Alpha Mensae
Template:Starbox observe 1s Template:Starbox observe 1s
Location of α Mensae (circled) | |
| Characteristics | |
|---|---|
| Evolutionary stage | main sequence[1] |
| Spectral type | G7 V[2] + M3.5-6.5 V[3] |
| U−B color index | 0.33[4] |
| B−V color index | 0.72[4] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | +36.06±0.12[1] km/s |
| Proper motion (μ) | RA: +121.596[1] mas/yr Dec.: −212.411[1] mas/yr |
| Parallax (π) | 97.9158±0.0573 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | 5.03[5] |
| B | |
| Proper motion (μ) | RA: 96.5[6] mas/yr Dec.: -195.927[6] mas/yr |
| Parallax (π) | 97.8666±0.0898 mas[6] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Details[3] | |
| α Men A | |
| Mass | 0.964±0.037 M☉ |
| Radius | 0.960±0.013 R☉ |
| Luminosity | 0.81±0.02 L☉ |
| Surface gravity (log g) | 4.459±0.006 cgs |
| Temperature | 5,569±50 K |
| Metallicity [Fe/H] | 0.11±0.05 dex |
| Rotational velocity (v sin i) | 0.6±0.6 km/s |
| Age | 6.2±1.4 Gyr |
| α Men B | |
| Mass | 0.169±0.006 M☉ |
| Radius | 0.19±0.01 R☉ |
| Temperature | 3,054±44 K |
| Other designations | |
| Template:Odlist[7] | |
| Database references | |
| SIMBAD | A |
| B | |
| Exoplanet Archive | data |
| ARICNS | data |
Alpha Mensae, also named Hoerikwaggo,[8] is the brightest star in the constellation Mensa. At a magnitude of 5.09, it is the dimmest lucida (a constellation's brightest star) in the sky, and the second-faintest star labeled "alpha", after Alpha Octantis.[9] Due to its declination, on Earth it is best visible from higher latitudes of the southern hemisphere, yet can also be seen, though low in the sky, from just north of the Equator when near its daily arc's highest point, the culmination. It is 33 light-years away from the Solar System. Alpha Mensae is a G-type main sequence star, forming a binary star system with a red dwarf companion.
Nomenclature
α Mensae (Latinised as Alpha Mensae, abbreviated to α Men or Alpha Men) is the star's Bayer designation. It had no traditional proper name. The IAU Working Group on Star Names approved the name Hoerikwaggo for Alpha Mensae A on 12 December 2024 and it is now so entered in the IAU Catalog of Star Names. It is named after Table Mountain in South Africa, which the constellation Mensa represents; Hoerikwaggo is the Afrikaans form of the Khoekhoe name Huriǂoaxa.[8]
Properties
This star has a stellar classification of G7 V,[7] indicating that it is a G-type main sequence star that is generating energy by fusing hydrogen into helium at its core. It is of similar size but slightly cooler than the Sun, with 96.4% of the mass, 96% of the radius, and 81% of the Sun's luminosity.[3] The effective temperature of the stellar atmosphere is 5,569 K, and it has a slightly higher (129%) proportion of elements other than hydrogen and helium—what astronomers call the star's metallicity—compared to the Sun.[3] The estimated age of this star is 6.2 billion years, and is rotating at a relatively leisurely projected rotational velocity of 0.6 km/s.[3]
Located 33 light-years distant from the Sun, Alpha Mensae has a relatively high proper motion across the sky. It has already made its closest approach to the Sun, coming within about 10 ly (3.2 pc) around 250,000 years ago.[10] It has a red dwarf companion star at an angular separation of 3.05 arcseconds; equivalent to a projected separation of roughly 30 AU.[7][11][12] With a mass just 16.9% that of the Sun, the companion is fully convective.[3]
Search for planets
A candidate infrared excess was detected around this star, which would indicate the presence of a circumstellar disk at a radius of over 147 AU. The derived temperature of this dust is below 22 K.[13] However, data from Herschel Space Observatory failed to confirm this excess, leaving the finding in doubt.[14]
A 2023 study found evidence for a candidate planet around Alpha Mensae via Doppler spectroscopy. Its period is close to one Earth year, raising concerns that it might be an instrumental false positive; further observations are needed to confirm it.[15]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| (unconfirmed) | ≥54.52+11.29 −9.14 M🜨 |
— | 359.5±1.2 | 0.4±0.14 | — | — |
References
Page Template:Reflist/styles.css has no content.
