Laevens 1

Coordinates: 11h 36m 16.5s, −10° 52′ 37.1″

Laevens 1
Observation data (J2000 epoch)
Constellation Crater
Right ascension 11h 36m 16.2s[1]
Declination –10° 52′ 38.8″[1]
Distance 145 kiloparsecs (470 kly)[2]
Apparent dimensions (V) 0.46 arcmins[3]
Physical characteristics
Mass 1×104[2] M☉
Radius 50 parsecs (160 ly)[3]
VHB 14.2
Metallicity \begin{smallmatrix}\left[{Fe}/{H}\right]\end{smallmatrix} = –1.65[2] dex
Estimated age 7.5 Gyr[2]
Notable features Unusually young and distant Milky way cluster.
Other designations Crater cluster, PSO J174.0675-10.8774

Laevens 1 is a faint globular cluster or perhaps a dwarf galaxy in the constellation Crater that was discovered in 2014. It is also known as Crater, the Crater cluster and PSO J174.0675-10.8774.

At a distance of 145 kiloparsecs (470 kly) it is the most distant Milky Way globular cluster yet known, located in the galactic halo surrounding the Milky way galaxy.[1] With an age of only 7.5 Gyr, it is likely to have been incorporated into our galaxy long after when the Milky way was formed, probably during an interaction with the Small Magellanic Cloud[2][4][5]

An alternative analysis categorizes it as a satellite galaxy, because of the presence of a handful of blue loop stars and a sparsely populated red clump. The existence of certain types of stars in Laevens 1 implies that star formation occurred as recently as 400 Myr ago - something very atypical for a globular cluster that is mostly populated by old stars.[6]

Laevens 1 is orbiting the galaxy at approximately the same distance as the ultrafaint dwarf galaxies Leo IV and Leo V. This hints that all three satellites may once have been closely associated before falling together into the Milky Way halo.[6]

See also

References

  1. 1 2 3 Laevens, Benjamin P. M.; Martin, Nicolas F.; Sesar, Branimir; Bernard, Edouard J.; Rix, Hans-Walter; Slater, Colin T.; Bell, Eric F.; Ferguson, Annette M. N.; Schlafly, Edward F. (2014-05-01). "A New Distant Milky Way Globular Cluster in the Pan-STARRS1 3pi Survey". The Astrophysical Journal Letters 786: L3. arXiv:1510.08533. doi:10.1088/2041-8205/786/1/L3. ISSN 0004-637X.
  2. 1 2 3 4 5 Weisz, Daniel R.; Koposov, Sergey E.; Dolphin, Andrew E.; Belokurov, Vasily; Gieles, Mark; Mateo, Mario L.; Olszewski, Edward W.; Sills, Alison; Walker, Matthew G. (2015-10-28). "A Hubble Space Telescope Study of the Enigmatic Milky Way Halo Globular Cluster Crater". arXiv:1510.08533.
  3. 1 2 effective radius
  4. ↑ "Thieving Milky Way stole distant star cluster from neighbour". New Scientist. 2015-11-19. Retrieved 2016-01-26.
  5. ↑ Kirby, Evan N.; Simon, Joshua D.; Cohen, Judith G. (2015-01-01). "Spectroscopic Confirmation of the Dwarf Galaxies Hydra II and Pisces II and the Globular Cluster Laevens 1". The Astrophysical Journal 810 (1): 56. arXiv:1506.01021. doi:10.1088/0004-637X/810/1/56. ISSN 0004-637X.
  6. 1 2 Belokurov, V.; Irwin, M. J.; Koposov, S. E.; Evans, N. W.; Gonzalez-Solares, E.; Metcalfe, N.; Shanks, T. (2014-07-01). "ATLAS lifts the Cup: discovery of a new Milky Way satellite in Crater". Monthly Notices of the Royal Astronomical Society 441 (3): 2124–2133. arXiv:1403.3406. Bibcode:2014MNRAS.441.2124B. doi:10.1093/mnras/stu626. ISSN 0035-8711.

External links


This article is issued from Wikipedia - version of the Saturday, April 16, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.