Super-Earth Found Orbiting Nearby Star

Gliese 536, also known as GJ 536 and HD 122303, is a high proper-motion M1-type star of about half the mass of the Sun.

The star’s low activity combined with its long rotation period of 45 days makes it a very promising candidate to search for terrestrial planets. The newfound planet, Gliese 536b (or GJ 536b), is about 5.4 times as massive as the Earth.

It has an orbital period of 8.7 days and is about 0.067 AU (astronomical units) from the parent star — much closer than our planet is to the Sun.

“So far the only planet we have found is Gliese 536b, but we are continuing to monitor the star to see if we can find other companions, rocky planets are usually found in groups, especially around stars of this type, and we are pretty sure that we can find other super-Earths in orbits further from the star, with periods from 100 days up to a few years.” said team member Alejandro Suarez Mascareno, from the Instituto de Astrofísica de Canarias and the University of La Laguna, Spain.

According to Suarez Mascareno and co-authors, Gliese 536b is too close to its star to be considered habitable. Based on the planet’s distance from the star, they estimate that the planet’s temperature ranges between 158 and 417 degrees Fahrenheit (70 – 214 degrees Celsius).

“For Gliese 536 the orbital periods of the habitable zone would be from 20 days to 40 days,” they explained.

Gliese 536b was detected using the HARPS spectrograph on the 3.6-m telescope at ESO’s La Silla Observatory in Chile and the HARPS-North instrument on the Telescopio Nacional Galileo at the Roque de los Muchachos Observatory in the Canary Islands.

“This rocky exoplanet is orbiting a star much smaller and cooler than the Sun, but sufficiently nearby and bright, it is also observable from both the northern and southern hemispheres, so that it is a very interesting for future high stability spectrographs and, in particular, for the possible detection of another rocky planet in the habitable zone of the star.” said team member Dr. Jonay Gonzalez Hernandez, also from the Instituto de Astrofísica de Canarias and the University of La Laguna.

The discovery is reported in the journal Astronomy & Astrophysics ( preprint).


Earth-Like Planets

Super Earth

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