YY Mensae

A light curve for YY Mensae, plotted from Hipparcos data[1]
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Mensa
Right ascension 04h 58m 17.93697s[2]
Declination −75° 16′ 37.9879″[2]
Apparent magnitude (V) 8.60 - 8.89[3]
Characteristics
Spectral type K1 III/IVe[4]
U−B color index +0.70[5]
B−V color index +1.04[5]
Variable type FK Com[3]
Astrometry
Radial velocity (Rv)−8.5±2.5[6] km/s
Proper motion (μ) RA: −4.149 mas/yr[2]
Dec.: −3.077 mas/yr[2]
Parallax (π)4.5587 ± 0.0161 mas[2]
Distance715 ± 3 ly
(219.4 ± 0.8 pc)
Absolute magnitude (MV)+0.81[7]
Details
Mass0.983[8] M☉
Radius12.3[9] R☉
Luminosity68.5[10] L☉
Surface gravity (log g)1.63[11] cgs
Temperature4,691±128[12] K
Metallicity [Fe/H]−0.59[11] dex
Rotational velocity (v sin i)45±2[13] km/s
Other designations
YY Men, CD−75°189, CPD−75°292, HD 32918, HIP 23106[14]
Database references
SIMBADdata

YY Mensae, also known as HD 32918, is a variable star located in the southern circumpolar constellation Mensa. It has an apparent magnitude that fluctuates between 8.6 and 8.9,[3] which is within the visibility of binoculars. Based on parallax measurements from Gaia DR3, it is estimated to be 715 light years distant.[2] It appears to be approaching the Solar System with a heliocentric radial velocity of −8.5 km/s.[6]

This star was known to have an unusual spectrum since the 1970's, but its variability wasn't observed until the 1980's. Collier (1982) found it to be a FK Comae Berenices variable, a class of rapidly rotating giant stars.[15] After a few additional years of observations, HD 32918 was given the variable star designation YY Mensae.[16] A paper in 1987 observed a long and powerful flare coming from the star.[17] X-ray emissions from YY Mensa have been detected in its corona, which may be a result of its fast rotation.[18]

YY Mensae has a stellar classification of K1 III/IVe,[4] indicating an evolved red giant with the blended luminosity class of a giant star and a subgiant. It is chromospherically active and emission lines are also present in its spectra. It has 98% the mass of the Sun[8] but has expanded to 12.3 times its girth.[9] It radiates 68.5 times the luminosity of the Sun[10] from its photosphere at an effective temperature of 4,691 K,[12] giving it an orange hue. Typical for stars its type, YY Mensae spins rapidly, having a projected rotational velocity of 45 km/s.[13] The star is metal deficient, having an iron abundance only 26% that of the Sun.[11]

