Tian Qiu, Wenting Wang, Sergey E. Koposov, Ting S. Li, Nathan R. Sandford, Joan Najita, Songting Li, Jiaxin Han, A. Dey, C. Rockosi, Boris Gaensicke, Jesse Han, Benjamin Alan Weaver, A. D. Myers, J. Aguilar, Steven Ahlen, C. Allende Prieto, Davide Bianchi, David Brooks, Todd Claybaugh, A. de la Macorra, Peter Doel, Andreu Font-Ribera, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Jorge Jimenez, Dick Joyce, Theodore Kisner, Claire Lamman, Martin Landriau, Laurent Le Guillou, Aaron Meisner, Ramon Miquel, Seshadri Nadathur, Will Percival, Claire Poppett, Francisco Prada, Ignasi Pérez-Ràfols, Graziano Rossi, Eusebio Sanchez, David Schlegel, Joseph Harry Silber, D. Sprayberry, Gregory Tarlé, Rongpu Zhou, Hu Zou Hu Zou
Abstract We utilize multiepoch line-of-sight velocity measurements from the Milky Way Survey of the Dark Energy Spectroscopic Instrument to estimate the binary fraction for member stars in the dwarf spheroidal galaxy Ursa Minor (UMi). Our dataset comprises 670 distinct member stars, with a total of more than 2000 observations collected over approximately one year. We constrain the binary fraction for UMi to be 0.6 1 − 0.20 + 0.16 and 0.6 9 − 0.17 + 0.19 , with the binary orbital parameter distributions based on solar neighborhood observation from A. Duquennoy & M. Mayor and M. Moe & R. Di Stefano, respectively. Furthermore, by dividing our data into two subsamples at the median metallicity, we identify that the binary fraction for the metal-rich ([Fe/H] > −2.14) population is slightly higher than that of the metal-poor ([Fe/H] < −2.14) population. Based on M. Moe & R. Di Stefano’s model, the best-constrained binary fractions for metal-rich and metal-poor populations in UMi are 0.8 6 − 0.24 + 0.14 and 0.4 8 − 0.19 + 0.26 , respectively. After a thorough examination, we find that this offset cannot be attributed to sample selection effects. We also divide our data into two subsamples according to their projected radius to the center of UMi, and find that the more centrally concentrated population in a denser environment has a lower binary fraction of 0.3 3 − 0.20 + 0.30 , compared with 1.0 0 − 0.32 + 0.00 for the subsample in the outskirts.