First nearby super-Earth
- The exoplanet is more massive than our own blue planet, and the discovery will provide insight into Earth’s heavyweight planetary cousins.
- Astronomers from the Institute of Astrophysics of the Canary Islands and the University of La Laguna, both in Spain, announced the discovery of the GJ 357 system in the journal Astronomy & Astrophysics.
- They showed that the distant solar system — with a diminutive M-type dwarf sun, about one-third the size of our own sun — harbours three planets, with one of those in that system’s habitable zone: GJ 357 d.
- Last February, the TESS satellite observed that the dwarf sun GJ 357 dimmed very slightly every 3.9 days, evidence of a transiting planet moving across the star’s face. That planet was GJ 357 b, a so-called “hot Earth” about 22 per cent larger than Earth, according to the NASA Goddard Space Flight Center, which guides TESS.
- Follow-up observations from the ground led to the discovery of two more exoplanetary siblings: GJ 357 c and GJ 357 d. The international team of scientists collected Earth-based telescopic data going back two decades — to reveal the newly found exoplanets’ tiny gravitational tugs on its host star, according to NASA.
- Exoplanet GJ 357 c sizzles at 127 degrees Celsius and has at least 3.4 times Earth’s mass. However, the system’s outermost known sibling planet — GJ 357 d, a super-Earth — could provide Earth-like conditions and orbits the dwarf star every 55.7 days at a distance about one-fifth of Earth’s distance from the sun. It is not yet known if this planet transits its sun.