Astronomers have discovered the youngest white dwarf ever seen to be partnered with a millisecond pulsar, offering a rare glimpse into the immediate aftermath of stellar recycling. The binary system, designated NGC 362D, was identified using archival data from the Hubble Space Telescope and the MeerKAT radio telescope in South Africa.
Discovering NGC 362D in Globular Cluster NGC 362
The white dwarf orbits a millisecond pulsar, which is a neutron star spinning hundreds of times per second while sweeping twin beams of radiation across the universe. Researchers utilized Hubble observations collected between 2006 and 2016 alongside radio data from MeerKAT to reconstruct the evolutionary history of the system located within the globular cluster NGC 362. Team leader Greta Ettorre of the University of Bologna stated that the system provides a unique opportunity to observe a white dwarf at a very early stage of its evolution.
Unusual Ultraviolet Emissions Point to Ejected Material
Analysis of the stellar ember revealed that it is emitting less ultraviolet radiation than it should. According to the research team, this attenuation indicates that when the white dwarf stopped transferring matter to its neutron star companion approximately 600 million years ago, it was left in an envelope of ejected material that is now blocking the ultraviolet signal. Emanuele Dalessandro of the National Institute for Astrophysics noted that the presence of surrounding material could produce radio signatures similar to those seen in systems with non-degenerate companions.
Supernova Explosion Creates Dense Neutron Star
The pulsar in NGC 362D originated from a massive supernova explosion of a star between eight and 12 times the mass of the sun. That event crushed a stellar core down to a width of about 12 miles, creating a neutron star so dense that a single teaspoon of its matter would weigh around 10 million tons, the equivalent of 85,000 adult blue whales. As the newborn neutron star accumulated material stripped from its companion star, the transferred angular momentum accelerated its rotation rate.
Implications for Pulsar Timing Arrays and General Relativity
The findings, published on September 30 in the journal Astronomy & Astrophysics Letters, provide data that could help astronomers interpret the properties of other young stellar systems. Researchers also utilize millisecond pulsars as natural cosmic clocks because they rotate with extraordinary regularity. Measuring the arrival times of their pulses allows scientists to study gravity under extreme conditions and test general relativity with high precision.
When and Where NGC 362D Was Discovered?
When was NGC 362D discovered?
The system was identified recently using radio data from the MeerKAT telescope, while the white dwarf companion was found in Hubble Space Telescope archival data collected between 2006 and 2016.
Where is the NGC 362D system located?
The binary system is located within the globular cluster NGC 362.
When was the study published?
The research findings were published on September 30 in the journal Astronomy & Astrophysics Letters.
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