Antares

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Double star
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.
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
Observation
dates equinox :  J2000.0 , epoch : J2000.0
AladinLite
Constellation Scorpio
Right ascension 16 h 29 m 24.461 s
declination −26 ° 25 ′ 55.21 ″
Apparent brightness  0.91 to 1.07 mag
Astrometry
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
Individual data
Names Antares ; α Sco B
Observation data:
Apparent brightness Antares +1.09 mag
α Sco B +5.5 mag
Typing:
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
Physical Properties:
Absolute vis.
Brightness M vis 		Antares −5.3 mag
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
Other names
and catalog entries
Bayer name α Scorpii
Flamsteed name 21 Scorpii
Cordoba Survey CD −26 ° 11359
Bright Star Catalog HR 6134 [1]
SAO catalog SAO 184415 [2]
Tycho catalog TYC 6803-2158-1 [3]
Hipparcos catalog HIP 80763 [4]
Henry Draper Catalog HD 148478 HD 148479
WDS catalog WDS 16294-2626
Further designations: Antares, CCDM J16294-2626, FK5 616

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.

Physical Properties

brightness

Antares is the brightest star in the Scorpius constellation.

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.

Like most red supergiants , Antares is a semi-regularly variable SRc-type star . The periods are 300 and 1700 days.

size

Comparison between the red giant Antares and the sun. The black circle is the orbit of Mars. Arcturus is added for size comparison.

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.

Antares has enough mass to generate an iron core after reaching the helium burn and to be able to explode in a supernova before it has expelled all gas layers.

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.

Others

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.

See also

Web links

Commons : Antares  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b SIMBAD
  2. ↑ HIP catalog at VizieR
  1. ↑ a b c ESO press release of August 23, 2017: The best image of the surface and atmosphere of a star so far
  2. ^ 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 .
  3. ↑ Süddeutsche Zeitung , Antares as a disc - first image of the surface of a distant star , August 25, 2017.
  4. ↑ Antares - ESO observatory shoots sharp constellation. Astronomers take a detailed picture of a star for the first time. , sueddeutsche.de, August 25, 2017.
  5. ↑ astronews: Detailed view of a giant star , August 25, 2017.