Astronomers are currently studying the star known as LP 40−365. It’s a breed of fast-moving star that is a remnant of a massive white dwarf that survived a massive supernova explosion. The star is currently about 2000 light-years away from Earth and is hurtling towards the edge of the Milky Way galaxy.
Astronomers say the star is moving so fast that it’s nearly certain it will leave the galaxy. Estimates peg the speed of LP 40−365 at nearly 2 million miles per hour. The star is a remnant from a supernova that is still being propelled forward by the force of the explosion. Researchers note that for the object to have gone through a partial supernova explosion and have survived is unique.
Only over the last few years have astronomers begin to think stars of this type could exist. LP 40−365 is described as “star shrapnel,” and objects such as it could give insight to other stars that have survived similar catastrophes in the past. Researchers analyzed the star using data from the Hubble Space Telescope and the Transitioning Exoplanet Survey Satellite. Using various kinds of data from both telescopes, the researchers and collaborators on the project found that not only is LP 40−365 on its way out of our galaxy, and it’s also rotating on its way out.
Researchers investigated to determine why the star was getting brighter and fainter as it exited the galaxy. The simplest explanation is that the star rotates in and out of view every nine hours suggesting its rotation rate. A rotation rate of every nine hours is considered relatively slow for a star fragment that survived a supernova explosion.
White dwarfs go supernova when they get too massive to support themselves, resulting in a massive detonation. The team says discovering the rotation rate of a star like LP 40−365 after a supernova shines light into the original two-star system it came from. Based on the relatively slow rotation, researchers are confident LP 40−365 is shrapnel from the star that self-destructed after gaining too much mass from its binary partner.