When large stars die, they do not do so quietly.
Their death is an event that lights up the entire universe. A supernova explosion ejects the star’s core into space in an extremely bright cloud of gas and dust. At the same time, the core of the star gasps as it collapses into a super dense neutron star or black hole.
If such an explosion occurs, it could send the collapsed core racing through the Milky Way at an incredibly frenetic speed, ultimately escaping our galaxy and plunging into intergalactic space. This spectacular event recently occurred and was discovered by scientists at the Chandra X-ray Observatory. A pulsar, or pulsating neutron star, tore itself apart at a speed of approximately 612 km/s.
Image of a pulsar escaping from the G292.0 + 1.8 supernova remnant.
This pulsar is one of the fastest objects ever discovered. Topping the speed chart is not a product of a supernova explosion but a star orbiting Sgr A* – the supermassive black hole at the center of our galaxy. At its fastest point in orbit, it can reach speeds of 24,000 km/s.
Astronomer Xi Long from the Harvard & Smithsonian Center for Astrophysics (CfA) stated: “We directly observed the pulsar’s movement in X-rays, all thanks to the keen vision of Chandra.”
The team discovered the pulsar while monitoring the remnants of a bright supernova located 20,000 light-years away from Earth, named G292.0 + 1.8. Xi Long also conceived the idea of studying this new object to better understand the history of the supernova by tracing its movement from the center of G292.0 + 1.8.
Astronomer Daniel Patnaude from CfA remarked: “We have only a few supernova explosions with clear records, so my team wanted to investigate whether G292.0 + 1.8 could be added to that list.”
They examined multiple images of the supernova remnants from 2006 and 2016 while utilizing Gaia data regarding its current position in the Milky Way to compare the positional differences of the pulsar. After conducting their research, they uncovered an interesting fact: the dead star appears to be moving 30% faster than previously estimated.
This implies that the process of moving away from the center of the supernova remnant took less time, suggesting that the timing of the supernova explosion occurred closer than initially inferred. Previous estimates dated the supernova to around 3,000 years ago, which has now been revised to approximately 2,000 years ago.
The changing speed of the pulsar also allowed the research team to investigate how it was ejected from the center of the supernova. They proposed two scenarios, both involving a similar mechanism.
The first scenario involves the star’s core being expelled from an asymmetric supernova explosion. In the second scenario, the debris from the explosion is ejected asymmetrically. However, since the energy required for the core is extremely high, the second scenario seems the most plausible.
Essentially, an asymmetric explosion could ‘kick’ the collapsed core of a dying star out into space at extremely high speeds. In this case, the star is currently moving at a speed higher than the escape velocity from the center of the Milky Way (approximately 550 km/s), although it still requires considerable time to achieve this, not to mention that its speed may decrease over time.
In reality, the actual speed of the pulsar may exceed the estimated 612 km/s, as it is moving very slightly from our perspective.
Astronomer Paul Plucinsky from CfA stated: “This pulsar has energy roughly 200 million times that of the Earth’s motion around the Sun. Clearly, it received an extremely strong kick from the asymmetric supernova explosion.”
The new study has been officially published in the Astrophysical Journal.
