A rare supernova is helping scientists unlock the mysteries of how these bright, exploding stars come to be.

Animation of a Type1a supernova. Credit: NASA/JPL-Caltech

Why it matters: Supernovas — the violent explosions of some dead stars at the end of their lives — are thought to be responsible for seeding our universe with many of the heavy elements we see around us today. If researchers can figure out exactly how these stellar explosions are created, it could help explain some of the inner-workings of our universe.

Background: On its surface, the supernova in question — named ASASSN-18tb — looked like other Type Ia supernovas, which are typically used to measure distances in our galaxy thanks to their predictable brightness.

  • These types of supernovas are thought to come from the explosions of white dwarf stars — the dead remnants of a sun-like star — in a binary system with another star.
  • Some astronomers think these types of explosions are triggered when a white dwarf eats up a large amount of the material from its companion in the binary, but another hypothesis suggests the explosion occurs when 2 white dwarfs slam into each other.

The big question: The chemistry of ASASSN-18tb is unlike others spotted before.

  • Most Ia supernovas have no hydrogen signature at all, but ASASSN-18tb appears to have ejected some hydrogen when it exploded, causing scientists to question exactly what made the star explode.
  • While some other Type Ia supernovas have been found enveloped in a large amount of hydrogen, ASASSN-18tb didn’t fit the usual model for those kinds of stellar explosions, since those supernovas usually occur in young galaxies that are still forming stars.
  • In contrast, ASASSN-18tb was found in a galaxy with older stars.

What they found: Scientists now think it’s possible the hydrogen ejected by ASASSN-18tb was actually from the white dwarf’s other star in the binary system.

  • “One exciting possibility is that we are seeing material being stripped from the exploding white dwarf’s companion star as the supernova collides with it,” Anthony Piro, one of the authors of the new supernova study in the journal Monthly Notices of the Royal Astronomical Society, said in a statement.
  • “If this is the case, it would be the first-ever observation of such an occurrence.”

Go deeper

Updated 22 mins ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 9:30 p.m. ET: 13,504,553 — Total deaths: 582,743 — Total recoveries — 7,522,796Map.
  2. U.S.: Total confirmed cases as of 9:30 p.m. ET: 3,495,537 — Total deaths: 137,357 — Total recoveries: 1,075,882 — Total tested: 42,521,027Map.
  3. States: Alabama's GOP governor issues statewide mask mandate — Oklahoma Gov. Kevin Stitt tests positive.
  4. Politics: Fauci says White House effort to discredit him is "bizarre" — Trump says trade adviser Peter Navarro shouldn't have written op-ed attacking Fauci.
  5. Schools: Houston and San Francisco public school districts to be online-only this fall
Updated 1 hour ago - Technology

Bitcoin scam hacks Twitter accounts of Obama, Biden, Bill Gates and others

Illustration: Rebecca Zisser/Axios

A number of prominent Twitter accounts, including those of Joe Biden, Barack Obama, Bill Gates and Elon Musk, appear to have been compromised Wednesday, posting messages tied to a cryptocurrency scam.

The latest: Twitter temporarily disabled all verified accounts from tweeting for several accounts. At about 8:45 pm ET, Twitter said in a statement: "Most accounts should be able to Tweet again. As we continue working on a fix, this functionality may come and go. We're working to get things back to normal as quickly as possible."

Trump announces new campaign manager

President Trump. Photo: Jim Watson/AFP/Getty Images

President Trump announced on Wednesday that Bill Stepien will take over as his new 2020 campaign manager.

Why it matters: The elevation of Stepien is a demotion for Brad Parscale, Trump's existing campaign manager. Parscale was hand-picked by Jared Kushner, the president's adviser and son-in-law. He had been in the role longer than any of Trump's previous campaign managers.