Stellar mosaic shows close relation with our galactic neighbour

Astronomers have found similarities between new-born stars in our galaxy and a neighbouring one.

An international team of astronomers at NASA used images from the Hubble Space Telescope and discovered that the percentage of new-born stars – based on mass – in the neighbouring Andromeda galaxy (M31) are similar to the stars in our galaxy.

In the study, published in Astrophysical Journal, the team assembled 414 Hubble photographs of M31 out of nearly 8,000 images of 117 million stars in the galaxy’s disk in near-ultraviolet, visible, and near-infrared wavelengths. They used the images of 2,753 young, blue star clusters to produce optical colour-magnitude diagrams and determined the initial mass function (IMF) by identifying what percentage of stars have particular mass within a cluster.

The results showed that the IMF is similar among all star clusters surveyed where the distribution of stars from blue supergiant stars to small red dwarfs is consistent.

“It’s hard to imagine that the IMF is so uniform across our neighbouring galaxy given the complex physics of star formation. Our efforts opened the door to a variety of new and interesting scientific investigations, including this new measurement of the IMF,” said research leader Dr Daniel Weisz of the University of Washington in Seattle.

By using light emission from the brightest stars, the astronomers weighed distant star clusters and galaxies and measured how rapidly the clusters are forming stars. They found that the brightest and most massive stars in these clusters are 25% less abundant than predicted in previous studies.

“The study represents the most robust measurement of the IMF to date,” the researchers said in their paper.

The scientists hope their findings will help in future interpretation of light from distant galaxies and in understanding the history of star formation in our Universe.