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W Orionis

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Star in the constellation Orion
W Orionis

The visual band light curve for W Orionis, plotted from ASAS data
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension 05 05 23.72142
Declination +01° 10′ 39.4512″
Apparent magnitude (V) 4.4 - 6.9
Characteristics
Evolutionary stage AGB
Spectral type C-N5 C25.5 (C5,4(N5))
U−B color index +6.84
B−V color index +3.42
Variable type SRb
Astrometry
Radial velocity (Rv)+16.50 km/s
Proper motion (μ) RA: +7.5 mas/yr
Dec.: -1.4 mas/yr
Parallax (π)2.65 ± 0.95 mas
Distanceapprox. 1,200 ly
(approx. 400 pc)
Absolute magnitude (MV)−5.76
Details
Mass1-2 M☉
Radius406 R☉
Luminosity6,761 L☉
Surface gravity (log g)−0.60 cgs
Temperature2,600 K
Metallicity 0.0 dex
Other designations
W Ori, BD+00°939, HD 32736, HIP 23680
Database references
SIMBADdata

W Orionis is a carbon star in the constellation Orion, approximately 400 parsecs (1,300 ly) away. It varies regularly in brightness between extremes of magnitude 4.4 and 6.9 roughly every 7 months. When it is near its maximum brightness, it is faintly visible to the naked eye of an observer with good observing conditions.

Variability

Evelyn Leland discovered that the star is a variable star based on observations done in the last decades of the 19th century, when it was known as BD +00°939. The discovery was announced in 1895. It was listed with its variable star designation, W Orionis, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars. W Orionis is a semiregular variable with an approximately 212‑day cycle. A long secondary period of 2,450 days has also been reported.

Properties

The angular diameter of W Orionis has been measured using interferometry and a value of 9.7 mas is found. Although it is known to be a pulsating variable star, no changes in the diameter were seen.

Technetium has not been detected in W Orionis, an unexpected result since this s-process element should be dredged up in all thermally-pulsating AGB stars and especially in carbon stars.

References

  1. "ASAS All Star Catalogue". The All Sky Automated Survey. Retrieved 8 December 2021.
  2. ^ 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.
  3. Watson, C. L; Henden, A. A; Price, A (2006). "The International Variable Star Index (VSX)". The Society for Astronomical Sciences 25th Annual Symposium on Telescope Science. Held May 23–25. 25: 47. Bibcode:2006SASS...25...47W.
  4. Barnbaum, Cecilia; Stone, Remington P. S; Keenan, Philip C (1996). "A Moderate-Resolution Spectral Atlas of Carbon Stars: R, J, N, CH, and Barium Stars". Astrophysical Journal Supplement. 105: 419. Bibcode:1996ApJS..105..419B. doi:10.1086/192323.
  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. ^ Ducati, J. R (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  7. Gontcharov, G. A (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. S2CID 119231169.
  8. Guandalini, R; Cristallo, S (2013). "Luminosities of carbon-rich asymptotic giant branch stars in the Milky Way". Astronomy & Astrophysics. 555: A120. arXiv:1305.4203. Bibcode:2013A&A...555A.120G. doi:10.1051/0004-6361/201321225. S2CID 54918450.
  9. ^ Cruzalèbes, P; Jorissen, A; Rabbia, Y; Sacuto, S; Chiavassa, A; Pasquato, E; Plez, B; Eriksson, K; Spang, A; Chesneau, O (2013). "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER". Monthly Notices of the Royal Astronomical Society. 434 (1): 437–450. arXiv:1306.3288. Bibcode:2013MNRAS.434..437C. doi:10.1093/mnras/stt1037. S2CID 49573767.
  10. Fleming, W. P. (October 1895). "Seven new variable stars". Astrophysical Journal. 2: 198–201. Bibcode:1895ApJ.....2..198F. doi:10.1086/140130. Retrieved 17 December 2024.
  11. Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 16 December 2024.
  12. Olivier, E. A; Wood, P. R (2003). "On the Origin of Long Secondary Periods in Semiregular Variables". The Astrophysical Journal. 584 (2): 1035. Bibcode:2003ApJ...584.1035O. doi:10.1086/345715.

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