Sigma Arae

Not to be confused with S Arae.
Sigma Arae
Diagram showing star positions and boundaries of the Ara constellation and its surroundings
The location of σ Arae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension 17h 35m 39.58957s[1]
Declination –46° 30′ 20.4618″[1]
Apparent magnitude (V) +4.575[2]
Characteristics
Spectral type A0 V[3]
U−B color index –0.064[2]
B−V color index –0.027[2]
Astrometry
Proper motion (μ) RA: –25.78[1] mas/yr
Dec.: –38.30[1] mas/yr
Parallax (π)8.62 ± 0.26 mas[1]
Distance380 ± 10 ly
(116 ± 3 pc)
Absolute magnitude (MV)1.40[4]
Details
Luminosity (bolometric)26.4[4] L☉
Temperature9,790[4] K
Other designations
CD–46 11661, HD 159217, HIP 86092, HR 6537, SAO 228162.[5]
Database references
SIMBADdata

Sigma Arae (σ Ara, σ Arae) is the Bayer designation for a star in the southern constellation of Ara. It is visible to the naked eye with an apparent visual magnitude of +4.575.[2] The distance to this star, based upon an annual parallax shift of 8.62 mas,[1] is around 380 light-years (120 parsecs).

This is an A-type main sequence star with a stellar classification of A0 V.[3] Unusually for an A-type star, X-ray emissions with a luminosity of 4.6 × 1029 erg s−1 have been detected from Sigma Arae. Normally this is explained by the presence of a lower mass orbiting companion star. However, such a scenario does not appear to hold true for this star. Instead, the signature of a surface magnetic field has been detected with a strength of roughly 128 ± 73 Gauss, indicating the source of the X-rays may be surface magnetic activity.[6]

  1. ^ a b c d e f Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference mras77_223 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference apj685_1_478 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference aaa484_2_479 was invoked but never defined (see the help page).