The exoplanet GJ 215 c. Can host lifeforms in the future.

“An international team of scientists dubbed the exoplanet, named GJ 251 c, a “super-Earth” as data suggest it has a rocky composition similar to Earth and is almost four times as massive. Credit: Illustration by University of California, Irvine.” (ScitechDaily, Astronomers Discover Potentially Habitable “Super-Earth” Just 18 Light-Years Away)

The new exoplanet. From 18 ly. away from Earth, can have liquid water on its surface. The exoplanet  GJ (Gliese) 251 c orbits the M-class star in a potentially habitable zone. The  GJ 251 c is a massive super-Earth that orbits the star GJ 215. That star has a spectral classification of M3V, and its age is about 6,6 GYR (Gigayears). Or, a simpler saying. 6,6 billion years. This means that. This M3V is still in its flare period. And there might not be lifeforms. On that exoplanet. Life formation begins after the flare period. The GJ 215 has two exoplanets. GJ 215b, whose mass is ≥ 3.85+0.35−0.33 Earth masses. And GJ 215 c, whose mass is ≥3.84±0.75 Earth masses. 

This means lifeforms start to advance later than on planets. That orbit the Sun (G2) type stars. But otherwise, the red dwarfs can live Tens to hundreds of billions of years. That means life has more time to advance on those planets than on planets that orbit G2V-type stars. In the future. The GJ215c might host. 

Even intelligent lifeforms.  But today, its star is too unstable for that. Those hypothetical civilizations require more mature stars. The problem with the red dwarf planets and technocivilization. This is how long radioactive isotopes can exist on those planets. There is a possibility that some of those planets run out of their fissile material. 

And their cores start to cool. That cooling process destroys the planet’s magnetic field. Those super-Earths that orbit M-type stars give a hint. About the possibility of lifeforms. Those super-Earths with a dense atmosphere can host life, but the star must be mature enough that it has ended its flare period. Those flares that the young red dwarfs create. It can raise. Those planets' temperatures. Into thousands of degrees. 

The atmosphere of those locked planets smooths their atmosphere’s temperature. All red dwarf-star planets that are in the habitable zone are locked. The tidal forces from the star lock the planet into position. There, it turns the same side to that star all the time. There is forever night in the side that is away from its star. And the other side is burning hot. The water and atmosphere, along with clouds, can smooth that effect. But that requires. The star will not create. It's flares anymore. 

https://science.nasa.gov/exoplanet-catalog/gj-251-c/

https://scitechdaily.com/astronomers-discover-potentially-habitable-super-earth-just-18-light-years-away/

https://en.wikipedia.org/wiki/Gliese_251

https://en.wikipedia.org/wiki/Stellar_classification

https://en.wikipedia.org/wiki/Sun

A new theory tries to explain how massive rocky planets form.

The super-Earth or massive rocky planets are a mystery. A new theory tries to explain why those rocky planets exist. Or why are no large rocky planets in some solar systems? Earth is the largest rocky planet in our solar system. And that thing might open a new way to think about the formation of giant rocky planets. 

The rocky planet can form in the distance from the star there is no iced gas. There must be enough heavy or solid elements that those planets can form. 

There is the possibility that the super-Earth is forming if there is no disturbance or not enough debris in the young solar system. That means the gravitational center that forms in the stable debris or planetary disk. That forms the super-Earth. The material continues to accumulate on that planet until there is no material in the planet's trajectory. Or some other thing like cosmic impact or eruption from a star stops the accumulation. 

The idea is that if there is no disturbance in that material disk. The gravitational center collects all material at one point. The disturbance, like energy impact or gravitational interaction, can cause a situation where the asteroids in that planetary disk start to change their trajectory.

Then that thing will break the rocky giant to pieces. That means the super-Earth can form when debris can accumulate without disturbance. The disturbance breaks the proto-planets. There are lots of eruptions in the young stars. And if the fusion reactions start at the wrong moment the energy impact from the star pushes the planet's shell away.  

