Fomal skin

from Wikipedia, the free encyclopedia
Stern form
skin (α PsA)
Heic0821f-s.jpg
DSS image of the star field around Fomalhaut (sky section of almost 3 degrees)
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Southern fish
Right ascension 22 h 57 m 39.05 s
declination -29 ° 37 ′ 20.1 ″
Apparent brightness 1.17 mag
Typing
Known exoplanets 1
B − V color index +0.09 
U − B color index +0.08 
R − I index +0.02 
Spectral class A3 V
Astrometry
Radial velocity (+6.5 ± 0.5) km / s
parallax (129.81 ± 0.47)  mas
distance (25.13 ± 0.09)  ly
(7.70 ± 0.03)  pc  
Visual absolute brightness M vis +1.7 mag
Proper movement 
Rec. Share: (+328.95 ± 0.50)  mas / a
Dec. portion: (−164.67 ± 0.35)  mas / a
Physical Properties
Dimensions (1.92 ± 0.02)  M ☉
radius (1.842 ± 0.019)  R ☉
Luminosity

17.3  L ☉

Effective temperature (8590 ± 73)  K.
Rotation time 0.6 days
Age (440 ± 40) mill.  A
Other names
and catalog entries
Bayer name α Piscis Austrini
Flamsteed name 24 Piscis Austrini
Cordoba Survey CD −30 ° 19370
Bright Star Catalog HR 8728 [1]
Henry Draper Catalog HD 216956 [2]
Gliese catalog FY 881 [3]
Hipparcos catalog HIP 113368 [4]
SAO catalog SAO 191524 [5]
Tycho catalog TYC 6977-1267-1 [6]
2MASS catalog 2MASS J22573901-2937193 [7]
Other names FK5  867

Fomalhaut [fom alhˈaɔ̯t] (α Piscis Austrini) is the brightest star in the constellation Southern Pisces and the 19th in the list of the brightest stars in the sky. The name means "mouth of the fish" (arab.فم الحوت fam al-ḥūt ). Other names: Difda al Auwel, Hastorang, Os Piscis Meridiani.

Like the sun, Fomalhaut is currently in the local flake .

Physical Properties

Fomalhaut is 25 light years from the sun. He is like the slightly hotter Wega a main sequence star of spectral type A. Its surface temperature is about 8500 K . It is believed that Fomalhaut is around 400 million years old. Its lifespan is classified at around a billion years.

origin

Fomalhaut is a member of the Castor movement group , which includes Vega among others. The next member of this cluster of motions , TW Piscis Austrini (a variable star of the BY Draconis type ), is only about 0.85 light years away from Fomalhaut and has a very similar proper motion .

The two stars together with the red dwarf LP876-10 ( Fomalhaut C ) form a triple system , as a new analysis of the parallax and the proper motion of Fomalhaut C have shown. The distance of 3.2 light years between Fomalhaut A and C is unusually large for a bound system. Because of the relatively short distance from the earth, the apparent distance in the sky is almost 6 °.

Dust disc and exoplanet

Image of the dust disc with the Hubble Space Telescope and the ALMA Observatory

Fomalhaut is surrounded by a disk of dust with a diameter of around 40 billion kilometers. The dust disk shows a ring structure that was thought to be caused by the gravitational effects of a planet. The infrared radiation of the disk could already be observed in the 1980s by NASA's Infrared Astronomical Satellite (IRAS) . The inside of the dust disk is sharply demarcated from the main star at a distance of about 133 astronomical units (AU) and itself has a width of about 25 AU.

The center of the disk does not coincide with the star, but is about 15 AU from Fomalhaut. In 2005, a planet was therefore assumed at a distance of about 7.4 to 10.5 billion kilometers (49 to 100 AU) around the star.

In 2008 the direct observation of the exoplanet Dagon (Fomalhaut b) was published. According to an April 2020 publication, the observed object could also be a cloud of dust as a result of a collision between two smaller bodies about 200 km in diameter. The object orbits the central star at an average distance of about 115 AU within the inner edge of the dust ring. Due to the eccentricity of the orbit of 0.11, the distance fluctuates between 102 and 128 AU and is currently around 119 AU.

Derived names

  • The barque Fomalhaut of the shipowner L. Wittenberg (245 loads , captain: Robert Bülow, 13 man owner ) from 1864/65, one of the largest sailing ships in the Greifswald merchant fleet in the 19th century, bore the name of the star.

photos

  • Fomalhaut is the brightest star in the constellation Piscis Austrinus (center).

See also

Web links

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

Individual evidence

  1. ↑ a b c d Hipparcos catalog (ESA 1997)
  2. ↑ a b c Bright Star Catalog, 5th Revised Ed. (Hoffleit +, 1991)
  3. ↑ Pulkovo radial velocities for 35493 HIP stars
  4. ↑ a b c Hipparcos, the New Reduction (van Leeuwen, 2007)
  5. ↑ calculated from apparent brightness and distance
  6. ↑ a b c d Exoplanet.eu
  7. ↑ Eva-Maria Krech , Eberhard Stock , Ursula Hirschfeld , Lutz-Christian Anders: German pronunciation dictionary , de Gruyter, Berlin 2009, ISBN 978-3-11-018202-6 , p. 515
  8. ↑ Paul Kunitzsch : The pronunciation of the Arabic star names and the Arabic-Persian names of moon objects , Die Sterne 56, 1980, pp. 358–363
  9. ↑ Stefan Deiters: Fomalhaut is a triple star system. October 7, 2013, accessed June 14, 2014 .
  10. ^ Robert Naeye: Fomalhaut's Kuiper Belt. July 22, 2005, accessed November 4, 2013 .
  11. ^ András Gáspár, George H. Rieke: New HST data and modeling reveal a massive planetesimal collision around Fomalhaut. PNAS , April 20, 2020, accessed April 21, 2020 . doi : 10.1073 / pnas.1912506117
  12. ↑ No planet, just dust. Spektrum.de , April 20, 2020, accessed on April 21, 2020 .