Stellar X-rays Exceeding Safety Limits | NASA Chandra

Stellar X-rays Exceeding Safety Limits | NASA Chandra

Summary: A new study of 10 star clusters provides insight into how active Sun-like stars are when they are very young. These clusters contain stars with ages between 7 million and 25 million years old. The research combined data from NASA’s Chandra X-ray Observatory with the European Space Agency (ESA) Gaia mission. The results showed relatively constant stellar activity for the first million years and then a decline.

Astronomers have made the most extensive study yet of how magnetically active stars are when they are young. This gives scientists a window into how X-rays from stars like the Sun, but billions of years younger, could partially or completely evaporate the atmospheres of planets orbiting them.

Many stars begin their lives in “open clusters,” loosely packed groups of stars with up to a few thousand members, all formed roughly at the same time. This makes open clusters valuable for astronomers investigating the evolution of stars and planets, because they allow the study of many stars of similar ages forged in the same environment.

A team of astronomers led by Konstantin Getman of Penn State University studied a sample of over 6,000 stars in 10 different open clusters with ages between 7 million and 25 million years. One of the goals of this study was to learn how the magnetic activity levels of stars like our Sun change during the first tens of millions of years after they form. Getman and his colleagues used NASA’s Chandra X-ray Observatory for this study because stars that have more activity linked to magnetic fields are brighter in X-rays.

They combined their results for the open clusters with previously published Chandra studies of stars as young as 500,000 years old. The team found that the X-ray brightness of young, Sun-like stars is roughly constant for the first few million years, and then fades from 7 to 25 million years of age. This decrease happens more quickly for heftier stars.

This composite image shows one of those clusters, NGC 3293, which is 11 million years old and is located about 8,300 light-years from Earth in the Milky Way galaxy. The image contains X-rays from Chandra (purple) as well as infrared data from ESA’s Herschel Space Observatory (red), longer-wavelength infrared data from NASA’s retired Spitzer Space Telescope (blue and white), and optical data from the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile appearing as red, white and blue.

Color Code:

X-ray: purple; Infrared: red, blue, white; Optical: red, green, blue

Image Credit: NASA/CXC/Penn State Univ./K. Getman et al.; Infrared: ESA/NASA JPL-Caltech/Herschel Space Observatory/JPL/IPAC; NASA JPL-Caltech/SSC/Spitzer Space Telescope; Optical: MPG/ESO/G. Beccari

Release Date: Dec. 15, 2022

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