Astronomers were able to create a guide that would help scientists detect signs of alien life in exoplanets that orbit dead stars. The guide works by observing exoplanet systems using space telescopes.

When it comes to the search for Earth-like planets, astronomers turn to distant star systems. These systems are often inhabited by a white dwarf, which is the remains of a dead star, and orbiting exoplanets.

Exoplanet
K2-33b, shown in this illustration, is one of the youngest exoplanets detected to date using NASA Kepler Space Telescope. It makes a complete orbit around its star in about five days. These two characteristics combined provide exciting new directions for planet-formation theories. K2-33b could have formed on a farther out orbit and quickly migrated inward. Alternatively, it could have formed in situ, or in place. NASA/JPL-Caltech

Finding Life In Exoplanets

Currently, astronomers try to determine the capability of an exoplanet to support life by analyzing its physical characteristics. Recently, astronomers developed a guide that could tell if alien life exists on an exoplanet. Details of their findings were presented in a study published in The Astrophysical Journal Letters.

They created a spectral field guide that contains models of different atmospheres at different temperatures, which serve as templates for an exoplanet's biosignature. Biosignatures are chemical traces found in an exoplanet's atmosphere. They are usually produced by the presence of life on the planet.

Identifying Exoplanets With Alien Life

To use the guide, astronomers using space telescopes should observe an exoplanet as it crosses in front of a white dwarf or its host star in order to see into its atmosphere. Using the collected data, they can then refer to the guide to check for signs of life.

"We are hoping for and looking for that kind of transit," doctoral candidate in astronomy Thea Kozakis, the lead author of the study, said in a statement. "If we observe a transit of that kind of planet, scientists can find out what is in its atmosphere, refer back to this paper, match it to spectral fingerprints and look for signs of life. Publishing this kind of guide allows observers to know what to look for."

White dwarf stars, which our Sun will eventually become, will become a solid crystal, according to new research. Pictured: In this NASA handout, the Moon transits across the Sun, as seen in 304 angstrom extreme ultraviolet light during the total eclipse M
White dwarf stars, which our Sun will eventually become, will become a solid crystal, according to new research. Pictured: In this NASA handout, the Moon transits across the Sun, as seen in 304 angstrom extreme ultraviolet light during the total eclipse Monday, August 21, 2017. NASA

Studying The Evolution Of Alien Life

Through the guide, astronomers are hoping to identify certain spectral biosignatures in a planet's atmosphere such as methane and nitrous oxide. As noted by the astronomers, these kinds of chemicals would indicate that life is thriving on the exoplanet. Once this discovery has been made, they could then focus on studying how life was affected by the death of the host star as it turned into a white dwarf.

"If we would find signs of life on planets orbiting under the light of long-dead stars, the next intriguing question would be whether life survived the star's death or started all over again—a second genesis, if you will," the study's co-author Lisa Kaltenegger said.