Sigma Arietis

σ Arietis
Location of σ Arietis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aries
Right ascension 02h 51m 29.58618s[1]
Declination +15° 04′ 55.4438″[1]
Apparent magnitude (V) +5.52[2]
Characteristics
Spectral type B7 V[3]
U−B color index –0.43[2]
B−V color index –0.09[2]
Astrometry
Radial velocity (Rv)+17.0[4] km/s
Proper motion (μ) RA: +29.843[1] mas/yr
Dec.: –24.661[1] mas/yr
Parallax (π)6.8952 ± 0.2164 mas[1]
Distance470 ± 10 ly
(145 ± 5 pc)
Absolute magnitude (MV)−0.38[5]
Details
A
Mass3.84±0.08[6] M☉
Radius3[7] R☉
Luminosity301[6] L☉
Surface gravity (log g)4.0±0.25[8] cgs
Temperature13,121[6] K
Rotational velocity (v sin i)165[6] km/s
Age36+57
−27[8] Myr
B
Mass1.0–1.2[8] M☉
Temperature5,524±150[8] K
Metallicity [Fe/H]−0.5[8] dex
Rotational velocity (v sin i)5 km/s
Other designations
σ Ari, 43 Arietis, BD+14 480, FK5 1079, HD 17769, HIP 13327, HR 847, SAO 93144[9]
Database references
SIMBADdata

Sigma Arietis, Latinized from σ Arietis, is the Bayer designation for a star in the northern constellation of Aries. It has an apparent visual magnitude of +5.52,[2] which is bright enough for the star to be seen with the naked eye from dark suburban skies. The star is located at a distance of approximately 470 light-years (140 parsecs) from the Sun based on parallax, and is drifting further away with a radial velocity of +17 km/s.[4] On November 20, 1952, it was observed being occulted by the planet Jupiter.[10]

Sigma Arietis is a B-type main sequence star with a stellar classification of B7 V.[3] This is a large star with three[7] times the radius of the Sun and 3.8[6] times the Sun's mass. It shines around 301[6] times as brightly as the helium and oxeygen, with this energy being radiated into space from its outer atmosphere at a scorching hot effective temperature of 13,121 K.[6] It is this heat that gives the star the blue-white hue of a B-type star. Sigma Arietis is spinning at a rapid clip, with a projected rotational velocity of 165 km/s.[6] It is a probable member of the Cas-Tau OB association of stars that share a common motion through space.[11]

In 2016, a stellar companion was reported based on observations using adaptive optics with the Gemini North Telescope.[8]

  1. ^ a b c d e Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference aj76_1058 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference apjs17_371 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference scfs was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b c d e f g h Cite error: The named reference aaa537_A120 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference aaa367_521 was invoked but never defined (see the help page).
  8. ^ a b c d e f Cite error: The named reference Gullikson_et_al_2016 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Salanave1953 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference aj117_1_354 was invoked but never defined (see the help page).