Three-dimensional Orbit and Dynamical Masses of GJ 105 AC
Article
Dedrick, Cayla M., Wright, Jason T., Eastman, Jason D., Blake, Cullen H., Johnson, Samson A., Plavchan, Peter, Johnson, John Asher, Sliski, David H., Wilson, Maurice L., Wittenmyer, Robert A., Barclay, Thomas, Horner, Jonathan, Kane, Stephen R. and Wang, Sharon X.. 2025. "Three-dimensional Orbit and Dynamical Masses of GJ 105 AC." The Astrophysical Journal: an international review of astronomy and astronomical physics. 985 (2). https://doi.org/10.3847/1538-4357/adc564
| Article Title | Three-dimensional Orbit and Dynamical Masses of GJ 105 AC |
|---|---|
| ERA Journal ID | 1057 |
| Article Category | Article |
| Authors | Dedrick, Cayla M., Wright, Jason T., Eastman, Jason D., Blake, Cullen H., Johnson, Samson A., Plavchan, Peter, Johnson, John Asher, Sliski, David H., Wilson, Maurice L., Wittenmyer, Robert A., Barclay, Thomas, Horner, Jonathan, Kane, Stephen R. and Wang, Sharon X. |
| Journal Title | The Astrophysical Journal: an international review of astronomy and astronomical physics |
| Journal Citation | 985 (2) |
| Article Number | 255 |
| Number of Pages | 16 |
| Year | 2025 |
| Publisher | IOP Publishing |
| Place of Publication | United States |
| ISSN | 0004-637X |
| 1538-4357 | |
| Digital Object Identifier (DOI) | https://doi.org/10.3847/1538-4357/adc564 |
| Web Address (URL) | https://iopscience.iop.org/article/10.3847/1538-4357/adc564 |
| Abstract | The precision of stellar models is higher than the precision at which we are able to measure the masses of most stars, with the notable exception of binaries where we can determine dynamical masses of the component stars. In addition to well-measured stellar properties, the ideal benchmark star is far enough from its companion that its properties are indistinguishable from an otherwise identical single star. Currently, there are a handful of stars with precise (±3%), model-independent mass measurements that are "effectively single" and for which we can obtain clean spectra (i.e., spectra that are not blended with a close companion). In this paper, we introduce GJ 105 AC as the newest members of this exclusive population. We present an updated orbital analysis for the long-period K3+M7 binary GJ 105 AC. We jointly analyze radial velocity (RV) and relative astrometry data, including new RVs from the Miniature Exoplanet Radial Velocity Array that capture the full periapsis passage and the RV minimum of the 76.0 ± 1.3 yr orbit for the first time. We derive precise dynamical masses of M<SUB>1</SUB> = 0.78 ± 0.02 M<SUB>⊙</SUB> and M<SUB>2</SUB> = 0.098 ± 0.002 M<SUB>⊙</SUB>. We find that of all stars with similarly precise masses (∼2%), GJ 105 AC stands out as having the widest on-sky separation after α Centauri AB, making it one of the most easily accessible to spectroscopy, as well as the the second-widest true separation, ensuring that its members are truly "effectively single" in terms of their evolution. |
| Keywords | Astrometric binary stars; Companion stars; Spectroscopic binary stars; Multiple star evolution; Radial velocity; Astrometry; Stellar evolution |
| Contains Sensitive Content | Does not contain sensitive content |
| ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
| Byline Affiliations | Pennsylvania State University, United States |
| Center for Astrophysics Harvard and Smithsonian, United States | |
| University of Pennsylvania, United States | |
| NASA Jet Propulsion Laboratory, United States | |
| George Mason University, United States | |
| David R. Mittelman Observatory, United States | |
| National Center for Atmospheric Research, United States | |
| Centre for Astrophysics | |
| NASA Goddard Space Flight Center, United States | |
| University of California Riverside, United Sates | |
| Tsinghua University, China |
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