Rare star system discovered in Magellanic Bridge
What's the story
An international team of astronomers, led by researchers from the Inter-University Centre for Astronomy and Astrophysics (IUCAA), has discovered a rare star system in the Magellanic Bridge. This is a massive stream of stars and gas connecting two dwarf galaxies, the Large and Small Magellanic Clouds. The discovery was made using data from Germany's eROSITA X-ray telescope.
Stellar evolution
What is a symbiotic accreting system?
The newly discovered star system, dubbed eRASSU J043115.8-711730 (J0431-71), is the first confirmed symbiotic accreting system in the Magellanic Bridge.
It comprises a white dwarf, a dense remnant core of a dead star, that pulls gas from a nearby red giant star.
The team, led by Tathagata Saha and Professor Chandreyee Maitra, made this discovery as part of the second public data release (DR2) from the German eROSITA Consortium.
Stellar interaction
How the unique system was identified
The red giant in the system expands and contracts in a cycle of some 500 days.
When it expands, some of its gas is pulled toward the white dwarf, resulting in X-ray emissions detected by eROSITA.
To confirm the location and nature of this unique system, scientists employed data from the Gaia space mission, optical observations from the Southern African Large Telescope (SALT), and long-term observations from the Optical Gravitational Lensing Experiment (OGLE).
Galactic evolution
Why this discovery is important
The Magellanic Bridge was formed by the gravitational interaction between the Large and Small Magellanic Clouds.
It is home to both young stars born within the bridge and older stars stripped from the Small Magellanic Cloud.
While optical and infrared telescopes have extensively studied this region, its X-ray sources remain largely unexplored.
The discovery of J0431-71 could help improve understanding of compact objects such as white dwarfs, neutron stars, and black holes.
Research impact
A 1st of its kind discovery
Studying such systems in the Magellanic Bridge could help researchers understand how interactions between galaxies influence the formation and evolution of binary star systems.
"This supersoft symbiotic binary system, powered by material transferred from a pulsating red giant star, is the first of its kind discovered in the Magellanic Bridge," Saha said.
The research paper detailing this discovery was published on July 30 in the Monthly Notices of the Royal Astronomical Society.