Star system, 130 light-years
HR 8799 and its four planets
HR 8799 e is an exoplanet 13.115 times Earth's width, about 1.2 times Jupiter's, 130 light-years away.
HR 8799 is a star of spectral type A5 V, 130 light-years from us, with four known planets. This page takes them one at a time.
Drawn at the system's own scale, every orbit from the Archive's numbers.
What is measured, what is computed, what is imagined.
measured The period, and where the table says so the width and the mass, by the method named in each section.
computed Anything marked computed: the size of an orbit where Kepler's third law corrects the table, the temperature of a bare ball at that distance, the starlight received, and the habitable zone.
imagined The picture is an artist's impression. Nobody has seen the surface of a planet of another star: its colour, clouds and land are not known, and the share picture says so in its corner.
The planets
HR 8799 e
HR 8799 e is an exoplanet 13.115 times Earth's width, about 1.2 times Jupiter's, 130 light-years away.
- Width
- 13.115 × Earth's measured
- Mass
- 3,178 times Earth's measured
- One year
- 20,816 days measured
- Distance from its star
- 16.95 au computed from the period and the star's mass
- Temperature of a bare ball there
- 92 K computed, not measured
- Starlight, against Earth's
- 0.0171 × computed
It was photographed directly, a faint dot beside the glare of its star in 2010. No habitable zone is computed for its star (a pulsar, a binary or a star outside the formula's range), so none is claimed. The Archive's own distance for it is 16.4 au; the three papers behind its period, its star's mass and that distance do not agree with Kepler's third law, so the page uses the one the period and the star's mass give.
See HR 8799 e in 3D · The picture is an artist's impression.
HR 8799 d
HR 8799 d is an exoplanet 13 times Earth's width, about 1.2 times Jupiter's, 130 light-years away.
- Width
- 13 × Earth's measured
- Mass
- 3,000 times Earth's measured
- One year
- 37,000 days measured
- Distance from its star
- 24.88 au computed from the period and the star's mass
- Temperature of a bare ball there
- 76 K computed, not measured
- Starlight, against Earth's
- 0.00795 × computed
It was photographed directly, a faint dot beside the glare of its star in 2008. No habitable zone is computed for its star (a pulsar, a binary or a star outside the formula's range), so none is claimed. The Archive's own distance for it is 24 au; the three papers behind its period, its star's mass and that distance do not agree with Kepler's third law, so the page uses the one the period and the star's mass give.
See HR 8799 d in 3D · The picture is an artist's impression.
HR 8799 c
HR 8799 c is an exoplanet 13 times Earth's width, about 1.2 times Jupiter's, 130 light-years away.
- Width
- 13 × Earth's measured
- Mass
- 3,000 times Earth's measured
- One year
- 69,000 days measured
- Distance from its star
- 38 au from the Archive
- Temperature of a bare ball there
- 62 K computed, not measured
- Starlight, against Earth's
- 0.00341 × computed
It was photographed directly, a faint dot beside the glare of its star in 2008. No habitable zone is computed for its star (a pulsar, a binary or a star outside the formula's range), so none is claimed.
See HR 8799 c in 3D · The picture is an artist's impression.
HR 8799 b
HR 8799 b is an exoplanet 13 times Earth's width, about 1.2 times Jupiter's, 130 light-years away.
- Width
- 13 × Earth's measured
- Mass
- 2,000 times Earth's measured
- One year
- 170,000 days measured
- Distance from its star
- 68 au from the Archive
- Temperature of a bare ball there
- 46 K computed, not measured
- Starlight, against Earth's
- 0.00106 × computed
It was photographed directly, a faint dot beside the glare of its star in 2008. No habitable zone is computed for its star (a pulsar, a binary or a star outside the formula's range), so none is claimed.
See HR 8799 b in 3D · The picture is an artist's impression.
The star
- Surface temperature
- 7,205 K
- Width
- 1.493 × the Sun's
- Mass
- 1.5 × the Sun's
- Spectral type
- A5 V
- Distance
- 130 light-years