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+--- Thread: Discoveries using the telescopes on Mauna Kea (/showthread.php?tid=17412)
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RE: Discoveries by the telescopes on Mauna Kea - TomK - 08-15-2019
A new type of supernova
A new breed of supernovae has been discovered with the use of the Gemini North Telescope on Mauna Kea. Depending on their mass, supernovae are massive stars that collapse in on themselves through gravity when they exhaust their fuel. The collapse causes a massive explosion leaving the core of the star behind, which is so compressed it turns into a neutron star or a black hole.
A recent supernova, SN 2016iet, is very different. The original star was supermassive, about 200 solar masses and lacked metals, i.e., atoms heavier than hydrogen and helium. When it ran out of fuel, the collapse was so intense that matter-antimatter particle pairs were created which led to a massive explosion when they recombined blowing the star to pieces and leaving no core behind.
https://www.gemini.edu/node/21217
"A renegade star exploding in a distant galaxy has forced astronomers to set aside decades of research and focus on a new breed of supernova that can utterly annihilate its parent star — leaving no remnant behind. The signature event, something astronomers had never witnessed before, may represent the way in which the most massive stars in the Universe, including the first stars, die."
RE: Discoveries by the telescopes on Mauna Kea - dan_c - 08-15-2019
Thanks Tom. That's really cool. I thought that most stars with ten times the Sun's mass would become black holes.
Also, that is one huge "nuke".
It seems to me that there is a lot more variety in the research being done on Mauna Kea than one would expect -- and that the other telescopes besides the Kecks are more important than realized.
RE: Discoveries by the telescopes on Mauna Kea - TomK - 08-15-2019
dan_c - I think the limit is less for black-hole formation, three or four solar masses, but will double-check. Things change over time as we better understand the physics of the universe.
For instance, as a student I was taught the "Eddington Limit", i.e., stars couldn't be more massive than about 100 solar masses because they would be too unstable and basically blow themselves to bits before they settled down to become stars. Things have changed over the last couple of decades but there is still a limit. If I recall correctly, the Eddington limit was based on a star made of pure hydrogen which is not the case in reality. However, we have now observed a few stars that are more massive than this theory allows, so there are other factors in play.
Thanks for your interest!
RE: Discoveries by the telescopes on Mauna Kea - TomK - 08-17-2019
There's been a new gravitational wave event tonight - we're busy looking for the source.
RE: Discoveries by the telescopes on Mauna Kea - kander - 08-18-2019
Is the gravitational data accessible by regular humans?
RE: Discoveries by the telescopes on Mauna Kea - TomK - 08-18-2019
Well, there's the Gravitational-Wave Candidate Event Database, but am not sure you'll find their products particularly useful.
https://gracedb.ligo.org/superevents/S190814bv/
RE: Discoveries by the telescopes on Mauna Kea - kander - 08-18-2019
Interesting indeed. Now to figure out what the data is indicating. the resolution is a lot higher than I figured for a gravitational waves. By the way did anyone find the target event?
RE: Discoveries by the telescopes on Mauna Kea - TomK - 08-18-2019
Not yet as far as I'm aware and it may take some time to do so. It's a large area to search. We're planning to search for roughly 10 nights but it might take months to trawl through that data to find an optical/IR source. Whatever caused the event is very distant and won't be bright, so there's an enormous amount of sky to search and detect subtle changes. Maybe we'll be lucky though...
RE: Discoveries by the telescopes on Mauna Kea - PaulW - 08-19-2019
Thanks Tom, great work you guys and gals are doing up there.
RE: Discoveries by the telescopes on Mauna Kea - TomK - 08-19-2019
The actual GW event looks to have been most likely the merging of a black hole and neutron star.
https://phys.org/news/2019-08-scientists-black-hole-swallowing-neutron.html
"Scientists are still analysing the data to confirm the exact size of the two objects, but initial findings indicate the very strong likelihood of a black hole enveloping a neutron star. The final results are expected to be published in scientific journals."
The ANU SkyMapper Telescope has already mapped out the region of interest at optical wavelengths but hasn't found anything yet. This is not too surprising, it's a very small telescope and works at optical wavelengths. The best chance of finding the target is with a larger telescope that has wide-field capabilities and works at infrared wavelengths. The event happened so far away the optical light would be redshifted into the infrared.