Astronomers using the Green Bank Telescope have observed the largest neutron star ever recorded. It is almost too massive to be in existence.
Neutron stars are super-dense stellar remnants that have reached the end of their evolutionary life. These objects pack a huge amount of material into a small space.
The object, called J0740+6620, is a rapidly rotating millisecond pulsar. It packs 2.14 solar masses into a sphere only 15 miles (24 km) across.
That’s almost the limit of how massive an object can get without crushing itself down into a black hole.
Neutron stars are very mysterious because we don’t know what they’re made of. Thus, we don’t even know how massive can these stars can get.
Some rotate hundreds of times each second, thus, emitting beams of radio waves from their magnetic poles.
Since neutron stars spin at an extremely fast rate, astronomers use them as the cosmic equivalent of atomic clocks.
This helps researchers study the nature of spacetime, measure the masses of stellar objects, and improve their understanding of general relativity.
J0740+6620, which lies some 4,600 light-years away from Earth, has a white dwarf companion.
In the case of this binary system, which is nearly edge-on to Earth, this cosmic precision helped astronomers to calculate the mass of the two stars.
As the ticking pulsar passes behind its white dwarf companion, there is a subtle delay in the arrival time of the signals. Scientists call this phenomenon the Shapiro Delay.
The gravity from the companion white dwarf star warps the surrounding space and makes radar signals of the neutron star travel further.
Astronomers can use the amount of that delay to calculate the mass of the white dwarf and once the mass of a companion object is known, it is a relatively straightforward process to accurately determine the mass of the other.
The researchers published their study in the journal Nature Astronomy.