OrbitalHub

NASA dicit:

Measurements from NASAs Transiting Exoplanet Survey Satellite (TESS) have enabled astronomers to greatly improve their understanding of the bizarre environment of KELT-9 b, one of the hottest planets known. Located about 670 light-years away in the constellation Cygnus, KELT-9 b was discovered in 2017 because the planet passed in front of its star for a part of each orbit, an event called a transit. Transits regularly dim the stars light by a small but detectable amount.

Between July 18 and Sept. 11, 2019, as part of the mission’s yearlong campaign to observe the northern sky, TESS observed 27 transits of KELT-9 b, and these observations allowed the team to model the systems unusual star and its impact on the planet. KELT-9 b is a gas giant world about 1.8 times bigger than Jupiter, with 2.9 times its mass. Tidal forces have locked its rotation so the same side always faces its star. The planet swings around its star in just 36 hours on an orbit that carries it almost directly above both of the star’s poles.

The close orbit means the planet’s dayside temperature is around 7,800 degrees Fahrenheit (4,300 C), hotter than the surfaces of some stars. This intense heating also causes the planets atmosphere to stream away into space.

Its odd host star is about twice the size of the Sun and averages about 56 percent hotter. But it spins 38 times faster than the Sun, completing a full rotation in just 16 hours. Its rapid spin distorts the stars shape, flattening it at the poles and widening its midsection. This causes the stars poles to heat up and brighten while its equatorial region cools and dims, a phenomenon called gravity darkening. The result is a temperature difference across the stars surface of almost 1,500 F (800 C).

With each orbit, KELT-9 b twice experiences the full range of stellar temperatures, producing what amounts to a peculiar seasonal sequence. The planet experiences summer when it swings over each hot pole and winter when it passes over the stars cooler midsection. So KELT-9 b experiences two summers and two winters every year, with each season about nine hours.

KELT-9 b begins its transit near the star’s bright poles, and then blocks less and less light as it travels over the star’s dimmer equator. This asymmetry provides clues to the temperature and brightness changes across the stars surface, and they permitted the team to reconstruct the stars out-of-round shape, how its oriented in space, its range of surface temperatures, and other factors impacting the planet.

Video credit: NASA Goddard

NASA dicit:

In 2017, NASA’s Hubble Space Telescope captured an image of a huge wing-shaped shadow cast by a fledgling star’s unseen, planet-forming disk. The young star, called HBC 672, is casting the shadow across a more distant cloud in a star-forming region—like a fly wandering into the beam of a flashlight shining on a wall.

Video credit: NASA’s Goddard Space Flight Center/Paul Morris (USRA): Producer / Editor/Visualization Credit: NASA, ESA, and A. James and G. Bacon (STScI)/Jason Steele [ ASCAP ]/Soundcast Music [ SESAC ] and Universal Production Music.

NASA dicit:

As of June 2020, NASA’s Solar Dynamics Observatory — SDO — has now been watching the Sun non-stop for over a full decade. From its orbit in space around the Earth, SDO has gathered 425 million high-resolution images of the Sun, amassing 20 million gigabytes of data over the past 10 years. This information has enabled countless new discoveries about the workings of our closest star and how it influences the solar system.

With a triad of instruments, SDO captures an image of the Sun every 0.75 seconds. The Atmospheric Imaging Assembly (AIA) instrument alone captures images every 12 seconds at 10 different wavelengths of light. This 10-year time lapse showcases photos taken at a wavelength of 17.1 nanometers, which is an extreme ultraviolet wavelength that shows the Sun’s outermost atmospheric layer — the corona. Compiling one photo every hour, the movie condenses a decade of the Sun into 61 minutes. The video shows the rise and fall in activity that occurs as part of the Sun’s 11-year solar cycle and notable events, like transiting planets and eruptions.

While SDO has kept an unblinking eye pointed towards the Sun, there have been a few moments it missed. The dark frames in the video are caused by Earth or the Moon eclipsing SDO as they pass between the spacecraft and the Sun. A longer blackout in 2016 was caused by a temporary issue with the AIA instrument that was successfully resolved after a week. The images where the Sun is off-center were observed when SDO was calibrating its instruments.

Video credit: NASA’s Goddard Space Flight Center/SDO/Scott Wiessinger (USRA): Lead Producer/Tom Bridgman (GST): Lead Data Visualizer/Mara Johnson-Groh (Wyle Information Systems): Lead Science Writer/Lars Leonhard

NASA dicit:

NASA’s Transiting Exoplanet Survey Satellite (TESS) and retired Spitzer Space Telescope have found a young Neptune-size world orbiting AU Microscopii, a cool, nearby M dwarf star surrounded by a vast disk of debris. The discovery makes the system a touchstone for understanding how stars and planets form and evolve.

Video credit: NASA’s Goddard Space Flight Center/Chris Smith (USRA): Lead Producer/Chris Smith (USRA): Lead Animator/Francis Reddy (University of Maryland College Park): Science Writer

NASA dicit:

Geronimo Villanueva, a planetary scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, created the sunset simulations while building a computer modeling tool for a possible future mission to Uranus, an icy-cold planet in the outer solar system. The animations show all-sky views as if you were looking up at the sky through a super wide camera lens from Earth, Venus, Mars, Uranus, and Titan.

Video credit: Geronimo Villanueva/James Tralie/NASA’s Goddard Space Flight Center

Wikipedia dicit:

K2-18b was identified as part of the Kepler space telescope program, one of over 1,200 exoplanets discovered during the “Second Light” K2 mission. The discovery of K2-18b was made in 2015, orbiting a red dwarf star (now known as K2-18) with a stellar spectral type of M2.8 about 124 light-years (38 pc) from Earth. The planet was detected through variations in the star’s light curve caused by the transit of the planet in front of the star as seen from Earth. The planet was designated “K2-18b” as it was the eighteenth planet discovered during the K2 mission. The predicted relatively low contrast between the planet and its host star would make it easier to observe K2-18b’s atmosphere in the future.

In 2017, data from the Spitzer Space Telescope confirmed that K2-18b orbits in the habitable zone around K2-18 with a 33-day period, short enough to allow for observations of multiple K2-18b orbital cycles and improving the statistical significance of the signal. This led to widespread interest in continued observations of K2-18b.

Later studies on K2-18b using the High Accuracy Radial Velocity Planet Searcher (HARPS) and the Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs (CARMENES) instruments also identified a likely second exoplanet, K2-18c, with an estimated mass of 5.62±0.84 M⊕ in a tighter, 9-day orbit, but this additional planet has not yet been confirmed, and may instead be due to stellar activity.

Video credit: NASA Goddard