If the young star is very active and erupts very often it can push dust and solid elements farther. Or at least out from the protoplanet's trajectory. The thing in planet formation is this. Planet's size will accumulate unless there is no dust in its gravitational field. So rocky planets form in distance from the center star where the star blows most of the light elements away. The radiation pressure from the star could clean some areas from the gas. And that is the area where rocky planets are forming. 

When we think about the gas giants that are extremely hot and orbit near their star those gas giants should form at longer distances. And then some cosmic disturbance or catastrophe would push those gas planets near their central star. The gas giant that orbits its star in an extremely short range must have a strong enough gravitational field so that the solar wind will not blow its atmosphere away.

If the planet's gravitational field is too weak, it loses its atmosphere and gas elements. So some rocky planets can be remnants of super-Earth. The liquid planet is elastic. And it stands for more powerful impacts than the rocky planet. When some gas giant impacts another planet its core can remain untouchable. That nucleus remains a remnant of the large gas planet even if cosmic impact blows its gas layer away. 

The planets start to form around heavy elements. For a long time, there is a dust cloud around that point. And the eruption from the star can push the dust away from the planet's trajectory. If that kind of eruption happens before gravitation pulls the planet to thick form this thing can destroy the entire protoplanet. 

When the protoplanet starts its formation the planet is not very thick. Before gravitational effects are strong enough the planet is not anything than some sand cloud. And if the fusion reactions in the star start or there is an eruption that would blow thin dust around the rocky planet away. 

https://scitechdaily.com/unlocking-the-mystery-of-super-earths-caltech-scientists-unveil-a-new-unified-theory/

https://astronomyandtechnology.blogspot.com/

Some planets are unlike any planet in our solar system.

The exoplanet Kepler 138d is a water world. The giant ocean and water vapor cover the entire planet. And there is the large solid nucleus and that planet's mass is 1,17 times Earth's. The size of that exoplanet is larger than Earth's. 

Its classification is "super earth".  But in the case of Kepler 138 d that classification comes from its size. Not from its gravitation. The mass of Kepler 138 d is, depending on sources 0,6-1,17 Earth. 

A planet's mass determines its gravitational field and whether it is larger than Earth. But if the mass of the planet is the same or less, it means that there are fewer heavy elements than on Earth. If a planet has a greater mass than Earth but is smaller in size.

This tells us that there are more heavy elements than there are on Earth. In other words, a planet may be smaller in size than Earth, but its gravitational field may be stronger than Earth's.

So because the mass of the Kepler 138d is almost similar to Earth that makes this planet interesting. There is some conflict between the sources that determine the mass of Kepler 138d. Wikipedia tells. That the mass of Kepler 138d is 1,17 Earth mass(1). 

But NASA's database tells. That the mass of Kepler 138d is 0,64 Earths. (2)If the last of those numbers is true. That means there are not so many heavy elements on that planet as on Earth. 

(1) https://en.wikipedia.org/wiki/Kepler-138

(2)https://exoplanets.nasa.gov/exoplanet-catalog/1557/kepler-138-d/

But its size is bigger which means the solid core of that planet is not formed of at least very heavy elements. There are fewer heavy elements than on Earth. And that makes Kepler 138d very interesting. The mass of the exoplanets is the thing that makes them similar to Earth, not the size. 

So that means the planet is very unlike Earth. The Kepler 136 B orbits the star Kepler 138 in 23,1 days. And the star Kepler 138 is an M-type star. Which means its surface temperature is about 2400–3700 Kelvin. So that star is very cold. And that means the Kepler 138 d has a level in its ocean where fish-type habitats could exist and live. 

The thing that makes Kepler 136B interesting is that this very hot exoplanet might have some kind of life forms. The extremely high temperature doesn't mean that the water can vaporize on that planet because there is so much water. There is high-pressure water inside the giant ocean. And clouds are cooling the surface of that strange world. 

https://exoplanets.nasa.gov/exoplanet-catalog/1557/kepler-138-d/

https://scitechdaily.com/water-worlds-astronomers-discover-that-two-exoplanets-are-unlike-any-planets-in-our-solar-system/

https://en.wikipedia.org/wiki/Stellar_classification