University of Washington associate professor of astronomy Eric Agol suggests that it may be a lot easier for astronomers to look for and identify extrasolar planets around ancient stars called white dwarfs. He says that exoplanets might reveal themselves a lot faster than usual at these locations.
White dwarfs are the helium-burning remnants of Sun-like stars. They are generated once their predecessors go beyond their bloated, red giant phase. White dwarfs are incapable of supporting nuclear fusion any further, due to insufficient amounts of hydrogen gas.
They can exist in this state up to 3 billion years after their precursors have been extinguished. The Sun itself will enter such a phase in about 5 billion years, after becoming a red giant some 4.5 billion years into the future, experts believe.
According to a paper Agol published recently in the esteemed Astrophysical Journal Letters, searching for exoplanets around such stars might provide more results than scanning for the objects. He also argues that there is a higher chance that these objects would be habitable.
White dwarfs tip the scales at about 60 percent the mass of the Sun, but they are only about the size of Earth, which makes them extremely dense. As they lose their ability to heat their surroundings, these objects' habitable zones move a lot closer to their surface than they usually are.
“If a planet is close enough to the star, it could have a stable temperature long enough to have liquid water at the surface – if it has water at all – and that's a big factor for habitability,” Agol argues.
The expert suggests that astronomers should set up a comprehensive survey of the 20,000 white dwarfs that can be found in close proximity to our planet. The closest one is located a mere 8.5 light-years away and is called Sirius B.
A 1-meter telescope could determine whether a white dwarf hosts an exoplanet in as little as 32 hours of observations, the expert says. A network of such telescopes would finish the job a lot sooner. Also, building such machines is a lot cheaper than constructing larger observatories.
“This could take a huge amount of time, even with such a network,” Agol believes. Instruments such as the Large Synoptic Survey Telescope, for which the University of Washington is a founding partner, could also join in on the hunt,
Daily Galaxy reports.
Knowing about prospective safe places in case something happens to Earth would be a remarkable asset. “Those are the reasons I find this project interesting. And there's also the question of, 'Just how special is Earth?” the astronomer concludes.
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