(ORDO NEWS) — Snapshots by a Dartmouth professor of the explosive aftermath of a two-star collision could help scientists study this rare astronomical event and perhaps definitively confirm the identity of a bright but short-lived star observed nearly 850 years ago.
Robert Fesen, professor of physics and astronomy, took telescopic images showing a burst of thin filaments emanating from a very unusual star at the center of the Pa 30 nebula.
The Pa 30 Nebula is a dense region of illuminated gas, dust, and other matter. Fesen et al report that Pa 30 appears to be virtually free of hydrogen and helium, but rich in sulfur and argon elements.
According to the astronomer, the unusual structure and characteristics of the nebula are consistent with the predicted outcome of the collision of two white dwarfs.
White dwarfs are faint, extremely dense stars about the size of the Earth and about the mass of the Sun. Fesen believes white dwarf mergers are one of the proposed explanations for the subclass of type Iax supernovae.
The size of Pa 30 and the speed at which it is expanding – about 3.86 million kilometers per hour – suggest that the explosive collision occurred around 1181, the researchers report.
Fesen’s images of the structure and luminosity of the nebula not only provide the most accurate estimate of its age, but may allow astronomers to refine existing models of white dwarf mergers.
Pa 30 was discovered in 2013 by study co-author and amateur astronomer Dana Patchik, but so far images of the nebula have shown only an extremely faint and diffuse object.
Fesen took images of Pa 30 in late 2022 with the 2.4-meter Hiltner Telescope at the MDM Observatory. The astronomer equipped the telescope with an optical filter sensitive to a specific line of sulfur emission.
He captured Pa 30 in three 2000-second images in very clear skies and obtained additional data on the structure, size and speed of the nebula.
The study by Fesen and his co-authors is based on work published in 2019 by Russian researchers who discovered an unusual star near the center of Pa 30.
This star had a number of properties that indicate a collision between two white dwarfs. Its surface temperature was almost 200,000 degrees Celsius with an astonishing wind speed of about 56 million kilometers per hour.
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