New technology to efficiently measure galaxy’s size

London, Sep 4 (IANS) Astronomers from University of Cambridge have developed a new, highly accurate method of measuring distances between stars.

The team developed a novel method to determine distances between stars by relying on stellar “twins” – two stars with identical spectra.

Using a set of around 600 stars for which high-resolution spectra are available, the researchers found 175 pairs of twins.

The method can be used to measure the size of the galaxy, enabling greater understanding of how it evolved.

“Determining distances is a key problem in astronomy because unless we know how far away a star or group of stars is, it is impossible to know the size of the galaxy or understand how it formed and evolved,” explained Dr Paula Jofre Pfeil from Cambridge’s Institute of Astronomy
and the paper’s lead author.

“Every time we make an accurate distance measurement, we take another step on the cosmic distance ladder,” he added.

The technique could be a valuable complement to the Gaia satellite – which is creating a three-dimensional map of the sky over five years – and could aid in the understanding of fundamental astrophysical processes at work in the furthest reaches of our galaxy.

Gaia will be able to measure the angles of inclination with far greater precision than ever before for stars up to 30,000 light years away.

Scientists will soon have precise distance measurements for the one billion stars that Gaia is mapping – but that’s still only one percent of the stars in the Milky Way.

The researchers found that the difference of the distances of the twin stars is directly related to the difference in their apparent brightness in the sky, meaning that distances can be accurately measured without having to rely on models.

“The further away a star is, the fainter it appears in the sky, and so if two stars have identical spectra, we can use the difference in brightness to calculate the distance,” Dr Pfeil noted.

The next step is to compile a “catalogue” of stars for which accurate distances are available and then search for twins among other stellar catalogues for which no distances are available.

The details of the new technique have been published in the journal Monthly Notices of the Royal Astronomical Society.

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