Kavli IPMU: UV Light from SLSN Key to Explosion Mechanism

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Kavli IPMU: UV Light from SLSN Key to Explosion Mechanism

Postby bystander » Thu Sep 07, 2017 5:48 pm

Ultraviolet Light from Superluminous Supernova Key to Revealing Explosion Mechanism
Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) | 2017 Sep 07

An international team of researchers has discovered a way to use observations at ultraviolet (UV) wavelengths to uncover characteristics about superluminous supernovae previously impossible to determine...

The team ... studies stellar explosions called Superluminous Supernovae (SLSNe), an extra bright type of supernova discovered in the last decade that is 10 to 100 times brighter than ordinary supernovae. Recently, the team came upon Gaia16apd in a faint dwarf galaxy 1.6 billion light years away.

This SLSNe had an extraordinary UV-bright emission (Figure 1) for a supernova of its kind, but no one could explain what explosion mechanism could produce that feature. Theorists have debated that Gaia16apd could fit one of three SLSNe scenarios. These are the pair-instability supernova, having a large mass of radioactive Nickel-56, or a magnetar-powered supernova where there would be a rapidly spinning and highly magnetized neutron star as an additional energy source, or a shock-interacting supernova where the supernova ejecta would interact with the surrounding dense circumstellar matter (Figure 2).

Researchers from Kavli IPMU therefore decided to simulate each model using multicolor radiation hydrodynamics to study light in different colors and ranges of wavelengths and see whether any of the simulations matched with the observed supernova. These simulations produced ultraviolet, visible-light and infrared light curves, photospheric radius and velocity, making it possible to investigate the appearance of the explosion at any wavelength. ...

Ultraviolet Light Curves of Gaia16apd in Superluminous Supernova Models - Alexey Tolstov et al

viewtopic.php?t=36740#p267945
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Re: Kavli IPMU: UV Light from SLSN Key to Explosion Mechanism

Postby MargaritaMc » Thu Sep 07, 2017 6:50 pm

Thanks, bystander, for the link to the topic posted in March. Very useful.
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Re: Kavli IPMU: UV Light from SLSN Key to Explosion Mechanism

Postby Ann » Fri Sep 08, 2017 4:12 am

Eta Carina. Photo:
N. Smith / J.A. Morse (U. Colorado) et al. / NASA
Extremely interesting. So a shock-interacting supernova is a supernova where fast-moving supernova ejecta slams into older, slow-moving, dense ejecta that was expelled by the star before it went supernova. And SLSN Gaia16apd was likely a shock-interacting supernova, and that is the reason why it was superluminous.

That makes me think of Eta Carina. The Homunculus Nebula surrounding Eta Carina is pretty dense, isn't it? But in spite of its enormous mass loss Eta Carina is still quite massive, isn't it? So if - I guess make that when - Eta Carina goes supernova, its fast ejecta will slam into the Homunculus Nebula and lead to - what? A superluminous supernova here in the Milky Way, some 7,500 light-years from the Earth?

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Re: Kavli IPMU: UV Light from SLSN Key to Explosion Mechanism

Postby MargaritaMc » Fri Sep 08, 2017 6:34 pm

Interesting to see that a similar process happens in superluminous NOVAE as well as reported in this post only a few days back:
viewtopic.php?f=31&t=37537
As the explosion begins, it ejects a cooler, slower wave of gaseous material, relatively speaking. Behind it, though, is a hot, fast wave speeding right behind it. The collision of the two ejections produces a shockwave, which results in a spectacular explosion of heat and light.

“The bigger the shock, the brighter the nova,” Chomiuk said. “We believe it’s the speed of the second wave that influences the explosion.”

This study explains a theory held by Brian Metzger, Columbia University astronomer, who also is a co-author for this paper.

"While the presence of shock waves in novae has been understood for some time, they were generally relegated to a side feature of the phenomenon," Metzger said. "This event shows that shocks are the main event."

Now that the theory has been proven, astronomers use novae to better understand other super-charged explosions, like those that mark the death of massive stars in galaxies far away.
http://msutoday.msu.edu/news/2017/shocking-discovery-explains-powerful-novae/

"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
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