S Canis Minoris
Variable star in the constellation Canis Minor
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S Canis Minoris is a variable star in the equatorial constellation Canis Minor. It has a peak apparent visual magnitude of 6.5, so not normally visible to the naked eye. The star is located at a distance of approximately 1,340 light-years from the Sun based on stellar parallax, and is drifting further away with a radial velocity of about +68 km/s.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Canis Minor[2] |
| Right ascension | 07h 32m 43.06942s[3] |
| Declination | +08° 19′ 05.1975″[3] |
| Apparent magnitude (V) | 6.5 to 13.7[4] |
| Characteristics | |
| Evolutionary stage | AGB[5] |
| Spectral type | M7-8e[6] |
| B−V color index | 1.50±0.51[2] |
| Variable type | Mira variable[7][4] |
| Astrometry | |
| Radial velocity (Rv) | 68.0±4.8[8] km/s |
| Proper motion (μ) | RA: −10.785 mas/yr[3] Dec.: −12.827 mas/yr[3] |
| Parallax (π) | 2.440±0.098 mas[9] |
| Distance | 1,340 ± 50 ly (410 ± 20 pc)[9] |
| Details | |
| Radius | 378 – 402[9] R☉ |
| Luminosity | 6,174+402 −378[9] L☉ |
| Surface gravity (log g) | −0.46 to −0.51[9] cgs |
| Temperature | 2,854 – 2,872[9] K |
| Metallicity [Fe/H] | +0.39[10] dex |
| Other designations | |
| S CMi, AAVSO 0727+08, BD+08°1800, HD 59950, HIP 36675, SAO 115591[11] | |
| Database references | |
| SIMBAD | data |
In 1856, John Russell Hind discovered that S Canis Minoris is a variable star.[12] This is an aging red giant star with a stellar classification of M7-8e,[6] where the 'e' suffix indicates emission lines in the spectrum. It is a Mira-type[7] long period variable that varies by an amplitude of 4.27 in visual magnitude over a period of 327.77±2.78 d.[13] Evidence has been found of asymmetry in this star, suggesting a non-spherical shape.[5] Abundance-wise, it is an oxygen-rich[14] giant and the emission feature is of the oxygen-rich silicate class as it sheds silicate dust from its atmosphere.[15] The star is shedding mass at the rate of 4.9×10−8 M☉/yr.[5]