This schematic reveals the different ejecta and winds (red and purple) emitted by the taking off star (left, yellow). The common-envelope disk (blue) surrounds both stars, the one taking off as a supernova and its binary partner (not revealed). The boundary layer around the common-envelope disk is the source of the hydrogen the team detected. Credit: B. Thomas et al./ UT Austin
A multinational group of astronomers led by Benjamin Thomas of The University of Texas at Austin has actually used observations from the Hobby-Eberly Telescope (HET) at the universitys McDonald Observatory to unlock a confusing mystery about an outstanding surge found numerous years ago and developing even now. The results, published in the April 27, 2022 issue of The Astrophysical Journal, will assist astronomers much better understand the procedure of how huge stars die and live.
When a taking off star is very first spotted, astronomers worldwide begin to follow it with telescopes as the light it provides off modifications quickly with time. They see the light from a supernova get brighter, eventually peak, and then start to dim. By keeping in mind the times of these peaks and valleys in the lights brightness, called a “light curve,” as well as the characteristic wavelengths of light released at various times, they can deduce the physical characteristics of the system.
” I think whats really cool about this kind of science is that were looking at the emission thats originating from matter thats been abandoned from the progenitor system before it exploded as a supernova,” Thomas said. “And so this makes a sort of time machine.”
Star routes wheel around Polaris, the North Star, above the Hobby-Eberly Telescope at The University of Texas at Austins McDonald Observatory. Credit: Ethan Tweedie Photography
The progenitor of supernova 2014C was a binary star, a system in which two stars orbited each other. The more massive star progressed much faster, expanded, and lost its external blanket of hydrogen to the companion star.
This makes it a kind of supernova astronomers call a “Type Ib.” In particular, Type Ib supernovae are identified by disappointing any hydrogen in their ejected product, at least in the beginning.
” I believe whats actually cool about this kind of science is that were looking at the emission thats originating from matter thats been abandoned from the progenitor system prior to it took off as a supernova. Therefore this makes a sort of time machine.”– Benjamin Thomas
The common-envelope disk (blue) surrounds both stars, the one exploding as a supernova and its binary partner (not shown). When a blowing up star is first discovered, astronomers around the world start to follow it with telescopes as the light it offers off modifications rapidly over time. The progenitor of supernova 2014C was a binary star, a system in which two stars orbited each other. The more massive star progressed quicker, broadened, and lost its outer blanket of hydrogen to the companion star. The group proposes a design where the hydrogen envelopes of the 2 stars in the progenitor binary system merged to form a “common-envelope setup,” where both were consisted of within a single envelope of gas.
Thomas and his team have been following SN 2014C from telescopes at McDonald Observatory since its discovery that year. Numerous other teams around the world likewise have actually studied it with telescopes on the ground and in area, and in various kinds of light, consisting of radio waves from the ground-based Very Large Array, infrared light, and X-rays from the space-based Chandra Observatory.
The research studies of SN 2014C from all of the different telescopes did not include up into a cohesive picture of how astronomers thought a Type Ib supernova need to act.
For something, the optical signature from the Hobby-Eberly Telescope (HET) showed SN 2014C consisted of hydrogen– an unexpected finding that also was found independently by another group using a different telescope.
” For a Type Ib supernova to begin revealing hydrogen is entirely unusual,” Thomas stated. “Theres just a handful of events that have been revealed to be comparable.”
For a 2nd thing, the optical brightness (light curve) of that hydrogen was behaving strangely. >> Most of the light curves from SN 2014C– radio, infrared, and X-rays– followed the expected pattern: they got brighter, peaked, and started to fall. But the optical light from the hydrogen remained consistent.
” The secret that weve battled with has been How do we fit our Texas HET observations of hydrogen and its characteristics into that [Type Ib] image?,” stated UT Austin professor and employee J. Craig Wheeler.
The issue, the team understood, was that previous designs of this system assumed that the supernova had actually taken off and sent its shockwave in a round way. The data from HET showed that this hypothesis was difficult– something else should have occurred.
” It just would not fit into a spherically symmetric photo,” Wheeler said.
The team proposes a model where the hydrogen envelopes of the two stars in the progenitor binary system merged to form a “common-envelope configuration,” where both were included within a single envelope of gas. When one of the stars took off, its fast-moving ejecta collided with the slow-moving disk, and also slid along the disk surface at a “limit layer” of intermediate velocity.
Hence the HET information ended up being the secret that unlocked the mystery of supernova SN 2014C.
” In a broad sense, the concern of how huge stars lose their mass is the big clinical concern we were pursuing,” Wheeler stated. By what physical procedure? Those were the macro questions we were going after.
” And 2014C simply ended up being a really crucial single event thats illustrating the procedure,” Wheeler stated.
Recommendation: “Seven Years of SN 2014C: a Multi-Wavelength Synthesis of an Extraordinary Supernova” by Benjamin P. Thomas, J. Craig Wheeler, Vikram V. Dwarkadas, Christopher Stockdale, Jozsef Vinko, David Pooley, Yerong Xu, Greg Zeimann and Phillip MacQueen, 27 April 2022, The Astrophysical Journal.arXiv: 2203.12747
