We frequently talk about merging objects here, whether they be galaxies or black holes, or in the case of our next story, white dwarf stars. In a new paper published in Astronomy & Astrophysics, researchers detail their study of nebula IRAS 00500+6713, whose central star was found by a previous team to have a stellar wind with unusually high speeds.
This most recent work shows that the central star, J005311, formed due to the collision of two white dwarfs. Generally, this type of collision causes a supernova and the destruction of both stars. Sometimes, one or both stars might manage to survive such a cataclysmic event. Even rarer, the two stars can merge, and that is what happened in this instance.
Of course, a rare occurrence wouldn’t be enough to merit our attention. In this event, the resulting star emitted unusual X-rays and appeared brighter than expected. These attributes, along with that incredibly strong wind, show that J005311 is actually too massive to be considered a white dwarf now. Additionally, it contains unusual amounts of the elements silicon, sulfur, and neon, making it an unknown type of star. And it’s also incredibly unstable and unlikely to exist for more than 10,000 years.
As for the nebula itself, per the paper: [T]he mass of IRAS 00500+6713 will likely remain above the Chandrasekhar limit. Its fate will therefore be to undergo core-collapse and to form a neutron star. Over the course of this event, IRAS 00500+6713 will manage to produce its second [supernova], possibly in the form of a fast blue optical transient.
This story is another of those “we’ve now seen one of these and need to see more” type stories. We’ll keep an eye out for further developments and studies.
“X-rays observations of a super-Chandrasekhar object reveal an ONe and a CO white dwarf merger product embedded in a putative SN Iax remnant,” Lidia M. Oskinova et al., 2020 December 14