viernes, 4 de septiembre de 2015

THE SECRETS TO STAR BIRTH IN ANDROMEDA GALAXY

Andromeda Galaxy

NASA's Hubble Space Telescope has revealed a bit more about star birth in a neighboring galaxy. The telescope has taken images of 2,753 young, blue star clusters in the neighboring Andromeda galaxy (M31) and has shown that this galaxy and our own have a similar percentage of newborn stars based on mass.

"Given the sheer volume of Hubble images, our study of the IMF would not have been possible without the help of citizen scientists," said Daniel Weisz, one of the researchers, in a news release.

Stars are born when a giant cloud of molecular hydrogen, dust and trace elements collapses. The cloud fragments into small knots of material that each precipitate hundreds of stars. The stars are not all created equally; their masses can range from 1/12th to a couple hundred times the mass of our sun.

In this case, the researchers managed to nail down what percentage of stars have a particular mass within a cluster, also known as the Initial Mass Function. This allows scientists to better interpret the light from distant galaxies and understand the formation history of stars in our universe.

Prior to Hubble's survey of the Andromeda galaxy, astronomers only had IMF measurements made in the local stellar neighborhood within our own galaxy. Hubble's bird's-eye view of M31, though, allowed astronomers to compare the IMF among a larger-than-ever sampling of star clusters that are approximately the same distance from Earth, 2.5 million light-years.

Surprisingly, the researchers found that the brightest and most massive stars are 25 percent less abundant than predicted. The researchers believe that mass estimates using previous work were too low because they assumed that there were too few faint, low-mass stars forming along with the bright, massive stars. This, in particular, implies that the early universe did not have as many heavy elements for making planets.