U Camelopardalis
Star in the constellation Camelopardalis
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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.
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 |
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]
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 Camelopardalis 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]