Astronomers detect “missing link” of black holes: neither too big nor too small

WASHINGTON, Apr 3 (Reuters) – Scientists detected a medium-sized black hole – considered the “missing link” in the understanding of these celestial giants – that was wiping out an unfortunate star that got too close.

Using data from the Hubble Space Telescope and two X-ray observatories, the researchers determined that this black hole is more than 50,000 times the mass of our Sun and is 740 million light years from Earth, in a dwarf galaxy with far fewer stars. than our Milky Way.

Black holes are extraordinarily dense objects that have such a powerful gravitational pull that not even light can escape them.

It is one of the few “intermediate mass” black holes ever identified, much smaller in size than the “supermassive” ones – located at the center of large galaxies – but considerably larger than the so-called “stellar” ones, formed by the collapse of large individual stars.

“We confirm that an object we originally discovered in 2010 is undoubtedly an intermediate-mass black hole that destroyed and engulfed a dying star,” said astrophysicist Natalie Webb of the University of Toulouse and co-author of the study published this week in Astrophysical Journal Letters. .

The star probably had about a third of the Sun’s mass, he added.

Webb said scientists have been searching for intermediate-mass black holes for four decades and that only 10 good examples are known, although there could be more.

“That’s why finding one is so significant. Also, a black hole swallowing a star is something that happens on average only once every 10,000 years or so in a particular galaxy, so these are unusual occurrences,” he added.

The supermassive black hole at the heart of the Milky Way is 4 million times the mass of the Sun and is 26,000 light years from Earth. The closest stellar black hole is about 6,000 light-years away, a measurement that indicates the distance light travels in one year (9.5 trillion kilometers).

Webb called intermediate black holes a “missing link” in understanding the range of these objects. Scientists know how stars – between three and 100 times the mass of the Sun – are formed, but not how this process occurs in the intermediates, although they suspect that the supermassive arise from their medium-sized siblings.

“Without finding these objects, it was impossible to validate this theory,” he said.

Intermediate-sized black holes have remained elusive.

“The best explanation is that they are mostly in an environment devoid of gas, which leaves black holes with no material to consume and therefore with little radiation to emit, which can greatly hinder their vision,” said Dacheng Lin. , an astronomer at the University of New Hampshire and director of the study.

(Edited in Spanish by Carlos Serrano)