In a recent study, a team of researchers led by Tian Qiu from the University of Arizona and including members from various institutions worldwide, utilized data from the Dark Energy Spectroscopic Instrument (DESI) to estimate the binary fraction of stars in the dwarf galaxy Ursa Minor. This research, published in the Astrophysical Journal, provides insights into the prevalence of binary star systems in different stellar populations and environments.
The researchers analyzed more than 2,000 observations of 670 distinct member stars in the Ursa Minor dwarf spheroidal galaxy, collected over approximately one year. By examining the line-of-sight velocity measurements, they estimated the binary fraction, which is the proportion of stars that have a companion star orbiting around them. The study found that the binary fraction in Ursa Minor is approximately 61% to 69%, depending on the model used for binary orbital parameter distributions.
The team further divided the data into subsamples based on metallicity, which is an indicator of the proportion of a star’s mass that is not hydrogen or helium. They found that the binary fraction for the metal-rich population ([Fe/H] > -2.14) is higher than that of the metal-poor population ([Fe/H] < -2.14). Specifically, the metal-rich population had a binary fraction of about 86%, while the metal-poor population had a binary fraction of about 48%, based on the Moe & Di Stefano model. Additionally, the researchers divided the data into subsamples according to the projected radius to the center of Ursa Minor. They discovered that the more centrally concentrated population in a denser environment has a lower binary fraction of about 33%, compared with a binary fraction of 100% for the subsample in the more outskirts of the galaxy. This offset in binary fraction could not be attributed to sample selection effects, suggesting that environmental factors may play a role in the prevalence of binary star systems. This research provides valuable insights into the distribution and prevalence of binary star systems in different stellar populations and environments. Understanding the binary fraction in various galaxies can help energy researchers and engineers better model and predict stellar evolution, which is crucial for developing advanced energy technologies that harness nuclear fusion, such as fusion reactors. By studying the behavior of binary star systems, scientists can gain a deeper understanding of the processes that drive stellar evolution and the potential for energy generation through nuclear fusion. The study, titled "The Binary Fraction of Stars in the Dwarf Galaxy Ursa Minor via Dark Energy Spectroscopic Instrument," was published in the Astrophysical Journal and can be accessed here. This article is based on research available at arXiv.