The star
The star
TOI-663
- Type
- M1 V
- Surface
- ≈ 3,681 K
- Size
- 0.51 × the Sun
- Mass
- 0.51 × the Sun
- Brightness
- 0.0426 × the Sun
- Habitable zone
- 0.168–0.433 AU
The planets
TOI-663
TOI-663 b
- Year
- 2.60 days
- Distance from star
- 0.0295 AU
- Mass
- 4.5 Earths
- Size
- 2.3 × Earth
- Temperature
- ≈ 674 K (+401 °C)
- Found
- 2024, transit (Transiting Exoplanet Survey Satellite (TESS))
TOI-663
TOI-663 c
- Year
- 4.70 days
- Distance from star
- 0.0437 AU
- Mass
- 3.6 Earths
- Size
- 2.3 × Earth
- Temperature
- ≈ 553 K (+280 °C)
- Found
- 2024, transit (Transiting Exoplanet Survey Satellite (TESS))
TOI-663
TOI-663 d
- Year
- 7.10 days
- Distance from star
- 0.0576 AU
- Mass
- 5.2 Earths
- Size
- 1.9 × Earth
- Temperature
- ≈ 482 K (+209 °C)
- Found
- 2024, transit (Transiting Exoplanet Survey Satellite (TESS))
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.
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.