HD 84810

Last updated
ℓ Carinae
Carina constellation map.svg
Red circle.svg
Location of l Carinae (circled in red)
Observation data
Epoch J2000       Equinox J2000
Constellation Carina
Right ascension 09h 45m 14.81122s [1]
Declination −62° 30′ 28.4519″ [1]
Apparent magnitude  (V)3.35 - 4.06 [2]
Characteristics
Spectral type G5 Iab/Ib; [3] F6Ib-K0Ib [2]
U−B color index +0.76 [4]
B−V color index +1.03 [4]
Variable type Classical Cepheid [2]
Astrometry
Radial velocity (Rv)+3.3 [5] km/s
Proper motion (μ)RA: −12.88 [1] mas/yr
Dec.: +8.19 [1] mas/yr
Parallax (π)2.01±0.20  mas [6]
Distance 498+55
−45 [7]   pc
Absolute magnitude  (MV)−5.22 [8]
Details
Mass 8.66±0.14 [7]   M☉
Radius 169±8 [9]   R☉
Luminosity 11,482 [7]   L☉
Surface gravity (log g)1.5 [10]   cgs
Temperature 5,000±60 [7]   K
Metallicity [Fe/H]0.30 [10]   dex
Age 31.25±1.05 [7]   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
SIMBAD data
ESO - Model Image of Cepheid l Carinae ESO - Model Image of Cepheid L Carinae (by).jpg
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. Its apparent magnitude varies from about 3.4 to 4.1, making it readily visible to the naked eye and one of the brightest 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. [3] 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. [9] As this is a massive star with 8.7 times the mass of the Sun, [7] 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. [11]

A light curve for l Carinae, plotted from Hipparcos data LCarLightCurve.png
A light curve for l Carinae, plotted from Hipparcos data

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. This unusually long period makes it essential for calibrating the period-luminosity relation for Cepheid variables; additionally, it is one of the nearest Cepheid variables, making it relatively easy to observe. [7] The radial velocity of the star likewise varies by 39 km/s during each pulsation cycle. [13] Its radius varies by about 40 R☉ as it pulsates, reaching maximum size as its brightness is decreasing towards minimum. [7]

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. [11]

The period of l Carinae is calculated to be slowly increasing and it is thought to be crossing the instability strip for the third time, cooling as it evolves towards a red supergiant after a blue loop. [7]

References

  1. 1 2 3 4 5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: 0708.1752 , Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID   18759600.
  2. 1 2 3 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: B/GCVS. Bibcode:2009yCat....102025S.
  3. 1 2 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: 1007.4883 , Bibcode:2011MNRAS.410..190T, doi: 10.1111/j.1365-2966.2010.17434.x , S2CID   118629873.
  4. 1 2 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 .
  5. ↑ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and Their Applications, Proceedings from IAU Symposium No. 30, 30, University of Toronto: International Astronomical Union: 57, Bibcode:1967IAUS...30...57E.
  6. ↑ Benedict, G. Fritz; et al. (April 2007), "Hubble Space Telescope Fine Guidance Sensor Parallaxes of Galactic Cepheid Variable Stars: Period-Luminosity Relations", Astronomical Journal, 133 (4): 1810–1827, arXiv: astro-ph/0612465 , Bibcode:2007AJ....133.1810B, doi:10.1086/511980, S2CID   16384267.
  7. 1 2 3 4 5 6 7 8 9 Neilson, Hilding R; Engle, Scott G; Guinan, Edward F; Bisol, Alexandra C; Butterworth, Neil (2016), "The Secret Lives of Cepheids: Evolution, Mass-Loss, and Ultraviolet Emission of the Long-period Classical Cepheid", The Astrophysical Journal, 824 (1): 1, arXiv: 1604.03128 , Bibcode:2016ApJ...824....1N, doi: 10.3847/0004-637X/824/1/1 , S2CID   118642210.
  8. ↑ 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 (1): 73–81. arXiv: 0709.3255 . Bibcode:2007A&A...476...73F. doi:10.1051/0004-6361:20078187. S2CID   17687829.
  9. 1 2 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: 0812.4791 , Bibcode:2009MNRAS.394.1620D, doi: 10.1111/j.1365-2966.2009.14433.x , S2CID   16697473.
  10. 1 2 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.
  11. 1 2 Kervella, P.; Mérand, A.; Gallenne, A. (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: 0902.1588 , Bibcode:2009A&A...498..425K, doi:10.1051/0004-6361/200811307, S2CID   14541935.
  12. ↑ "Light Curve", Hipparcos ESA, ESA, retrieved 17 February 2022.
  13. ↑ 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: 0908.3561 , Bibcode:2009A&A...504..959K, doi:10.1051/0004-6361/200811464, S2CID   18283579.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.