TOI-700

TOI-700 planetary system as of 2020 Credit:NASA'sGoddard Space Flight Center
Observation data Epoch J2000      Equinox J2000
Constellation	Dorado[1][2]
Right ascension	06h 28m 22.97s[3]
Declination	−65° 34′ 43.01″[3]
Apparent magnitude (V)	13.10±0.01[4]
Characteristics
Evolutionary stage	Main sequence
Spectral type	M2V[4]
Astrometry
Radial velocity (Rv)	-4.4±0.1[4] km/s
Proper motion (μ)	RA: -102.750±0.051[5]mas/yr Dec.: 161.805±0.060[5]mas/yr
Parallax (π)	32.0980±0.0211 mas[5]
Distance	101.61 ± 0.07 ly (31.15 ± 0.02 pc)
Details
Mass	0.416 ± 0.010[4] M☉
Radius	0.420 ± 0.031[4] R☉
Luminosity	0.0233 ± 0.0011[4] L☉
Surface gravity (log g)	4.81 ± 0.06[4] cgs
Temperature	3480 ± 135[4] K
Metallicity[Fe/H]	-0.07 ± 0.11[4] dex
Rotation	54.0 ± 0.8[4]d
Age	>1.5[4] Gyr
Other designations
TIC 150428135, UCAC3 49-21611, 2MASS J06282325-6534456, WISE J062823.05-653443.7, APASS 31812705, Gaia DR2 5284517766615492736
Database references
SIMBAD	data

TOI-700 is ared dwarf 101.4 light-years away fromEarth^[3][5] located in theDoradoconstellation that hostsTOI-700 d, the firstEarth-sizedexoplanet in thehabitable zone discovered by theTransiting Exoplanet Survey Satellite (TESS).^[1][2][6]

The acronym "TOI" refers to stars and exoplanets studied by TESS, and is short for: "Transiting Exoplanet Survey SatelliteObject ofInterest".

TOI-700 is a red dwarf ofspectral class M (much redder, cooler, and dimmer than the sun) that is 40% the mass, 40% the radius and 55% of the temperature of the Sun.^[6] 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-lightflare. The low rotation rate is also an indicator of low stellar activity.^[4]

Four exoplanets have been detected by TESS to be orbiting the host star TOI-700. All four exoplanets may betidally locked to TOI-700.^[6][9]

Three papers describe the validation of the planetary system, the follow-up observations of TOI-700 d with theSpitzer Space Telescope and the characterization of TOI-700 d.^[4][10][11]

The composition of planets b and d is more likelyrocky and the composition of planet c is more likely similar to that ofNeptune.^[4][8]

The two inner planets might have grown faster and accreted significant gaseous envelopes, but the outer planet formed more slowly and accreted less gas. The innermost planet may later have lost its envelope due tophotoevaporation. Another scenario that could explain the arrangement of densities in this system is long-termplanetary migration. Planet c might have migrated inwards, but this scenario is more plausible if future studies show that planet c is significantly more massive than planet b or d.^[4]

TOI-700 d lies in thehabitable zone. It receives 35 times moreEUV photons than Earth, but also 50 times less thanTRAPPIST-1 e. The host star has low stellar activity. The atmosphere of a planet with an Earth-like pressure would survive for longer than 1Gyr.^[4] Simulations of the planet have shown that TOI-700 d is a robust candidate for a habitable world. The simulated spectral feature depths from transmission spectra and the peak flux and variations from synthesized phase curves do not exceed 10ppm. This will likely prohibitJWST from characterizing the atmosphere of TOI-700 d.^[11]

In November 2021, a fourth possible planet, Earth-sized and receiving approximately 30% more flux from TOI-700 than Earth does from the Sun, was found at the inner edge of the habitable zone of TOI-700.^[12] In January 2023 the existence of this planet, designated 700 e, was confirmed.^[9]

Discovered in 2023, TOI-700 e is a terrestrial exoplanet that NASA claims to be an "earth-like" planet, with 95 percent of theEarth’s radius. Discovered by NASA's TESS (Transitioning Exoplanet Survey Satellite), TOI-700 e has a mass of about 0.818 Earths and takes 27.8 days to orbit once around its star.^[13] The planet is in a habitable zone distance from the M-type star TOI-700 it orbits, leading NASA scientists to believe that there is potential for liquid water on its surface. Ten percent smaller than its neighboring planet TOI-700 d, both are at a distance from their sun to be considered habitable, however, TESS requires an additional year to acquire more data about the exoplanets.^[14] Being one in only about a dozen habitable zone planets known, further research and data collection of the TOI-700 solar system is important for understanding Earth-like planets.^[15]

The system is near (but not in) orbital resonance: from planets b to d, period ratios are approximately 5:8, 4:7, 3:4.

• TESS – Official WebSite
• ExoFOP TIC 150428135 TOI 700 in the Exoplanet Follow-up Observing Program website
• The First Habitable Zone Earth-sized Planet from TESS. I: Validation of the TOI-700 System, Emily A. Gilbert et al., 3 Jan 2020
• The First Habitable Zone Earth-Sized Planet From TESS II: Spitzer Confirms TOI-700 d, Joseph E. Rodriguez et al., 3 Jan 2020
• The First Habitable Zone Earth-sized Planet from TESS. III: Climate States and Characterization Prospects for TOI-700 d, Gabrielle Suissa et al., 3 Jan 2020

• Dorado
• M-type main-sequence stars
• TESS Objects of Interest
• Planetary systems with four confirmed planets
• Planetary transit variables

• Articles with short description
• Short description is different from Wikidata
• Use dmy dates from January 2020