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The Hubble Space Telescope, despite celebrating its 35th anniversary on April 24th, continues to contribute substantially to the field. Recent research utilizes Hubble, along with the Chandra X-ray space observatory, the Australia Telescope Compact Array (ATCA), and the Parkes 64-meter telescope, to examine supernova wreckage within the Large Magellanic Cloud (LMC). This collaborative effort seeks to unravel the mysteries surrounding these powerful stellar explosions and their aftermath, offering valuable insights into cosmic phenomena.
Hubble Investigates Supernova Remnant MC SNR J0519–6902
Astronomers have been using a suite of telescopes, including the venerable Hubble, to probe the remnants of a supernova in the Large Magellanic Cloud (LMC), a satellite galaxy of our own Milky Way.
The focus of their investigation is MC SNR J0519–6902, a supernova remnant initially observed in 1981. This remnant exhibits a ring-like structure spanning approximately 26 light-years in diameter. The precise circumstances surrounding its creation have puzzled scientists, with the prevailing theory suggesting it originated from the destruction of a white dwarf star in a Type Ia supernova. However, specifics about this event have been elusive.
Recent findings might shed light on this cosmic enigma. “We have showcased state-of-the-art images of this supernova remnant,” said Rami Alsaberi of Gifu University. “Furthermore, we now have dependable readings for its polarisation and magnetic field. As a result of the enhanced resolution of our images, we managed to spot what appeared to be a dim form on the northeast flank of this particular remnant – the first reported case thereof.”
The team also detected a concentration of atomic hydrogen potentially linked to the supernova remnant.
Cosmic Explosion: How White Dwarfs Become Supernovas
White dwarfs represent the final evolutionary stage for stars, similar in mass to our sun, after they have exhausted their hydrogen supply. Without hydrogen to fuse into helium, the outward radiative pressure that counteracts gravity diminishes, causing the star’s core to collapse while its outer layers are expelled. Isolated stars like our sun will simply cool into white dwarfs, but for the roughly 50% of sun-like stars that exist in binary systems, a more dramatic end awaits.
“Scientists classify this remnant as the product of a single Type Ia supernova,” Alsaberi stated. “These supernovae occur during binary star formations once one of the participants, the white dwarf, falls prey to an explosion.”
Type Ia Supernova Scenarios
Alsaberi detailed two common paths that lead to Type Ia supernova explosions in binary systems:
- Accretion scenario: A white dwarf gravitationally pulls matter from its companion star, gradually increasing its mass.
- Chandrasekhar limit: As the white dwarf approaches approximately 1.4 times the mass of the sun, it reaches a critical threshold known as the Chandrasekhar limit. This triggers a thermonuclear explosion, resulting in a Type Ia supernova.
Alternatively, both stars in the companion system may have turned into white dwarfs, which leads them to move inexorably towards one another until an eventual cataclysmic collision sparks a Type Ia supernova.
“At this time, which of the preceding possibilities accounts for this remnant appears to be an open question,” Alsaberi added.
Irrespective of the precise initiator, Type Ia supernovas entail the virtual erasure of the original entity. The aftermath involves the emergence of a rapidly expanding array of gaseous substances surging outward from within the epicenter of the blast.
However, his team discovered more about MC SNR J0519–6902.
Insights from Polarization and Magnetic Field Analysis
By carefully examining the polarization of light and the magnetic field surrounding MC SNR J0519–6902, Alsaberi’s team was able to find out a few other things.
- Similarities found between young supernova remnants in the Large Magellanic Cloud (LMC) and the Milky Way.
- Age estimate of approximately 2,000 years for MC SNR J0519–6902.
- Blast wave concluding this active expansion signals the beginning of a phase referred to as the “Sedov-Taylor phase.” During this time period the remnants pull materials from the interstellar medium.
“MC SNR J0519–6902 figures as one of only four known recent supernova remnants throughout the LMC that are estimated to be less than 2,000 years old,” Alsaberi explained.
The research isn’t yet complete, however. “Our plans call for making observations out of the Australian Square Kilometer Array Pathfinder (ASKAP) telescope,” Alsaberi concluded. “Data regarding atomic hydrogen coming by the high-resolution of ASKAP shall allow for verification of said atomic hydrogen mass as pertaining to this particular remnant.”
A preliminary draft from the team has been placed onto the arXiv archive for everyone to see.