The star
The star
TOI-199
- Type
- G9 V
- Surface
- ≈ 5,255 K
- Size
- 0.82 × the Sun
- Mass
- 0.94 × the Sun
- Brightness
- 0.459 × the Sun
- Habitable zone
- 0.524–1.25 AU
The planets
TOI-199
TOI-199 b
- Year
- 104.85 days
- Distance from star
- 0.425 AU
- Mass
- 54 Earths
- Size
- 9.1 × Earth
- Temperature
- ≈ 325 K (+52 °C)
- Found
- 2023, transit (Transiting Exoplanet Survey Satellite (TESS))
TOI-199
TOI-199 c
- Year
- 273.69 days
- Distance from star
- 0.807 AU
- Mass
- 89 Earths
- Size
- 11 × Earth
- Temperature
- ≈ 255 K (-18 °C)
- Found
- 2023, transit timing variations (Multiple Observatories)
Masses found by the wobble method are minimums, because the orbit's tilt is unknown. Temperatures are equilibrium estimates for a bare planet, before any atmosphere.
How we know
The shadow
The planet passes in front of its star and dims it by a fraction of a percent, every orbit. The dip gives the planet's size and year.
Early and late
A known planet arrives early or late for its transits, betraying the pull of another, unseen planet.
Sources
- Planet and star parameters: NASA Exoplanet Archive, Planetary Systems Composite Parameters, retrieved 1 Nov 2026. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program.
- Position: HYG Database v4.1 (CC BY-SA 4.0).
- Habitable zone: a simple estimate from the star's brightness (√L × 0.95 to 1.67 AU), shown as a guide.