HR 6819

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Multiple star
HR 6819
HR 6819 in the starry sky, image field size approx. 3 °
HR 6819 in the starry sky , image field size approx. 3 °
HR 6819 in the constellation Telescope
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation telescope
Right ascension 18 h 17 m 7.53 s
declination −56 ° 01 ′ 24.1 ″
Apparent brightness 5.36 likes
Typing
B − V color index −0.06 
U − B color index −0.68 
R − I index −0.04 
Spectral class B3II / III D
Astrometry
Radial velocity (15.0 ± 4.2) km / s
parallax (2.91 ± 0.18)  mas
distance (1120 ± 70)  ly
(343 ± 22)  pc
Proper movement 
Rec. Share: (−3.67 ± 0.28)  mas / a
Dec. portion: (−11.12 ± 0.30)  mas / a
Physical Properties
Other names
and catalog entries
Cordoba Survey CD −56 ° 7256
Bright Star Catalog HR 6819 [1]
Henry Draper Catalog HD 167128 [2]
Hipparcos catalog HIP 89605 [3]
SAO catalog SAO 245369 [4]
Tycho catalog TYC 8748-2276-1 [5]Template: Infobox star / maintenance / specification of the TYC catalog
2MASS catalog 2MASS J18170753-5601240 [6]
Other names QV Tel
Gaia DR2 6649357561810851328

HR 6819 is a star system in the constellation Telescope . Two of the components are ordinary stars, the third appears to be a black hole . Of all known black holes (as of May 2020), this would be the closest to Earth and the only one that belongs to a star system that is visible to the naked eye , but not from Europe due to its declination of −56 °.

HR 6819 was originally described as a blue star with strong emission lines in the spectrum ( Be star ). These types of stars are characterized by an extremely fast rotation and, as a result, a disc of material around their equator. Special features in the spectrum could only be traced back to the existence of a second blue giant star ( spectral class B3 III) in 2003 . This second blue star shows a movement pattern in its spectrum that already indicated the existence of a third, invisible object. In evaluations of measurements with the FEROS Échelle spectrograph of the MPG / ESO 2.2 m telescope at the La Silla Observatory from 2004, it was confirmed in 2020 that the B3 star moves with a period of 40.3 days in moves in an almost circular path around an invisible object. From the data it could be further deduced that the B3 star has a mass of at least 5 solar masses , while the invisible object must be at least 4.2 solar masses. The mutual distance is at least 0.22  AU .

If the third object were a star, a spectrum should also be clearly detectable with its mass. However, since this is not the case and the object is also heavier than a neutron star , the researchers conclude that it must be a black hole. An emission of X-rays could not be determined, this indicates that no mass falls into the black hole to any significant extent, so there is no interaction with the B3 star and the black hole does not grow.

Web links

Commons : QV Telescopii  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c VizieR Online Data Catalog: Gaia DR2. Gaia Collaboration. 2018.
  2. ^ A b c d VizieR Online Data Catalog: Catalog of Stellar Photometry in Johnson's 11-color system. 2002.
  3. ^ VizieR Online Data Catalog: Catalog of two dimentional spectral types for the HD stars, Vol. 1. 1975.
  4. ^ VizieR Online Data Catalog: Pulkovo compilation of radial velocities for 35495 stars in a common system. 2006.
  5. ↑ Th. Rivinius, D. Baade, P. Hadrava, M. Heida, R. Klement: A naked-eye triple system with a nonaccreting black hole in the inner binary. In: Astronomy & Astrophysics . Vol. 637, L3, 2020, pp. 1-11. doi: 10.1051 / 0004-6361 / 202038020 ( PDF; 2.4 MB ).