OrbitalHub

Wikipedia dicit:

Juno is a NASA space probe orbiting the planet Jupiter. It was built by Lockheed Martin and is operated by NASA’s Jet Propulsion Laboratory. The spacecraft was launched from Cape Canaveral Air Force Station on 5 August 2011 UTC, as part of the New Frontiers program. Juno entered a polar orbit of Jupiter on 5 July 2016 UTC, to begin a scientific investigation of the planet. After completing its mission, Juno will be intentionally deorbited into Jupiter’s atmosphere.

Juno’s mission is to measure Jupiter’s composition, gravitational field, magnetic field, and polar magnetosphere. It will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, mass distribution, and its deep winds, which can reach speeds up to 620 km/h (390 mph).

Juno is the second spacecraft to orbit Jupiter, after the nuclear powered Galileo orbiter, which orbited from 1995 to 2003. Unlike all earlier spacecraft sent to the outer planets, Juno is powered by solar arrays, commonly used by satellites orbiting Earth and working in the inner Solar System, whereas radioisotope thermoelectric generators are commonly used for missions to the outer Solar System and beyond. For Juno, however, the three largest solar array wings ever deployed on a planetary probe play an integral role in stabilizing the spacecraft as well as generating power.

Video credit: NASA/JPL-Caltech/SwRI/UVS/ULiège/Bonfond

NASA dicit:

NASA’s Juno mission to Jupiter has made an unexpected discovery about a different planet – Mars. Juno scientists discovered that Martian dust may be the source of a sky phenomenon known as the zodiacal light.

Look up to the night sky just before dawn, or after dusk, and you might see a faint column of light extending up from the horizon. That glow is the zodiacal light, or sunlight reflected toward Earth by a cloud of tiny dust particles orbiting the Sun.

Astronomers have long thought that the dust is brought into the inner solar system by asteroids and comets. But now, a team of Juno scientists argues that the planet Mars may be the source. The discovery resulted from dust particles slamming into the Juno spacecraft during its journey from Earth to Jupiter. Juno’s expansive solar panels unintentionally became the biggest and most sensitive dust detector ever built. Impacts on the solar panels provided important clues to the origin and orbital evolution of the dust, resolving some of the mysterious variations observed in the zodiacal light.

Video credit: NASA’s Goddard Space Flight Center/Dan Gallagher (USRA): Lead Producer/Michael Lentz (USRA): Lead Animator/Kel Elkins (USRA):Lead Data Visualizer/Lonnie Shekhtman (ADNET): Writer/Rani Gran (NASA/GSFC): Public Affairs Officer/John Connerney (NASA/GSFC): Scientist/David Agle (JPL): Support/Aaron E. Lepsch (ADNET): Technical Support/Original musical score by Vangelis, used with permission.

NASA dicit:

As a planet moves around its host star, it exerts a tiny gravitational tug that shifts the star’s position a bit. This can pull the distant star closer and farther from a perfect alignment. Since the nearer star acts as a natural lens, it’s like the distant star’s light will be pulled slightly in and out of focus by the orbiting planet. By picking out little shudders in the starlight, astronomers will be able to infer the presence of planets.

Xallarap is parallax spelled backward. Parallax relies on motion of the observer – Earth moving around the Sun – to produce a change in the alignment between the distant source star, the closer lens star and the observer. Xallarap works the opposite way, modifying the alignment due to the motion of the source.

While microlensing is generally best suited to finding worlds farther from their star than Venus is from the Sun, the xallarap effect works best with very massive planets in small orbits, since they make their host star move the most. Revealing more distant planets will also allow us to probe a different population of worlds.

Video credit: NASA

NASA dicit:

Globular clusters are extremely dense stellar systems, which host stars that are closely packed together. These systems are also typically very old — the globular cluster at the focus of this study, NGC 6397, is almost as old as the universe itself. This cluster resides 7,800 light-years away, making it one of the closest globular clusters to Earth. Due to its very dense nucleus, it is known as a core-collapsed cluster.

