selected stars: implications on their nature as stellar population". Astronomy and Astrophysics. 326: 221–227. Bibcode:1997A&A...326..221M.
  16. 1 2 Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (January 2022). "Stellar and substellar companions from Gaia EDR3. Proper-motion anomaly and resolved common proper-motion pairs". Astronomy and Astrophysics. 657: A7. arXiv:2109.10912. Bibcode:2022A&A...657A...7K. doi:10.1051/0004-6361/202142146. ISSN 0004-6361.
  17. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 27 日 Archived 2011-05-22 at the Wayback Machine