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A press release from the Carnegie Institute today described a recent paper by astronomers that might have identified a star in the Milky Way that might go supernova sometime in the future. The star QU Carinae, is a cataclysmic variable, a binary system in which material dumped from one star onto another periodically causes an outburst of X-rays.
I emailed Stella Kafka, the lead scientist of the research paper, to find out how far away QU Carinae is and how soon it might go supernova. She responded as follows:
The distance to QU Carinae has been determined in the past through ultraviolet observations that have revealed a rich suite of interstellar lines. Those interstellar lines come from gas in between our solar system and the object, indicating that QU Carinae is not in our sun’s neighborhood. Actually, the preferred distance to QU Carinae is ~2 kiloparsecs away from us [6,500 light years], close to the Carina arm of our galaxy. So, we would certainly see it if it goes supernova, but it wouldn’t necessarily affect us. It would certainly stir and enrich our galaxy’s interstellar medium though, with high-metal elements, which will in turn supply new stars with metals. Supernovae are part of nature’s recycling bin!
Objects like QU Carinae theory predicts that will become [a type Ia supernova] after a couple of million of years, which is quite fast. As an observer, though, I need more information on the object itself in order to make a prediction: I need to find out how fast the mass of the white dwarf is growing, how stable mass is transferred onto the white dwarf, and whether there are processes that lead to mass loss from the white dwarf (perhaps nova explosions??) that could compromise its mass gain towards it reaching the Chandrasekhar mass limit. Those are questions my team and I are planning to address in the future, along with identifying more objects with similar characteristics, and establishing the properties of stars that will become [type Ia supernovae].
In other words, this potential star would likely put on a good show for us if it went supernova, but poses only slight risk. Also, it could be a long time on a human time scale before anything happens.
There are caveats however. First, the distance is not known with total precision. QU Carinae could be closer. Second, the scientists don’t yet know enough to predict how far along in this process QU Carinae is. It is likely not to go supernovae in the near future, but it might also do so tomorrow.
Finally, on a less worrisome note, QU Carinae might never go supernova, as it is only a theory that this kind of star results in a supernova. At the moment astronomers still do not know with certainty what causes these types of supernovae explosions.