With an age of 4.57 billion years, the Sun is currently in its comfortable middle age, fusing hydrogen into helium and generally being rather stable; staid even. That will not always be the case. As the hydrogen fuel runs out in its core, and changes begin in the fusion process, astronomers expect it to swell into a red giant, lowering its surface temperature in the process. Exactly how this happens depends on how much mass a star contains and its chemical composition. This is where the third data release (DR3) of ESA’s Gaia star-mapping mission comes in.
On August 31, 2012, a long filament of solar material that had been hovering in the Sun’s atmosphere, the corona, erupted out into space at 4:36 p.m. EDT. The CME traveled at over 900 miles per second. It did not travel directly toward Earth, but did connect with Earth’s magnetic environment, or magnetosphere, with a glancing blow, causing aurora to appear on the night of September 3. Image credit: NASA’s Goddard Space Flight Center.
In a new study, Dr. Orlagh Creevey from the Observatoire de la Côte d’Azur and colleagues combed the Gaia DR3 data looking for the most accurate stellar observations that the spacecraft could offer.
“We wanted to have a really pure sample of stars with high precision measurements,” Dr. Creevey said.
The astronomers concentrated their efforts on stars that have surface temperatures of between 3,000 and 10,000 K because these are the longest-lived stars in the Milky Way and hence can reveal the history of our Galaxy.
These star are also promising candidates for finding exoplanets because they are broadly similar to the Sun, which has a surface temperature of 6,000 K.
More than 4 million stars within 5,000 light-years from the Sun are plotted on this diagram using information about their brightness, color and distance from the second data release from ESA’s Gaia satellite. It is known as a Hertzsprung-Russell diagram after the astronomers who devised it in the early 20th century, and it is a fundamental tool to study populations of stars and their evolution. Image credit: Gaia Data Processing and Analysis Consortium (DPAC) / Carine Babusiaux, IPAG / Université Grenoble Alpes, GEPI / Observatoire de Paris.
Next, the researchers filtered the sample to only show those stars that had the same mass and chemical composition as the Sun.
Since they allowed the age to be different, the stars they selected ended up tracing out a line across the Hertzsprung-Russell diagram that represents the evolution of the Sun from its past into its future.
It revealed the way our star will vary its temperature and luminosity as it ages.
From the work, it becomes clear that our Sun will reach a maximum temperature at approximately 8 billion years of age, then it will cool down and increase in size, becoming a red giant star around 10-11 billion years of age.
The Sun will reach the end of its life after this phase, when it eventually becomes a dim white dwarf.
Finding stars similar to the Sun is essential for understanding how we fit into the wider Universe.
“If we don’t understand our own Sun — and there are many things we don’t know about it — how can we expect to understand all of the other stars that make up our wonderful Galaxy,” Dr. Creevey said.
To identify ‘solar analogues’ in the Gaia data, the scientists looked for stars with temperatures, surface gravities, compositions, masses and radii that are all similar to the present-day Sun.
They found a total of 5,863 stars that matched their criteria.
“We fully encourage all users to exploit all of the astrophysical parameters in Gaia DR3 independent of our specific selection criteria highlighted in our work,” they said.
“Indeed, there are up to 470 million stars with stellar parameters, up to 130 million masses and ages, and many other new stellar products that have not been mentioned in the work.”
The team’s paper was published in the journal Astronomy & Astrophysics.
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O.L. Creevey et al. 2022. Gaia Data Release 3: A golden sample of astrophysical parameters. A&A, in press; doi: 10.1051/0004-6361/202243800
Source link: https://www.sci.news/astronomy/sun-future-11093.html
