Discovery of two neighbouring satellites in the Carina constellation with MagLiteS

Journal Article · 23 January 2018 · Monthly Notices of the Royal Astronomical Society

DOI: https://doi.org/10.1093/mnras/sty170 · OSTI ID:1438044

Torrealba, G.  ^[1]; Belokurov, V. ^[2]; Koposov, S. E. ^[3]; Bechtol, K. ^[4]; Drlica-Wagner, A. ^[5]; Olsen, K. A. G. ^[6]; Vivas, A. K. ^[7]; Yanny, B. ^[5]; Jethwa, P. ^[8]; Walker, A. R. ^[7]; Li, T. S. ^[5]; Allam, S. ^[5]; Conn, B. C. ^[9]; Gallart, C. ^[10]; Gruendl, R. A. ^[11]; James, D. J. ^[12]; Johnson, M. D. ^[13]; Kuehn, K. ^[14]; Kuropatkin, N. ^[5]; Martin, N. F. ^[15] ; Martinez-Delgado, D. ^[16]; Nidever, D. L. ^[6]; Noel, N. E. D. ^[17]; Simon, J. D. ^[18]; Stringfellow, G. S.  ^[19]; Tucker, D. L. ^[5]

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1. Univ. of Cambridge, Cambridge (United Kingdom); Academia Sinica, Taipei (Taiwan)
2. Univ. of Cambridge, Cambridge (United Kingdom); Flatiron Institute, New York, NY (United States)
3. Univ. of Cambridge, Cambridge (United Kingdom); Carnegie Mellon Univ., Pittsburgh, PA (United States)
4. Large Synoptic Survey Telescope, Tucson, AZ (United States)
5. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
6. National Optical Astronomy Observatory, Tucson, AZ (United States)
7. Cerro Tololo Inter-American Observatory, La Serena (Chile)
8. Univ. of Cambridge, Cambridge (United Kingdom)
9. Mount Stromlo Observatory, Weston Creek, ACT (Australia)
10. Instituto de Astrofisica de Canarias, Tenerife (Spain); Univ. de La Laguna, Tenerife (Spain)
11. Univ. of Illinois, Urbana, IL (United States); National Center for Supercomputing Applications, Urbana, IL (United States)
12. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
13. National Center for Supercomputing Applications, Urbana, IL (United States)
14. Australian Astronomical Observatory, North Ryde, NSW (Australia)
15. Univ. de Strasbourg, Strasbourg (France); Max-Planck-Institut fur Astronomie, Heidelberg (Germany)
16. Univ. Heidelberg, Heidelberg (Germany)
17. Univ. of Surrey, Guildford (United Kingdom)
18. Observatories of the Carnegie Institution for Science, Pasadena, CA (United States)
19. Univ. of Colorado, Boulder, CO (United States)

Here, we report the discovery of two ultra-faint satellites in the vicinity of the Large Magellanic Cloud (LMC) in data from the Magellanic Satellites Survey (MagLiteS). Situated 18$$^{\circ}$$ ($$\sim 20$$ kpc) from the LMC and separated from each other by only $$18^\prime$$, Carina~II and III form an intriguing pair. By simultaneously modeling the spatial and the color-magnitude stellar distributions, we find that both Carina~II and Carina~III are likely dwarf galaxies, although this is less clear for Carina~III. There are in fact several obvious differences between the two satellites. While both are well described by an old and metal poor population, Carina~II is located at $$\sim 36$$ kpc from the Sun, with $$M_V\sim-4.5$$ and $$r_h\sim 90$$ pc, and it is further confirmed by the discovery of 3 RR Lyrae at the right distance. In contrast, Carina~III is much more elongated, measured to be fainter ($$M_V\sim-2.4$$), significantly more compact ($$r_h\sim30$$ pc), and closer to the Sun, at $$\sim 28$$ kpc, placing it only 8 kpc away from Car~II. Together with several other systems detected by the Dark Energy Camera, Carina~II and III form a strongly anisotropic cloud of satellites in the vicinity of the Magellanic Clouds.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1438044
• Report Number(s): arXiv:1801.07279; FERMILAB-PUB-18-156-AE-CD; 1671470; TRN: US1900397
• Journal Information: Monthly Notices of the Royal Astronomical Society, Vol. 475, Issue 4; ISSN 0035-8711
• Publisher: Royal Astronomical SocietyCopyright Statement
• Country of Publication: United States
• Language: English