White Dwarf Stars May Be Best Chance for Discovering Extra-terrestrial Life
A new study titled, "Detecting Bio-Markers In Habitable-Zone Earths Transiting White Dwarfs", published by the Royal Astronomical Society, has concluded that dying White Dwarf systems could host planets with life and they might be able to detect it within the next decade.
When a star dies, it ejects its outer layers, leaving behind a hot core called a white dwarf, which is typically about the size of Earth. It slowly cools and fades over time, but it can retain heat long enough to warm a nearby world for billions of years.
White dwarfs help in the search for extra-terrestrial life by first finding the planets that exist in the habitable zone of white dwarfs. This can be achieved by observing lights from a star and checking to see if it dims at regular intervals – a phenomenon that suggests the starlight is being blocked by an orbiting planet.
Once a planet is discovered orbiting around a white dwarf, the next stage is to determine if it can sustain life. For tell-tale signs of life, astronomers are particularly interested in finding oxygen. According to the study, oxygen could be detected in the atmosphere of a white dwarf's planet much more easily than for an Earth-like planet orbiting a Sun-like star. They found that both oxygen and water vapor would be detectable with only a few hours of total observation time.
You can read more here.