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  • 21 Aug, 2019

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U Camelopardalis
U Camelopardalis is a semiregular variable star in the constellation Camelopardalis. Based on parallax measurements made by the Hipparcos spacecraft, it is located about 3,000 light-years (1,000 parsecs) away from the Earth. Its apparent visual magnitude is about 8, which is dim enough that it cannot be seen with the unaided eye.

The spectral type of U Camelopardalis in the revised MK system is C-N5, which indicates a classical carbon star spectrum approximately corresponding to late K or early M. The C2 index is 5.5 which is typical of a C-N star. It is also given an alternative spectral type of MS4, indicating a star similar to an M4 class but with somewhat enhanced ZrO bands. The spectral type may vary between C3,9 and C6,4e.

A visual band light curve for U Camelopardalis, plotted from AAVSO data

In 1891, Williamina Fleming announced that the star (then known as DM +62°.596) is a variable star, based on 13 photographs taken in 1890 and 1891. It was listed with its variable star designation, U Camelopardalis, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars. U Camelopardalis is a carbon star. These types of stars have greater levels of carbon in their atmospheres than oxygen, which means they form carbon compounds that make the star appear strikingly red. U Camelopardalis is nearly 4 magnitudes fainter at blue wavelengths than in the centre of the visual range. In the infrared K band it has an apparent magnitude of 0.37. Its brightness varies without a dominant period and it is classified as semi-regular, although a period of 400 days has been published. In the V photometric band the brightness varies by around half a magnitude, but the amplitude is nearly two magnitudes at blue wavelengths. The maximum visual magnitude has been given as 7.2.

The shell of gas surrounding U Camelopardalis was imaged by the Hubble Space Telescope in 2012, showing a nearly perfect sphere of gas surrounding the star.

U Cameloparadlis has a 10th magnitude companion 308" away. It is a B8 main sequence star, hotter but less luminous than U Cam itself. They are not thought to be physically associated.

References

  1. ^ 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. ^ Nicolet, B. (1978). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics. 34: 1–49. Bibcode:1978A&AS...34....1N.
  3. ^ 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.
  4. ^ 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.
  5. ^ 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.
  6. ^ Guandalini, R.; Busso, M.; Ciprini, S.; Silvestro, G.; Persi, P. (2006). "Infrared photometry and evolution of mass-losing AGB stars. I. Carbon stars revisited". Astronomy and Astrophysics. 445 (3): 1069–1080. arXiv:astro-ph/0509739. Bibcode:2006A&A...445.1069G. doi:10.1051/0004-6361:20053208. S2CID 16797565.
  7. ^ Olson, B. I.; Richer, H. B. (1975). "The absolute magnitudes of carbon stars - Carbon stars in binary systems". Astrophysical Journal. 200: 88. Bibcode:1975ApJ...200...88O. doi:10.1086/153763.
  8. ^ Bergeat, J.; Chevallier, L. (2005). "The mass loss of C-rich giants". Astronomy and Astrophysics. 429: 235–246. arXiv:astro-ph/0601366. Bibcode:2005A&A...429..235B. doi:10.1051/0004-6361:20041280. S2CID 56424665.
  9. ^ Tanaka, Masuo; Letip, Ahmatjan; Nishimaki, Yuichirou; Yamamuro, Tomoyasu; Motohara, Kentaro; Miyata, Takashi; Aoki, Wako (2007). "Near-Infrared Spectra of 29 Carbon Stars: Simple Estimates of Effective Temperature". Publications of the Astronomical Society of Japan. 59 (5): 939. Bibcode:2007PASJ...59..939T. doi:10.1093/pasj/59.5.939.
  10. ^ Keenan, Philip C. (1993). "Revised MK spectral classification of the red carbon stars". Astronomical Society of the Pacific. 105: 905. Bibcode:1993PASP..105..905K. doi:10.1086/133252.
  11. ^ Keenan, P. C.; Morgan, W. W. (1941). "The Classification of the Red Carbon Stars". The Astrophysical Journal. 94: 501. Bibcode:1941ApJ....94..501K. doi:10.1086/144356.
  12. ^ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
  13. ^ Pickering, E. C. (March 1891). "Stars having Peculiar Spectra. New Variable Stars in Aquarius, Delphinus and Camelopardalus". Astronomische Nachrichten. 127: 5–6. Bibcode:1891AN....127Q...5P. Retrieved 20 December 2024.
  14. ^ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 20 December 2024.
  15. ^ Knapp, G. R.; Pourbaix, D.; Platais, I.; Jorissen, A. (2003). "Reprocessing the Hipparcos data of evolved stars. III. Revised Hipparcos period-luminosity relationship for galactic long-period variable stars". Astronomy and Astrophysics. 403 (3): 993–1002. arXiv:astro-ph/0301579. Bibcode:2003A&A...403..993K. doi:10.1051/0004-6361:20030429. S2CID 5603380.
  16. ^ Adelman, Saul J. (2001). "Stars with the Largest Hipparcos Photometric Amplitudes". Baltic Astronomy. 10 (4): 589. Bibcode:2001BaltA..10..589A. doi:10.1515/astro-2001-0403. S2CID 116386247.
  17. ^ "Red Giant Blows a Bubble". ESA/Hubble Picture of the Week. Retrieved 18 February 2017.
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