Gaia Sausage

The Gaia Sausage is the remains of a dwarf galaxy, the "Sausage Galaxy", that merged with the Milky Way about 8 - 11 billion years ago. At least eight globular clusters were added to the Milky Way along with 50 billion solar masses of stars, gas and dark matter.[1] The "Gaia Sausage" is so-called because of the characteristic sausage shape of the population in velocity space, the appearance on a plot of radial versus azimuthal and vertical velocities of stars measured in the Gaia Mission.[1] The stars that have merged with the Milky Way have orbits that are highly radial. The outermost points of their orbits are around 20 kiloparsecs from the galactic centre at what is called the halo break.[2]

Components

The Sausage globular clusters are NGC 1851 NGC 1904 NGC 2298 NGC 2808 (possibly the old galactic core) NGC 5286 NGC 6864 NGC 6779 NGC 7089[1]

The stars from this dwarf have eccentricities of about 0.9. Their metallicity is also typically higher than other halo stars, with many with [Fe/H] over -1.7 dex.[2]

The ‘Gaia Sausage’ reconstructed the Milky Way, by puffing up the thin disk to make it a thick disk, whilst the gas it brought into the Milky Way triggered a fresh round of star formation and replenished the thin disk. The debris from the dwarf galaxy provides most of the metal-rich halo.[1]

See also

References

  1. 1 2 3 4 Myeong, G.C.; Evans, N.W.; Belokurov, V.,; Sanders, J.L.; Koposov, S. (2018). "The Sausage Globular Clusters". arXiv:1805.00453. Bibcode:2018ApJ...863L..28M. doi:10.3847/2041-8213/aad7f7.
  2. 1 2 Deason, Alis; Belokurov, Vasily; Koposov, Sergey; Lancaster, Lachlan, (2018). "Apocenter Pile-Up: Origin of the Stellar Halo Density Break". The Astrophysical Journal. 862: L1. arXiv:1805.10288. Bibcode:2018ApJ...862L...1D. doi:10.3847/2041-8213/aad0ee.

Further reading

  • Belokurov, V.; Erkal, D.; Evans, N. W.; Koposov, S. E.; Deason, A. J.; (July 2018). "Co-formation of the disc and the stellar halo". Monthly Notices of the Royal Astronomical Society. 478 (1): 611–619. arXiv:1802.03414. Bibcode:2018MNRAS.478..611B. doi:10.1093/mnras/sty982.
  • Deason, Alis J.; Belokurov, Vasily; Koposov, Sergey E.; Lancaster, Lachlan; (May 2018). "Apocenter Pile-Up: Origin of the Stellar Halo Density Break". The Astrophysical Journal Letters. 862: L1. arXiv:1805.10288. Bibcode:2018ApJ...862L...1D. doi:10.3847/2041-8213/aad0ee.
  • Myeong, G. C.; Evans, N. W.; Belokurov, V.; Sanders, J. L.; Koposov, S. E.; (May 2018). "The Sausage Globular Clusters". arXiv:1805.00453 [astro-ph.GA].
  • Myeong, G. C.; Evans, N. W.; Belokurov, V.; Sanders, J. L.; Koposov, S. E.; (April 2018). "The Milky Way Halo in Action Space". The Astrophysical Journal Letters. 856 (2): L26. arXiv:1802.03351. Bibcode:2018ApJ...856L..26M. doi:10.3847/2041-8213/aab613.
  • Myeong, G. C.; Evans, N. W.; Belokurov, V.; Sanders, J. L.; Koposov, S. E.; (April 2018). "The Shards of ω Centauri". arXiv:1804.07050 [astro-ph.GA].
  • Gaia Sausage Simulation on YouTube
  • Jocelyn Duffy (4 July 2018). "The Gaia Sausage: The Major Collision that Changed the Milky Way Galaxy". Carnegie Mellon University.
  • Sarah Collins (4 July 2018). "The Gaia Sausage: the major collision that changed the Milky Way". University of Cambridge.
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