Sagittarius Stream


In astronomy, the Sagittarius Stream is a long, complex structure made of stars that wrap around the Milky Way galaxy in an orbit that nearly crosses the galactic poles. It consists of tidally stripped stars from the Sagittarius Dwarf Elliptical Galaxy, resulting from the process of merging with the Milky Way over a period of billions of years.

This stellar stream was originally proposed in 1995 by Donald Lynden-Bell after analyzing the distribution of globular clusters in the Milky Way.[1] The actual structure was identified by Newberg and associates (2002)[2] plus Majewski and associates (2003)[3] using data from the 2MASS and SDSS surveys. In 2006, Belokurov and his collaborators[4] found that the Sagittarius Stream has two branches.

When the progenitor object was shredded apart during the interaction, it sent oscillations (analogous to sound waves) through the Milky Way spiral arm structure. The effects of the oscillations are observed today as layers of alternately denser and sparser star distributions, above and below the Solar System. Presently, the position of the Sagittarius Stream relative to the observed layers[5] make the Sagittarius Dwarf Elliptical Galaxy the strongest candidate for this intruding object.


  1. ^ Lynden-Bell, R. M.; Lynden-Bell, D. (July 1995). "Ghostly streams from the formation of the Galaxy's halo". Monthly Notices of the Royal Astronomical Society. 275 (2): 429–442. Bibcode:1995MNRAS.275..429L. doi:10.1093/mnras/275.2.429.
  2. ^ Newberg, Heidi Jo; et al. (April 2002). "The Ghost of Sagittarius and Lumps in the Halo of the Milky Way". The Astrophysical Journal. 569 (1): 245–274. arXiv:astro-ph/0111095. Bibcode:2002ApJ...569..245N. doi:10.1086/338983.
  3. ^ Majewski, Steven R.; et al. (December 2003). "A Two Micron All Sky Survey View of the Sagittarius Dwarf Galaxy. I. Morphology of the Sagittarius Core and Tidal Arms". The Astrophysical Journal. 599 (2): 1082–1115. arXiv:astro-ph/0304198. Bibcode:2003ApJ...599.1082M. doi:10.1086/379504.
  4. ^ Belokurov, V.; et al. (May 2006). "The Field of Streams: Sagittarius and Its Siblings". The Astrophysical Journal. 642 (2): L137–L140. arXiv:astro-ph/0605025. Bibcode:2006ApJ...642L.137B. doi:10.1086/504797.
  5. ^ Yanny, Brian; Gardner, Susan (Sep 2013). "The Stellar Number Density Distribution in the Local Solar Neighborhood is North-South Asymmetric". The Astrophysical Journal. 777 (2): 91. arXiv:1309.2300. Bibcode:2013ApJ...777...91Y. doi:10.1088/0004-637X/777/2/91. S2CID 118314811.

External linksEdit

  • Deriving The Shape Of The Galactic Stellar Disc (SkyNightly) March 17, 2006
  • Deriving the shape of the Galactic stellar disc, A&A press release, March 16, 2006