HR 8799 b: Photographed, Not Inferred
Gas giant around HR 8799
It is 1.16 times Jupiter's radius, closest in size to Jupiter, and 2000.0 times Earth's mass. A year there lasts 465.4 years, on an orbit 175.7 times Mercury's distance from the Sun.
HR 8799 from the inside out
Orbit
/
Planet
Radius
13.00 Earth radii
Mass
2000.0 Earth masses
One year
465.4 years
Orbit radius
68.0000 AU
Distance
135 light-years
What the archive holds on this planet
A size. Yes.
A measured mass. Yes.
A density, which decides rock or gas. No.
An orbital distance. Yes.
A measured temperature rather than a derived one. No.
An eccentricity, so we know if the orbit is a circle. No.
What a direct image buys you
A position, a brightness, and light that can be split into a spectrum.
This is one of the rare planets that has actually been photographed. Fewer than a hundred of the thousands known were found this way, and they are mostly young giants far from their stars.
HR 8799 has 4 known planets. A crowded system is worth more than the sum of its planets: the timing of each transit constrains the others.
Found by Gemini Observatory in 2008.
Fewer than a hundred planets have been photographed rather than inferred. Does \
seeing one directly change how real it feels to you?
