TRAPPIST-1, an ultracool dwarf star located just
40 light-years from Earth in the Aquarius constellation,
was first detected by researchers from Liege using
the Transiting Planets and Planetesimals Small
Telescope (TRAPPIST) in Chile, and later confirmed by
NASA’s Spitzer Space Telescope and the Very Large
Telescope, also in Chile.The planets were detected by
observing dips in the star’s light output caused by each
of the seven planets passing in front of it, events known
as transits. The researchers found that all of the planets
are comparable in size to the Earth, while density
measurements suggest that the innermost six are rocky.
Current climate models suggest the three innermost
planets are probably too hot to support liquid water,
and the one furthest from the star is too cold. However,
the remaining three sit comfortably within the habitable
zone and could host oceans of surface water –
a feature thought to be essential for the existence of life.
“The energy output from dwarf stars like TRAPPIST-1
is much weaker than that of our Sun. Planets would need
to be in far closer orbits than we see in the Solar System
if there is to be surface water,” said researcher
Dr Amaury Triaud. “Fortunately, it seems that this kind
of compact configuration is just what we see
around TRAPPIST-1.”June 2017 21DISPATCHES
F R O M T H E
CUTTING EDGE
DISCOVERIES