Reticulum II
Coordinates: 
02h 35m 42.14s, −54° 2′ 57.1″
| Reticulum II | |
|---|---|
| Observation data (J2000 epoch) | |
| Constellation | Reticulum |
| Right ascension | 02h 35m 42.14s[1] |
| Declination | -54° 2′ 57.1″[1] |
| Distance (comoving) | 30 ± 2 kpc (97.8 ± 6.5 kly) [1] |
| Distance | 97.8 ± 6.5 kly (30 ± 2 kpc) [1] |
| Apparent dimensions (V) | 3.37′ × 3.64′[1] |
| Apparent magnitude (V) | 17.4[1] |
| Other designations | |
| Reticulum II, Reticulum 2[1] | |
Reticulum II (or Reticulum 2) is an old dwarf galaxy in the Local Group. Reticulum II was discovered in 2015 by analysing images from the Dark Energy Survey. It is elongated, having an axis ratio of 0.6. The size is given by a half light distance of 30 pc. This is too large for it to be a globular cluster. Magnitude Mv is -2.7. The distance is 30 kpc. The galaxy contains some blue horizontal branch stars. Other features visible are a main sequence, and a main sequence turn off, and a red giant branch.[1][2] It has an unusual enhancement of r-process elements; meaning that gold and europium are extra common in the brightest stars in the galaxy.[3] The implication of the unusual enrichment in elements heavier than zinc, is that the r-process is very rare, and only happened once in this galaxy, possibly by the collision of two neutron stars.[4]
References
- 1 2 3 4 5 6 7 8 Sergey E. Koposov, Vasily Belokurov, Gabriel Torrealba, N. Wyn Evans (10 March 2015). "Beasts of the Southern Wild. Discovery of a large number of Ultra Faint satellites in the vicinity of the Magellanic Clouds". The Astrophysical Journal 805: 130. arXiv:1503.02079. Bibcode:2015ApJ...805..130K. doi:10.1088/0004-637X/805/2/130.
- ↑ DES Collaboration (10 March 2015). "Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data". The Astrophysical Journal 807: 50. arXiv:1503.02584. Bibcode:2015ApJ...807...50B. doi:10.1088/0004-637X/807/1/50.
- ↑ Ji, Alex (22 March 2016). "The Orogin of the Cosmos' Heaviest Elements". Phys.org. Retrieved 24 March 2016.
- ↑ Ji, Alexander P.; Frebel, Anna; Chiti, Anirudh; Simon, Joshua D. (21 March 2016). "R-process enrichment from a single event in an ancient dwarf galaxy". Nature. arXiv:1512.01558. Bibcode:2016Natur.531..610J. doi:10.1038/nature17425.