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Cygnus OB2 is the young massive stellar association closest to our Sun.
In this new composite image, Chandra data (purple) show diffuse X-ray emission and young stars in Cygnus OB2, and infrared data from NASA’s now-retired Spitzer Space Telescope (red, green, blue and cyan) reveal young stars. and colder dust and gases throughout the region. Image credit: NASA/CXC/SAO/Drake and others. / JPL-Caltech / Spitzer / N. Wolk.
At a distance of approximately 1,400 parsecs (4,600 light years), Swan OB2 is the young massive association closest to the Sun.
It contains hundreds of massive stars as well as thousands of lower mass stars.
Dr. Mario Giuseppe Guarcello of the National Institute of Astrophysics, Dr. Juan Facundo Albacete-Colombo of the University of Rio Negro and their colleagues used NASA’s Chandra X-ray Observatory to observe different regions of Cygnus OB2 .
The extensive observations mapped the diffuse X-ray glow between the stars and also provided an inventory of the cluster’s young stars.
This inventory was combined with others using optical and infrared data to create the association’s best census of young stars.
“In these crowded stellar environments, large amounts of high-energy radiation produced by stars and planets are present,” the astronomers explained.
“Together, X-rays and intense ultraviolet light can have a devastating impact on planetary disks and forming systems.”
Protoplanetary disks around stars naturally disappear over time. Part of the disk falls on the star and another part is heated by the star’s X-rays and ultraviolet rays and evaporates in the wind.
This latter process, called photoevaporation, typically takes between 5 and 10 million years for medium-sized stars before the disk disappears.
If massive stars, which produce the most X-rays and ultraviolet radiation, are nearby, this process can be accelerated.
The researchers find clear evidence that protoplanetary disks around stars do indeed disappear much more quickly when they are close to massive stars producing lots of high-energy radiation.
The disks also disappear more quickly in regions where the stars are closer together.
For regions of Cygnus OB2 with less high-energy radiation and a smaller number of stars, the proportion of young stars with disks is about 40%.
For regions with more energetic radiation and a higher number of stars, the proportion is around 18%.
The strongest effect – that is, the worst place for a potential planetary system to be – is about 1.6 light years from the most massive stars in the cluster.
In a separate study, the same team examined the properties of diffuse X-ray emission in Cygnus OB2.
They found that the higher-energy diffuse emission came from areas where winds of gas blowing from massive stars had collided.
“This makes the gas hotter and produces X-rays,” they said.
“The least energetic emission likely comes from gas in the cluster colliding with gas surrounding the cluster.”
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MG Guarcello and others. 2024. Photoevaporation and close encounters: how the environment around Cygnus OB2 affects the evolution of protoplanetary disks. ApJS 269, 13; doi: 10.3847/1538-4365/acdd67
JF Albacete-Colombo and others. 2024. Diffuse X-ray emission in the Cygnus OB2 association. ApJS 269, 14; doi: 10.3847/1538-4365/acdd65
Disclaimer: The content on this website is provided for educational and informational purposes only.