Finding Earth 2.0
TOI-700 · M2.5 V

TOI-700 d

Rank #10 of the ranked catalogue · Discovered by Transit in 2020

HZ 59%inferred

0.684

Earth-2.0 index

rank #10

0.943

Earth Similarity Index

0.918–0.964 (68% CI)

59%

Conservative HZ probability

1.07 R⊕

Radius

mass: inferred_mass_radius

At a glance

TOI-700 lies 101.52 light-years (31.127 pc) from the Sun. TOI-700 is a M2.5 V star with 0.415× the Sun's mass and 0.421× its radius (effective temperature 3459 K, versus the Sun's 5772 K). It is a single star hosting 4 known planets. TOI-700 d is 1.07× Earth's radius, an estimated 1.25× Earth's mass, inferred from its radius rather than measured, completing one orbit every 37.4 days at 0.1633 AU, on a mildly eccentric orbit (e = 0.04). It receives about 0.85× the flux Earth gets from the Sun, for an equilibrium temperature near 244 K (Earth's is 254 K).

Orbit and habitable-zone boundaries computed in Python from this system’s actual parameters. Sizes and the overall scale are compressed for visibility, not literal; green = conservative HZ, gold = optimistic HZ.

Planet parameters
Radius1.073 R⊕+0.059 / -0.054
Mass1.250 M⊕inferredNOT measured. Predicted from the radius by a mass-radius relation, so it carries no information beyond the radius.
Bulk density5.560 g/cm³source: catalogue
Escape velocity12.07 km/s
Orbital period37.4240 days
Semi-major axis0.16330 au
Eccentricity0.042
Incident flux0.850 S⊕source: catalogue
Equilibrium temperature244.1 KBond albedo assumed: 0.306. Equilibrium temperature excludes greenhouse warming by construction. Earth's is 254 K against a 288 K surface.
Host star
NameTOI-700
Spectral typeM2.5 V
Effective temperature3459 K
Radius0.421 R☉
Mass0.415 M☉
Luminosity10^-1.640 L☉
Metallicity [Fe/H]-0.070
Age1.50 Gyr
Distance31.1 pc / 101.5 ly
Multiplicity1 star(s), 4 known planet(s)
Gaia DR3 cross-check
Parallax distance31.12 pc0.02% vs. archive-adopted distance
RUWE1.353
Habitable zone
Boundary modelKopparapu et al. (2013), ApJ 765, 131, with the 2013 erratum coefficients
BoundaryS_eff (Earth units)
recent venus1.5227
runaway greenhouse0.8728
moist greenhouse0.8697
maximum greenhouse0.2439
early mars0.2185
Atmospheric spectroscopy

No published transmission spectrum exists for this planet in the NASA Exoplanet Archive.

Transit analysis
fit not validated

Fitted depth disagrees with the published value. In a multi-planet system this usually means the fold is contaminated by other planets' transits rather than isolating the target. This fit is NOT reported as a measurement.

Radial-velocity analysis
Measurements241baseline 3.6 yr across 2 instrument(s)
Activity coincidences7RV periodogram peaks matching a stellar-activity indicator period
Fitted semi-amplitude0.93 ± 0.10 m/sM sin i = 2.71 M⊕
Measurement sources
ParameterValueSource
Planet radius1.0730Gilbert et al. 2023
Planet mass1.2500archive-calculated (not a publication)
Orbital period37.4240Gilbert et al. 2023
Semi-major axis0.1633Gilbert et al. 2023
Incident flux0.8500Gilbert et al. 2023
Equilibrium temperature268.8000Rodriguez et al. 2020
Bulk density5.5600archive-calculated (not a publication)
Orbital eccentricity0.0420Gilbert et al. 2023
Stellar effective temperature3459.0000Gilbert et al. 2023
Stellar radius0.4210Gilbert et al. 2023
Stellar mass0.4150Gilbert et al. 2023
Stellar luminosity-1.6402Gilbert et al. 2023
Stellar metallicity-0.0700Gilbert et al. 2023
Stellar age1.5000Kokori et al. 2023
System distance31.1265TICv8

Component scores

Earth similarity

0.943

Conservative habitability

0.552

Observational confidence

0.613

Characterisation potential

0.519

Evidence

Independent references
4
Published parameter sets
4
Composite parameter sources
5 · mixed
Default-solution coverage
75%
Composite ↔ default difference
0% median
Uncertainty coverage
83%
Discovery method
Transit
Discovery year
2020

The archive composite selects values from multiple publications. This is disclosed separately and is not automatically penalised.

Observability

TSM
3.62
RV semi-amplitude (expected)
0.430 m/s
Transit-time σ at 2030
55.1 min
Max angular separation
5.25 mas
Reflected-light contrast
7.49e-9

Follow-up lanes are diagnostics, not ranking inputs. Reflected light assumes Ag = 0.30 and Lambertian quadrature.

Other planets in this system

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Any rendering of this world is a scientifically informed visualisation, not an image. No exoplanet has been imaged at surface resolution. Surface and cloud appearance are illustrative of a physically plausible class, not observations.