Discoveries using the telescopes on Mauna Kea

[Eric1600]

http://www.keckobservatory.org/recent/entry/S02_Single

Local astronomers taking key roles in the work too.

Maunakea, Hawaii– Astronomers have the “all-clear” for an exciting test of Einstein’s Theory of General Relativity, thanks to a new discovery about S0-2’s star status.

Up until now, it was thought that S0-2 may be a binary, a system where two stars circle around each other. Having such a partner would have complicated the upcoming gravity test.

But in a study published recently in The Astrophysical Journal, a team of astronomers led by a UCLA scientist from Hawaii has found that S0-2 does not have a significant other after all, or at least one that is massive enough to get in the way of critical measurements that astronomers need to test Einstein’s theory..... (see article)

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FWIW, the maunakea scholarship program is a really great event that TomK mentioned above. I encourage people to check out future events from them. The high school students are doing very advanced work.

[TomK]

Thank you, Eric. That study looks interesting as our Galactic Center is becoming a very important part of current astronomical research, mainly because it's our closest supermassive black hole. It's good to see local astronomers lead some of the research. And I second your comment about the Maunakea scholarship program. Teachers do a wonderful job, but there's nothing like working one-to-one with experts in a field to show where education and a little hard work can take you.

[TomK]

First light from a supernova

Many observatories around the world, including those on Mauna Kea, have a system that allows them to override current observations if something of significance has just occurred. The problem is, you have to be quite lucky to catch those events in the first place.

For gamma-ray bursts which produce X-rays, there's the Swift orbiting telescope which can detect these and send automated emails to observatories, but for supernovae (exploding stars), there's no system. You just have to be looking in the right place. One amateur astronomer was and the observations are now being followed up by the Keck Observatory on Mauna Kea. Catching a supernova just as it explodes is incredibly lucky, but to follow things up so quickly will give us insight into what happens right after the explosion that we haven't been able to do before.

http://www.keckobservatory.org/recent/en...k_breakout

Although an amateur astronomy, Buso finds himself as a co-author in the most prestigious science journal there is - Nature.

https://www.nature.com/articles/nature25151

[TomK]

Galactic eviction

In a new study, a group of astronomers discovered that two separate groups of associated stars, one group way above the Galactic plane, and one way below, were likely moved out of the Galactic plane by interactions with passing galaxies. The stars all have identical chemical properties to stars in the plane meaning they are unlikely to have come from other galaxies, rather, they were evicted from their original area by the gravitational effects of passing galaxies. The study used the Keck Observatory on Mauna Kea to determine the stars' chemical properties.

https://phys.org/news/2018-02-stars-milk...aders.html

"Bergemann and her team, for the first time, now presented detailed chemical abundance patterns of these stars, obtained with high-resolution spectra taken with the Keck and VLT (Very Large Telescope, ESO) telescopes. "The analysis of chemical abundances is a very powerful test, which allows, in a way similar to the DNA matching, to identify the parent population of the star. Different parent populations, such as the Milky Way disc or halo, dwarf satellite galaxies or globular clusters, are known to have radically different chemical compositions. So once we know what the stars are made of, we can immediately link them to their parent populations.", explains Bergemann.

When comparing the chemical compositions of these stars with the ones found in other cosmic structures, the scientists were surprised to find that the chemical compositions are almost identical, both within and between these groups, and closely match the abundance patterns of the Milky Way disc stars. This provides compelling evidence that these stars most likely originate from the Galactic thin disc (the younger part of Milky Way, concentrated towards the Galactic plane) itself, rather being debris from invasive galaxies!"

[TomK]

"Unprecedentedly wide and sharp dark matter map"

This is related to a couple of recent posts, and although I'm not an expert in the field of cosmology, this is a very clever and challenging observation using Hyper Suprime-Cam at Subaru on Mauna Kea. The astronomers used "weak gravitational lensing" to map the distribution of dark matter in a relatively large area. Weak gravitational lensing essentially means they didn't use the gravity of one particular massive galaxy to measure what was behind it. They used the tiny effects of lensing that occur by chance when observing distant objects to map the distribution of dark matter nearer by.

https://phys.org/news/2018-03-unpreceden...-dark.html

"It is important to note that growth rate cannot be probed well if we only observe visible matter (stars and galaxies). This is because we now know that nearly 80 % of the matter is an invisible substance called dark matter. The team adopted the 'weak gravitation lensing technique." The images of distant galaxies are slightly distorted by the gravitational field generated by the foreground dark matter distribution. Analysis of the systematic distortion enables us to reconstruct the foreground dark matter distribution."

[TomK]

"From Honokaa to a distant starburst galaxy: Maunakea Scholars present discoveries at West Hawaii Science Fair"

West Hawaii Today: https://goo.gl/znBCwA

Congratulations to all the students!

[TomK]

Not Hawaii related, apologies, but Professor Stephen Hawking has passed away, about 50 years after he was supposed to have succumbed to his illness. One of the greatest minds of all time has now returned to stardust. Much of his theoretical work has been tested using the telescopes on Mauna Kea.

https://youtu.be/ZTpBWhmamWo

[Eric1600]

Hilo Astronomer Devin Chu was quoted in an article about Stephen Hawking. While not a discovery their work is closely linked.

The black hole radiation that Hawking tripped over transformed the study of physics. "I remember learning about Hawking radiation while taking classes in undergraduate astronomy," says Devin Chu, an astronomy graduate student at UCLA. "At the time I didn't have any plans to study environments around black holes, and as I continued my studies in the field, I began to realize more about his contributions."

Chu is now leading a project to observe a star as it passes very close to the black hole at the center of the Milky Way galaxy to determine if the gravitational influence on the star matches the theory of relativity. "To this day, I think I can still do a better job appreciating the crucial work he did for black hole astrophysics," Chu says of Hawking.

https://www.popularmechanics.com/space/d...n-hawking/

[SBH]

Just watched the Chinese space station trajectory pass over Hawai‘i.

http://www.satview.org/?sat_id=37820U

[HereOnThePrimalEdge]

SBH -
Thanks for the reminder that it's still up there, even overhead on occasion. I've seen two recent updates for the Tiangong-1 reentry:

Popular Science: March 31st, +- 3 days
Aerospace: April 1st, +- 4 days
http://www.aerospace.org/cords/reentry-p...1-reentry/

If you want to combine the dual pleasures of insanity and social acceptance, religion is your only choice. - Last Aphorisms