science
Model with One Intermediate-Mass Object Proposed to Explain Three Star Populations at Sagittarius A*
@NewScientist reported that a new model accounts for three distinct stellar populations orbiting Sagittarius A* through gravitational interactions with a single tilted intermediate-mass object. All populations are said to have formed in one original disc. Researchers identify IRS-13E as a possible candidate requiring further observations.
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A model incorporating one intermediate-mass object accounts for the three distinct populations of stars orbiting Sagittarius A*, @NewScientist reported. Xiaochen Zheng at the Beijing Planetarium and colleagues constructed the model, which assumes the object has a mass several hundred to one thousand times that of the Sun and orbits on a steep tilt relative to an original stellar disc.
The model states that all three populations originated in the same disc of gas and dust.
Gravitational interactions with the intermediate-mass object stretch and tilt the orbits of the outermost stars, producing some retrograde orbits among the off-disc stars. A resonance between the object and Sagittarius A* stretches the orbits of the clockwise disc stars without major perturbation. Interactions among the S-stars themselves create the zone of avoidance by disrupting binary systems.
"Through three distinct gravitational dances, this cosmic companion pulled the family apart," Zheng said. She added that the approach avoids the need to postulate multiple independent formation events with no obvious reason to coincide in space and time.
Albert Zijlstra at the University of Manchester noted that finding intermediate-mass black holes in this mass range remains difficult and that all candidates identified so far have been ruled out due to lack of evidence.
The researchers identify IRS-13E, a cluster of stars near the galactic center, as a candidate for the intermediate-mass black hole. Further precise measurements over an extended period will be required to confirm whether IRS-13E can explain the observed stellar distributions.
