Produção Nacional
Revisado por pares
Two Ultra-faint Milky Way Stellar Systems Discovered in Early Data from the DECam Local Volume Exploration Survey
2020; IOP Publishing; Volume: 890; Issue: 2 Linguagem: Inglês
10.3847/1538-4357/ab6c67
ISSN1538-4357
AutoresS. Mau, W. Cerny, Andrew B. Pace, Yumi Choi, A. Drlica-Wagner, L. Santana-Silva, A. H. Riley, Denis Erkal, Guy S. Stringfellow, M. Adamów, Jeffrey L. Carlin, R. A. Gruendl, D. Hernández-Lang, N. Kuropatkin, Ting S. Li, C. E. Martínez-Vázquez, E. Morganson, Burçı̇n Mutlu-Pakdı̇l, Eric H. Neilsen, David L. Nidever, Knut Olsen, David J. Sand, Erik Tollerud, D. L. Tucker, B. Yanny, A. Zenteno, S. Allam, W. A. Barkhouse, K. Bechtol, Eric F. Bell, P. Balaji, Denija Crnojević, Johnny Esteves, P. S. Ferguson, Carme Gallart, Allison Hughes, D. J. James, Prashin Jethwa, L. Clifton Johnson, K. Kuehn, Steven R. Majewski, Yao-Yuan Mao, Pol Massana, M. McNanna, Antonela Monachesi, Ethan O. Nadler, N. E. D. Noël, A. Palmese, F. Paz-Chinchón, A. Pieres, Javier Sánchez, Nora Shipp, Joshua D. Simon, M. Soares-Santos, Kiyan Tavangar, Roeland P. van der Marel, A. K. Vivas, A. R. Walker, Risa H. Wechsler,
Tópico(s)Gamma-ray bursts and supernovae
ResumoWe 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.
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