The dead star is 1,300 light-years away.
X-ray data from the Chandra space telescope has shown that a white dwarf named KPD 0005+5106 is making extreme violence on its companion. The star is giving its companion an absolute drubbing by blasting it with radiation from close proximity, which is pretty normal for white dwarfs.
It's difficult to predict the fate of the companion, since we can't see what it is, and how long it will take to be completely destroyed.
"We didn't know this white dwarf had a companion before we saw the X-ray data," said astronomer You-Hua Chu. "We've looked for the companion with optical light telescopes but haven't seen anything, which means it is a very dim star, a brown dwarf, or a planet."
White dwarfs are stars under eight times the mass of the Sun that can be fused in their core. When the fuel runs low, the core will no longer be able to support itself and will collapse into a dense object about the size of Earth.
The white dwarf is so hot that it will continue to shine brightly for billions of years even without fuel. Once the core stops contracting, the average white dwarf will have a temperature of over 100,000Kelvin. The effective temperature of the Sun is 5,772 kelvin.
KPD 0005+5106 is an outlier. It's the hottest white dwarf we've found so far, with an effective temperature of 200,000 Kelvin. This makes it very interesting to scientists since they can look at the limits of what's possible in the Universe.
Chu and her team decided to take a closer look at the X-ray activity that KPD 0005+5106 exhibited. They found that the white dwarf increases and decreases in X-ray brightness on a regular basis.
We know that stripping material from a companion object can change the brightness of a white dwarf. The material will be taken to the white dwarf, where it will be deposited into the poles. The hot spot moves in and out of view when the star and its companion are in motion.
The system's orbital period would correspond with the 4.7-hour period, which would make them very close together. The white dwarf and its companion would be separated by just 1.3 times the Sun's radius. That's around 550,000 miles. That would be very hot.
"It's getting blasted with heat, whatever it is," said astronomer Jess Toala of the National Autonomous University of Mexico.
The researchers concluded that the companion was most likely an exoplanet with a mass around Jupiter. exoplanets can be found around white dwarfs if they're far enough away during the red giant phase. A gas giant has been found near a white dwarf.
The gas giant doesn't have much time to live, according to the team's models. The material stripped by the white dwarf would form a ring around the star and be slowly slurped onto it.
"This is a slow demise for this object that's basically being ripped apart by the constant forces of gravity," said an astronomer. It would be very unpleasant to be there.
Two other white dwarf stars have strange X-ray behavior. The behavior of the other two stars was similar to that of KPD 0005+5106, suggesting that they have unseen companion objects.
It is possible that exoplanet survival around a white dwarf is more common than we thought.
The team's research was published in a journal.
