Chandra X-ray study reveals young stars in cluster

Most stars begin their lives in clusters before dispersing.
By Laurel Kornfeld | May 03, 2018
By studying the stars in a cluster in X-ray wavelengths using NASA's Chandra X-ray Observatory, scientists successfully identified the cluster's young stars, all of which originated in the same cloud of gas and dust.

Most stars, including our Sun, are believed to form in clusters whose individual stars are gravitationally bound to one another. The stars often disperse once star formation in the cluster stops.

The cluster in which our Sun formed likely dispersed approximately 4.6 billion years ago. However, by studying other young clusters where star formation is still ongoing, astronomers can learn more about stars' formation and evolution processes.

A group of researchers used Chandra to observe NGC 6231, a cluster approximately 5,200 light years from Earth located in the southwest region of the "tail" in the constellation Scorpius. This cluster was discovered in 1654 by the Italian mathematician Giovanni Battista Hodierna.

Until now, young Sun-like stars in the cluster have been difficult to see because they are both hidden and outnumbered by older stars either in front of or behind them in the plane of the Milky Way. The older stars wandered into the area and are not part of the cluster.

Chandra can identify the younger stars that are part of the cluster by searching for characteristics typical of young stars, such as strong magnetic activity, which heats up their outer layers to tens of millions of degrees Celsius, causing the stars to emit X-rays.

An image of the inner cluster taken by Chandra was done by dividing X-ray light into three bands--red, green, and blue, which represent a spectrum of X-rays from lower to higher energy.

The scientists then combined data collected by Chandra with infrared data taken of the same cluster by the European Southern Observatory's (ESO) Visible and Infrared Survey Telescope for Astronomy Variables (VISTA) in the Via Lactea Survey to produce the most accurate census of young stars in the cluster.

They counted 5,700 to 7,500 young stars in the Chandra image, which provided the most detailed ever look at a cluster in which star formation has just ended.

Additionally, they determined that while NGC 6231 has expanded from its initial, more compact state, it has not done so sufficiently for individual stars to escape its gravitational pull.

To gain an understanding of young clusters' properties, scientists compare data regarding the sizes, masses, and ages of many different star clusters.

Two separate papers have been published on the Chandra study of NGC 6231 in The Astronomical Journal.



We are dedicated to maintaining a respectful community that actively engages in lively discussions about news stories and blog posts. Please keep the following in mind when writing your comments.