Sigma Draconis
Star in the constellation Draco / From Wikipedia, the free encyclopedia
Sigma Draconis is a single star in the northern constellation of Draco. It has the proper name Alsafi /ælˈseɪfi/,[12] while Sigma Draconis, which is latinised from σ Draconis and abbreviated Sig Dra or σ Dra, is the Bayer designation. It has an apparent visual magnitude of 4.7,[2] which is bright enough to be faintly visible to the naked eye. Based on parallax measurements, this star is located at a distance of 18.8 light years from the Sun. It is receding from the Sun with a radial velocity of 26.6 km/s.[13]
Quick Facts Observation data Epoch J2000 Equinox J2000, Constellation ...
Observation data Epoch J2000 Equinox J2000 | |
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Constellation | Draco |
Right ascension | 19h 32m 21.59021s[1] |
Declination | +69° 39′ 40.2358″[1] |
Apparent magnitude (V) | 4.674[2] |
Characteristics | |
Evolutionary stage | Main sequence |
Spectral type | K0 V[3] |
U−B color index | +0.386[2] |
B−V color index | +0.791[2] |
Variable type | None[4] |
Astrometry | |
Radial velocity (Rv) | 26.55±0.13[1] km/s |
Proper motion (μ) | RA: 597.384 mas/yr[1] Dec.: −1738.286 mas/yr[1] |
Parallax (π) | 173.4939 ± 0.0748 mas[1] |
Distance | 18.799 ± 0.008 ly (5.764 ± 0.002 pc) |
Absolute magnitude (MV) | 5.89[5] |
Details | |
Mass | 0.84±0.01[6] M☉ |
Radius | 0.772±0.005[6] R☉ |
Luminosity | 0.42±0.04[6] L☉ |
Surface gravity (log g) | 4.589±0.008[6] cgs |
Temperature | 5,299±32[6] K |
Metallicity [Fe/H] | −0.254[7] dex |
Rotation | 27.7±0.77 days[8] |
Rotational velocity (v sin i) | 1.4[9] km/s |
Age | 3.00±0.60[10] – 4.54±0.92[6] Gyr |
Other designations | |
Alsafi, σ Draconis, Sig Dra, σ Dra, 61 Draconis, BD+69°1053, GJ 764, HD 185144, HIP 96100, HR 7462, LHS 477[11] | |
Database references | |
SIMBAD | data |
ARICNS | data |
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