Pre-main sequence low mass stars have X-ray emission 2-4 orders of
magnitude greater than main sequence stars. This emission is thought
to arise from enhanced solar--like activity including
coronae and flares. The bulk of the pre-main sequence stars observed
in X-rays are G, K and early M stars. Such bright emission can be
used to identify
young stars in the absence of other indication of youth such as a disk.
enhancements are thought to come from a rotational dynamo.
High mass stars have a different emission mechanism stemming from
their winds and can fill huge
volumes of space, parsecs on a side, with extremely hot (10MK), X-ray
We use X-ray studies of regions of star formation in
as part of an observatory wide program. The X-rays from young
stars penetrate gas and dust. This allows us to see stars in their earliest
stages as they are being built up. Infrared observations also allow us to see stars and their disks through their natal phases. Combining the observations allows us to study the survival time of planet forming disks around young stars. Studies of older clusters allows us to investigate how the stars effect planets in the earliest stages of planet formation. Some of the stars produce flares
so large that they may reach into the surrounding disk disturbing embryonic planets.
Scott Wolk, Nancy Evans, Nancy Brickhouse
Vinay Kashyap, Jeremy Drake,Tyler Bourke, Lori Allen, Robert Gutermuth
This animation shows how X-ray flares from a young star affect a planet-forming disk. Light from the young star is reflected off the inner part of the disk, making it glow. The view zooms in to show small white flares continually erupting on the surface of the young star. A set of huge white magnetic loops then erupts from the star and hits the inside edge of the disk, resulting in an extremely bright flare. X-rays from the flare then heat up the planet-forming disk and will later result in turbulence that affects the positions of planets.
At a distance of 6,000 light years from Earth, the star cluster RCW 38 is a relatively close star-forming region. This image covers an area about 5 light years across, and contains thousands of hot, very young stars formed less than a million years ago. In addition to the point-like emission from stars, the Chandra image revealed a diffuse cloud of X-rays enveloping the star cluster. The X-ray spectrum of the cloud shows an excess of high-energy X-rays coming from a 10 million degree (Kelvin) plasma.
"NGC 3576 is a giant HII region of glowing gas located about 9,000 light years
from Earth. In the Chandra image of this star forming region, lower-energy
X-rays (0.5-2.0 keV) are shown in red and higher-energy X-rays (2-8 keV) are in
blue. Chandra reveals a cluster of point-like X-ray sources, some of which are
massive young stars that are shredding the cloud of gas from which they formed.
The blue sources are stars that are deeply embedded in gas. Regions of diffuse
X-ray emission are likely caused by hot winds flowing away from the most
massive stars." Learn more...