While trying to confirm a possible exoplanet, researchers found a different one.
Two new rocky super-Earths can be added to the now long list
of known exoplanets, worlds that orbit stars outside the Solar System. This finding
is exciting for multiple reasons. They orbit an ultra-cool star, they are
relatively close to Earth – about 100 light-years away – and one of them is in
the habitable zone, the region where a planet gets enough starlight for water
to be liquid.
As reported in the journal Astronomy & Astrophysics, the
team set out to confirm the detection of one of the exoplanets by NASA’s
planet-hunting space telescope, TESS. The planet is orbiting star TOI-4306,
which has a temperature less than half as hot as the Sun. While there, they
found another.
Exoplanets can only be confirmed when observed with two
different techniques, so this follow-up was necessary.
“This follow-up is particularly important in the case of
relatively cold stars, such as TOI-4306, which emit most of their light in the
near-infrared and for which TESS has a rather limited sensitivity,” lead author
Dr Laetitia Delrez, from the University of Liège, explained.
This follow-up actually led to a new discovery, one-upping
what TESS was able to spot.
“Using the combined near-infrared sensitive ground-based
telescopes of the SPECULOOS consortium – including the Bern led SAINT-EX
telescope in Mexico – we were not only able to confirm and characterize the
candidate planet that TESS had detected, but also discovered a rather special second,
previously unknown planet,” co-author Brice-Olivier Demory, from the University
of Bern, added.
The team estimates that both planets are made of rocky
material and they are between 30 to 40 percent larger than Earth, bigger but
not vastly different. They orbit the star respectively in 2.7 days and 8.5
days. But the star is smaller and cooler than the Sun, so the second planet is
in the habitable zone, just like our own.
“This second planet receives about the same amount of
stellar radiation as our Earth receives from the Sun and could therefore
potentially have liquid water on its surface,” said co-author Dr. Robert Wells
from the University of Bern.
“But we should not get ahead of ourselves. Being in the
right spot does not guarantee a palm beach. Our neighbor planet Venus, which
is, so to speak, a CO2-rich, near 500°C pressure cooker, is also near this
so-called habitable zone around the Sun.”
JWST may be able to study this planet's atmosphere and
determine if it has the right ingredients to be Earth-like or if it is a
different kind of world altogether.