The Binary Fraction of Stars in the Dwarf Galaxy Ursa Minor via Dark Energy Spectroscopic Instrument
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| Format: | Preprint |
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2025
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| author | Qiu, Tian Wang, Wenting Koposov, Sergey Li, Ting S. Sandford, Nathan R. Najita, Joan Li, Songting Han, Jiaxin Dey, Arjun Rockosi, Constance Gaensicke, Boris Han, Jesse Weaver, Benjamin Alan Myers, Adam Aguilar, Jessica Nicole Ahlen, Steven Prieto, Carlos Allende Bianchi, Davide Brooks, David Claybaugh, Todd de la Macorra, Axel Doel, Peter Font-Ribera, Andreu Forero-Romero, Jaime Gaztanaga, Enrique Gontcho, Satya Gontcho A Gutierrez, Gaston Jimenez, Jorge Joyce, Dick Kisner, Theodore Lamman, Claire Landriau, Martin Guillou, Laurent Le Meisner, Aaron Miquel, Ramon Nadathur, Seshadri Percival, Will Poppett, Claire Prada, Francisco Perez-Rafols, Ignasi Rossi, Graziano Sanchez, Eusebio Schlegel, David Silber, Joseph Harry Sprayberry, David Tarle, Gregory Zhou, Rongpu Zou, Hu |
| author_facet | Qiu, Tian Wang, Wenting Koposov, Sergey Li, Ting S. Sandford, Nathan R. Najita, Joan Li, Songting Han, Jiaxin Dey, Arjun Rockosi, Constance Gaensicke, Boris Han, Jesse Weaver, Benjamin Alan Myers, Adam Aguilar, Jessica Nicole Ahlen, Steven Prieto, Carlos Allende Bianchi, Davide Brooks, David Claybaugh, Todd de la Macorra, Axel Doel, Peter Font-Ribera, Andreu Forero-Romero, Jaime Gaztanaga, Enrique Gontcho, Satya Gontcho A Gutierrez, Gaston Jimenez, Jorge Joyce, Dick Kisner, Theodore Lamman, Claire Landriau, Martin Guillou, Laurent Le Meisner, Aaron Miquel, Ramon Nadathur, Seshadri Percival, Will Poppett, Claire Prada, Francisco Perez-Rafols, Ignasi Rossi, Graziano Sanchez, Eusebio Schlegel, David Silber, Joseph Harry Sprayberry, David Tarle, Gregory Zhou, Rongpu Zou, Hu |
| contents | We utilize multi-epoch 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. Our dataset comprises 670 distinct member stars, with a total of more than 2,000 observations collected over approximately one year. We constrain the binary fraction for UMi to be $0.61^{+0.16}_{-0.20}$ and $0.69^{+0.19}_{-0.17}$, with the binary orbital parameter distributions based on solar neighborhood observation from Duquennoy & Mayor (1991) and Moe & Di Stefano (2017), 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 the Moe & Di Stefano model, the best-constrained binary fractions for metal-rich and metal-poor populations in UMi are $0.86^{+0.14}_{-0.24}$ and $0.48^{+0.26}_{-0.19}$, 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 $0.33^{+0.30}_{-0.20}$, compared with $1.00^{+0.00}_{-0.32}$ for the subsample in more outskirts. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_04477 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Binary Fraction of Stars in the Dwarf Galaxy Ursa Minor via Dark Energy Spectroscopic Instrument Qiu, Tian Wang, Wenting Koposov, Sergey Li, Ting S. Sandford, Nathan R. Najita, Joan Li, Songting Han, Jiaxin Dey, Arjun Rockosi, Constance Gaensicke, Boris Han, Jesse Weaver, Benjamin Alan Myers, Adam Aguilar, Jessica Nicole Ahlen, Steven Prieto, Carlos Allende Bianchi, Davide Brooks, David Claybaugh, Todd de la Macorra, Axel Doel, Peter Font-Ribera, Andreu Forero-Romero, Jaime Gaztanaga, Enrique Gontcho, Satya Gontcho A Gutierrez, Gaston Jimenez, Jorge Joyce, Dick Kisner, Theodore Lamman, Claire Landriau, Martin Guillou, Laurent Le Meisner, Aaron Miquel, Ramon Nadathur, Seshadri Percival, Will Poppett, Claire Prada, Francisco Perez-Rafols, Ignasi Rossi, Graziano Sanchez, Eusebio Schlegel, David Silber, Joseph Harry Sprayberry, David Tarle, Gregory Zhou, Rongpu Zou, Hu Solar and Stellar Astrophysics Astrophysics of Galaxies We utilize multi-epoch 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. Our dataset comprises 670 distinct member stars, with a total of more than 2,000 observations collected over approximately one year. We constrain the binary fraction for UMi to be $0.61^{+0.16}_{-0.20}$ and $0.69^{+0.19}_{-0.17}$, with the binary orbital parameter distributions based on solar neighborhood observation from Duquennoy & Mayor (1991) and Moe & Di Stefano (2017), 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 the Moe & Di Stefano model, the best-constrained binary fractions for metal-rich and metal-poor populations in UMi are $0.86^{+0.14}_{-0.24}$ and $0.48^{+0.26}_{-0.19}$, 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 $0.33^{+0.30}_{-0.20}$, compared with $1.00^{+0.00}_{-0.32}$ for the subsample in more outskirts. |
| title | The Binary Fraction of Stars in the Dwarf Galaxy Ursa Minor via Dark Energy Spectroscopic Instrument |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2512.04477 |