- ^ a b c d e Template:Cite Gaia DR3
- ^ Page Module:Citation/CS1/styles.css has no content.Gray, R. O.; et al. (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): 161–70. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
- ^ a b c d e f Page Module:Citation/CS1/styles.css has no content.Chontos, Ashley; et al. (2021). "TESS Asteroseismology of α Mensae: Benchmark Ages for a G7 Dwarf and its M-dwarf Companion". The Astrophysical Journal. 922 (2): 229. arXiv:2012.10797. Bibcode:2021ApJ...922..229C. doi:10.3847/1538-4357/ac1269. S2CID 229340231.
- ^ a b Page Module:Citation/CS1/styles.css has no content.Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99): 99. Bibcode:1966CoLPL...4...99J.
- ^ Page Module:Citation/CS1/styles.css has no content.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. arXiv:0811.3982. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191. S2CID 118577511.
- ^ a b c Template:Cite Gaia DR3
- ^ a b c Page Module:Citation/CS1/styles.css has no content."LTT 2490 -- High proper-motion star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-09-11.
- ^ a b Page Module:Citation/CS1/styles.css has no content."IAU Catalog of Star Names". Retrieved 22 February 2025.
- ^ Page Module:Citation/CS1/styles.css has no content.Ridpath, Ian. "Star Tales - Octans". Retrieved 16 July 2025.
- ^ Page Module:Citation/CS1/styles.css has no content.Bailer-Jones, C. A. L. (March 2015). "Close encounters of the stellar kind". Astronomy & Astrophysics. 575: 13. arXiv:1412.3648. Bibcode:2015A&A...575A..35B. doi:10.1051/0004-6361/201425221. S2CID 59039482. A35.
- ^ Page Module:Citation/CS1/styles.css has no content.Eggenberger, A.; et al. (2007). "The impact of stellar duplicity on planet occurrence and properties. I. Observational results of a VLT/NACO search for stellar companions to 130 nearby stars with and without planets". Astronomy and Astrophysics. 474 (1): 273–291. Bibcode:2007A&A...474..273E. doi:10.1051/0004-6361:20077447.
- ^ Page Module:Citation/CS1/styles.css has no content."HD 43834B – Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-03-26. (details on the stellar properties of the companion star)
- ^ Page Module:Citation/CS1/styles.css has no content.Eiroa, C.; et al. (July 2013). "DUst around NEarby Stars. The survey observational results". Astronomy & Astrophysics. 555: A11. arXiv:1305.0155. Bibcode:2013A&A...555A..11E. doi:10.1051/0004-6361/201321050. S2CID 377244.
- ^ Page Module:Citation/CS1/styles.css has no content.Sibthorpe, B.; et al. (April 2018). "Analysis of the Herschel DEBRIS Sun-like star sample". Monthly Notices of the Royal Astronomical Society. 475 (3): 3046–3064. arXiv:1803.00072. Bibcode:2018MNRAS.475.3046S. doi:10.1093/mnras/stx3188.
- ^ a b Page Module:Citation/CS1/styles.css has no content.Laliotis, Katherine; Burt, Jennifer A.; et al. (April 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.
External links
- Page Module:Citation/CS1/styles.css has no content."Alpha Mensae". SolStation. Archived from the original on 26 June 2006. Retrieved 2006-07-24.
- Page Module:Citation/CS1/styles.css has no content.Kaler, Jim. "Alpha Mensae". Stars. University of Illinois. Retrieved 2014-01-01.
- Page Module:Citation/CS1/styles.css has no content."Gl 231". ARICNS. Archived from the original on 2006-02-20. Retrieved 2006-07-24.
- Page Module:Citation/CS1/styles.css has no content."HD 43834". Alcyone ephemeris. Retrieved 2006-07-24.
