U Camelopardalis

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U Camelopardalis
U Camelopardalis.jpeg
U Camelopardalis is a bright star surrounded by a tenuous shell of gas. Its atmosphere contains more carbon than oxygen.
Observation data
Epoch J2000        Equinox J2000
Constellation Camelopardalis
Right ascension 03h 41m 48.17393s [1]
Declination +62° 38′ 54.3906″ [1]
Apparent magnitude  (V)7.55 [2]
Characteristics
Spectral type C-N55.5 (MS4) [3]
U−B color index +3.50 [2]
B−V color index +1.95 [2]
Variable type SRb [4]
Astrometry
Radial velocity (Rv)-3.00 [5]  km/s
Proper motion (μ)RA: 3.50 [1]   mas/yr
Dec.: -3.62 [1]   mas/yr
Parallax (π)1.03 ± 0.59  mas [1]
Distance 530 [6]   pc
Absolute magnitude  (MV)−2.4 (max) [7]
Details
Luminosity 8,472 [8]   L☉
Temperature 3,000 [9]   K
Other designations
U Cam, BD+62° 596, HD 22611, HIP 17257, SAO 12870, GC 4371
Database references
SIMBAD data

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. [1] 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. [10] The C2 index is 5.5 which is typical of a C-N star. [11] It is also given an alternative spectral type of MS4, indicating a star similar to an M4 class but with somewhat enhanced ZrO bands. [3] The spectral type may vary between C3,9 and C6,4e. [4]

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

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. [13] Its brightness varies without a dominant period and it is classified as semi-regular, although a period of 400 days has been published. [13] In the V photometric band the brightness varies by around half a magnitude, [14] but the amplitude is nearly two magnitudes at blue wavelengths. [4] The maximum visual magnitude has been given as 7.2. [7]

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. [15]

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. [7]

Related Research Articles

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<span class="mw-page-title-main">HD 27022</span> Star in the constellation Camelopardalis

HD 27022, also known as HR 1327, is a star located in the northern circumpolar constellation Camelopardalis. The object has also been designated as 20 H. Camelopardalis, but is not commonly used in modern times. It has an apparent magnitude of 5.27, allowing it to be faintly visible to the naked eye. Based on parallax measurements from Gaia DR3, the star has been estimated to be 347 light years away. It appears to be approaching the Solar System, having a heliocentric radial velocity of −19.5 km/s.

References

  1. 1 2 3 4 5 6 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 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. 1 2 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. 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. 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. 1 2 3 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. 1 2 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.
  14. ↑ 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.
  15. ↑ "Red Giant Blows a Bubble". ESA/Hubble Picture of the Week. Retrieved 18 February 2017.
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