Scientists Discover the Fastest Stars Ever Seen in the Milky Way

Scientists have made an astonishing discovery in our own Milky Way galaxy. They have found a star that is racing through space at an incredible speed. This star, known as J0927, is a type of star called a white dwarf. It is moving at a mind-boggling rate of 5.112 million miles per hour (8,226,967 kilometers per hour).

Hypervelocity star

J0927 is what scientists call a “hypervelocity star.” This means that it is moving so fast that one day it will be able to escape completely from the gravitational pull of our galaxy, the Milky Way. It was observed alongside three other stars that are also moving at high speeds.

All of these stars are believed to be the remnants of a Type Ia supernova, which is one of the most powerful explosions in the entire universe.

The researchers who made this discovery shared their findings on June 6 through a platform called arXiv, which is used for sharing scientific papers before they undergo a process called peer review.

Peer review involves other experts in the field carefully examining the research to ensure its accuracy and reliability. However, it’s important to note that these findings have not yet gone through this peer review process.

Science behind supernovas

Type Ia supernovas occur when two stars, one of which is a collapsed white dwarf, come together in orbit. This gravitational dance causes the white dwarf to pull hydrogen from its companion star, triggering a chain reaction that leads to a massive thermonuclear explosion.

However, ordinary supernovas don’t possess the power to propel stars at such incredible speeds. Scientists speculate that hypervelocity stars are launched into motion by a unique type of Type Ia supernova known as a dynamically driven double-degenerate double-detonation (D6) supernova.

In D6 supernovas, two white dwarf stars revolve around each other, with one white dwarf gradually stripping away the remaining layers of helium from its partner’s surface. This process generates an immense amount of energy on the surface of the helium-snatching white dwarf.

The energy rekindles nuclear fusion within the white dwarf’s core, generating a powerful shockwave that ripples through its center, leading to a detonation.

Presence of white dwarfs

Although powerful supernovas and the resulting runaway white dwarfs are believed to exist in significant numbers, locating evidence of their existence has proven to be a challenge.

In order to identify potential candidates, the researchers utilized the Gaia star catalog, an ongoing initiative aimed at constructing the most comprehensive star map of our galaxy to date.

The Milky Way can be seen above Brighton's iconic West Pier on a warm evening as holidaymakers spend a night under the stars on the hottest night ever recorded in the UK, smashing the previous record measured in the city in 1990. (19/07/22)#Brighton #Milkyway #Stormhour #Sussex pic.twitter.com/jtvAUVnDQ8

— Andrew Gardner (@andrewgardnr) July 30, 2022

Through analysis of the Gaia data, the astronomers successfully identified the presence of white dwarfs. To validate their findings, further observations were conducted to assess the chemical composition of these white dwarfs.

These follow-up investigations revealed that the runaway white dwarfs primarily consisted of oxygen and carbon, indicating that their helium and hydrogen had been stripped away due to an explosive event.

Fastest runaway star in our galaxy

By carefully measuring the properties of the white dwarfs, scientists discovered that J0927, the white dwarf discussed earlier, has broken the record as the fastest runaway star ever observed in our galaxy.

It zooms through space at an astonishing speed, surpassing the previous record held by another white dwarf named D6-1, which traveled at 4,921,200 mph (7,919,904 km/h). Additionally, another white dwarf observed during this study claimed the title of the second-fastest star ever recorded within our galaxy.

Based on their findings, the researchers speculate that D6 supernovas could potentially make up half of all Type Ia supernovas. However, in order to obtain conclusive evidence, they will need to identify more runaway stars racing across the cosmos.