Glowing faintly on the Milky Way’s outskirts, astronomers have found a nearly perfect spherical relic of a supernova, challenging accepted knowledge of stellar explosions. Apart from its terrible symmetry, the orb, G305.4–2.2 or “Telios”—Greek for “perfect”—is confusing in terms of size and distance. Captured on radio pictures from the Australian Square Kilometre Array Pathfinder (ASKAP), the object might be either remarkably young or old. Its remarkable shape raises fundamental questions about how such near-perfect remnants form, especially given the chaotic nature of typical stellar deaths.

Astronomers Find Rarely Symmetrical Supernova Remnant in Milky Way Outskirts

As per a recent study published on the preprint server arXiv and accepted by Publications of the Astronomical Society of Australia, Telios was detected during the Evolutionary Map of the Universe project. Most supernova remnants (SNRs) have spheroidal shapes, none close to the smooth circular extremity of this record-holding SNR. “This object is circularly symmetric, indicating that it is one of the most circular galactic SNRs ever seen,” the authors mentioned.

Telios’ unusual symmetry is paired with extremely low brightness, making it difficult to pinpoint its distance or dimensions. Ranging from 45.6 to 156.5, it lets astronomers pin down that it could be anywhere from 7,170 to 25,101 light-years away from us. Its position below the galactic plane, in the thin disc of the galaxy where very few stars live, adds another layer of complexity. Its symmetric shape indicates a recently born neutron star, albeit with fainter light, supporting two other possibilities: an old, slowing-down neutron star or a young one that hasn’t lost its initial shape.

Though the source of Telios is yet unknown, astronomers choose Type Ia supernovae, explosions from less massive stars with a more constant force. Starting from more massive red giants, these are not as far-off or as lovely in quality as core-collapse supernovae. That notion is called into doubt, though, by the absence of a recognised parent star. Although the Type Ia scenario was recommended without direct data, the writers actively argued for more high-resolution studies.