What is a Super-Earth?

July 10, 2024

New information has been found about LHS 1140 b, an exoplanet 48 light-years away in the constellation Cetus. The team of foreign researchers was led by the Université de Montréal. Their study, which was published in The Astrophysical Journal Letters, suggests that LHS 1140 b may be a super-Earth that is probably full of water or ice. This goes against the earlier idea that it was a miniature Neptune.

Initial Assumptions

LHS 1140 b was once thought to be a small Neptune with a thick, hydrogen-rich atmosphere. This classification was based on how big it was and what scientists thought it was made of based on studies made with telescopes in the past.

Groundbreaking Data from JWST

Scientists’ ideas about LHS 1140 b have changed since they got new information from the James Webb Space Telescope (JWST). Based on the findings, the planet might not have a gas envelope but instead have a rocky or water-rich surface. Dr. Charles Cadieux, the study’s lead author, talked about how LHS 1140 b might have liquid water, highlighting the planet’s fit for more research into habitability.

Planetary Characteristics and Habitability

LHS 1140 b goes around a red dwarf star in its habitable zone. This is the range of distances where temperatures are right for water to be liquid. This area is very important for keeping life going as we know it. When you look at JWST data along with data from other space telescopes, you can see that the atmosphere is nitrogen-rich, like Earth’s. Ryan MacDonald, a contributing NASA Sagan Fellow, said that this was the first time that an atmosphere in these conditions had been seen around a world that might be rocky or icy.

Potential Water Composition and Climate

The study thinks that water could make up 10 to 20% of LHS 1140 b’s mass. Models of the future imagine a “snowball” state with a large marine area and a comfortable temperature of about 20 degrees Celsius in the middle. This temperature is very mild and good for living things.

About LHS 1140 b

Discovery and Characteristics: LHS 1140 b is an exoplanet discovered in 2017, orbiting the red dwarf star LHS 1140, located about 49 light-years away in the constellation Cetus. It is roughly 1.4 times the size of Earth but nearly 7 times more massive, suggesting a dense, possibly rocky composition.
Habitability Potential: Significantly, LHS 1140 b resides in the star’s habitable zone, where temperatures could allow liquid water to exist. The planet receives only about half as much sunlight from its star as Earth does from the Sun, offering a unique environment for potential life.
Observational Advantages: Unlike many exoplanets, LHS 1140 b transits its star, making it easier to study its atmosphere and composition. Despite its proximity and favorable observation conditions, its atmosphere and surface conditions remain subjects of ongoing research.

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