Triangulum II

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Triangulum II ( Tri II or Laevens 2 ) is an extremely faint, spheroid dwarf galaxy . It was published in 2015 by Benjamin PM Laevens et al. discovered at the Keck Observatory . According to the astrometric measurements of Gaia ( ESA , 2018), Tri II orbits the Milky Way at the edge of the outer halo on an almost circular path at a distance of 30,000 parsecs . Previous measurements had mostly shown a shorter distance.

The dwarf galaxy Tri II comprises about 1000 stars and has a luminosity of only 450 L ☉ . Triangulum II corresponds to the definition of a "galaxy".

Although the Milky Way has clearly effective tidal forces , Tri II is in dynamic equilibrium. Given the relatively small number of stars, this physical cohesion cannot be taken for granted.

Detailed measurements of the speed distributions of the stars within the dwarf galaxy suggest that Triangulum II has an extremely high proportion of dark matter . According to current estimates by astronomers, Triangulum II is an important candidate for the experimental detection of dark matter.

Individual evidence

  1. ↑ Daniel Fischer: The halo of the Milky Way consists of two components. In: Adventure Astronomy. January 4, 2008, accessed June 14, 2020 (German).
  2. ↑ Joshua D. Simon: Gaia Proper Motions and Orbits of the Ultra-faint Milky Way Satellites . In: The Astrophysical Journal . tape 863 , no. 1 , August 13, 2018, ISSN  1538-4357 , p. 89 , doi : 10.3847 / 1538-4357 / aacdfb ( iop.org [accessed June 14, 2020]).
  3. ↑ Evan N. Kirby, Judith G. Cohen, Joshua D. Simon, Puragra Guhathakurta: Triangulum II: Possibly a Very Dense Ultra-faint Dwarf Galaxy . In: ApJL . tape 814 , no. 1 , November 2015, ISSN  0004-637X , p. L7 , doi : 10.1088 / 2041-8205 / 814/1 / L7 ( harvard.edu [accessed June 14, 2020]).
  4. ↑ Evan N. Kirby, Judith G. Cohen, Joshua D. Simon, Puragra Guhathakurta: TRIANGULUM II: POSSIBLY A VERY DENSE ULTRA-FAINT DWARF GALAXY . In: The Astrophysical Journal . tape 814 , no. 1 , November 16, 2015, ISSN  2041-8213 , p. L7 , doi : 10.1088 / 2041-8205 / 814/1 / l7 ( iop.org [accessed June 14, 2020]).
  5. ↑ Gaia Proper Motions and Orbits of the Ultra-faint Milky Way Satellites . In: The Astrophysical Journal . tape 863 , no. 1 , August 13, 2018, ISSN  1538-4357 , p. 89 , doi : 10.3847 / 1538-4357 / aacdfb ( iop.org [accessed June 14, 2020]).
  6. ↑ B. Willman, J. Strader: “GALAXY,” DEFINED . In: The Astronomical Journal . tape 144 , no. 3 , August 3, 2012, ISSN  0004-6256 , p. 76 , doi : 10.1088 / 0004-6256 / 144/3/76 ( iop.org [accessed June 14, 2020]).
  7. ↑ Evan N. Kirby, Judith G. Cohen, Joshua D. Simon, Puragra Guhathakurta: TRIANGULUM II: POSSIBLY A VERY DENSE ULTRA-FAINT DWARF GALAXY . In: The Astrophysical Journal . tape 814 , no. 1 , November 16, 2015, ISSN  2041-8213 , p. L7 , doi : 10.1088 / 2041-8205 / 814/1 / l7 ( iop.org [accessed June 14, 2020]).
  8. ↑ Triangulum II: Possibly a Very Dense ultra-faint dwarf galaxy . In: ApJL . tape 814 , no. 1 , November 2015, ISSN  0004-637X , p. L7 , doi : 10.1088 / 2041-8205 / 814/1 / L7 ( harvard.edu [accessed June 14, 2020]).
  9. ↑ Largest concentration of dark matter discovered in dwarf galaxy. In: The Standard . November 21, 2015, accessed June 9, 2020 .