Astronomy:Alpha Mensae
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Mensa |
| Right ascension | 06h 10m 14.47261s[1] |
| Declination | −74° 45′ 10.9585″[1] |
| Apparent magnitude (V) | 5.09[2] |
| Characteristics | |
| Spectral type | G7 V[3] + M3.5-6.5 V[4] |
| U−B color index | 0.33[5] |
| B−V color index | 0.72[5] |
| Astrometry | |
| 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[1] mas |
| Distance | 33.31 ± 0.02 ly (10.213 ± 0.006 pc) |
| Absolute magnitude (MV) | 5.03[6] |
| Details[4] | |
| 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 | |
| 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. The IAU Working Group on Star Names approved the name Hoerikwaggo for this star 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.[4] 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.[4] 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.[4]
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.[4]
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 |
|---|
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 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.
- ↑ Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data (SIMBAD). Bibcode: 1986EgUBV........0M.
- ↑ 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, doi:10.1086/504637, Bibcode: 2006AJ....132..161G.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 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. doi:10.3847/1538-4357/ac1269. Bibcode: 2021ApJ...922..229C.
- ↑ 5.0 5.1 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.
- ↑ 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.
- ↑ 7.0 7.1 7.2 "LTT 2490 -- High proper-motion star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=alpha+mensae&submit=SIMBAD+search.
- ↑ 8.0 8.1 "IAU Catalog of Star Names". https://exopla.net/star-names/modern-iau-star-names/.
- ↑ Ridpath, Ian. "Star Tales - Octans". http://www.ianridpath.com/startales/octans.html.
- ↑ 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.
- ↑ 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. doi:10.1051/0004-6361:20077447. Bibcode: 2007A&A...474..273E.
- ↑ "HD 43834B – Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD%2043834B. (details on the stellar properties of the companion star)
- ↑ Eiroa, C. et al. (July 2013). "DUst around NEarby Stars. The survey observational results". Astronomy & Astrophysics 555: A11. doi:10.1051/0004-6361/201321050. Bibcode: 2013A&A...555A..11E.
- ↑ 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, doi:10.1093/mnras/stx3188, Bibcode: 2018MNRAS.475.3046S.
- ↑ 15.0 15.1 Laliotis, Katherine 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. doi:10.3847/1538-3881/acc067. Bibcode: 2023AJ....165..176L.
External links
- "Alpha Mensae". SolStation. http://www.solstation.com/stars/alpmensa.htm.
- Kaler, Jim. "Alpha Mensae". Stars. University of Illinois. http://stars.astro.illinois.edu/sow/alphamen.html.
- "Gl 231". ARICNS. http://www.ari.uni-heidelberg.de/aricns/cnspages/4c00493.htm.
- "HD 43834". Alcyone ephemeris. http://www.alcyone.de/SIT/mainstars/SIT000600.htm.
Coordinates: 
6h 10m 14.4s, −74° 45′ 11″
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