TOI-700 d is a near-Earth-sized

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

, likely rocky, orbiting within the

habitable zone In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kas ...

of the

red dwarf ''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...

TOI-700, the outermost planet within the system. It is located roughly away from Earth in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Dorado Dorado () is a constellation in the southern sky. It was named in the late 16th century and is now one of the 88 modern constellations. Its name refers to the dolphinfish (''Coryphaena hippurus''), which is known as ''dorado'' in Spanish, altho ...

. The exoplanet is the first Earth-sized exoplanet in the

discovered by the

Transiting Exoplanet Survey Satellite Transiting Exoplanet Survey Satellite (TESS, Explorer 95 or MIDEX-7) is a space telescope for NASA's Explorer program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the ''Kepler' ...

(TESS). TOI-700 d orbits its star at a distance of from its host star with an orbital period of roughly 37.4

days A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours, 1440 minutes, or 86,400 seconds. In everyday life, the word "day" often refers to a solar day, which is the length between two solar ...

, has a mass about 1.7 times that of Earth, and has a radius of around 1.19 times that of Earth. It has been estimated that the planet receives about 86% the energy that the Earth receives from the Sun. It was discovered in early January 2020 by the

(TESS).

Physical characteristics

Mass, radius and temperature

TOI-700 d is Earth-sized, an exoplanet that has a radius and mass similar to the Earth. It has an estimated mass of around and a radius of about . If it has an earthlike atmosphere, then its average temperature would be about . A small chance of a

runaway greenhouse effect A runaway greenhouse effect occurs when a planet's atmosphere contains greenhouse gas in an amount sufficient to block thermal radiation from leaving the planet, preventing the planet from cooling and from having liquid water on its surface. A ...

exists.

Host star

TOI-700 is a

spectral class In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

M that is about 40% the mass and radius, and very roughly 50% of the temperature of the Sun. The star is bright with low levels of stellar activity. Over the 11 sectors observed with TESS, the star does not show a single white-light

flare A flare, also sometimes called a fusée, fusee, or bengala in some Latin-speaking countries, is a type of pyrotechnic that produces a bright light or intense heat without an explosion. Flares are used for distress signaling, illumination, ...

. The low rotation rate is also an indicator of low stellar activity.

Orbit

TOI-700 d orbits its host star every 37.42 days.

Proposed habitability

TOI-700 d orbits in the

of its host star TOI-700. The solar wind ram pressure and intensity of the interplanetary magnetic field are expected to be similar to the Earth's, therefore retention of the planetary atmosphere is likely.

History and discovery

TOI-700 d was discovered by Professor Sara Seager, using the

(TESS) in early January 2020. This was the first Earth-sized exoplanet discovered by the TESS.

References

External links

TESS – Official WebSite

ExoFOP TIC 150428135
TOI-700 in the Exoplanet Follow-up Observing Program website {{Sky, 06, 28, 22.97, -, 65, 34, 43.01, 101.4 Exoplanets discovered by TESS Exoplanets discovered in 2020 Near-Earth-sized exoplanets in the habitable zone Transiting exoplanets Dorado