Sigma Draconis

Sigma Draconis

Photograph of Sigma Draconis (center)
Observation data
Epoch J2000      Equinox J2000
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]
Distance18.799 ± 0.008 ly
(5.764 ± 0.002 pc)
Absolute magnitude (MV)5.89[5]
Details
Mass0.84±0.01[6] M☉
Radius0.772±0.005[6] R☉
Luminosity0.42±0.04[6] L☉
Surface gravity (log g)4.589±0.008[6] cgs
Temperature5,299±32[6] K
Metallicity [Fe/H]−0.254[7] dex
Rotation27.7±0.77 days[8]
Rotational velocity (v sin i)1.4[9] km/s
Age3.00±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
SIMBADdata
ARICNSdata
Sigma Draconis is located in the constellation Draco
Sigma Draconis is located in the constellation Draco
σ
Location of Sigma Draconis (in red circle).

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]

  1. ^ a b c d e Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference aaass65_2_405 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Keenan89 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Radick1998 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Kim2016 was invoked but never defined (see the help page).
  6. ^ a b c d e f Cite error: The named reference Hon2024 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference gray2019 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference 2018A&A...619A...6O was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference aaa555_A104 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Ramirez2012 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ "Naming Stars". IAU.org. Retrieved 16 December 2017.
  13. ^ Cite error: The named reference Bailer_et_al_2018 was invoked but never defined (see the help page).