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1 known planet · 449.8 light years

USco1621 A

USco1621 A is a red dwarf (M2.5 V) 449.8 light years away, with 1 confirmed planet. Distances and orbital speeds are to scale; the star and planets are enlarged so you can see them.

Day 0
habitable zone (estimate)planet orbits

Green band: where liquid water could exist on a planet's surface. Drag to turn the system, pinch or scroll to zoom.

The star

The star

USco1621 A

Type
M2.5 V
Surface
≈ 3,460 K
Size
0.71 × the Sun
Mass
0.36 × the Sun
Brightness
0.0955 × the Sun
Habitable zone
0.253–0.658 AU

The planets

USco1621 A

USco1621 b

Year
257595.0 years
Distance from star
2.88e+03 AU
Mass
16 Jupiters
Size
12 × Earth
Temperature
≈ 2270 K (+1997 °C)
Found
2019, imaging (Multiple Observatories)
Too hot

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

A direct picture

The star's glare is blocked or subtracted, leaving the planet's own faint light as a dot that moves along its orbit over the years.

Sources

  1. 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.
  2. Position: HYG Database v4.1 (CC BY-SA 4.0).
  3. Habitable zone: a simple estimate from the star's brightness (√L × 0.95 to 1.67 AU), shown as a guide.
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