Astronomers have identified the fastest fleeing star ever observed within the Milky Way Galaxy. It is propelled at an unbelievable velocity by a massive explosion. The white dwarf star named J0927 races through space at 8,226,967 km/h. Dubbed the “supersonic star” due to its speed, it is expected to eventually escape the gravitational pull of the Milky Way. J0927 is accompanied by three other rapidly moving stars, believed to be the aftermath of a Type Ia supernova, one of the most powerful explosions in the universe. The research team, led by Kareem El-Badry at the Harvard-Smithsonian Center for Astrophysics, announced the discovery on the arXiv data repository, as reported by Live Science on June 15.
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Simulated Ejection of a White Dwarf from a Supernova Explosion. Image: Mark Garlick/Science Photo Library.
A Type Ia supernova occurs when two stars orbit each other in a circular pattern, one of which is a white dwarf. The process involves the white dwarf siphoning off hydrogen from the companion star, resulting in a nuclear fusion reaction that triggers an enormous thermonuclear explosion. However, a simple supernova explosion is not sufficient to propel a star at such high speeds. Astronomers suspect that the supersonic ejection of the star is due to a special form of Type Ia supernova known as a D6 supernova.
In a D6 supernova, two white dwarf stars orbit each other, with one star stripping away the remaining helium layer on the surface of its companion. This process releases a significant amount of energy on the surface of the white dwarf, “feeding” on its companion until it triggers another thermonuclear reaction, causing a powerful shockwave to propagate deep into the core, leading to a stellar explosion.
Although such powerful Type Ia supernova events are numerous, evidence of them and the ejected white dwarfs remains elusive. To search for candidates, El-Badry and colleagues examined the Gaia star catalog, a project aimed at creating the most detailed map of the Milky Way. From the Gaia data, the research team identified white dwarf stars. By examining their chemical composition more closely (primarily oxygen and carbon), they confirmed that the fleeing white dwarfs were the result of explosions that caused the loss of helium and hydrogen.
Measurements of the white dwarf stars revealed that J0927 is the fastest fleeing white dwarf ever observed within the Milky Way Galaxy, surpassing the previous record of 7,919,904 km/h held by the star D6-1. The research team estimates that D6 supernovae may account for half of all Type Ia supernovae. However, to be certain, they will need to find more runaway stars traversing through space.
(Source: Live Science)