EV Carinae

EV Carinae is a red supergiant and pulsating variable star of spectral type M4Ia in the constellation Carina. It is a semiregular variable star with its apparent magnitude varying between 7.4 and 9.0 in the visible band, making it only seen by binoculars or a telescope. Various periods have been identified, but the dominant one is around 347 days.[5]

EV Carinae
Location of EV Carinae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Carina
Right ascension  10h 20m 21.608s[1]
Declination −60° 27′ 15.55″[1]
Apparent magnitude (V) 7.4 - 9.0[2]
Characteristics
Evolutionary stage Red supergiant
Spectral type M4.5Ia[3]
U−B color index +2.34[4]
B−V color index +2.20[4]
Variable type SRc[5][2][6]
Astrometry
Radial velocity (Rv)2.0[7] km/s
Proper motion (μ) RA: −6.1[8] mas/yr
Dec.: 2.4[8] mas/yr
Parallax (π)0.7759 ± 0.1098[9] mas
Distance2,960+220
−200[10] pc
Absolute magnitude (MV)−5.24[4]
Details
Radius574[11] R☉
Luminosity (bolometric)288,000[10] L☉
Temperature3,535±170[11] K
Other designations
EV Carinae, HD 89845, CD-59°3024, 2MASS J10202160-6027155, TYC 8956-3486-1, AAVSO 1016-59
Database references
SIMBADdata

EV Car is one of the largest known stars although its properties depend on its distance. In the late of the 20th century, EV Carinae, based on an assumed distance of 4.2 kpc, was found to be an extremely luminous and large supergiant star with an unusual luminosity between 550,000 and 675,000 times that of the Sun (L☉), which would imply radii of 2,880 to 3,190 times the Sun's radius (R☉) at a temperature of 2,930 K, making it larger than the orbit of Saturn.[12]

More recently, new calculations of the distance derived closer distances below 3 kpc which would put EV Car part of the Carina OB2 association along the Carina Nebula and give the star lower luminosities below 300,000 L☉, higher temperatures, and correspondingly lower radius values,[13][4][10] while calculation of the bolometric luminosity based on its Gaia Data Release 2 parallax gives a luminosity below 50,000 L☉ with a corresponding radius of 574 R☉.[11]

References
  1. Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. Originally Published in: 2003yCat.2246....0C. 2246. Bibcode:2003yCat.2246....0C.
  2. Kiss, L. L.; Szabó, Gy. M.; Bedding, T. R. (2006). "Variability in red supergiant stars: Pulsations, long secondary periods and convection noise". Monthly Notices of the Royal Astronomical Society. 372 (4): 1721. arXiv:astro-ph/0608438. Bibcode:2006MNRAS.372.1721K. doi:10.1111/j.1365-2966.2006.10973.x.
  3. "GCVS Query=EV Car". Sternberg Astronomical Institute. General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2020-08-11.
  4. Mauron, N.; Josselin, E. (2011). "The mass-loss rates of red supergiants and the de Jager prescription". Astronomy and Astrophysics. 526: A156. arXiv:1010.5369. Bibcode:2011A&A...526A.156M. doi:10.1051/0004-6361/201013993.
  5. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  6. Percy, John R.; Sato, Hiromitsu (2009). "Long Secondary Periods in Pulsating Red Supergiant Stars". Journal of the Royal Astronomical Society of Canada. 103: 11. Bibcode:2009JRASC.103...11P.
  7. Feast, M. W.; Woolley, R.; Yilmaz, N. (1972). "The kinematics of semi-regular red variables in the solar neighbourhood". Monthly Notices of the Royal Astronomical Society. 158: 23. Bibcode:1972MNRAS.158...23F. doi:10.1093/mnras/158.1.23.
  8. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862.
  9. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  10. Davies, Ben; Beasor, Emma R. (March 2020). "The `red supergiant problem': the upper luminosity boundary of Type II supernova progenitors". MNRAS. 493 (1): 468–476. arXiv:2001.06020. Bibcode:2020MNRAS.493..468D. doi:10.1093/mnras/staa174.
  11. Messineo, M.; Brown, A. G. A. (2019). "A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2". The Astronomical Journal. 158: 20. arXiv:1905.03744. Bibcode:2019AJ....158...20M. doi:10.3847/1538-3881/ab1cbd.
  12. de Jager, C.; Nieuwenhuijzen, H.; van der Hucht, K. A. (1988). "Mass loss rates in the Hertzsprung-Russell diagram". Astronomy and Astrophysics Supplement Series. 72 (2): 259–289. Bibcode:1988A&AS...72..259D.
  13. Van Loon, J. Th.; Cioni, M.-R. L.; Zijlstra, A. A.; Loup, C. (2005). "An empirical formula for the mass-loss rates of dust-enshrouded red supergiants and oxygen-rich Asymptotic Giant Branch stars". Astronomy and Astrophysics. 438: 273. arXiv:astro-ph/0504379. Bibcode:2005A&A...438..273V. doi:10.1051/0004-6361:20042555.
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