Webb Can Detect Planets Orbiting White Dwarfs, And Maybe Even See Signs of Life
OCTOBER 26, 2022 BY LAURENCE TOGNETTI
In a recent study accepted to the Monthly Notices of the Royal Astronomical Society, an international team of researchers led by Texas A&M University investigate how the James Webb Space Telescope (JWST) can detect a variety of exoplanets orbiting the nearest 15 white dwarfs to Earth using its Mid-Infrared Instrument (MIRI) Medium Resolution Spectrograph (MRS). This study holds the potential to expand our knowledge of exoplanets, their planetary compositions, and if they can support life.
A white dwarf is an incredibly dense star about the size of Earth that is the result of a Sun-like star exhausting all their nuclear fuel. Essentially, a white dwarf is what our Sun will become at the end of its lifetime billions of years from now. So, why are white dwarfs of particular interest for the search for life beyond Earth?
Mary Anne Limbach, who is a PhD Candidate in the Department of Physics & Astronomy at Texas A&M University and lead author of the study, explains how difficult it is to detect biosignatures on planets within the habitable zone (HZ) of Sun-like stars due to the Sun being 10 billion times brighter than the Earth. She says this means the JWST instruments would not be able to detect an Earth-analog exoplanet due to the starlight drowning out the light of the Earth-analog that is being imaged.
“On the other hand, white dwarfs, the remnants of dead stars, are much smaller than the Sun,” said Limbach. “In fact, the size (radius) of a white dwarf is about the same as Earth. In the infrared a white dwarf is only about 100 times brighter than an Earth analog. Also, most white dwarfs do not have star spots or flares, but rather remain at constant brightness over time. So, if we instead place a white dwarf and Earth-analog at 5 parsecs, we still cannot image Earth-analog, but we should detect the 1% of extra light we receive due to the presence of an Earth. This extra light is referred to as ‘infrared excess’ which is the method we propose in the paper to detect white dwarf exoplanets.” For context, one parsec is equivalent to 3.26 light-years.
More:
https://www.universetoday.com/158341/webb-can-detect-planets-orbiting-white-dwarfs-and-maybe-even-see-signs-of-life/