Australian observatory hunts Earth-like planets by watching for wobbling stars
A powerful new tool designed to aid in the search for Earth-like exoplanets has been installed onto an Australian telescope. Dubbed Veloce, the instrument is designed to look out for the signature wobble of a star caused by the gravitational tug of orbiting planets, and it specializes in red dwarfs – the most common type of star in the universe.
According to NASA, there are currently over 3,800 confirmed planets orbiting stars other than the Sun, but given how comparatively dim they are they need to be detected indirectly. The most common technique, used by telescopes such as the recently-retired Kepler or the newly-launched TESS, involves watching for the shadows of planets passing in front of stars, in what's known as the transit method.
But that can't teach us everything. Other instruments can back up these observations by looking at the radial velocity of stars – the way they wobble as they swing planets around. The size of that movement can give astronomers a better understanding of the mass of those planets.
And that's just what Veloce is designed to do. This instrument was recently installed on the Anglo-Australian Telescope (AAT) at the ANU Siding Spring Observatory in New South Wales.
"Veloce will allow us to detect the tiny velocity wobbles that planets produce in their host stars," says Chris Tinney, an exoplanetary scientist from the University of New South Wales (UNSW). "It is the first Australian facility able to deliver the extraordinarily high velocity precision needed to detect very small planets. These planets are important, because it's on these small, rocky and potentially habitable planets that astronomers will one day search for signs of life."
Veloce is particularly well-suited to studying planets around red dwarfs, and is the only such instrument in the Southern Hemisphere. It works at the wavelengths of light that these faint stars give off, and since any potentially habitable planets need to tuck up nice and close to these relatively cool stars to keep warm, the wobbles they cause in the star are more pronounced.
Veloce began its science operations back in September, first looking at the nearby Sun-like star Tau Ceti, before moving on to examine stars that are already known to either host or not host planets, in order to test how stable the instrument is. Its first real job was to help confirm some of the 75 exoplanet candidates identified by TESS during its first month of observations.
"There now is a global race on to be first to measure the masses of these planets, and to determine whether they are rocky like Earth, ice giants like Neptune, or gas giants like Jupiter," says Tinney. "Or, even better, if they are something stranger. Veloce is one of just a handful of facilities available in the Southern Hemisphere that can transform those candidates into confirmed planets with measured masses. And it's the only one working at the red wavelengths ideal for observing these faint, red, M-dwarf planet hosts."
Veloce's first test results are expected to be delivered within the next month or so. Here's to many years of hunting down small, Earth-like exoplanets that could be the best places to search for extraterrestrial life.