HD 219134
Star
HD 219134 - a naked-eye orange dwarf 21.3 light-years away in Cassiopeia, and the nearest star known to host a TRANSITING rocky planet. Four planets are confirmed; the two innermost cross the star's face, giving them measured sizes and densities - a rare, direct check on nearby small worlds.
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Key facts
Mass
1.61 × 10³⁰ kg
0.81 M☉
Radius
541,255 km
78% of the Sun's radius
Surface temperature
4,699 K (4426 °C)
Luminosity
1.01 × 10²⁶ W
Spectral type
K3V (orange dwarf)
Science
Physical
- Mass
- 1.61 × 10³⁰ kg · 0.81 M☉
- Radius
- 541,255 km · 78% of the Sun's radius
- Density
- 2,426 kg/m³ · 2.4× water
- Spectral type
- K3V (orange dwarf)
Rotation
- Note
- An old, magnetically quiet K dwarf (rotation ~42 days) — the calm that let its planets be measured, but also the source of the two false signals (f, g) now discounted.
Composition
- By mass
- A hydrogen/helium orange dwarf about 0.81 solar mass and ~26% of the Sun's light, 21.3 light-years away in Cassiopeia — just bright enough to see with the unaided eye. Old and quiet, it is the nearest star known to have a planet that transits, giving rare direct measurements of small nearby worlds.
Temperature
- Surface
- 4,699 K (4426 °C)
Radiation & temperature
- Luminosity
- 1.01 × 10²⁶ W · 0.265 L☉
- Surface temperature
- 4,699 K (4426 °C)
- Peak wavelength
- 617 nm · orange light
Discovery & history
- Name
- A catalogue designation (Henry Draper 219134); also Gliese 892 and HR 8832. Just bright enough to see with the unaided eye.
In 2015 two teams found a compact family of planets here; the innermost, HD 219134 b, was caught transiting by NASA's Spitzer Space Telescope, making it the nearest transiting rocky planet known. Planet c was later shown to transit too. Two further RV signals (f and g) are now regarded as unconfirmed activity artefacts and are not shown.
Images
Images from open archives · credit shown per image