A “zombie star” is an informal name for a white dwarf that may survive a partial thermonuclear explosion. The best-known candidate, the white dwarf associated with Type Iax supernova SN 2012Z, was observed before and after the blast—but the evidence does not show that it exploded a second time.
What astronomers mean by “zombie star”
The term describes a possible surviving remnant of a Type Iax supernova, a comparatively faint and diverse class of thermonuclear explosions involving white dwarfs. It is not a formal star type, and “zombie” does not mean that a star has been confirmed to return to life.
In a leading model, a white dwarf in a binary system draws material from a companion. Thermonuclear burning ignites, but the explosion fails to unbind the entire white dwarf: some material is ejected and a gravitationally bound remnant may remain. That possible survival is what gives rise to the nickname.
How Type Iax compares with an ordinary Type Ia
| Feature | Ordinary Type Ia | Type Iax |
|---|---|---|
| What happens to the white dwarf | In the usual picture, it is completely disrupted. | Some explosions may leave a bound remnant; outcomes can vary. |
| Brightness and strength | Typically brighter than Type Iax events. | Fainter on average, but the class ranges from weak to relatively powerful events. |
| Evidence relevant to a remnant | The comparisons here do not establish a surviving remnant. | SN 2012Z offers observations consistent with a remnant, but they do not uniquely prove one. |
Not every Type Iax event is known to leave a surviving white dwarf. NASA quoted Ryan Foley, lead author of the SN 2008ha paper, describing the class’s range: “SN 2012Z is one of the more powerful Type Iax supernovae and SN 2008ha is one of the weakest of the class, showing that Type Iax systems are very diverse.”
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →#1 Best Overall
What the observations of SN 2012Z show
Before the explosion: a blue source in Hubble images
SN 2012Z occurred in NGC 1309, about 110 million light-years away, according to NASA’s 2014 account. Researchers found a luminous blue source at the supernova’s position in archived Hubble images taken before the explosion. The study interpreted the source as consistent with an accreting white dwarf and a helium-star companion. The image shows a source, not the white dwarf itself, so the proposed system is an interpretation.
After the explosion: the source remained brighter
A 2022 study of late-time Hubble observations, including measurements roughly 1,400 days after the explosion, found that the source remained brighter than the pre-explosion detection. The authors found that radioactive heating of a bound remnant could explain the excess, but also considered light from the ejecta, a shock-heated companion, and possible interaction with surrounding material. The brightness therefore supports the remnant explanation without identifying it as the only cause.
Does a zombie star explode more than once?
Not on the evidence described here. The observations make it plausible that a white dwarf can survive a partial Type Iax explosion, but they do not document a confirmed second explosion by the same remnant. “May survive” or “candidate zombie star” is more accurate than saying the star has definitively exploded twice.
The distinction matters because the measured evidence and the proposed explanation are not the same thing: astronomers observed the pre-explosion blue source and later excess brightness; identifying those observations as a progenitor system and a surviving white dwarf remains an interpretation.
How common are Type Iax supernovae?
A 2014 Nature paper estimated that Type Iax supernovae occur at a rate between 5 and 30 percent of the normal Type Ia rate. NASA reported in 2014 that more than 30 Type Iax events that may leave a surviving white dwarf had been identified; that is a historical count, not a current total.
NASA also quoted Rutgers scientist Saurabh Jha on why these events matter: “The similarities between Type Iax’s and normal Type Ia’s make understanding Type Iax progenitors important, especially because no Type Ia progenitor has been conclusively identified.”
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
