Spectral ’ruler’ is first standardised way to measure stars

A team of astronomers have created the first standardised set of measurement guidelines for analysing and cataloguing stars. This is the first attempt to cover a wide range of stellar classifications, and do everything from the beginning - methodically and homogenously - Paula Jofre Previously, as with the longitude problem 300 years earlier for fixing locations on Earth, there was no unified system of reference for calibrating the heavens. But now, when investigating the atmospheric structure and chemical make-up of stars, astronomers can use a new stellar scale as a 'ruler' - making it much easier for them to classify and compare data on star discoveries. In fact, the work is a critical first step in the Gaia satellite's mission to map the Milky Way, as the unprecedented levels of stellar data that will result need "consistent stellar parameters", the same way we need values to measure everything from temperature to time, say astronomers. The guidelines are free to download and are already being used by the world's largest astronomy projects. The work has recently been published in the journal Astronomy & Astrophysics . The team, including Dr Paula Jofre from the University of Cambridge's Institute of Astronomy, selected 34 initial 'benchmark' stars to represent the different kinds of stellar populations in our galaxy, such as hot stars, cold stars, red giants and dwarfs, as well as stars that cover the different chemical patterns - or 'metallicity' - in their spectrum, as this is the "cosmic clock" which allows astronomers to read a star's age.