Most stars orbit the core of the galaxy at a relatively orderly speed, but some are moving away as if they are afraid that a cosmic police force is chasing them. The newly discovered member of this group, LP 40-365, has acquired many more unusual features that make it a festival for astronomical investigations. Fast-moving stars are thought to be close to the time a supernova occurred, but LP 40-365 shows evidence of a supernova remnant that only partially occurred.
The concept of LP 40-365 was accelerated by the supernova explosion proposed in 2017, and it has been so widely accepted that it has been used as a comparison to other candidates in the class. Now, in the astrophysical journal Letters, astronomers have questioned the question of its possible role in the explosion. “LP 40−365 […] is an exceptionally strange star: it is one of the most metallic stars, an atmosphere affected by oxygen and neon, which is also rich in heavier material than partial oxygen and silicon combustion, identifying hydrogen or helium,” the paper said.
The fact that it is a white dwarf – a stellar core where fusion has stopped – with a mass of 28 percent does not rate the Sun in its eccentricity. It is exiting the galaxy at 850 kilometers per second (1.9 million miles), but unlike other “hypervelocity stars,” it did not originate from the galactic center. The speed of the LP 40-365 is attributed to a type IX supernova explosion when a white dwarf pulls material from a companion star but is not thought to have exploded as a normal type IA.
This explanation was once theoretical, but the discovery of LP 40-365 and an apparent residual nebula has boosted the confidence of astronomers. The shockwave from the supernova sends two stars in opposite directions instead of swallowing the companion star completely. This raises the question of whether a fast-moving star has partially exploded or the “donor” from which the material was created to produce fire. The paper reports that the Hubble and TESS space telescopes reveal a 1 percent variation in the visible brightness of the LP 40-365 over a nine-hour cycle large enough in ultraviolet colors.
