Two Ultra-faint Milky Way Stellar Systems Discovered in Early Data from the DECam Local Volume Exploration Survey
| Autor: | Erik Tollerud, L. C. Johnson, D. Hernandez-Lang, Steven R. Majewski, Guy S. Stringfellow, David J. Sand, M. McNanna, Keith Bechtol, J. D. Simon, C. E. Martínez-Vázquez, Yao-Yuan Mao, N. P. Kuropatkin, Alistair R. Walker, David James, Eric H. Neilsen, Prashin Jethwa, Marcelle Soares-Santos, Brian Yanny, Risa H. Wechsler, Andrew B. Pace, R. P. van der Marel, Y. Choi, Adriano Pieres, Sahar S. Allam, Allison K. Hughes, Pol Massana, Eric F. Bell, Denis Erkal, S. Mau, Jeffrey L. Carlin, F. Paz-Chinchón, Wayne A. Barkhouse, Knut Olsen, P. S. Ferguson, Burçin Mutlu-Pakdil, Monika Adamów, Tenglin Li, David L. Nidever, A. Zenteno, P. Balaji, Eric Morganson, K. Tavangar, Carme Gallart, Ethan O. Nadler, Kyler Kuehn, Noelia E. D. Noël, Alex Drlica-Wagner, Javier Sanchez, Denija Crnojević, L. Santana-Silva, A. H. Riley, W. Cerny, Antonella Palmese, Douglas L. Tucker, Nora Shipp, Antonela Monachesi, A. K. Vivas, J. Esteves, Robert A. Gruendl |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
education.field_of_study Proper motion 010504 meteorology & atmospheric sciences Metallicity Milky Way Population FOS: Physical sciences Astronomy and Astrophysics Astrophysics Horizontal branch Astrophysics - Astrophysics of Galaxies 01 natural sciences Stars Star cluster Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences education Large Magellanic Cloud 010303 astronomy & astrophysics 0105 earth and related environmental sciences |
| Zdroj: | The Astrophysical Journal. 890:136 |
| ISSN: | 1538-4357 1238-4054 |
| DOI: | 10.3847/1538-4357/ab6c67 |
| Popis: | We report the discovery of two ultra-faint stellar systems found in early data from the DECam Local Volume Exploration survey (DELVE). The first system, Centaurus I (DELVE J1238-4054), is identified as a resolved overdensity of old and metal-poor stars with a heliocentric distance of ${\rm D}_{\odot} = 116.3_{-0.6}^{+0.6}$ kpc, a half-light radius of $r_h = 2.3_{-0.3}^{+0.4}$ arcmin, an age of $\tau > 12.85$ Gyr, a metallicity of $Z = 0.0002_{-0.0002}^{+0.0001}$, and an absolute magnitude of $M_V = -5.55_{-0.11}^{+0.11}$ mag. This characterization is consistent with the population of ultra-faint satellites, and confirmation of this system would make Centaurus I one of the brightest recently discovered ultra-faint dwarf galaxies. Centaurus I is detected in Gaia DR2 with a clear and distinct proper motion signal, confirming that it is a real association of stars distinct from the Milky Way foreground; this is further supported by the clustering of blue horizontal branch stars near the centroid of the system. The second system, DELVE 1 (DELVE J1630-0058), is identified as a resolved overdensity of stars with a heliocentric distance of ${\rm D}_{\odot} = 19.0_{-0.6}^{+0.5} kpc$, a half-light radius of $r_h = 0.97_{-0.17}^{+0.24}$ arcmin, an age of $\tau = 12.5_{-0.7}^{+1.0}$ Gyr, a metallicity of $Z = 0.0005_{-0.0001}^{+0.0002}$, and an absolute magnitude of $M_V = -0.2_{-0.6}^{+0.8}$ mag, consistent with the known population of faint halo star clusters. Given the low number of probable member stars at magnitudes accessible with Gaia DR2, a proper motion signal for DELVE 1 is only marginally detected. We compare the spatial position and proper motion of both Centaurus I and DELVE 1 with simulations of the accreted satellite population of the Large Magellanic Cloud (LMC) and find that neither is likely to be associated with the LMC. Comment: 17 pages, 6 figures, 1 table; updated to match published version; updated to address erratum |
| Databáze: | OpenAIRE |
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