Chandra Reveals 'Wing' of Small Magellanic Cloud, NGC 602: Insight into Metal-Poor Stars

The Small Magellanic Cloud has fascinated astronomers for centuries. Now, they're getting an opportunity to study it like never before. New data has provided the first detection of X-ray emission from young stars with masses similar to our own sun.

Because the SMC is so close and bright, it offers an opportunity to study phenomena that are difficult to examine in more distant galaxies. Using Chandra, astronomers discovered extended X-ray emission from two of the most densely populated regions in NGC 602a, a small star cluster in the tip of the "Wing" of the SMC. The area where this is located, named NGC 602, is known for its ability to form stars and contains a collection of at least three star clusters.

Researchers have studied NGC 602a for years since it's similar in age, mass and size to the famous Orion Nebula Cluster. In the past, they've wanted to find out if young stars have different properties when they have low levels of metals.

In this latest study, astronomers discovered that the extended X-ray cloud that the data revealed probably came from the population of young, low-mass stars in the cluster, which have been previously picked out by infrared and optical surveys. This emission is not likely to be hot gas blown away by massive stars since the low metal content of stars in NGC 602a suggests that they have weak winds. In fact, researchers failed to detect emission from the most massive star in this cluster, which supports this theory since X-ray emission is an indicator of the strength of winds.

So how did the scientists detect this emission in the first place? The overlapping emission from several thousand stars was bright enough to be observed by the researchers.

The latest findings seem to suggest that young, metal-poor stars in NGC 602a produce X-rays in a manner that's similar to stars with much higher metal content found in the Orion cluster. In fact, the X-ray properties of young stars are likely to be similar even when they're in vastly different environments. Therefore, other related properties are likely to be similar--such as the formation and evolution of disks where planets form.

The findings are published online in The Astrophysical Journal.