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In an encouraging sign of life beyond
earth, NASA scientists have found faint signatures of water in the atmospheres
of five distant planets.
Though the presence of atmospheric water was
reported previously on a few exoplanets orbiting stars beyond the solar system,
but this is the first study to conclusively measure and compare the profiles
and intensities of these signatures on multiple worlds, NASA said.
The five planets - WASP-17b, HD209458b, WASP-12b, WASP-19b and XO-1b - orbit
nearby stars, a NASA report said adding that this was based on the research
done through the Hubble telescope.
The strengths of their water signatures varied, it said. WASP-17b, a planet
with an especially puffed-up atmosphere, and HD209458b had the strongest
signals.
The signatures for the other three planets, WASP-12b, WASP-19b and XO-1b, also
are consistent with water, NASA said.
"We're very confident that we see a water signature for multiple
planets," said Avi Mandell, a planetary scientist at NASA's Goddard Space
Flight Center in Greenbelt, Maryland, and lead author of an Astrophysical
Journal paper, published on Tuesday, describing the findings for WASP-12b, WASP-17b
and WASP-19b.
"This work really opens the door for comparing how much water is present
in atmospheres on different kinds of exoplanets, for example hotter versus
cooler ones," Mandell said.
NASA said the five planets are hot Jupiters, massive worlds that orbit close to
their host stars. The researchers were initially surprised that all five
appeared to be hazy.
"These studies, combined with other Hubble observations, are showing us
that there are a surprisingly large number of systems for which the signal of
water is either attenuated or completely absent," said Heather Knutson of
the California Institute of Technology, a co-author.
"This suggests that cloudy or hazy atmospheres may in fact be rather
common for hot Jupiters," he added.
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