Hypervelocity star found at the center of our Galaxy

(ORDO NEWS) — The blue-white dwarf S4716 revolves around the supermassive black hole Sgr A *, reaching speeds of up to eight thousand kilometers per second.

European astronomers have discovered a new star in a cluster surrounding the supermassive black hole at the center of the Milky Way. S4716 travels at and extremely close to great speed, making a complete revolution in just four years.

The center of our Galaxy is perhaps the most turbulent part of it. There is a supermassive hole , Sgr A* , about four million times the mass of the Sun, surrounded by smaller holes, clouds of gas, and stars that orbit it.

Dozens of stars are known in the Sgr A* (S-cluster) cluster, the most studied of which is S2, which is quite bright and located especially well for observations.

However, it also makes it difficult to observe some neighboring stars, allowing them to be seen only in those short moments when S2 itself passes at a relative distance from the black hole.

Hypervelocity star found at the center of our Galaxy 2
A snapshot of the center of the Galaxy: Sgr A* is marked with a cross, the orbits of some stars are shown in colors. The light green trajectory of S4716 is closest to the black hole

Florian Peissker and his colleagues from the University of Cologne took advantage of this. Working at the Keck Observatory and ESO, they spotted a new star, S4716, that orbits closer to the supermassive black hole than any other in the cluster.

Moving along it, S4716 either moves away from the hole at a distance of up to 702 astronomical units (the average distance from the Earth to the Sun), then approaches it at a distance of up to 98 astronomical units – only ten times further than from the Sun to Saturn.

A complete revolution in this highly elongated orbit takes only four of our years. S4716 develops tremendous speed, up to eight thousand kilometers per second.

This is comparable to the record holder among the known stars of the Milky Way – the hypervelocity star US 708, which is gaining speed up to 12 thousand kilometers per second.

At the same time, US 708 is located far on the periphery of the galaxy, while S4716 remains in a stable orbit around its very center.

The star itself belongs to the spectral class B: it is a blue-white dwarf with a mass and luminosity several times greater than that of the Sun.

“The short-period, compact orbit of S4716 is extremely unusual,” the authors of the paper note. “Stars are not easy to form in such close proximity to a black hole.

S4716 must have moved toward the center from the outside, for example, under the influence of other stars and S-cluster objects, which led to a strong decrease in its orbit.”


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