Antares (α Scorpii)
|Reconstructed image of Antares, based on interferometry with the AMBER instrument with 3 auxiliary telescopes at a distance of up to 82 m at a wavelength of 2 µm.|
|The position of Antares|
dates equinox : J2000.0 , epoch : J2000.0
|Right ascension||16 h 29 m 24.461 s|
|declination||−26 ° 25 ′ 55.21 ″|
|Apparent brightness||0.91 to 1.07 mag|
|Radial velocity||(−3.4 ± 0.9) km / s|
|parallax||(5.4 ± 1.7) mas|
|distance||approx. 600 ly
(approx. 185 pc )
|Proper movement :|
|Rec. Share:||−10.16 mas / a|
|Dec. portion:||−23.21 mas / a|
|Names||Antares ; α Sco B|
|Apparent brightness||Antares||+1.09 mag|
|α Sco B||+5.5 mag|
|Spectral class||Antares||M1.5 Iab-b|
|α Sco B||B2.5 V|
|B − V color index||Antares||1.87|
|U − B color index||Antares||1.34|
Brightness M vis
|α Sco B||−0.8 mag|
|Dimensions||Antares||12 M ☉|
|α Sco B|
|radius||Antares||700 R ☉|
|α Sco B|
|Luminosity||Antares||65,000 L ☉|
|α Sco B|
|Effective temperature||Antares||3,500 K|
|α Sco B|
|Rotation time||Antares||? d|
|α Sco B|
and catalog entries
Antares (hyphenation: Antares), also Alpha Scorpii ( α Scorpii ) called , is the brightest star in the constellation Scorpio . It is about 600 light years from Earth. The name comes from the ancient Greek ἀντί antí , German 'against' , and the name Ἄρης Ares and means “Gegenares” ( Gegenmars ). The god Ares was called Mars by the Romans . Antares has a similar color to Mars , which is why the two are easy to confuse, especially since they are always close to the ecliptic and have a similar brightness in phases. Other names are Qalbu l-ʿAqrab (Arabic قلب العقرب, heart of the scorpion), An ta er (mandarin 安塔尔) and Vespertilio.
With an apparent magnitude of 1.09 mag, it is the 16th brightest star in the sky. Its absolute brightness is −5.3 mag, making the star around 10,000 times brighter than the sun in the visible range. The surface is relatively cool, the temperature is only 3400 Kelvin , which is why Antares is orange-red in color and emits a particularly large amount of infrared that is invisible to the eye . Taking this into account, Antares emits around 65,000 times more energy than the sun . Its spectral class is M1, the luminosity class Iab.
From the relatively low temperature and the great brightness it can be concluded that Antares is enormous. Its diameter is about 1000 million kilometers. This would mean that it would, in the place of the sun, protrude far beyond the orbit of Mars . Like Betelgeuse, Antares is one of the red supergiants. In its current phase of development, it is losing its outer gas layers, forming a planetary nebula that is visible due to a hot companion star.
α Scorpii B
Antares forms a binary star system with a companion . At an angular distance of 2.6 "there is a blue-white star (spectral type B3 V) with an apparent magnitude of 5.5 mag at a position angle of 273 °. Thus, α Sco B has 1/370 the brightness of Antares, but still has the 170- times the luminosity of the sun . The orbital period is 878 years at a distance of 550 AU . To see this companion, a telescope with a 10 centimeter lens opening is required.
As a star near the ecliptic, Antares can be covered by the moon and (very rarely) planets. The last occultation of Antares by a planet took place on September 17th, 525 BC. Chr. By Venus, the next will take place again by Venus on November 17, 2400. Antares is a member of the Gouldian Belt . In Mesopotamian mythology, Antares received in the first millennium BC The name of the Sumerian goddess Lisin . Antares is also considered to be one of the four royal Persian stars .
Antares is the first star outside our solar system from which a picture of the solar disk could be made. To do this, astronomers from the European Southern Observatory ESO in Chile connected the images from four telescopes in 2017, thereby increasing the resolution considerably.
- ESO press release of August 23, 2017: The best image of the surface and atmosphere of a star so far
- Richard B. Stothers: Giant Convection Cell Turnover as an Explanation of the Long Secondary Periods in Semiregular Red Variable Stars. In: The Astrophysical Journal . Vol. 725, 2010, pp. 1170-1174; doi: 10.1088 / 0004-637X / 725/1/1170 ; PDF; 184 kB .
- Süddeutsche Zeitung , Antares as a disc - first image of the surface of a distant star , August 25, 2017.
- Antares - ESO observatory shoots sharp constellation. Astronomers take a detailed picture of a star for the first time. , sueddeutsche.de, August 25, 2017.
- astronews: Detailed view of a giant star , August 25, 2017.