NASA’s TESS satellite claims its first Earth-size exoplanet in the habitable zone

Posted: January 7, 2020 by oldbrew in Astronomy, modelling, News

Having one side of the planet constantly facing the star due to tidal locking could make habitability tricky though. There are three known planets in the system.
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From Wikipedia:
NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star’s habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface.

Scientists confirmed the find, called TOI 700 d, using NASA’s Spitzer Space Telescope and have modeled the planet’s potential environments to help inform future observations.

TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It’s roughly 40 of the Sun’s mass and size and about half its surface temperature.

The star appears in 11 of the 13 sectors TESS observed during the mission’s first year, and scientists caught multiple transits by its three planets.

The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth — between the sizes of Earth and Neptune — orbits every 16 days and is likely a gas-dominated world.

Credit: NASA

TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20 larger than Earth, orbits every 37 days and receives from its star 86% of the energy that the Sun provides to Earth.

All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed in daylight.

The Spitzer data increased scientists’ confidence that TOI 700 d is a real planet and sharpened their measurements of its orbital period by 56% and its size by 38%. It also ruled out other possible astrophysical causes of the transit signal, such as the presence of a smaller, dimmer companion star in the system.

While the exact conditions on TOI 700 d are unknown, scientists used current information, like the planet’s size and the type of star it orbits, and modeled 20 potential environments for TOI 700 d to gauge if any version would result in surface temperatures and pressures suitable for habitability.

One simulation included an ocean-covered TOI 700 d with a dense, carbon-dioxide-dominated atmosphere similar to what scientists suspect surrounded Mars when it was young. The model atmosphere contains a deep layer of clouds on the star-facing side.

Another model depicts TOI 700 d as a cloudless, all-land version of modern Earth, where winds flow away from the night side of the planet and converge on the point directly facing the star.
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Talkshop analysis of the 3-planet system

For the orbits:
169 b = 1686.115 days
105 c = 1685.365
45 d = 1684.17
b:c ratio = 13²:(21*5) in Fibonacci numbers
c:d ratio = 7:3 in Lucas numbers

Synodic frequencies:
64 (169-105) b-c = 1687.345 days
60 (105-45) c-d = 1686.263
(b-d = 124 = 64+60)
b-c:c-d ratio = 16:15
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  1. Jim says:

    Interesting, but no imagery was listed in the nasa news. Just the electronic graph. And then artists rendition of imagery? Wonder if it really is a blue color, that would be neat.

  2. oldbrew says:

    They are detecting changes in stellar brightness to infer the presence of planets, so no actual pictures 😐

  3. Gamecock says:

    ‘TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado.’

    Referring to some place 100 light-years away as having a habitable zone has to be a joke. Figure out how you could possibly get there before using such ridiculous attributes as ‘habitable zone.’