Young stellar clusters

Jan 17, 2011
An image of the young star forming region in Perseus, as seen by the infrared cameras onboard the Spitzer Space Telescope. Young stars are seen as pinkish dots. Although the stellar population here differs from that seen in more massive clusters, new research indicates that the processes at work in these modest groups (and the consequent properties of the stars) are one end of a range of normal situations that includes both massive and smaller clusters. Credit: NASA and Spitzer

( -- Most stars are thought to form in clusters rather than in isolation, as the gas and dust in a molecular cloud coalesces under the influence of gravity until clumps develop that are dense enough to become stars. Most massive stars are also found in such groupings, rather than in isolation.

There are some nearby star-forming regions, however, that for some reason deviate from this norm: their low mass stars are found in isolation, and they have no . It is not understood whether the differences arise because there are two distinct contexts for making stars, or because normal clustering occurs across a large continuum of cloud properties with a consequent range of group characteristics.

CfA astronomers Helen Kirk and Phil Myers analyzed the mass and spatial distributions of fourteen nearby, intermediate size young stellar groups looking for evidence of a sharp distinction between clustered and isolated modes of . The groups were chosen because they are young (their stars have not moved very far away from their birthplaces), yet old enough that the mass of each young star can be accurately determined from its spectrum. In addition, the stars are spatially distinct, and the stellar population of each group has been well determined.

The astronomers conclude that, at least for the groups they examined, the properties are scaled-down versions of large cluster characteristics. The groups' masses span a wide range that is statistically consistent with the normal distribution seen, and moreover there is a correlation between the mass of the most massive star in each group and that of the whole group.

Finally, they find that the most massive member tends to be found near the center of the cluster, just as it does in more massive examples. The results, besides quantifying the cluster properties of these nearby regions, support the conclusion that there is only one mode of star formation at work in both regimes of isolated and clustered star formation.

Explore further: Is the universe finite or infinite?

add to favorites email to friend print save as pdf

Related Stories

Young Star Clusters

Oct 12, 2009

( -- Most stars form in clusters. Recent studies of nearby star forming regions find that about three-quarters of their young stars are located in groups with ten or more members. The formation ...

An abundance of small stars

Dec 10, 2010

( -- Stars form from giant clouds of gas and dust in space, as the matter in these clouds comes together under the influence of gravity.

Making massive stars

Sep 10, 2010

Massive stars -- those with more than about eight times the mass of the sun -- are arguably the most important actors in the universe. Much hotter and more luminous than the sun, they live only hundreds of ...

Hubble Sees Star Cluster 'Infant Mortality'

Jan 10, 2007

Astronomers have long known that young or "open" star clusters must eventually disrupt and dissolve into the host galaxy. They simply don't have enough gravity to hold them together, unlike their much more ...

The rate of star formation

Nov 26, 2010

( -- New stars continue to appear in the night sky, as the gas and dust in giant interstellar clouds gradually coalesces under the influence of gravity until nuclear burning begins.

Recommended for you

Is the universe finite or infinite?

23 hours ago

Two possiblities exist: either the Universe is finite and has a size, or it's infinite and goes on forever. Both possibilities have mind-bending implications.

'Teapot' nova begins to wane

Mar 27, 2015

A star, or nova, has appeared in the constellation of Sagittarius and, even though it is now waning, it is still bright enough to be visible in the sky over Perth through binoculars or a telescope.

Dark matter is darker than once thought

Mar 27, 2015

This panel of images represents a study of 72 colliding galaxy clusters conducted by a team of astronomers using NASA's Chandra X-ray Observatory and Hubble Space Telescope. The research sets new limits on ...

Galaxy clusters collide—dark matter still a mystery

Mar 26, 2015

When galaxy clusters collide, their dark matters pass through each other, with very little interaction. Deepening the mystery, a study by scientists at EPFL and the University of Edinburgh challenges the ...

Using 19th century technology to time travel to the stars

Mar 26, 2015

In the late 19th century, astronomers developed the technique of capturing telescopic images of stars and galaxies on glass photographic plates. This allowed them to study the night sky in detail. Over 500,000 ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jan 17, 2011
Speaking as a statistician, this result looks unthinking and almost stupid. It is pretty well established that the lifetimes of these star nurseries are determined by the size of the largest star formed. (When it becomes a supernova or for Wolf-Rayet stars, almost as soon as they are created.)

This means that smaller clusters have much longer lifetimes and should be vastly overrepresented in the cluster population. (I'm ignoring globular clusters, as those seem to be remnants of small galaxies stripped of their outer stars by larger galaxies (or galaxies with larger black holes.)

There is a counter bias in favor of discovering larger star forming regions, but if we try to count all clusters within say 500 parsecs we will find that large clusters are significantly overrepresented, considering their short star-forming lifetimes.

So what gives? My guess is that smaller clusters have their gas blown out by supernovas in nearby large clusters.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.