Researchers found the second Earth-size planet in the habitable zone of the TOI 700 system.

"Newly discovered Earth-size planet TOI 700 e orbits within the habitable zone of its star in this illustration. Its Earth-size sibling, TOI 700 d, can be seen in the distance. Credit: NASA/JPL-Caltech/Robert Hurt" (ScitechDaily.com/NASA Planet Hunter Discovers Second Habitable, Earth-Size World in TOI 700 System)

The light exoplanet must be at a longer distance from its star, than the heavy exoplanet that liquid water can exist on its surface. The weak gravitation decreases boiling temperature. And that means the distance to the central star must be longer in the case of weak gravitation planets than in strong gravitation planets. 

If we think that liquid water is the only requirement for life, we must realize that a weak gravitational field decreases the boiling temperature. That means a light exoplanet's habitable zone is at a longer distance from its central star, than a heavy exoplanet. 

So lightweight exoplanet that is quite far away from its star can host life. And heavy exoplanet must be closer to its star so that liquid water can exist on its surface. 

TOI 700 is a red dwarf star in the Dorado constellation, about 101,4 light-years from Earth. The remarkable thing is that the red dwarf has two Earth-size exoplanets in the habitable zone. And that thing causes re-estimation about the descriptions of planets. The TOI 700 system is an extremely compact-size system. 

The TOI 700's surface temperature is about 3000-3500 celsius. And its habitable zone is much thinner than the Sun's habitable zone. So two Earth-size exoplanets in the habitable zone mean those exoplanets are orbiting their star almost by the same trajectory. This is one of the most interesting details about the TOI 700 system.  

We believed that two planets cannot orbit their star by following the same trajectory. But the TOI 700 has shown that two planets might be almost at the same orbiter. That means that also bigger stars can have similar exoplanets. 

The gravitation, not the planet's size, determines if there is liquid water. 

When we search for exoplanets and especially habitable exoplanets. We are facing one thing. There are lots of larger rocky planets than Earth. But some of those exoplanets are lighter than Earth even if they are over 2 times bigger than Earth. 

There are no heavy elements in those exoplanets' mantle or core. And that means their gravitational field is weaker than Earth's. Even their size is bigger. And that is one of the most interesting details in searching for life. 

A weak gravitational field decreases the gas pressure and boiling temperature. 

The exoplanet GJ 436b is a heavy exoplanet. Its gravitation pulls water to ice on its surface. So that thing gives the nickname "world of burning ice for GJ 436b  But there could be an opposite case about the GJ 436b. 

The opposite case could be the lightweight exoplanet that orbits quite far away from its sun. A long-distance allows water could be liquid even if the gravitation is weak. On light exoplanets, the boiling temperature is lower than on heavy exoplanets. 

So if we think only the liquid water the habitable zone of lightweight exoplanets is at a longer distance than heavy exoplanets' habitable zone. And that thing makes this a very interesting thing. 

https://futurism.com/the-strangest-exoplanet-ever

https://scitechdaily.com/nasa-planet-hunter-discovers-second-habitable-earth-size-world-in-toi-700-system/

https://en.wikipedia.org/wiki/TOI_700

https://shorttextsofoldscholars.blogspot.com/