LB-1

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Star
LB-1
Image taken from Sky-Map.org
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Twins
Right ascension 06 h 11 m 49.08 s
declination + 22 ° 49 ′ 32.7 ″
Apparent brightness (+11.51) mag
Typing
Astrometry
parallax 0.4403 ± 0.0856  mas
distance 7000 (star)  Lj
2300 (star)  pc
Physical Properties
Luminosity

7000  L ☉

Effective temperature 19100 ± 820  K
Other names
and catalog entries
Tycho catalog TYC ....-....-. [1]Template: Infobox star / maintenance / specification of the TYC catalog

LB-1 is the name of a star of the class B as well as the name of a associated therewith massive stellar black hole . Both were discovered in November 2019.

discovery

Stellar black hole

The discoverers of the black hole put its mass at almost 70 solar masses. This would be more than twice the maximum suggested by most current theories of stellar evolution . There are indications of black holes in this mass range from observations of gravitational waves, but only in distant galaxies, which correspond accordingly to times far back. In our galaxy and the metallicity of the stars occurring here, according to current theory, they should not occur due to the mechanism of pair instability supernovae , which leave no compact residues in the observed mass range, and solar winds.

One of the discoverers said: “This discovery forces us to re-examine our models of how black holes with star mass are formed. [...] This remarkable result, together with the observations of LIGO - Virgo about collisions of two black holes during the past four years, really indicate a renaissance in our understanding of astrophysics in black holes. "

Several papers published in December 2019, however, question the mass determination. Results of the spectral analysis of the main star published in January 2020 indicate that this is not a main sequence star of spectral class B, but an extreme helium star . This means that the companion could have a mass down to 2 to 3 solar masses. LB-1 could therefore also be a neutron star or a “normal” black hole.

According to Michael Abdul-Masih and colleagues, it also appears possible that the observed fluctuations in the profile of the H-alpha line, from which Liu and colleagues inferred a black hole, is explained by the absorption in the atmosphere of a second star in a binary system , which consists of two ordinary stars, each around four solar masses. Then, however, the binary star system would have to be embedded in a gas disk, which is the source of the H-alpha radiation. In a reply, Liu and colleagues thought this was possible, but unlikely.

star

The star, which is eight times the size of the Sun and is 15,000 light years from Earth in the constellation of Gemini , was discovered by Chinese astronomers with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and with the help of the Doppler spectroscopy method ( radial-velocity method ) discovered. The astronomers watched the star orbit the black hole every 79 days in what the researchers called a "surprisingly circular" orbit .

Subsequent observations with the Gran Telescopio Canarias in Spain and the Keck Observatory in the USA helped with the determination.

See also

Individual evidence

  1. ↑ Jifeng Liu, Haotong Zhang, Andrew W. Howard, Zhongrui Bai, Youjun Lu: A wide star – black-hole binary system from radial-velocity measurements . In: Nature . tape 575 , no. 7784 , November 2019, ISSN  1476-4687 , p. 618-621 , doi : 10.1038 / s41586-019-1766-2 .
  2. ↑ a b c Chinese Academy of Science : Chinese Academy of Sciences leads discovery of unpredicted stellar black hole . In: EurekAlert! . November 27, 2019. Retrieved November 29, 2019.
  3. ↑ Researchers discover a black hole that shouldn't actually exist. November 30, 2019, accessed December 1, 2019 .
  4. ↑ Jifeng Liu, Haotong Zhang, Andrew W. Howard, Zhongrui Bai, Youjun Lu: A wide star – black-hole binary system from radial-velocity measurements . In: Nature . tape 575 , no. 7784 , November 2019, ISSN  1476-4687 , p. 618–621 , doi : 10.1038 / s41586-019-1766-2 , arxiv : 1911.11989v1 ( nature.com [accessed April 13, 2020]).
  5. ↑ JJ Eldridge, ER Stanway, K. Breivik, AR Casey, DTH Steeghs: Weighing in on black hole binaries with BPASS: LB-1 does not contain a 70M $ _ {\ odot} $ black hole . In: Submitted to MNRAS . December 7, 2019, arxiv : 1912.03599 .
  6. ↑ Kareem El-Badry, Eliot Quataert: Not so fast: LB-1 is unlikely to contain a 70 M ⊙ black hole . In: Monthly Notices of the Royal Astronomical Society: Letters . tape 493 , no. 1 , March 21, 2020, ISSN  1745-3925 , p. L22 – L27 , doi : 10.1093 / mnrasl / slaa004 , arxiv : 1912.04185 ( oup.com [accessed April 13, 2020]).
  7. ↑ Michael Abdul-Masih, Gareth Banyard, Julia Bodensteiner, Dominic M. Bowman, Karan Dsilva: No signature of the orbital motion of a putative 70 solar mass black hole in LB-1 . December 9, 2019, arxiv : 1912.04092 .
  8. ↑ A. Irrgang et al .: A stripped helium star in the potential black hole binary LB-1 . In: Astronomy & Astrophysics . tape 633 , p. L5 , doi : 10.1051 / 0004-6361 / 201937343 ( aanda.org [accessed January 28, 2020]).
  9. ↑ Abdul-Masih et al. a., On the signature of a 70-solar-mass black hole in LB-1, Nature, Volume 580, 2020, E11
  10. ^ Rainer Kayser, Dispute over a black hole , pro-physik.de, April 30, 2020
  11. ↑ J. Liu et al. a .: Reply to: On the signature of a 70-solar-mass black hole in LB-1, Nature, online April 30, 2020
  12. ^ A b Michelle Starr: Scientists Just Found an "Impossible" Black Hole in The Milky Way Galaxy . In: ScienceAlert.com , November 27, 2019. Retrieved November 29, 2019.