Hubble Images Provide Insight on Star Birth in a Neighboring Galaxy

Using the NASA Hubble Space Telescope images, astronomers recently discovered that our galaxy and our neighboring Andromeda galaxy (M31) have more in common that we thought. The telescope captured images of 2,753 young, blue star clusters in M31, which shows us this galaxy and our own have a similar percentage of newborn stars based on mass.

The researchers in part determined the percentage of stars that have a particular mass within a cluster. This is called the Initial Mass Function (IMF). From this, researchers can better interpret the light from distant galaxies and understand the formation history of stars in our universe. They also obtained 8,000 images of 117 million stars by looking at the Andromeda galaxy in near-ultraviolet, visible, and near-infrared wavelengths, according to a release.

Citizen scientists helped in going through the huge volume of Hubble images, submitting 1.82 million classifications regarding the images, based on the stars' concentration levels, shapes, and how distinctively the stars stood out from their background. "Given the sheer volume of Hubble images, our study of the IMF would not have been possible without the help of citizen scientists," Daniel Weisz, lead author from the University of Washington in Seattle, said in that release.

The release also explained that stars are born when a giant cloud of molecular hydrogen, dust and trace elements collapses. The cloud then breaks apart into small knots of material that each precipitates hundreds of stars of varying sizes.

According to their study, the IMF was very similar among all the clusters surveyed. Surprisingly, they also found that the brightest and most massive stars in these clusters are 25 percent less abundant that previously predicted.

"It's hard to imagine that the IMF is so uniform across our neighboring galaxy given the complex physics of star formation," Weisz said in the release.

The researchers were able to measure how rapidly the clusters are forming stars by using the light from these brightest stars to weigh distant star clusters and galaxies. This evidence suggests that previous predictions were low due to too few faint, low-mass stars forming along with the bright, massive stars. From this, the researchers concluded that the early universe did not have as many heavy elements for making planets.

Their findings were published in Astrophysical Journal.