A binary system in the S cluster close to the supermassive black hole Sagittarius A.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39690145.
- Also identified by DOI 10.1038/s41467-024-54748-3 and PMC identifier 11652627.
- Licence recorded as CC BY.
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Abstract
High-velocity stars and peculiar G objects orbit the central supermassive black hole (SMBH) Sagittarius A* (Sgr A*). Together, the G objects and high-velocity stars constitute the S cluster. In contrast with theoretical predictions, no binary system near Sgr A* has been identified. Here, we report the detection of a spectroscopic binary system in the S cluster with the masses of the components of 2.80 ± 0.50 M<sub>⊙</sub> and 0.73 ± 0.14 M<sub>⊙</sub>, assuming an edge-on configuration. Based on periodic changes in the radial velocity, we find an orbital period of 372±3 days for the two components. The binary system is stable against the disruption by Sgr A* due to the semi-major axis of the secondary being 1.59±0.01 AU, which is well below its tidal disruption radius of approximately 42.4 AU. The system, known as D9, shows similarities to the G objects. We estimate an age for D9 of <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn> <mo>.</mo> <msubsup><mrow><mn>7</mn></mrow> <mrow><mo>-</mo> <mn>0.3</mn></mrow> <mrow><mo>+</mo> <mn>1.9</mn></mrow> </msubsup> <mspace></mspace> <mo>×</mo> <mspace></mspace> <mn>1</mn> <msup><mrow><mn>0</mn></mrow> <mrow><mn>6</mn></mrow> </msup> </math> yr that is comparable to the timescale of the SMBH-induced von Zeipel-Lidov-Kozai cycle period of about 10<sup>6</sup> yr, causing the system to merge in the near future. Consequently, the population of G objects may consist of pre-merger binaries and post-merger products. The detection of D9 implies that binary systems in the S cluster have the potential to reside in the vicinity of the supermassive black hole Sgr A* for approximately 10<sup>6</sup> years.