Astronomers Discover a Strange new Star That Might be From the Collision Between two Dead Stars

With how many stars there are in our galaxy, there are sure to be plenty of different types of them.  But they still continue to amaze us with their differences and constantly challenge our models on how exactly they form.  Now a new class of stars was discovered by Dr. Klaus Werner of the University of Tübingen, and they are covered in different materials than expected.

Those materials are carbon and oxygen – the byproduct of “helium-burning,” which happens when a star starts to use helium as fuel for its fusion reactions. Usually, this takes place in the star’s core rather than its outer shell, making these stars unique.  Even more strangely, the stars still seem to be burning helium themselves, which generally happens only in much older stars that have exhausted their hydrogen supply.  

The white dwarf ZTF J1901+1458 is about 2,670 miles across, while the moon is 2,174 miles across. The white dwarf is depicted above the Moon in this artistic representation; in reality, the white dwarf lies 130 light-years away in the constellation of Aquila.
Credit: Giuseppe Parisi

A team from the Institue for Astrophysics of La Plata, headed by Dr. Miller Bertolami, think they have an answer to why the stars have such unique properties – they formed from a rare stellar merger of two white dwarf stars.  White dwarves usually have the carbon and oxygen shells observed in these other, still active stars.  They have also been known to merge, though the results aren’t the same as what Dr. Werner and his team observed.

But in very particular instances, and at precise masses, a helium-rich white dwarf could merge with a carbon and oxygen-rich one, leading to the types of stars recently found.  Dr. Bertolami and his team developed a model that could explain it, but it remains to be tested against the data.  

White dwarfs, such as the ones that potentially merge to form this new kind of star, can have planets around them.
Credit – Anton Petrov YouTube channel

Still, any improvement in stellar merger modeling is a welcome one, and any data that offers insight into those improvements are also welcome.  Now astronomers have a whole class of new stars and theories about their formation to ponder.  There are sure to be plenty more types of stars out in our galaxy that will bring about similar questions about stellar formation. Astronomers will have to science those secrets out for a long time.

Learn More:
RAS – Astronomers discover a new type of star covered in helium burning ashes
KRDO – Astronomers discover new type of star, covered in helium-burning ash
UT – Who Discovered Helium?

Lead Image:
Artist’s impression of a white dwarf star merger
Credit – Nicole Reindl