At first, astronomers thought the globular cluster hosted an intermediate-mass black hole. These are the long-sought “missing link” between supermassive black holes (many millions of times our Sun’s mass) that lie at the cores of galaxies, and stellar-mass black holes (a few times our Sun’s mass) that form following the collapse of a single massive star. Their mere existence is hotly debated. Only a few candidates have been identified to date.

The researchers used previous estimates of the stars’ tiny proper motions (their apparent motions on the sky), which allow for determining their true velocities within the cluster. These precise measurements for stars in the cluster’s core could only be made with Hubble over several years of observation. The Hubble data were added to well-calibrated proper motion measurements provided by the European Space Agency’s Gaia space observatory which are less precise than Hubble’s observations in the core.

Video credit: NASA’s Goddard Space Flight Center/Paul Morris: Lead Producer/Music: “Glass Ships” by Chris Constantinou [PRS] and Paul Frazer [PRS] via Killer Tracks [BMI] and Universal Production Music/Visual Credits: Artist’s Impression of the Black Hole Concentration in NGC 6397/Video credit: ESA/Hubble, N. Bartmann/Callout of the Black Hole Concentration in NGC 6397/Video credit: ESA/Hubble, N. Bartmann/Artist Rendition of Gaia Spacecraft/Image credit: ESA, C. Carreau

Wikipedia dicit:

A brown dwarf is a type of substellar object that has a mass between the most massive gas giant planets and the least massive stars, approximately 13 to 80 times that of Jupiter (MJ).

Unlike main sequence stars, brown dwarfs do not acquire enough mass to trigger sustained nuclear fusion of ordinary hydrogen (1H) into helium in their cores. For this reason brown dwarfs are sometimes referred to as failed stars. They are, however, thought to fuse deuterium (2H), and to fuse lithium (7Li) if their mass is > 65 MJ. The minimum mass required to trigger sustained hydrogen-burning forms the upper limit of the definition currently used by the International Astronomical Union, while the deuterium-burning minimum mass of ~13 MJ forms the lower limit of the class, below which lie the planets.

It is also debated whether brown dwarfs would be better defined by their formation process rather than by theoretical mass limits based on nuclear fusion reactions. Under this interpretation brown dwarfs are those objects that represent the lowest-mass products of the star formation process, while planets are objects formed in an accretion disk surrounding a star. The coolest free-floating objects discovered such as WISE 0855, as well as the lowest-mass young objects known like PSO J318.5−22, are thought to have masses below 13 MJ, and as a result are sometimes referred to as planetary mass objects due to the ambiguity of whether they should be regarded as rogue planets or brown dwarfs. There are planetary mass objects known to orbit brown dwarfs, such as 2M1207b, MOA-2007-BLG-192Lb, and 2MASS J044144b.

Astronomers classify self-luminous objects by spectral class, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M, L, T, and Y. As brown dwarfs do not undergo stable hydrogen fusion they cool down over time, progressively passing through later spectral types as they age.

Video credit: NASA’s Goddard Space Flight Center/Scott Wiessinger (USRA): Animator/Scott Wiessinger (USRA): Producer/Ashley Balzer (ADNET): Science Writer/Claire Andreoli (NASA/GSFC): Public Affairs Officer

NASA dicit:

The Crab Nebula has been studied by people since it first appeared in Earth’s sky in 1054 A.D. Modern telescopes have captured its enduring engine powered by a quickly spinning neutron star that formed when a massive star collapsed. The combination of rapid rotation and a strong magnetic field generates jets of matter and anti-matter flowing away from its poles, and winds outward from its equator. For the translation of these data into sound, which also pans left to right, each wavelength of light has been paired with a different family of instruments. X-rays from Chandra X-ray Observatory (blue and white) are brass, optical light data from Hubble Space Telescope (purple) are strings, and infrared data from Spitzer (pink) can be heard in the woodwinds. In each case, light received towards the top of the image is played as higher pitched notes and brighter light is played louder.

Video credit: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)