HD 84810

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ℓ Carinae
Carina constellation map.svg
Red circle.svg

Location of l Carinae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Carina
Right ascension 09h 45m 14.81122s[1]
Declination –62° 30′ 28.4519″[1]
Apparent magnitude (V) 3.39[2] (3.35 - 4.06[3])
Spectral type F6Ib-K0Ib[3]
U−B color index +0.76[2]
B−V color index +1.03[2]
Variable type Classical Cepheid[3]
Radial velocity (Rv) +3.3[4] km/s
Proper motion (μ) RA: –12.88[1] mas/yr
Dec.: +8.19[1] mas/yr
Parallax (π) 2.09 ± 0.29[1] mas
Distance 525[5] pc
Absolute magnitude (MV) –5.22[6]
Mass 8.4[7] to 13[8] M
Radius 169±8[5] R
Surface gravity (log g) 1.5[9] cgs
Temperature 5,091[9] K
Metallicity [Fe/H] 0.30[9] dex
Age 17-19[8] Myr
Other designations
l Carinae, 2MASS J09451481-6230284, CD–61 2349, FK5 1254, HD 84810, HIP 47854, HR 3884, IRAS 09438-6216, SAO 250683.
Database references
ESO - Model Image of Cepheid l Carinae

HD 84810, also known as l Carinae (l Car), is a star in the southern constellation of Carina. It has a mean apparent magnitude of +3.4,[2] making it readily visible to the naked eye and one of the brighter members of Carina. Based upon parallax measurements, it is approximately 1,600 light-years (490 parsecs) from Earth.[1]

From the characteristics of its spectrum, l Carinae has a stellar classification of G5 Iab/Ib.[7] This indicates the star has reached a stage in its evolution where it has expanded to become a supergiant with 169 times the radius of the Sun.[5] As this is a massive star with 8[7]–13[8] times the mass of the Sun, it rapidly burns through its supply of nuclear fuel and has become a supergiant in roughly 17-19 million years, after spending 15–17 million years as a main sequence star.[8]

l Carinae is classified as a Cepheid variable star and its brightness varies over an amplitude range of 0.725 in magnitude with a long period of 35.560 days. The radial velocity of the star likewise varies by 39 km/s during each pulsation cycle.[10] It has a compact circumstellar envelope that can be discerned using interferometry. The envelope has been resolved at an infrared wavelength of 10μm, showing a radius of 10–100 AU at a mean temperature of 100 K. The material for this envelope was supplied by mass ejected from the central star.[8]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Madore, B. F. (June 1975), "Photoelectric UBV photometry of Cepheids in the Magellanic Clouds and in the southern Milky Way", Astrophysical Journal Supplement Series, 29: 219–284, Bibcode:1975ApJS...29..219M, doi:10.1086/190342. 
  3. ^ a b c 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. 
  4. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick. Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. Determination of Radial Velocities and their Applications. 30. University of Toronto: International Astronomical Union. p. 57. Bibcode:1967IAUS...30...57E. 
  5. ^ a b c Davis, J.; et al. (April 2009), "Observations of the pulsation of the Cepheid l Car with the Sydney University Stellar Interferometer", Monthly Notices of the Royal Astronomical Society, 394 (3): 1620–1630, arXiv:0812.4791Freely accessible, Bibcode:2009MNRAS.394.1620D, doi:10.1111/j.1365-2966.2009.14433.x. 
  6. ^ Fouqué, P.; Arriagada, P.; Storm, J.; Barnes, T. G.; Nardetto, N.; Mérand, A.; Kervella, P.; Gieren, W.; Bersier, D.; Benedict, G. F.; McArthur, B. E. (2007). "A new calibration of Galactic Cepheid period-luminosity relations from B to K bands, and a comparison to LMC relations". Astronomy and Astrophysics. 476: 73. Bibcode:2007A&A...476...73F. doi:10.1051/0004-6361:20078187. 
  7. ^ a b c Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883Freely accessible, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x. 
  8. ^ a b c d e Kervella, P.; Mérand, A.; Gallenne, A. (May 2009), "The circumstellar envelopes of the Cepheids ℓ Carinae and RS Puppis. Comparative study in the infrared with Spitzer, VLT/VISIR, and VLTI/MIDI", Astronomy and Astrophysics, 498 (2): 425–443, arXiv:0902.1588Freely accessible, Bibcode:2009A&A...498..425K, doi:10.1051/0004-6361/200811307. 
  9. ^ a b c Luck, R. E. (September 1979), "The chemical compositions of nine southern supergiant stars", Astrophysical Journal, Part 1, 232: 797–806, Bibcode:1979ApJ...232..797L, doi:10.1086/157340. 
  10. ^ Klagyivik, P.; Szabados, L. (September 2009), "Observational studies of Cepheid amplitudes. I. Period-amplitude relationships for Galactic Cepheids and interrelation of amplitudes", Astronomy and Astrophysics, 504 (3): 959–972, arXiv:0908.3561Freely accessible, Bibcode:2009A&A...504..959K, doi:10.1051/0004-6361/200811464.