Scientists were surprised to spot an aptly-named ‘vampire star’ draining life from another star while looking at data from NASA’s Kepler mission.
Though the planet-hunting mission came to an end in 2018, astronomers are still analysing the data, leading to new and unexpected discoveries.
The vampire star was found with the help of Ryan Ridden-Harper, a postdoctoral fellow at the Space Telescope Science Institute in Baltimore, Maryland, who developed a program called the ‘Kepler/K2: Background Survey’ during his PhD at the Australian National University.
Ridden-Harper’s system works by analysing every single pixel of archival Kepler data, looking for sudden jumps in brightness.
3,000 light years from us
The scientist and his colleagues were searching for ‘extremely rapid explosions outside of our galaxy that might only exist for a few hours’, though the events were theoretical, meaning Ridden-Harper didn’t know if there actually would be any to find.
The hunt was made possible with data from Kepler and NASA’s latest planet-hunter, TESS, and while searching the team came across an intense brightening in a star system about 3,000 light years from Earth, which was home to a white dwarf star and a brown dwarf star.
Brown dwarf stars are considered ‘failed stars’, whereas white dwarfs are created when a sun-like star reaches the end of its life and burns through all of its fuel. The star puffs up to form a red giant before blasting out about half of its mass, consuming nearby planets and asteroids in the process and leaving behind a blazing hot white dwarf.
The findings, published in the Monthly Notices of the Royal Astronomical Society on Friday, January 24, revealed the intense brightening unfolded across 30 days, during which time the white dwarf ‘stripped material’ from the brown dwarf, which was about one-tenth as massive as the ‘vampire’ it was up against.
“1,600 times brighter”
This rare event was a super-outburst from a dwarf nova, which can be thought of as a vampire star system.
The incredible data from Kepler reveals a 30-day period during which the dwarf nova rapidly became 1,600 times brighter before dimming quickly and gradually returning to its normal brightness.
The spike in brightness was caused by material stripped from the brown dwarf that’s being coiled around the white dwarf in a disk. That disk reached up to 11,700 degrees Celsius [21,092 degrees Fahrenheit] at the peak of the super-outburst.
NASA explained the phenomenon in somewhat simpler terms, saying:
The brown dwarf circles the white dwarf star every 83 minutes at a distance of only 250,000 miles (400,000 km) – about the distance from Earth to the Moon.
They are so close that the white dwarf’s strong gravity strips material from the brown dwarf, sucking its essence away like a vampire. The stripped material forms a disk as it spirals toward the white dwarf.
The observation could reveal new insights about the physics behind such bright super-outbursts as it provided ‘excellent data and new insights’ into these vampire star systems. Ridden-Harper’s system is also capable of finding gamma-ray bursts, neutron star collisions and other rare space phenomena.
Study co-author Brad Tucker commented on the ways in which the program is useful, saying:
We’ve used it to see stars as they explode, the secret lives of black holes and now things previously missed — this vampire star that had been lurking in the darkness of space.
Ridden-Harper admitted finding the dwarf nova was ‘unexpected’ as it ‘wasn’t what [they] were searching for’, but he said the team plans to continue searching for events that were captured by ‘pure chance’ while Kepler and TESS were gathering data, CNN report.
We don’t yet know what we will find, which I find incredibly exciting! We’re ready to complete analysis on the nine years of Kepler data and launch into the enormous quantity of incredible data from TESS.
This will give us the best understanding of the most rapid explosions in the Universe. Along the way, we might discover some rare events that no other telescope could find.
It will be interesting to see what else Ridden-Harper and his team uncover!