Antares

This article is about the star. For other uses, see Antares (disambiguation).
Antares
Location of Antares (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Pronunciation /ænˈtɛəriːz/ an-TAIR-eez,[1][2]
Right ascension 16h 29m 24.45970s[3]
Declination −26° 25′ 55.2094″[3]
Apparent magnitude (V) 0.6–1.6[4] + 5.5[5]
Characteristics
Evolutionary stage Red supergiant
Spectral type M1.5Iab-Ib[6] + B2.5V[7]
U−B color index +1.34[5]
B−V color index +1.83[5]
Variable type Lc[4]
Astrometry
Radial velocity (Rv)−3.4[8] km/s
Proper motion (μ) RA: −12.11[3] mas/yr
Dec.: −23.30[3] mas/yr
Parallax (π)5.89 ± 1.00 mas[3]
Distanceapprox. 550 ly
(approx. 170 pc)
Absolute magnitude (MV)−5.28[9] (variable)
Details
A
Mass13, 15–16 (but not 14)[10] M☉
Radius680[11] (varies by 19%)[12] R☉
Luminosity75900+53000
−31200[12] L☉
Surface gravity (log g)−0.1 to −0.2[11] cgs
Temperature3,660±120[11] K
Rotational velocity (v sin i)20[5] km/s
Age15±5[11] Myr
B
Mass7.2[13] M☉
Radius5.2[13] R☉
Luminosity2,754[13] L☉
Surface gravity (log g)3.9[13] cgs
Temperature18,500[14] K
Rotational velocity (v sin i)250[13] km/s
Other designations
Cor Scorpii, Kalb al Akrab, Scorpion's Heart, Vespertilio[15], Alpha Sco, α Sco, 21 Sco, CD−26°11359, FK5 616, HIP 80763, HR 6134, SAO 184415, CCDM J16294-2626, WDS 16294-2626
A: HD 148478, AAVSO 1623-26
B: HD 148479
Database references
SIMBADAntares
α Scorpii A
α Scorpii B

Antares is the brightest star in the constellation of Scorpius. It has the Bayer designation α Scorpii, which is Latinised to Alpha Scorpii. Often referred to as "the heart of the scorpion", Antares is flanked by σ Scorpii and τ Scorpii near the center of the constellation. Distinctly reddish when viewed with the naked eye, Antares is a slow irregular variable star that ranges in brightness from an apparent visual magnitude of +0.6 down to +1.6. It is on average the fifteenth-brightest star in the night sky. Antares is the brightest and most evolved stellar member of the Scorpius–Centaurus association, the nearest OB association to the Sun. It is located about 170 parsecs (550 ly) from Earth at the rim of the Upper Scorpius subgroup, and is illuminating the Rho Ophiuchi cloud complex in its foreground.

Classified as spectral type M1.5Iab-Ib, Antares is a red supergiant, a large evolved massive star and one of the largest stars visible to the naked eye. If placed at the center of the Solar System, it would extend out to somewhere in the asteroid belt. Its mass is calculated to be around 13 or 15 to 16 times that of the Sun.[10] Antares appears as a single star when viewed with the naked eye, but it is actually a binary star system, with its two components called α Scorpii A and α Scorpii B. The brighter of the pair is the red supergiant, while the fainter is a hot main sequence star of magnitude 5.5. They have a projected separation of about 79.1 Tm (529 AU).

Its traditional name Antares derives from the Ancient Greek Ἀντάρης, meaning "rival to Ares", due to the similarity of its reddish hue to the appearance of the planet Mars.

  1. ^ "Antares". Merriam-Webster.com Dictionary. Merriam-Webster.
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