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

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. [13] It was listed with its variable star designation, U Camelopardalis, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars. [14] 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. [15] Its brightness varies without a dominant period and it is classified as semi-regular, although a period of 400 days has been published. [15] In the V photometric band the brightness varies by around half a magnitude, [16] 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. [17]

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]

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−2.1
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