Either a massive neutron star or low-mass black hole found

Subject: S&T

Section: Space tech

In the news:

Researchers who used a telescope in South Africa reported the discovery of an object in the Milky Way that could either be the most massive — mass between 2.09 and 2.71 solar masses — neutron star ever observed, or the least massive black hole.
There is a substantial gap between the masses of the heaviest measured neutron star and the lightest measured black hole — the most massive neutron stars generally range between 2.2 to 2.5 solar masses, while black holes of less than 5 solar masses are rare.

Neutron star:

A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses (M☉), possibly more if the star was especially metal-rich.
Except for black holes,neutron stars are the smallest and densest known class of stellar objects.
Neutron stars have a radius on the order of 10 kilometres (6 mi) and a mass of about 1.4 M☉.
They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei.
Once formed, neutron stars no longer actively generate heat and cool over time; however, they may still evolve further through collision or accretion.

Black hole:

A black hole is a region of spacetime where gravity is so strong that nothing, including light and other electromagnetic waves, has enough energy to escape it.
The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.
The boundary of no escape is called the event horizon.
A black hole has a great effect on the fate and circumstances of an object crossing it, but it has no locally detectable features according to general relativity.
In many ways, a black hole acts like an ideal black body, as it reflects no light.
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.)

Source: TH