Approaching the identity of the mysterious celestial body “X7” at the center of the Milky Way | Sorae Portal site to the universe

The center of the Milky Way is a region of extremely high material density. There’sarch a* There is a massive black hole called (Aster), and many celestial bodies revolve around it at high speed.

Most of the celestial bodies orbiting Sagittarius A* are stars, but there are also several other small clusters of gas and dust with masses tens of times that of planets.Luminary (Object G)”. The origin of G objects is being investigated, but interstellar interaction is assumed to be the source. In the center of the galaxy, where the distances between celestial bodies are short, stars are thought to come very close and collide with each other. Since the gas blocks the light from within , It is believed that even if there is a star inside the G-body, it cannot be found.In addition, there is also a theory that there is no fixed star inside the G-body, and that it is a lump of gas caused by the collision between a red giant star and a compact star.

However, in the center of the Milky Way, an object was found that is neither a fixed star nor a G-type object. The object, dubbed “X7”, was first imaged in 2002.

At first glance, X7 looks like a G object. It has an estimated mass of about 50 times that of Earth, has an extended orbit like other G objects, and is thought to reach its closest approach to Sagittarius A* at 480 billion km in 2036. This distance is very close to Sagittarius. A*,X7 ends up absorbing in arc A*As it is expected to be, it is attracting attention as a possibility to observe in “real time” the state of matter being sucked into a black hole.

[▲ الشكل 2: التغييرات في شكل X7. كما ترى من خلال مقارنتها بالنجمة S0-14 ، فإن X7 لها شكل ممدود يتغير بسرعة بمرور الوقت (Credit: Anna Ciurlo / UCLA)]

However, about 20 years after its discovery, when continuous monitoring data were collected, it became clear that X7 had different properties than G objects. For example, object G is elongated in shape at its closest approach to arc A*, but it does not Still about the size of a point. On the other hand, the X7 can be identified as an elongated linear object long before the closest approach and displays approximately the same brightness all the time. For this reason, the X7’s identity has been a subject of debate.

A research team led by Anna Ciorlo of the University of California, Los Angeles, explored the identity of the mysterious celestial body X7. There are several clues to the identity of the X7. For example, X7’s orbital period is about 165 years, but it is estimated to have formed less than 200 years ago, as it was sucked into Sagittarius A* on its closest approach. Also, photos taken in 2020 indicated that the X7 may be fragmented.

In this study, it was possible to estimate that the following probabilities are low. First, the inferred X7’s orbit does not intersect the gas giant mass at the galactic center or the stars orbiting Sagittarius A*, making these origins less likely. Second, the possibility of a prestellar gas mass does not fit either with X7 observations or with physical models. In addition, the strange shape of X7 can be fully explained by the tidal force of Sagittarius A*, and the influence of strong radiation and magnetic fields from Sagittarius A* appears to be low. Matter, i.e. the possibility that the hypothesized mass of gas and dust in the celestial body G.

[▲ الشكل 3: مدارات X7 و G3. تم الكشف عن أن المدارات متشابهة جدًا ، واستنتج الباحثون أنه من المحتمل أن يكون لها أصل مشترك (مصدر الصورة: Anna Ciurlo / UCLA)]

And as conclusive evidence, the X7 says “G3It became clear that the orbit is similar to one of the named G objects. From this,The X7 and G3 are believed to have a common origin. However, on the other hand, the X7 and G3 have different characteristics, so the detailed characteristics are thought to be different.

After ruling out other possibilities, Ciurlo said:X7 and G3 originated from stellar collisionsI assumed it was. In this case, it is assumed that there are stars in G3 that cannot be seen because they are surrounded by gas. X7, on the other hand, is a lump of gas ejected during the collision, presumably with no orb inside. The difference in the contents of these gas masses is hypothesized to be the source of X7’s different properties from other G objects.

In this study, the identity and origin of the X7 can be inferred to some extent, but not conclusively. Ongoing observations including the closest approach in 2036 are essential to the investigation of X7’s identity. At that time, X7 Sagittarius A*’s tidal forces are expected to change more dramatically. The X7’s identity may be revealed through more observations in the future.

source

• Anna Ciorlo and others. “The Swansong of the Galactic Center Source X7: An extreme example of tidal evolution near a supermassive black hole”. (The Astrophysical Journal)
• Holly Ober. A mysterious object is being dragged into the supermassive black hole at the center of the Milky Way. (University of California, Los Angeles)

Text: Rare Aya