This graph shows measured features of the seven TRAPPIST-1 exoplanets (named b through h), showing how they accumulate together as well as the Earth and other rocky worlds. within our own solar system. The relative dimensions of the planets are indicated by the circles. All known TRAPPIST-1 planets are larger than Mars, with five within 15% of Earth’s diameter.
The vertical axis shows the unobstructed density of the planets. Density, measured from the mass and size of a planet, is the first important step in understanding its combination. Uncluttered density implies that the larger a planet is, the more its own weight packs the planet’s material together and increases its density. So unobstructed density, therefore, usually provides a better way to compare the shape of planets.
The plot shows that the unbroken density of the TRAPPIST-1 planets is similar, suggesting that they could all have the same type of writing. The four rocky planets in our own solar system show a greater difference in density compared to the seven TRAPPIST-1 planets. Mercury, for example, contains a much higher percentage of iron than the other three rocky planets and therefore has a much higher unrefined density.
The horizontal axis shows the amount of illumination each planet receives from its host star. Our star TRAPPIST-1 has just 9% of the mass of our sun, and its temperature is much colder. But because the TRAPPIST-1 planets move so close to their star, they receive comparable levels of light and heat to Earth and the adjacent planets.
The corresponding “arable zones” – areas where an Earth-like planet could support meltwater at its surface – of the two planetary systems are identified near the top of the plot. Both zones do not extend upwards just because the cooler star TRAPPIST-1 emits more of its light in the form of infrared radiation that is absorbed more efficiently by a similar atmosphere. to the Earth. As it takes less illumination to reach the same temperatures, the residential zone moves further away from the star.
The masses and densities of the TRAPPIST-1 planets were determined by measurements of small differences in orbital times using extensive observations made by NASA Spitzer and Kepler space telescopes, in combination with data from Hubble and several telescopes grounded. The latest analysis, which includes Spitzer’s total record of more than 1,000 hours of TRAPPIST-1 observations, has reduced the uncertainty of large measurements to just 3-6%. These are among the most accurate measurements of many planets anywhere outside our solar system.