References

  1. ↑ "Light Curve". Hipparcos ESA. ESA. Retrieved 17 February 2022.
  2. 1 2 3 4 5 6 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. 1 2 3 Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. eISSN 1562-6881. ISSN 1063-7729. S2CID 125853869.
  4. 1 2 Bidelman, W. P.; MacConnel, D. J. (October 1973). "The brighter stars of astrophysical interest in the southern sky". The Astronomical Journal. 78: 687. Bibcode:1973AJ.....78..687B. doi:10.1086/111475. ISSN 0004-6256.
  5. 1 2 Cutispoto, G.; Messina, S.; Rodonò, M. (March 2001). "Long-term monitoring of active stars". Astronomy & Astrophysics. 367 (3): 910–930. Bibcode:2001A&A...367..910C. doi:10.1051/0004-6361:20000549. eISSN 1432-0746. ISSN 0004-6361.
  6. 1 2 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
  7. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
  8. 1 2 Anders, F.; et al. (February 2022). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G = 18.5". Astronomy & Astrophysics. 658: A91. arXiv:2111.01860. Bibcode:2022A&A...658A..91A. doi:10.1051/0004-6361/202142369. eISSN 1432-0746. ISSN 0004-6361.
  9. 1 2 Strassmeier, Klaus G. (2 May 2009). "Starspots". The Astronomy and Astrophysics Review. 17 (3): 251–308. Bibcode:2009A&ARv..17..251S. doi:10.1007/s00159-009-0020-6. eISSN 1432-0754. ISSN 0935-4956.
  10. 1 2 McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. ISSN 0035-8711.
  11. 1 2 3 Sprague, Dani; et al. (8 March 2022). "APOGEE Net: An Expanded Spectral Model of Both Low-mass and High-mass Stars". The Astronomical Journal. 163 (4): 152. arXiv:2201.03661. Bibcode:2022AJ....163..152S. doi:10.3847/1538-3881/ac4de7. eISSN 1538-3881. ISSN 0004-6256.
  12. 1 2 Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881.
  13. 1 2 Fekel, Francis C.; Balachandran, Suchitra (February 1993). "Lithium and rapid rotation in chromospherically active single giants". The Astrophysical Journal. 403: 708. Bibcode:1993ApJ...403..708F. doi:10.1086/172242. eISSN 1538-4357. ISSN 0004-637X.
  14. ↑ "YY Mensae". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 28, 2022.
  15. ↑ Collier, A. C. (August 1982). "Discovery of two FK Comae stars in the southern hemisphere". Monthly Notices of the Royal Astronomical Society. 200: 489–496. Bibcode:1982MNRAS.200..589C. doi:10.1093/mnras/200.3.589 (inactive 1 August 2023). ISSN 0035-8711.{{cite journal}}: CS1 maint: DOI inactive as of August 2023 (link)
  16. ↑ Kholopov, P. N.; Samus, N. N.; Kazarovets, E. V.; Perova, N. B. (March 1985). "The 67th Name-List of Variable Stars". Information Bulletin on Variable Stars. 2681: 1. Bibcode:1985IBVS.2681....1K. ISSN 0374-0676.
  17. ↑ Slee, O. B.; Nelson, G. J.; Stewart, R. T.; Wright, A. E.; Jauncey, D. L.; Heisler, L. H.; Bunton, J. D.; Vaughan, A. E.; Large, M. I.; Peters, W. L.; Ryan, S. G. (1 July 1987). "A very intense, long-lasting radio flare on HD 32918". Monthly Notices of the Royal Astronomical Society. 227 (2): 467–479. Bibcode:1987MNRAS.227..467S. doi:10.1093/mnras/227.2.467. eISSN 1365-2966. ISSN 0035-8711.
  18. ↑ Audard, Marc; Telleschi, Alessandra; Gudel, Manuel; Skinner, Stephen L.; Pallavicini, Roberto; Mitra‐Kraev, Urmila (10 December 2004). "Some Like It Hot: The X‐Ray Emission of the Giant Star YY Mensae". The Astrophysical Journal. 617 (1): 531–550. arXiv:astro-ph/0408345. Bibcode:2004ApJ...617..531A. doi:10.1086/424590. eISSN 1538-4357. ISSN 0004-637X.

Further reading

Audard, M.; Güdel, M.; Skinner, S. L.; Pallavicini, R.; Drake, S. A.; Mewe, R. (December 2002). "Chandra and XMM-Newton X-Ray Spectroscopy of the Hot Corona of YY Mensae". American Astronomical Society Meeting Abstracts. 201: 33.07. Bibcode:2002AAS...201.3307A.

Strassmeier, K.G. (August 2002). "Doppler images of starspots". Astronomische Nachrichten. 323 (3–4): 309–316. Bibcode:2002AN....323..309S. doi:10.1002/1521-3994(200208)323:3/4<309::AID-ASNA309>3.0.CO;2-U. eISSN 1521-3994. ISSN 0004-6337.

Gondoin, P. (December 1999). "Evolution of X-ray activity and rotation on G-K giants". Astronomy and Astrophysics. 352: 217–227. Bibcode:1999A&A...352..217G. ISSN 0004-6361.

Grewing, M.; Bianchi, L.; Cassatella, A. (August 1986). "HD 32918 : Ultraviolet spectrum and optical behaviour". Astronomy and Astrophysics. 164: 31–39. Bibcode:1986A&A...164...31G. ISSN 0004-6361.

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