{"id":2027,"date":"2017-07-04T14:40:32","date_gmt":"2017-07-04T13:40:32","guid":{"rendered":"http:\/\/abergavennyas.org.uk\/?page_id=2027"},"modified":"2019-12-13T21:38:30","modified_gmt":"2019-12-13T21:38:30","slug":"2016-posts-c","status":"publish","type":"page","link":"http:\/\/abergavennyas.org.uk\/?page_id=2027","title":{"rendered":"2016 Posts (C)"},"content":{"rendered":"

Comments, criticism (constructive only), suggestions etc contact : cosmology@AbergavennyAS.org.uk<\/a><\/em><\/p>\n

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News Items discussed at the December 12th<\/sup>, 2016, meeting<\/u><\/strong><\/h4>\n

Desperately Seeking\u2026.11 things we are sure exist but have never seen.  –  Black Holes
\n<\/strong>Date: 19th<\/sup> March, 2016        :           Source: New Scientist, pp 30-37<\/em><\/p>\n

Don\u2019t know if the news this week can be called \u201cseeing\u201d a black hole but see what you think.<\/p>\n

 Spinning black hole swallowing star explains superluminous event
\nESO telescopes help reinterpret brilliant explosion
\n<\/strong>Date: December 12, 2016  :           Source: ESO<\/em><\/p>\n

An extraordinarily brilliant point of light seen in a distant galaxy, and dubbed ASASSN15lh, was thought to be the brightest supernova ever seen. But new observations from several observatories, including ESO, have now cast doubt on this classification. Instead, a group of astronomers propose that the source was an even more extreme and very rare event a rapidly spinning black hole ripping apart a passing star that came too close<\/em>.  Link<\/a><\/em><\/p>\n

Or, as the BBC (NI) put it<\/p>\n

Black hole ‘swallowed star’, say Queen’s astronomers<\/strong><\/p>\n

 <\/strong>Belfast-based astronomers have helped to discover a very rare celestial event – a star being “swallowed” after it passed too close to a black hole…………<\/em><\/p>\n

(Prof Smartt) said the light “puzzled us for months” but based on their telescopic observations, the QUB team proposed a new explanation for the object in a galaxy far, far away.<\/em><\/p>\n

It believes the sun-like star wandered too close to the black hole and was “ripped apart”, a phenomenon known in astronomy as a “tidal disruption event”.<\/em><\/p>\n

In the process, the star was “spaghettified and some of the material was converted into huge amounts of radiated light,” said a QUB statement.<\/em><\/p>\n

“This gave the event the appearance of a very bright supernova explosion, even though the star would not have become a supernova on its own as it did not have enough mass.”   Link<\/a> <\/em><\/p>\n

\"_92941666_starnearsupermassiveblackhole_original\"<\/a><\/p>\n

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 <\/strong>New evidence on the formation of the solar system
\n<\/strong>Date:   December 2, 2016   :           Source:          Monash University<\/em><\/p>\n

International research is using new computer models and evidence from meteorites to show that a low-mass supernova triggered the formation of our solar system.<\/em><\/p>\n

A question was asked as to how small a star involved in a Low Mass Supernova is.  If you want to read the paper the link is below.<\/p>\n

Evidence from stable isotopes and 10<\/sup>Be for solar system formation triggered by a low-mass supernova.   <\/em><\/strong>http:\/\/www.nature.com\/articles\/ncomms13639<\/a><\/em><\/p>\n

By investigating isotope abundance they showed that the problems of abundances in our sun created by the assumption that a large supernova (>15 Solar Masses) triggered collapse of the gas and dust cloud  are removed if <12 solar mass core collapse super nova are modelled instead.<\/p>\n

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Second-generation stars identified, giving clues about their predecessors
\n<\/strong>Date: December 6, 2016     :           Source: University of Notre Dame<\/em><\/p>\n

Astronomers have identified what they believe to be the 2nd generation of stars, shedding light on the nature of the universe’s first stars.<\/em><\/p>\n

Couple of quotes from the ScienceDaily article:-<\/p>\n

“The CEMPno stars we see today, at least many of them, were born shortly after the Big Bang, 13.5 billion years ago, out of almost completely unpolluted material,” Yoon says. “These stars, located in the halo system of our galaxy, are true second generation stars born out of the nucleosynthesis products of the very first stars.”<\/em><\/p>\n

Beers says it’s unlikely that any of the universe’s first stars still exist, but much can be learned about them from detailed studies of the next generation of stars.<\/em><\/p>\n

A question was also asked if we can see the stars that were investigated.  One star, from a companion paper to this one,
\n(Observational Constraints on First-Star Nucleosynthesis. II. Spectroscopy of an Ultra Metal-Poor CEMPno Star)<\/em><\/strong>
\n<\/em> was \u201cHE 0020-1741\u201d or \u201cBPS CS 30324-0063\u201d with a magnitude of 12.89 <\/strong><\/p>\n

Another example is BPS CS22892-0052 (Sneden’s Star), an old population II star located at a distance of 4.7 kpc in the galactic halo. It belongs to a class of ultra-metal-poor stars (Metallicity [Fe\/H]=-3.1) with a magnitude of 13.99<\/p>\n

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News Items discussed at the March 7th, 2016, Cosmology Group meeting<\/u><\/strong><\/p>\n