Collaborators led by ZJ Zhang at the University of Hawaii have discovered a bound pair of stars that serve as an exciting benchmark: one is a T4 (<1300 K) brown dwarf, the other is a very cool (5100 K) white dwarf. White dwarfs can serve as useful age indicators, and so we used this very cool white dwarf (which we suspect is roughly 7.3 billion years old) to constrain the age of the pair of stars. This old age puts unique constraints on interpreting the brown dwarf -- modeling the atmosphere of these failed stars is very complicated! A thread with more information from is located on Twitter: https://twitter.com/astrozjzhang/status/1229514446118121472
Group members and collaborators have laid claim to a new class of zombie stars that are shattered remnants of thermonuclear supernova that did not fully disrupt the white dwarf! Led by Roberto Raddi at Dr.Karl-Remeis-Sternwarte Bamberg, we have now published at least three likely members of this new class of star named after the prototype LP 40-365.
The research is well summarized by Shannon Hall writing in Scientific American: This “newly discovered class of odd stars appears to have persevered through supernova explosions — providing a rare glimpse into these astrophysical catastrophes.” Another summary is detailed in a Twitter thread: https://twitter.com/jotajotahermes/status/1096054102327525376?s=20.
Last year we published in Nature the most comprehensive evidence that white dwarf stars, at the end of their lives, solidify into crystals!
The research is best summarized in this quote from Deborah Netburn of The Los Angeles Times: “New research suggests that long after our roiling, boiling life-giving star runs out of fuel, it will slowly transform into a cold, dead, super-dense crystal sphere about the size of Earth that will linger like a translucent tombstone for close to eternity.”
The manuscript was led by Pier-Emmanuel Tremblay at the University of Warwick, and was made possible by the excellent data from the second data release of the Gaia mission. Another write-up of the results can be found here: https://twitter.com/jotajotahermes/status/1083068794455707648?s=20.