The NASA mission known as TESS (Transiting Exoplanet Survey Satellite) has been very successful and has discovered a huge number of exoplanets so far. TESS was specifically designed to detect planets orbiting distant stars, but NASA has also used the spacecraft to make other discoveries. Recently, NASA turned to TESS to discover red giant stars.
NASA says astronomers using TESS have discovered an entire collection of pulsating red giant stars across the sky. Pulsating red giant stars have rhythms produced by internal soundwaves. NASA scientists Marc Hon says that the initial results using stellar measurements taken from the first two years of TESS’s operation has allowed the team to determine the size and mass of some oscillating red giant stars.
Hon also says that as time passes, the measurements TESS can take will become more precise. Hon also notes that one of the most important factors is how unparalleled TESS’s coverage is, allowing scientists to make measurements uniformly across almost the entire sky.
Researchers are looking for soundwaves, which are capable of traveling through any object. The soundwaves reflect and interact, meaning that some of the soundwaves are canceled while others are reinforced. That phenomenon creates something called standing waves, which are responsible for creating tones in musical instruments. Below the surface of stars, hot gas rises, cools, and then sinks where it heats up again. That motion creates waves of changing pressure, which are soundwaves that interact to drive stable oscillations.
Those oscillations can last a few minutes and produce slight changes in brightness that TESS can detect. Between 2009 and 2018, a French-led spacecraft called the Convection, Rotation, and planetary Transits space telescope found tens of thousands of oscillating red giants in the sky. TESS has been able to extend that number by a factor of 10.