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Stellar discoveries by the observatory are aiding our knowledge of ‘white dwarfs’
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Simon Jeffery, astronomer at Armagh Observatory and Planetarium
An artist's impression of Sirius A and B
NASA, ESA and G. Bacon (STScI)
An artist's impression of Sirius A and B. Credit NASA ESA and G. Bacon (Picture: Armagh Observatory and Planetarium)
NASA, ESA and G. Bacon (STScI)
A sky survey image centred on the newly-discovered O(H) star SALT J203959.5-034117 J2039 (Picture Tom Watts (AOP), STScINASA, The Dark Energy Survey on behalf of Armagh Observatory and Planetarium)
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Armagh Observatory and Planetarium has been involved in the discovery of eight new stars, some of which are many times hotter than our own sun.
The most searing has a surface temperature of 180,000K (Kelvin) — the sun’s surface is around 5,800K.
One is also the central star of a newly discovered planetary nebula that’s a light year in diameter (5.8 trillion miles).
A report co-authored by the renowned research centre is based on data gathered using the Southern African Large Telescope (SALT).
Armagh Observatory astronomer Professor Simon Jeffery said the discoveries came from surveys he has been leading for several years into a certain class of hot star.
“For the benefit of readers, it sounds as if the sun is quite hot with a temperature of around 6,000 degrees Kelvin, but we’re looking at stars which are around 20-50,000 degrees, which is obviously a lot hotter than the sun,” he explained.
It was “by chance” his study found that some of the stars turned out to be “extremely hot”.
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An artist's impression of Sirius A and B
NASA, ESA and G. Bacon (STScI)
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His survey of helium-rich sub-dwarf stars — almost completely dead stars which still radiate heat — led to the discovery of several “very hot white dwarf and pre-white dwarf stars”.
“These stars are between 100,000-180,000 degrees, so up to 20 times hotter than the surface of the sun,” he added.
“So, what started as looking at devolved stars, we ended up picking up these extraordinary objects as part of the survey.”
Two of the new stars are pulsating — or variable — stars, meaning they vary in brightness.
All are at an advanced stage of their life cycle, and “are approaching death as white dwarfs”.
White dwarfs are roughly the same size as Earth. “These discoveries will help to increase our understanding of the late stages of stellar evolution and demonstrate that SALT is a fantastic telescope for our project” said Professor Jeffery.
“It has been exciting to work with an experienced team, who collectively enabled the discovery of the stars, the analysis of their atmospheres, and the discovery of pulsations and a nebula in a very short space of time.”
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A sky survey image centred on the newly-discovered O(H) star SALT J203959.5-034117 J2039 (Picture Tom Watts (AOP), STScINASA, The Dark Energy Survey on behalf of Armagh Observatory and Planetarium)
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He added the success highlighted the day-to-day work going on in Armagh — the Observatory and Planetarium has been operating for over 200 years.
He said: “We want to continue to make discoveries which are ‘out there’ and novel.
“It’s part of what we do and a consequence of the support we get from the Department for Communities and the Science and Technology Facilities Council.
“Without making discoveries like this, we would have far less reason to exist.”
The ‘Hot White Dwarfs And Pre-White Dwarfs Discovered With SALT’ report was co-authored with universities and laboratories in Germany, Australia and South Africa.
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