Astronomers Spot Extraordinarily Uncommon Hydrogen-Cloaked Sort Ia Supernova


Astronomers utilizing the Magellan telescopes at Las Campanas Observatory, Chile, have detected the faint sign emitted by hydrogen fuel within the remnant of the Sort Ia supernova ASASSN-18tb. The researchers consider the detection might present new insights into elusive progenitors of those violent explosions.

This image from Data Release 1 of the Dark Energy Survey shows 2MASX J04180598-6336523, the host galaxy of the Type Ia supernova ASASSN-18tb; the position of the supernova is marked by the white ticks. Image credit: Kollmeier et al, doi: 10.1093/mnras/stz953.

This picture from Knowledge Launch 1 of the Darkish Power Survey reveals 2MASX J04180598-6336523, the host galaxy of the Sort Ia supernova ASASSN-18tb; the place of the supernova is marked by the white ticks. Picture credit score: Kollmeier et al, doi: 10.1093/mnras/stz953.

Sort Ia supernovae play an important position in serving to astronomers perceive the Universe. Their brilliance permits them to be seen throughout nice distances and for use as cosmic mile-markers. These explosions synthesize most of the parts that make up the world round us, that are ejected into the galaxy to generate future stars and stellar methods.

Though hydrogen is the most-abundant ingredient within the Universe, it’s nearly by no means seen in Sort Ia supernova explosions. In truth, the dearth of hydrogen is among the defining options of this class of supernovae and is regarded as a key clue to understanding what got here earlier than their explosions.

Sort Ia supernovae originate from the thermonuclear explosion of a white dwarf that’s a part of a binary system. However what precisely triggers the explosion of the white dwarf is a superb puzzle.

A prevailing concept is that, the white dwarf positive aspects matter from its companion star, a course of which will finally set off the explosion, however whether or not that is the right principle has been hotly debated for many years.

Astronomers eagerly examine the chemical signatures of the fabric ejected throughout these explosions to be able to perceive the mechanism and gamers concerned in creating Sort Ia supernovae.

In recent times, they’ve found a small variety of uncommon Sort Ia supernovae which are cloaked in great amount of hydrogen — possibly as a lot because the mass of our Solar.

However in a number of respects, ASASSN-18tb — also called SN 2018fhw — is completely different from these earlier occasions.

“It’s potential that the hydrogen we see when learning ASASSN-18tb is like these earlier supernovae, however there are some placing variations that aren’t really easy to elucidate,” mentioned Dr. Juna Kollmeier, an astronomer with the Observatories of the Carnegie Establishment for Science.

First, in all earlier instances these hydrogen-cloaked Sort Ia supernovae have been present in younger, star-forming galaxies the place loads of hydrogen-rich fuel could also be current. However ASASSN-18tb occurred in an early-type galaxy dominated by outdated stellar populations.

Second, the quantity of hydrogen ejected by ASASSN-18tb is considerably lower than that seen surrounding these different Sort Ia supernovae. It in all probability quantities to about one-hundredth the mass of our Solar.

“One thrilling chance is that we’re seeing materials being stripped from the exploding white dwarf’s companion star because the supernova collides with it. If so, it might be the first-ever remark of such an prevalence,” mentioned Dr. Anthony Piro, from the Observatories of the Carnegie Establishment for Science.

“I’ve been on the lookout for this signature for a decade! We lastly discovered it, but it surely’s so uncommon, which is a vital piece of the puzzle for fixing the thriller of how Sort Ia supernovae originate,” mentioned Dr. Josh Simon, additionally from the Observatories of the Carnegie Establishment for Science.

The workforce’s work was printed within the Month-to-month Notices of the Royal Astronomical Society.


Juna A. Kollmeier et al. 2019. H α emission within the nebular spectrum of the Sort Ia supernova ASASSN-18tb. MNRAS 486 (three): 3041-3046; doi: 10.1093/mnras/stz953

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