1500 light years: Black hole "unicorn" to become the closest black hole to Earth?

Astronomers recently discovered the unicorn black hole, which is currently the closest black hole to Earth. It is a small black hole, 1,500 light-years from Earth, with a mass about three times that of the Sun.

The unicorn black hole has a "companion", a dying red giant, which has been seen by many astronomical observatories and is gravitationally distorted, resembling a water drop in overall shape. This strange phenomenon has led many astronomers to suspect the existence of other objects near this red giant, which has at least three solar masses and is likely to be a small black hole.

Finding hidden black holes through gravitational analysis.

The discovery of the unicorn black hole cannot be separated from the study of the red giant. Astronomers have been observing the strange red giant for a long time and have found that the red giant itself is subject to periodic gravitational forces, which in turn are distorted, suggesting that another object is moving around the red giant, which in turn generates the gravitational forces that allow the red giant to undergo binaries.

From stellar transit observations of the object, astronomers have determined that the object causing the anomalies in the red giant is a small black hole. Just as the moon's gravity distorts the Earth's oceans, the black hole's gravity distorts the red giant's surface, changing its shape.

If the object rotating around this particular red giant is a black hole, then this black hole would be the closest black hole to Earth known to man to date, and likely the smallest.

Since the unicorn black hole is only about three times the mass of the Sun, which is almost near the edge of the masses of neutron stars and black holes, this black hole may become a key clue for humans to find the difference between neutron stars and black holes.

Stars that are only about three times the mass of the Sun can evolve into neutron stars or black holes, and the discovery of a unicorn black hole will make this boundary clearer, and may even allow astronomers to discover a whole new way for black holes to be born.

The supermassive black hole at the center of the Milky Way has about 4.3 million times the mass of the Sun. Such supermassive black holes are generally not evolved from stars but are directly generated at the beginning of the universe, during a period of dense material energy, then theoretically, at the beginning of the universe, not only will supermassive black holes be directly generated, but there will also be small black holes directly born, these small black holes are called primordial black holes, but astronomers have not exactly found the existence of primordial black holes.

Is it a unicorn black hole, possibly a primordial black hole?

A unicorn black hole is only three times the mass of the Sun, and that is only an estimate. Three times the mass of the Sun is at the threshold for a star to evolve into a black hole, so a unicorn black hole may not be a star, but a primordial black hole.

In the early days of the Big Bang, the ultra-high density of matter collapsed into black holes, and supermassive black holes gradually gathered energy matter to form galaxies, while primordial black holes, due to their small size and mass, most of them gradually evaporated through Hawking radiation, so astronomers have not found the shadow of primordial black holes until today.

Another reason is that the size of a primordial black hole may only be the size of a grapefruit, with the current human astronomical observation equipment, it is almost a nightmare to discover a primordial black hole.

Although primordial black holes are difficult to observe directly, astronomers can infer the existence of objects in some regions by observing their orbital anomalies, and then possibly calculate the location of the black hole and its mass.

A closely related project is the search for "Planet Nine," in which astronomers have found orbital anomalies of many objects in the outer solar system that suggest the existence of an object 10 times the mass of Earth in the outer solar system, most likely Planet Nine. ".

Although astronomers have roughly determined the location of Planet Nine based on the orbital changes of several objects, after years of observation, Planet Nine is still an enigma. Since Planet Nine has not been observed with certainty, some astronomers have suggested that Planet Nine might be a primordial black hole.

If Planet Nine is indeed a primordial black hole, then the size of this black hole is only the size of a volleyball, and it is almost impossible to observe it directly. And astronomers struggling to find the original black hole, perhaps hidden in the human side, which is also very science fiction.

If "Planet Nine" really exists, then the planet's orbit will be very close to the outer reaches of the solar system, the rotation period is very long, so a short period can not observe the location of the planet is normal, if the "Planet Nine" is the original black hole, then If Planet Nine is indeed the primordial black hole, it may take a longer time for humans to discover this volleyball-sized black hole.

Since the primordial black hole did not go through a stellar phase, it is itself a collapse of matter from the early universe, which can help humans understand the origin of the universe and the thermal expansion of the early universe, and explore the mystery of the origin of the universe! Human curiosity will eventually conquer the secrets of the universe.