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TOI 700 d. Finally a planet the size of Earth is discovered


2020 is marked as a very rich year in terms of astronomy. Several relevant discoveries have changed human perception of the Universe. The ships went further and several exoplanets discovered opened up new possibilities for an Earth 2.0. Thus, using the images captured by the TESS space telescope, some of the thousands of discovered planets can harbor life. According to the researchers, the first “habitable” planet the size of Earth has now finally been discovered.

It’s called TOI-700 d orbits a category M dwarf star and the conditions could be similar to those of our planet.

TESS discovers TOI-700 d that is Earth-sized

The observatory TESS Transiting Exoplanet Survey Satellite), was launched in 2018 with the aim of discovering small planets around stars neighboring our Sun. These stars had to be bright enough to allow the later characterization of the masses and atmospheres of their planets.

The latest findings account for seventeen small planets around eleven nearby stars that are category M dwarf stars. These stars are smaller than our Sun (less than about 60% of the Sun's mass) and cooler (temperatures of surface below 3,700 ºC, our Sun has a temperature of about 5,505 ° C).

According to information referred to in three articles published this month, astronomers report that one of these planets, TOI-700 d, is the size of the Earth.

Illustration of TESS that discovered TOI 700 d, a planet that is the size of Earth.

Habitable planet is 102 light years from us

Scientists studied the TOI-700 d, one of three small planets orbiting a dwarf star M, which has a mass of 0.415 solar masses and determined that it is located 102 light years from Earth. The exoplanet is in the system TRAPPIST-1.

The TESS data analysis found the provisional dimensions of the 3 planets to be approximately the size of the Earth, 1.04, 2.65 and 1.14 Earth rays, respectively, and their orbital periods as 9.98, 16.05 , and 37.42 days, respectively.

For comparison, in our solar system, Mercury orbits the Sun in about 88 days. It is so close to the sun that its temperature can reach over 400 ° C. However, as this dwarf star is comparatively cold the orbit of its third planet, although much closer to the star than Mercury is from the Sun, places it in the habitable zone - the region within which temperatures allow water from surface (if any) remains liquid when there is also an atmosphere.

This makes this planet the size of the Earth, TOI-700 d, particularly interesting as a potential host for life.

Team used infrared matrix camera to “not miss the planet”

The findings of the TESS observatory were exciting, but uncertain. This is because the signals were faint and there was a small possibility that the detection of TOI-700 d was illegitimate.

However, due to the potential importance of finding a nearby Earth-sized planet in a habitable zone, TESS scientists turned to the IRAC camera. This is an infrared array camera installed on NASA's Spitzer Space Telescope that was used to confirm what was suspected.

This camera, before being shut down by NASA in February 2020, was by far the most sensitive infrared camera in space.

So, with this tool, the TESS team observed the TOI-700 star with the IRAC from October 2019 to January 2020. As a result, clear detections of the planets were collected with about twice the signal achieved by TESS. Therefore, these data were sufficient to improve information about the planet's orbit by about 61%.

In addition, it was equally important to significantly refine the knowledge of its other characteristics. The information about the planet's radius was refined, which after all is 2.1 land mass. The results, especially when compared to the properties of other planets, suggest that this planet may be rocky and susceptible to being "tidy" with one side of the planet always facing the star.

Illustration of dwarf star M and TOI 700 d

Will there be water on this Earth-sized exoplanet?

If there was liquid water on the surface of the TOI-700 d, astronomers argue, there would also be clouds of water in the atmosphere. In this sense, the team is using models of climatic systems to estimate their possible properties and what the most sensitive measurements may find.

Therefore, scientists conclude that pending space missions, including the new JWST, are unlikely to have the sensitivity to detect atmospheric features by a factor of ten or more. Their detailed climate studies will, however, help astronomers to restrict the types of telescopes and instruments that will be needed to investigate this exciting new neighbor.

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