{"id":15741,"date":"2022-07-21T17:00:12","date_gmt":"2022-07-21T15:00:12","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=124378"},"modified":"2022-07-21T17:07:10","modified_gmt":"2022-07-21T15:07:10","slug":"earliest-stars-in-the-universe-observed-by-astronomers-peering-through-a-foggy-cosmic-dawn","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/earliest-stars-in-the-universe-observed-by-astronomers-peering-through-a-foggy-cosmic-dawn\/","title":{"rendered":"Earliest stars in the universe observed by astronomers peering through a foggy cosmic dawn"},"content":{"rendered":"

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By Neil McKim\n \t\t<\/p>

Published: Thursday, 21 July 2022 at 12:00 am<\/p>

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Observing the birth of the first stars and galaxies has been a sought-after goal of astronomers for decades. And now a worldwide team, co-led by the Universities of Cambridge and Stellenbosch, South Africa, has developed a technique to observe and study these ancient stars\u00a0by looking through the clouds of fog<\/a> that filled the Universe around 378,000 years after the Big Bang.<\/p>\n

The team\u2019s research, part of the REACH (Radio Experiment for the Analysis of Cosmic Hydrogen) experiment, will allow astronomers to observe the earliest stars by studying these primordial hydrogen clouds with a radio telescope \u2013 in the same way we might define a landscape by looking at shadows in the fog.<\/p>\n

\u201cAt the formation of the first stars, the Universe was mostly empty and composed mostly of hydrogen and helium. Because of gravity, these elements eventually came together and the conditions were right for nuclear fusion<\/a>, which is what formed the first stars,\u201d said lead researcher Dr Eloy de Lera Acedo<\/a>, from Cambridge\u2019s Cavendish Laboratory.<\/p>\n

\u201cThey were surrounded by clouds of so-called neutral hydrogen, which absorb light really well, so it\u2019s hard to detect or observe the light behind the clouds directly.\u201d<\/p>\n

The REACH team has had to overcome issues relating to radio telescope observations \u2013 where distortions are introduced to the signal received \u2013 which can completely obscure a cosmological signal of interest.<\/p>\n

Furthermore, the elusive signal the team is searching for is expected to be around 100,000 times weaker than other radio signals coming from the sky \u2013 for example, those from our own Galaxy.<\/p>\n

To study the cosmic dawn, the team are looking at the \u201821cm line\u2019 (also known as the Hydrogen line, or H I line) \u2013 an electromagnetic radiation signature from hydrogen in the early Universe.<\/p>\n

They are looking for a radio signal that measures the contrast between the radiation from the hydrogen and the radiation behind the hydrogen fog.<\/p>\n

The REACH researchers have used simulations to mimic a real observation using multiple antennas \u2013 when earlier observations have relied on a single antenna \u2013 to improve the reliability of the data.<\/p>\n

\u201cWe forgot about traditional design strategies and instead focused on designing a telescope suited to the way we plan to analyse the data \u2013 something like an inverse design,\u201d said de Lera Acedo. \u201cThis could help us measure things from the cosmic dawn and into the epoch of reionisation, when hydrogen in the Universe was reionised.\u201d<\/p>\n

With the research method in place, the first observations from the REACH telescope are expected later this year. Meanwhile, its construction is being finalised at the Karoo radio reserve in South Africa, a location which boasts excellent conditions for radio observations.<\/p>\n