Three-dimensional Orbit and Dynamical Masses of GJ 105 AC

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 f...

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Main Authors: Cayla M. Dedrick, Jason T. Wright, Jason D. Eastman, Cullen H. Blake, Samson A. Johnson, Peter Plavchan, John Asher Johnson, David H. Sliski, Maurice L. Wilson, Robert A. Wittenmyer, Thomas Barclay, Jonathan Horner, Stephen R. Kane, Sharon X. Wang
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adc564
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author Cayla M. Dedrick
Jason T. Wright
Jason D. Eastman
Cullen H. Blake
Samson A. Johnson
Peter Plavchan
John Asher Johnson
David H. Sliski
Maurice L. Wilson
Robert A. Wittenmyer
Thomas Barclay
Jonathan Horner
Stephen R. Kane
Sharon X. Wang
author_facet Cayla M. Dedrick
Jason T. Wright
Jason D. Eastman
Cullen H. Blake
Samson A. Johnson
Peter Plavchan
John Asher Johnson
David H. Sliski
Maurice L. Wilson
Robert A. Wittenmyer
Thomas Barclay
Jonathan Horner
Stephen R. Kane
Sharon X. Wang
author_sort Cayla M. Dedrick
collection DOAJ
description 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 _1 = 0.78 ± 0.02 M _⊙ and M _2 = 0.098 ± 0.002 M _⊙ . 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.
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spelling doaj-art-b078f8bce57543bba08b5ef5bc018a062025-08-20T03:12:43ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01985225510.3847/1538-4357/adc564Three-dimensional Orbit and Dynamical Masses of GJ 105 ACCayla M. Dedrick0https://orcid.org/0000-0001-9408-8848Jason T. Wright1https://orcid.org/0000-0001-6160-5888Jason D. Eastman2https://orcid.org/0000-0003-3773-5142Cullen H. Blake3https://orcid.org/0000-0002-6096-1749Samson A. Johnson4https://orcid.org/0000-0001-9397-4768Peter Plavchan5https://orcid.org/0000-0002-8864-1667John Asher Johnson6https://orcid.org/0000-0002-1159-1083David H. Sliski7https://orcid.org/0000-0002-6228-8244Maurice L. Wilson8https://orcid.org/0000-0003-1928-0578Robert A. Wittenmyer9https://orcid.org/0000-0001-9957-9304Thomas Barclay10https://orcid.org/0000-0001-7139-2724Jonathan Horner11https://orcid.org/0000-0002-1160-7970Stephen R. Kane12https://orcid.org/0000-0002-7084-0529Sharon X. Wang13https://orcid.org/0000-0002-6937-9034Department of Astronomy and Astrophysics, The Pennsylvania State University , 525 Davey Laboratory, 251 Pollock Road, University Park, PA 16802, USA ; ckd5370@psu.edu; Center for Exoplanets and Habitable Worlds, The Pennsylvania State University , University Park, PA 16802, USADepartment of Astronomy and Astrophysics, The Pennsylvania State University , 525 Davey Laboratory, 251 Pollock Road, University Park, PA 16802, USA ; ckd5370@psu.edu; Center for Exoplanets and Habitable Worlds, The Pennsylvania State University , University Park, PA 16802, USA; Penn State Extraterrestrial Intelligence Center, The Pennsylvania State University , University Park, PA 16802, USACenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USADepartment of Physics and Astronomy, University of Pennsylvania , 209 South 33rd Street, Philadelphia, PA 19104, USANASA JPL , 4800 Oak Grove Drive, Pasadena, CA 91109, USAGeorge Mason University , 4400 University Drive, Fairfax, VA 22030, USACenter for Astrophysics ∣ Harvard & Smithsonian , 60 Garden St., Cambridge, MA 02138, USADavid R. Mittelman Observatory , Mayhill, NM 88339, USAHigh Altitude Observatory, National Center for Atmospheric Research , 3080 Center Green Dr., Boulder, CO 80301, USACentre for Astrophysics, University of Southern Queensland , UniSQ Toowoomba, QLD 4350, AustraliaNASA Goddard Space Flight Center , 8800 Greenbelt Road, Greenbelt, MD 20771, USACentre for Astrophysics, University of Southern Queensland , UniSQ Toowoomba, QLD 4350, AustraliaDepartment of Earth and Planetary Sciences, University of California , Riverside, CA 92521, USADepartment of Astronomy, Tsinghua University , Beijing 100084, People’s Republic of ChinaThe 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 _1 = 0.78 ± 0.02 M _⊙ and M _2 = 0.098 ± 0.002 M _⊙ . 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.https://doi.org/10.3847/1538-4357/adc564Astrometric binary starsSpectroscopic binary starsCompanion starsRadial velocityAstrometryStellar evolution
spellingShingle Cayla M. Dedrick
Jason T. Wright
Jason D. Eastman
Cullen H. Blake
Samson A. Johnson
Peter Plavchan
John Asher Johnson
David H. Sliski
Maurice L. Wilson
Robert A. Wittenmyer
Thomas Barclay
Jonathan Horner
Stephen R. Kane
Sharon X. Wang
Three-dimensional Orbit and Dynamical Masses of GJ 105 AC
The Astrophysical Journal
Astrometric binary stars
Spectroscopic binary stars
Companion stars
Radial velocity
Astrometry
Stellar evolution
title Three-dimensional Orbit and Dynamical Masses of GJ 105 AC
title_full Three-dimensional Orbit and Dynamical Masses of GJ 105 AC
title_fullStr Three-dimensional Orbit and Dynamical Masses of GJ 105 AC
title_full_unstemmed Three-dimensional Orbit and Dynamical Masses of GJ 105 AC
title_short Three-dimensional Orbit and Dynamical Masses of GJ 105 AC
title_sort three dimensional orbit and dynamical masses of gj 105 ac
topic Astrometric binary stars
Spectroscopic binary stars
Companion stars
Radial velocity
Astrometry
Stellar evolution
url https://doi.org/10.3847/1538-4357/adc564
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