Another day, another astronomical discovery that leaves us speechless. This seems to be the right pattern for how things are going for us humans. There’s no wonder why: whether we like to admit it or not, science still has a long road to travel before it can claim that it understands how the Universe works.
One of the recent discoveries is the neutron star binary GW190425. It stands out as the most massive such type of structure ever found in our Milky Way galaxy, as it has a combined mass of 3.4 times the mass of our sun.
Why is GW190425 so massive
Astronomers had been long wondering why the pair of neutron stars is so massive, but now a team of scientists from Australia’s ARC Center of Excellence for Gravitational Wave Discovery (OzGrav) believe they have the right answer.
PhD candidate Romero-Shaw says, “We propose that GW190425 formed through a process called ‘unstable case BB mass transfer,” a procedure that was originally defined in 1981. It starts with a neutron star that has a stellar partner: a helium (He) star with a carbon-oxygen (CO) core. If the helium part of the star expands far enough to engulf the neutron star, this helium cloud ends up pushing the binary closer together before it dissipates. The carbon-oxygen core of the star then explodes in a supernova and collapses to a neutron star.”
He further explains: “Binary neutron stars that form in this way can be significantly more massive than those observed through radio waves. They also merge very fast following the supernova explosion, making them unlikely to be captured in radio astronomy surveys. “Our study points out that the process of unstable case BB mass transfer could be how the massive star system formed,”
The gravitational waves from GW190425 reveal a neutron star binary that it’s more massive than any other neutron star binary previously observed. Gravitational waves are caused when two massive cosmic objects collide with each other causing literal shaking in the fabric of spacetime throughout the Universe.