Discovery of second exoplanet in habitable zone of star TOI 700, 100 light years away | sorae Space Portal Site

【▲ A rendering of the Earth-sized exoplanet TOI 700 e. The same star system “TOI 700 d” is also drawn in the back left (Credit: NASA/JPL-Caltech/Robert Hurt)]

A research team headed by Emily Gilbert, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory (JPL), orbited the red dwarf star TOI 700, about 100 light years away in the direction of Dorado. At the 241st meeting of the American Astronomical Society, researchers announced that they had discovered a fourth exoplanet in the solar system.

■ Revolves within the “optimistic” habitable zone of TOI 700 with a period of about 27.8 days

TOI 700 has so far discovered three exoplanets: TOI 700 b, TOI 700 c, and TOI 700 d. The outermost of the three, TOI 700 d, orbits its primary star, TOI 700, with a period of about 37.4 days, and its surface temperature is estimated to be about -4 degrees Celsius. Since this temperature does not take into account the influence of the atmosphere, if TOI 700 d has an atmosphere, it seems possible that liquid water exists on the surface.

Relation:An exoplanet that may be the perfect environment for life. found 100 light years away(January 2020)

This time, the research team reported on the fourth exoplanet “TOI 700 e” discovered in this planetary system. TOI 700 e is about 95 percent the diameter of Earth, orbits its star with a period of about 27.8 days, and is within TOI 700’s “optimistic habitable zone.”

[▲ A diagram showing the habitable zone of TOI 700 and the orbit of the planet. The outermost TOI 700 d orbits within the conservative habitable zone (dark green), while the inner TOI 700 e orbits within the optimistic habitable zone (light green) (Credit: Gilbert et al. .)]

According to JPL, the optimistic habitable zone is a region in a planet’s history where liquid water could have existed on its surface, even temporarily. It extends inside and outside the area where liquid water could have existed on the surface for most of its history. The previously discovered TOI 700 d is believed to be revolving within TOI 700’s conservative habitable zone.

The exoplanet revolving around TOI 700 was discovered by NASA’s exoplanet exploration satellite “TESS”. According to Gilbert, follow-up surveys with space and ground observations are currently underway, and may provide more insight into the TOI 700 star system.

In addition, the name of the exoplanet is the “name of the main star” with “lowercase alphabet” added（※）. Alphabets are given “c” and “d” in order from “b” according to the distance from the main star and the order in which they were discovered, but even if another planet is found in the same star system, the already named name is The alphabetical order does not necessarily match the order of distance from the primary star, as they are not changed.

TOI 700 e reported this time is “the fourth exoplanet discovered in TOI 700”, so it is given an “e”, but it revolves between the previously discovered TOI 700 c and TOI 700 d. Therefore, when arranging the planets from those closest to TOI 700, the order is ‘b’, ‘c’, ‘e’, ​​and ‘d’.

[▲ The diameters and orbital periods of the four planets revolving around TOI 700 (*The size ratio of the circles does not reflect the actual size of the main star or planet) (Credit: sorae)]

*…Some exoplanets have been named by the International Astronomical Union (IAU) from all over the world.

Source

• Image Credit: NASA/JPL-Caltech/Robert Hurt, Gilbert et al.
• NASA/JPL – NASA’s TESS Discovers Planetary System’s Second Earth-Size World
• Gilbert et al. – A Second Earth-Sized Planet in the Habitable Zone of the M Dwarf, TOI-700 (arXiv)

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