Diagrams: Polar plot

The following interactive plot gives a new way of looking at the population of exoplanets that we know of in the nearby solar neighbourhood. Indeed, in this plot, our Sun is at the origin and each planet is distributed radially depending on its distance to our Sun (we show the 10, 100, 1000 and 10000pc concentric circles), and azimuthally depending on its orientation in the sky (based on their right ascension RA).

The systems located on the outermost circle are those that have no distances defined in the exoplanet.eu database.

When hovering over the planets, one can see their names. By clicking on them, one can access their webpages listing their known properties (star+planet).

The planets can be added or removed from the plots based on their radii by ticking the boxes that follow:

Mini-earth (0 to 0.5 R_⊕)

Earth (0.5 to 1.5 R_⊕)

Super-earth (1.5 to 2 R_⊕)

Mini-neptune (2 to 4 R_⊕)

Neptune (4 to 6 R_⊕)

Jupiter (>6 R_⊕) and those with no known distances from our Sun.

R_⊕ is the Earth radius.

We note that for planets without known radii (e.g. planets detected through the radial velocity method), we used the following mass range instead (in Earth masses): [0,0.1,2,10,15,30,>30].

Variable Planet types

The colour scale on each plot shows the parameter of interest. You can tick or untick the log-scale checkbox on the grey panel to switch on/off the logarithmic colour scale.

On this plot, we are interested in visualising the irradiation received on each planet compared to Earth. The irradiation is calculated as

S = ¼ σ * T_star⁴ (R_star / a)² (in W/m²),

where

T_star is the temperature of the star (in K)

R_star its radius (in m),

a is the semi-major axis of the planet (in m)

σ is Stefan Boltzmann constant (equal to 5.67·10^-8 W m^-2 K^-4).

The Earth irradiation (S_⊕) is therefore found to be 340 W/m².

As we use a logscale, a planet that would receive the same flux as Earth would be yellow (0 on the colour bar). Less irradiated planets, i.e., planets that are far away from their host stars or orbiting low-mass stars tend towards the blue part of the colour bar. At the opposite end, very irradiated planets are redder. Planets in grey are those for which the irradiation could not be calculated from the exoplanet.eu database because of a lack of measured parameters (e.g. the star temperature). This plot has been initially suggested by and developed for the French magazine 'Science & Vie'.

All the Kepler planets are located in a small patch in the sky because the Kepler telescope only observed a narrow region of the sky, called the Kepler field.

This plot is updated in real time as more planets are added to the exoplanet.eu database every day.