The planet, named TOI 700 e, is one of four known planets orbiting a cool star approximately 100 light years away. The planet was discovered by NASA’s planet-hunting telescope.
The Transiting Exoplanet Survey Satellite (TESS), a NASA planet-hunting telescope, has found a second Earth-sized planet in a neighbouring star's habitable zone.
The planet, TOI 700 e, is one of four recognized planets that orbit a cold star around 100 light-years away. One planet, TOI 700 d, in the habitable zone of the system was previously known to exist, but new study that will be published in the Astrophysical Journal Letters shows that it is joined by another planet inside its orbit. TOI 700 b and TOI 700 c, the other two planets in the system, orbit closer to the star and are thus probably hotter, putting them beyond the habitable zone.
"Is snuggled in there between" the old and new planets
While the previously known planet TOI 700 d is located within what is known as the cautious habitable zone, the recently discovered planet. TOI 700 e is located in what is known as the optimistic habitable zone. The habitable zone, according to conventional definitions, is the region around a host star where temperatures are suitable for liquid water to exist on the surface of planets. The labels "optimistic" and "conservative" are used by these academics since it is trickier than it appears to apply this criteria in practice.
The term "optimistic habitable zone" refers to an area in which a planet's history may have included liquid water, while "conservative habitable zone" refers to a smaller portion of the optimistic habitable zone in which planets would continue to be habitable. These two can vary greatly over time based on factors like the thickness and composition of a planet's atmosphere and the surface temperature of the planet, which determines whether or not water exists in liquid form.
This extension of the conventional livable zone is "to represent the way that we accept Mars and Venus once had fluid water on their surfaces," Gilbert made sense of, alluding to the proof that there was water on the two planets billions of years prior. The number of potentially habitable planets that astronomers can use to understand the history of our own solar system grows as a result of studying planets in this optimistic zone.
The four planets in the TOI 700 system can also be compared by astronomers. We know that these planets formed around the same star and from the same disk when they first formed. Therefore, this enables us to study how various planet characteristics, such as the planet's size or the boundaries of its habitable zone, may affect its habitability, Gilbert stated.
In addition to well-known systems like the TRAPPIST system, this system is one of the few that we are aware of that contains multiple planets of Earth's size within its habitable zone. The discovery was also made public the day before LHS 475 b, the first exoplanet discovered by the James Webb Space Telescope (JWST) and another rocky planet of Earth's size. However, that planet is outside the habitable zone and is much closer to its star. The TESS and JWST missions collaborated to find this new exoplanet because TESS had found a first sign of a possible exoplanet before JWST did.
The research team for this TESS discovery says they will continue with follow-up studies of the TOI 700 system to learn more about its exoplanets. In addition, we can anticipate more exoplanet discoveries from both telescopes in the future.
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