NASA scientists have devised a new way to use planets that cross, or “transit,” the face of their parent stars to investigate stellar “spottiness.” The new technique, called the “StarryStarryProcess,” could also be used to discover more about the atmospheres of planets.
The StarryStarryProcess builds upon the transit method that has been employed by NASA’s TESS (Transiting Exoplanet Survey Satellite) and now-retired Kepler space telescope missions to detect exoplanets. It could be employed by astronomers to assess data from these missions and from NASA’s forthcoming Pandora exoplanet-observing satellite.
“Many of the models researchers use to analyze data from exoplanets, or worlds beyond our solar system, assume that stars are uniformly bright disks,” study team leader Sabina Sagynbayeva, of Stony Brook University in New York, said in a statement. “But we know just by looking at our own sun that stars are more complicated than that. Modeling complexity can be difficult, but our approach gives astronomers an idea of how many spots a star might have, where they are located and how bright or dark they are.”
What do transits tell us?
TESS and Kepler have used the transit method to great effect to discover planets beyond the solar system. In fact, the majority of the over 5,000 worlds in the exoplanet catalog were discovered via the tiny dips in starlight they cause as they cross the face of their parent star.
Tracking how a star’s light changes as a planet moves across its face from our position here on Earth helps build a light curve. Brightness falls slightly as the planet moves in front of the star, with minimum brightness achieved when the exoplanet is fully in front of the star. The brightness then steadily increases as the planet moves past the star, bringing the transit to a close.
In addition to helping discover planets, measuring transits can help determine the distance between a planet and its star, as well as the planet’s size and rough surface temperature. Additionally, because chemicals absorb light at characteristic wavelengths, as starlight passes through the atmosphere of a planet, a process called spectroscopy can be used to determine the chemical composition of that atmosphere.
However, astronomers often find that light curves aren’t as straightforward as they appear. In addition to the drops caused by planetary transits, scientists have spotted dips that…
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