NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton have observed stars that are close enough to be prime targets in the search for direct images of planets using future telescopes. Astronomers are using this X-ray data to determine how habitable exoplanets may be, based on whether they receive lethal radiation from the stars they orbit, as described in our latest press release. This type of research will help guide observations with the next generation of telescopes, which seek to capture the first images of Earth-like planets.
Researchers examined stars close enough to Earth so that telescopes, which will begin operating in the next decade or two, including the Habitable Worlds Observatory in space and Extremely Large Telescopes on the ground, can image planets in the so-called habitable zones of stars. This term defines the orbits where planets could have liquid water on their surfaces.
There are several factors that influence what might make a planet suitable for life as we know it. One of those factors is the amount of harmful X-rays and ultraviolet light they receive, which can damage or even strip the planet’s atmosphere. Based on X-ray observations of some of these stars using data from Chandra and XMM-Newton, The research team examined which stars might have conditions conducive to life forming and thrive on the planets they orbit. They studied how bright stars are in X-rays, how energetic the X-rays are, and how much and how quickly they change in X-ray emission, for example due to flares. Brighter, more energetic X-rays can cause more damage to the atmospheres of the planets they orbit.
The researchers used nearly 10 days of Chandra observations and about 26 days of XMM observations., available in archives, to examine the X-ray behavior of 57 nearby stars, some of them with known planets. Most of these are giant planets like Jupiter, Saturn or Neptune, while only a handful of planets or planet candidates could be less than about twice the mass of Earth.
These results were presented at the 244th meeting of the American Astronomical Society in Madison, Wisconsin, by Breanna Binder of California Polytechnic State University in Pomona. NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
