The star
The star
XO-4
- Type
- F5 V
- Surface
- ≈ 6,397 K
- Size
- 1.45 × the Sun
- Mass
- 1.10 × the Sun
- Brightness
- 3.43 × the Sun
- Habitable zone
- 1.34–3.11 AU
The planets
XO-4
XO-4 b
- Year
- 4.13 days
- Distance from star
- 0.0552 AU
- Mass
- 1.4 Jupiters
- Size
- 14 × Earth
- Temperature
- ≈ 1630 K (+1357 °C)
- Found
- 2010, transit (Lowell Observatory)
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.