3/27/2023 0 Comments Neptunes inside![]() ![]() The Spitzer observations confirmed an atmospheric presence and enabled a measurement of the planet's very high temperature, approximately 2,000 Kelvin (about 3,000 degrees Fahrenheit). To investigate its atmospheric composition and shed further light on its origin, scientists obtained secondary eclipse observations with the Spitzer Infrared Array Camera (IRAC) of the hot Neptune. So how did it manage? LTT9779b had us scratching our heads, but the fact that it has an atmosphere gives us a rare way to investigate this type of planet, so we decided to probe it with another telescope,” Dragomir added. “Hot Neptunes are rare, and one in such an extreme environment as this one is difficult to explain because its mass isn’t large enough to hold on to an atmosphere for very long. At this high temperature, the planet’s atmosphere should have evaporated long ago, early in the system’s life. The age of this system is 2 billion years. “This ultra-hot Neptune is a ‘medium-sized’ exoplanet that orbits very close to its star (it takes just 19 hours to complete an orbit), but its low density indicates that it still has an atmosphere weighing at least 10 percent of the planet’s mass,” explained University of New Mexico Physics and Astronomy Assistant Professor Diana Dragomir, who is leading the work which involved more than 25 institutions. Indeed, most close-in hot exoplanets are either gas giants the size of Jupiter or Saturn that have enough mass to retain most of their atmosphere using their high gravity against the evaporation caused by the star, or small rocky exoplanets that have lost their atmosphere to the star long ago. The planet is found in the "hot Neptune desert," where planets shouldn't exist. This planet, a little larger than Neptune, orbits very close to its star. Early in its mission, it found LTT9779b, a planet orbiting a Sun-like star located 260 light years away from Earth. One of the main goals of NASA’s TESS mission is to find new, small planets that would be good targets for atmospheric characterization. The discovery was made with data provided from the now-retired NASA Spitzer Space Telescope, which allows a unique, infrared view of the universe to look into regions of space that are hidden from optical telescopes. Like all the other gas giants, Neptune has a ring system, but it's so faint that it hadn't been definitely confirmed before 1989 when Voyager 2 had its flyby.An international team of scientists recently measured the spectrum of the atmosphere of a rare hot Neptune exoplanet, whose discovery by NASA's Transiting Exoplanet Survey Satellite (TESS) was announced just last month. The conditions in the centre of Neptune are quite extreme: a pressure of 7 million bar causes temperatures to rise above 5000 K, which is still much lower than the 40 million bar and 36000 K inside the super-massive planet Jupiter. Like the other gas giants Neptune is also believed to have a solid core made of iron, nickel and silicates (rock). This ocean makes up most of the mass of the planet. The internal structure of Neptune is a bit different from those of the other gas giants: an atmosphere of gas (mainly hydrogen, helium and methane) overlays a huge ocean of liquid water and ammonia. Under these conditions the ‘moderate' wind speeds of the most extreme tornado measured here on Earth (480 km/h) would feel like a light breeze. Neptune is the absolute record holder when it comes to storms, and wind speeds can reach up to 2100 km/h (1300 mph), almost reaching supersonic speeds. During the Voyager 2 flyby in 1989 the Great Dark Spot - a storm system like the Great Red Spot on Jupiter - was observed. Whilst the surface of neighbouring Uranus is nearly featureless, Neptune has many observable surface features caused by an active weather system. Methane molecules absorb the red part and reflect the blue frequencies of the sunlight. ![]() Like Uranus, Neptune shines so blue due to traces of methane in the topmost layer of its atmosphere. ![]() One orbit around the Sun takes almost 165 Earth years instead of just one year here on Earth. Neptune, the farthest planet in our Solar System (sorry, Pluto is not designated as a planet any more), has the longest year of all the planets. ![]()
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