Crater 2 Dwarf Explained
| Crater 2 |
| Epoch: | J2000.0 |
| Constellation Name: | Crater |
| Ra: |
|
| Dec: |
|
| H Radial V: | 88 km/s[1] |
| Gal V: | -74 km/s |
| Type: | dSph |
| Size V: | 62.4′ (rh=31.2′ ± 2.5′)
rh=1066pc ± 84pc |
| Notes: | 4th largest satellite
galaxy to Milky Way |
Crater 2 is a low-surface-brightness dwarf satellite galaxy of the Milky Way,[2] located approximately 380,000 ly from Earth. Its discovery in 2016 revealed significant gaps in astronomers' understanding of galaxies possessing relatively small half-light diameters and suggested the possibility of many undiscovered dwarf galaxies orbiting the Milky Way.[3] Crater 2 was identified in imaging data from the VST ATLAS survey.[3]
The galaxy has a half-light radius of ~, making it the fourth largest satellite of the Milky Way.[2] It has an angular size about double of that of the moon.[4] Despite the large size, Crater 2 has a surprisingly low surface brightness, implying that it is not very massive. In addition, its velocity dispersion is also low, suggesting it may have formed in a halo of low dark matter density.[5] Alternatively, it may be a result of tidal interactions with it and larger galaxies, such as the Milky Way and the Large Magellanic Cloud,[6] but according to some simulations, this would not explain the relatively large size.[5] This unusually low velocity dispersion was predicted using Modified Newtonian Dynamics, an alternative to the dark matter hypothesis.[7] This prediction was later confirmed by observations.[8]
See also
External links
Notes and References
- Olga G. . Kashibadze . Igor D. . Karachentsev . 2018 . Cosmic flow around local massive galaxies . Astronomy & Astrophysics . 609 . A11 . 10.1051/0004-6361/201731645 . 1709.09420. 2018A&A...609A..11K . 55486336 .
- G. . Torrealba . S. E. . Koposov . V. . Belokurov . M. . Irwin . 2016 . The feeble giant. Discovery of a large and diffuse Milky Way dwarf galaxy in the constellation of Crater . Monthly Notices of the Royal Astronomical Society . 459 . 3 . 2370–2378 . 10.1093/mnras/stw733 . free . 1601.07178. 2016MNRAS.459.2370T .
- Web site: Ken . Croswell . Ken Croswell . 14 April 2016 . Never-before-seen galaxy spotted orbiting the Milky Way . . 14 April 2016.
- News: Elusive Dwarf Galaxy Found Orbiting Our Milky Way . Huffington Post . 2016-04-19 . 2016-04-16 . Howard . Jacqueline .
- 10.1093/mnras/stac653. Galactic tides and the Crater II dwarf spheroidal: A challenge to LCDM? . 2022 . Borukhovetskaya . Alexandra . Navarro . Julio F. . Errani . Raphaël . Fattahi . Azadeh . Monthly Notices of the Royal Astronomical Society . 512 . 4 . 5247–5257 . free . 2022MNRAS.512.5247B. 2112.01540.
- 10.3847/1538-4357/ac1869. Kinematics of Antlia 2 and Crater 2 from the Southern Stellar Stream Spectroscopic Survey (S 5). 2021. Ji. Alexander P.. Koposov. Sergey E.. Li. Ting S.. Erkal. Denis. Pace. Andrew B.. Simon. Joshua D.. Belokurov. Vasily. Cullinane. Lara R.. Da Costa. Gary S.. Kuehn. Kyler. Lewis. Geraint F.. MacKey. Dougal. Shipp. Nora. Simpson. Jeffrey D.. Zucker. Daniel B.. Hansen. Terese T.. Bland-Hawthorn. Joss. S5 Collaboration. The Astrophysical Journal. 921. 1. 32. 2106.12656. 2021ApJ...921...32J. 235624056 . free .
- McGaugh . Stacy S. . 2016-11-14 . MOND Prediction for the Velocity Dispersion of the 'Feeble Giant' Crater II . The Astrophysical Journal . 832 . 1 . L8 . 10.3847/2041-8205/832/1/L8 . 2041-8213. 1610.06189 . 2016ApJ...832L...8M . 51764960 . free .
- Caldwell . Nelson . Walker . Matthew G. . Mateo . Mario . Olszewski . Edward W. . Koposov . Sergey . Belokurov . Vasily . Torrealba . Gabriel . Geringer-Sameth . Alex . Johnson . Christian I. . 2017-04-10 . Crater 2: An Extremely Cold Dark Matter Halo . The Astrophysical Journal . 839 . 1 . 20 . 10.3847/1538-4357/aa688e . 1612.06398 . 2017ApJ...839...20C . 1538-4357. 10150/623952 . 119422981 . free . free .
