From The Liverpool John Moores University (UK): “Cosmic explosions offer new clue to how stars become Black Holes”
From The Liverpool John Moores University (UK)
1.12.22
Scientists have witnessed for the first time exactly what happens to the most massive stars at the end of their lives.
Most very large stars explode in a fiery supernova explosion that leaves behind a neutron star in a process frequently witnessed by Earth’s most powerful telescopes.
But some – the most massive, 30 times the size of the Sun or more – are believed to undergo a less visible metamorphosis and transform into black holes without the same cosmic fireworks produced by smaller stars.
Now, a group of astronomers have described what may be one of these in detail, by detecting unusual behaviour in the explosion of a star within a galaxy 1.2 billion light years from Earth.
Big surprise
“Normally, when a massive star dies, almost the entire star is blown apart by the explosion” explains Dr. Daniel Perley, an astrophysicist at Liverpool John Moores University and lead author on a paper accepted for publication in The Astrophysical Journal.
“What we witnessed in this case is something quite different: a much briefer explosion caused by collisions between a small amount of material exiting the star at extremely high speeds with other material that had built up in its vicinity before it collapsed.”
While collisions of this nature are not entirely unusual, the big surprise was what happened next.
“Once the collisions were over, we had expected to see signs of the bulk of the star dissipating into space after being blown apart. But we saw no sign of this – suggesting only a tiny fraction of the star was released in the explosion. We infer that the rest of it collapsed inward to produce a massive black hole.”
“Death throes”
Although this explosion was very unusual, the team, which includes scientists from The Weizmann Institute of Science (IL), The Oskar Klein Centre (SE), The California Institute of Technology (US) and The University of California-Berkeley (US) believes this scenario may actually be quite common.
They say that as a very massive star enters its “death throes” it starts shedding material at high speeds in dense “winds” or in much smaller eruptions. The result is that the space around the star is filled with enriched gas in the months or even years before the final explosion. However, the amount of material released varies from star to star.
In this case, telescopes got lucky because there was a particularly large amount of pre-existing material around the star, which made the explosion very bright and easy to find.
“The same scenario could happen far more frequently and not produce enough light for us to be able to detect most of the time,” added Dr. Perley, who is based at The Liverpool John Moores University Astrophysics Research Institute and collaborated on the research with Professor Chris Copperwheat.
“In fact, if a similar explosion occurred without an environment rich in gas, we might never know it even happened.”
Liverpool Telescope’s role
The explosion was discovered by the Zwicky Transient Facility at Palomar, California and tracked by the Liverpool Telescope on La Palma – a robotic scope which reacts immediately to events in the night-sky – the Hubble Space Telescope, the Nordic Optical Telescope, the Keck Observatory and NASA’s Neil Gehrels Swift Observatory.
2-metre Liverpool Telescope interior
2-metre Liverpool Telescope at The Roque de los Muchachos Observatory | IAC Institute of Astrophysics of the Canary Islands[Instituto de Astrofísica de Canarias](ES), altitude 2,363 m (7,753 ft)
National Aeronautics and Space Administration(US)/European Space Agency [Agence spatiale européenne] [Europäische Weltraumorganisation](EU) Hubble Space Telescope.
Nordic Optical Telescope [funded by Denmark, Sweden, Norway, Finland, and (since 1997) Iceland], at IAC Institute of Astrophysics of the Canary Islands[Instituto de Astrofísica de Canarias](ES) The Roque de los Muchachos Observatory on La Palma in The Canary Islands[Instituto de Astrofísica de Canarias ](ES) Altitude 2,396 m (7,861 ft).
W.M. Keck Observatory two ten meter telescopes operated by California Institute of Technology(US) and The University of California(US), at Mauna Kea Observatory, Hawaii USA, altitude 4,207 m (13,802 ft). Credit: Caltech.
National Aeronautics and Space Administration(US) Neil Gehrels Swift Observatory.
