NASA's TESS Planet Hunter Finds Its 1st Earth-Size World in 'Habitable Zone'

rod

Oct 22, 2019
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For the first time, the agency's Transiting Exoplanet Survey Satellite (TESS) has discovered a roughly Earth- planet in the habitable zone of its host star, the zone of orbital distances where liquid water could be stable on a world's surface.

NASA's TESS Planet Hunter Finds Its 1st Earth-Size World in 'Habitable Zone' : Read more
Interesting, perhaps pushing the paradigm limits here. 86% of solar energy is similar to Precambrian earth during the Faint Young Sun, a snow ball earth. Part of the report that is a bit confusing to me is the comment "One of the other planets is a red dwarf about 40% as massive, 40% as wide and 50% as hot as Earth's sun." I think this is about the host star being a red dwarf star. Red dwarfs can be flaring stars and cause problems for *habitable* exoplanets. The Sun spins about 2 km/s at the its equator, red dwarf stars can spin faster like 4 km/s or faster, rotation periods 1 day to 10 days so red dwarfs can emit more flares. The report does comment "In 11 months of data, we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions," discovery team leader Emily Gilbert, a graduate student at the University of Chicago, said in the same statement. (Red dwarfs are generally much more active than the sun, and there's considerable debate about how habitable their planets may be as a result."
 

Sam

Jan 5, 2020
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This great. But there is an error in the text. One of the other planets is a red dwarf about 40% as massive, 40% as wide and 50% as hot as Earth's sun. The star is the red dwarf, not the planet.
 
Jan 7, 2020
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I'd love to turn off my adblocker to support space.com, but loading this article takes over a minute with it turned off and the text jumps every time the ads reload.
 
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rod

Oct 22, 2019
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For the first time, the agency's Transiting Exoplanet Survey Satellite (TESS) has discovered a roughly Earth- planet in the habitable zone of its host star, the zone of orbital distances where liquid water could be stable on a world's surface.

NASA's TESS Planet Hunter Finds Its 1st Earth-Size World in 'Habitable Zone' : Read more
I note is needed here I feel. The report said "TOI 700 d, the outermost known planet in the system, is the really intriguing one. It's just 20% larger than Earth and completes one orbit every 37 days. "

This looks interesting but the exoplanet is 1.19 earth radii, its mass is listed near 2.26 earth masses, this fits descriptions of a super-earth. http://exoplanet.eu/catalog/toi-700_d/
 
Oct 22, 2019
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So basically there could be more than one habitable zone in a solar system that has a smaller star orbiting the larger star.
 
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Jan 7, 2020
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The star being a relatively inactive red dwarf now doesn't mean it wasn't at times past. With an orbital period of 37 days that planet is very close to the star, which in eons past would have been more energetic. I wouldn't pin my hopes on this one, it's likely a cinder long ago burned up, ie imagine Venus once it cools if the Sun were to shrink instead of expand.
 
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Oct 22, 2019
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The star being a relatively inactive red dwarf now doesn't mean it wasn't at times past. With an orbital period of 37 days that planet is very close to the star, which in eons past would have been more energetic. I wouldn't pin my hopes on this one, it's likely a cinder long ago burned up, ie imagine Venus once it cools if the Sun were to shrink instead of expand.
Lets say a planet was outside of the normal habitable zone of our sun, somewhere around Jupiter, but the second sun orbited the first sun at the same distance that Pluto orbits our Sun. Could both stars provide enough light and heat for life to exist on the planet?
 
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rod

Oct 22, 2019
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Okay, I will try and put this all together here. "So basically there could be more than one habitable zone in a solar system that has a smaller star orbiting the larger star. Lets say a planet was outside of the normal habitable zone of our sun, somewhere around Jupiter, but the second sun orbited the first sun at the same distance that Pluto orbits our Sun. Could both stars provide enough light and heat for life to exist on the planet?"

Rod's note. M1 = 1 solar mass, the Sun. M2 = 0.75 solar mass, the smaller star. Semimajor axis = 39 a.u. so the period is about 184 years for both stars to move around the barycenter using Kepler’s 3rd law in a binary star relationship. The planet is orbiting M1 near 5 a.u. so the planet period like Jupiter, close to 12-year period about M1. M2 as a main sequence star is 4500 K surface temperature so peak radiation (Wien black body law) emitted near 644 nm, orange end of the spectrum compared to M1, the Sun in the yellow. M2 emits less energy than the Sun, and the planet is still 34 a.u. from M2 star. The planet is also some 5 a.u. from M1 so similar to Jupiter's solar energy window in our solar system.
 

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