VLBA detections in the Oph-S1 binary system near periastron confirmation of its orbital elements and mass
ABSTRACT Oph-S1 is the most luminous and massive stellar member of the nearby Ophiuchus star-forming region. Previous Very Long Baseline Array (VLBA) observations have shown it to be an intermediate-mass binary system ($\sim 5\, {\rm M}_\odot$) with an orbital period of about 21 months, but a paucity of radio detections of the secondary near periastron could potentially have affected the determination of its orbital parameters. Here, we present nine new VLBA observations of Oph-S1 focused on its periastron passage in early 2024. We detect the primary in all observations and the secondary at five epochs, including three within about a month of periastron passage. The updated orbit, determined by combining our new data with 35 previous observations, agrees well with previous calculations and yields masses of $4.115 \pm 0.039 \, {\rm M}_\odot$ and $0.814\pm 0.006 \, {\rm M}_\odot$ for the two stars in the system.
Authors
- Gisela N. Ortiz-León (ORCID: https://orcid.org/0000-0002-2863-676X)
- Sergio A. Dzib (ORCID: https://orcid.org/0000-0001-6010-6200)
- Laurent Loinard (ORCID: https://orcid.org/0000-0002-5635-3345)
- Luis F. Rodrı́guez (ORCID: https://orcid.org/0000-0003-2737-5681)
- Josep M. Masqué (ORCID: https://orcid.org/0000-0002-1963-6848)
- Trent J. Dupuy (ORCID: https://orcid.org/0000-0001-9823-1445)
- Luis Henry Quiroga-Nuñez (ORCID: https://orcid.org/0000-0002-9390-955X)
- P. A. B. Galli (ORCID: https://orcid.org/0000-0003-2271-9297)
- Marina Kounkel (ORCID: https://orcid.org/0000-0002-5365-1267)
- Jazmín Ordóñez-Toro (ORCID: https://orcid.org/0000-0001-7776-498X)
Institutions
- Florida Institute of Technology (US)
- University of North Florida (US)
- Universidad de Guanajuato (MX)
- Woodwell Climate Research Center (US)
- Harvard University (US)
- Universidade de São Paulo (BR)
- National Institute of Astrophysics, Optics and Electronics (MX)
- Royal Observatory (GB)
- Instituto de Geofísica y Astronomía (CU)
- Max Planck Institute for Radio Astronomy (DE)
- Universidad Nacional Autónoma de México (MX)
- University of Edinburgh (GB)
Publication Details
- Journal
- Monthly Notices of the Royal Astronomical Society
- Published
- 2025-03-12
- DOI
- https://doi.org/10.1093/mnras/staf396
- Citations
- 1
- Primary Topic
- Astro and Planetary Science
- Type
- article
- Field-Weighted Citation Impact
- 1.15