Dr. Perley and collaborators unveiled their findings at a media conference for The American Astronomical Society(US) in California at 9.15pm (GMT).
See the full article here .
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The Liverpool John Moores University (UK) is a public research university in the city of Liverpool, England. It has 21,875 students, of which 18,375 are undergraduate students and 3,500 are postgraduate, making it the 33rd largest university in the UK by total student population.
The university can trace its origins to the Liverpool Mechanics’ School of Arts, established in 1823 making it a contestant as the third-oldest university in England; this later merged to become Liverpool Polytechnic. In 1992, following an Act of Parliament the Liverpool Polytechnic became what is now The Liverpool John Moores University.
It is a member of The University Alliance, a mission group of British universities which was established in 2007. and The European University Association.
The Liverpool John Moores University now has more than 24,000 students from over 100 countries world-wide, 2,400 staff and 250 degree courses. The Liverpool John Moores University was awarded the Queen’s Anniversary Prize in 2005.
Currently, Liverpool John Moores University is receiving more applications than previously seen; according to data in 2009, the total number of applications submitted to LJMU was 27,784.
On 14 April 2008, Brian May was inducted into the university as the fourth Chancellor of The Liverpool John Moores University. May is also the lead guitarist for the rock band Queen. He replaced outgoing Chancellor Cherie Booth QC, wife of former Prime Minister Tony Blair. Honorary fellows in attendance at the ceremony included Sir Patrick Moore and Pete Postlethwaite. May was succeeded as Chancellor in 2013 by Sir Brian Leveson.
The Liverpool John Moores University is a founding member of The Northern Consortium, an educational charity, owned by eleven universities in the north of England.
Faculties
The university is organised into five faculties (which are each split into schools or centres), most of the faculties are based at a particular campus site however, with many joint honours degrees and some conventional degrees, the faculties overlap meaning students’ degrees are from both faculties. The five faculties are:
Faculty of Business & Law
Liverpool Business School
School of Law
Faculty of Arts, Professional and Social Studies
Liverpool School of Art and Design
Liverpool Screen School
School of Education
School of Humanities and Social Science
School of Justice Studies
Institute of Culture Capital
Faculty of Health
School of Nursing and Allied Health
Public Health Institute
Faculty of Science
School of Biological and Environmental Sciences
School of Pharmacy and Biomolecular Sciences
School of Sport and Exercise Sciences
Faculty of Engineering and Technology
Astrophysics Research Institute
Department of Applied Mathematics
Department of the Built Environment
Department of Civil Engineering
Department of Computer Science
Department of Electronics and Electronic Engineering
Department of Maritime and Mechanical Engineering
LJMU Maritime Centre
Centre for Entrepreneurship
LJMU is highly ranked for teaching and research in Sports and Exercise Sciences. The Higher Education Funding Council for England (HEFCE) awarded LJMU £4.5 million over five years for the establishment of a Centre for Excellence in Teaching and Learning (CETL). The CETL award recognises LJMU’s record for Physical Education; Dance; Sport and Exercises Sciences. LJMU is the only United Kingdom university to be awarded an Ofsted Grade A in Physical Education and it is also the premier institution for both teaching and research in Sport and Exercise Sciences.
Research
In the 2001 Research Assessment Exercise (RAE), LJMU reported notable research strengths in general engineering and sports-related sciences. By the 2008 RAE, LJMU was the top-performing post-92 university for Anthropology; Electrical and Electronic Engineering; General Engineering; Physics (Astrophysics) and Sports-Related Studies. According to the UK Research Assessment Exercise 2014 (RAE 2014), every unit of assessment submitted was rated as at least 45% internationally excellent or better.
Liverpool John Moores University was included in the new 2013 Times Higher Education 100 under 50, ranking 72 out of 100. The list aims to show the rising stars in the global academy under the age of 50 years.
First Destination Survey results show that 89% of LJMU graduates are in employment or undertaking postgraduate study within six months of graduating.
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