Dust Traps and Planet Factories

From ESO. Astronomers now know that planets around other stars are plentiful. But they do not fully understand how they form and there are many aspects of the formation of comets, planets and other rocky bodies that remain a mystery. However, new observations exploiting the power of the ALMA telescope array are now answering one of the biggest questions: how do tiny grains of dust in the disc around a young star grow bigger and bigger — to eventually become rubble, and even boulders well beyond a metre in size?

Computer models suggest that dust grains grow when they collide and stick together. However, when these bigger grains collide again at high speed they are often smashed to pieces and sent back to square one. Even when this does not happen, the models show that the larger grains would quickly move inwards because of friction between the dust and gas and fall onto their parent star, leaving no chance that they could grow even further.

Somehow the dust needs a safe haven where the particles can continue growing until they are big enough to survive on their own [1]. Such “dust traps” have been proposed, but there was no observational proof of Continue reading Dust Traps and Planet Factories

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No Gentle Galaxy Collision

From Hubblecast, a vivid new image of colliding galaxies known as Arp 142. When two galaxies stray too close to each other they begin to interact, causing spectacular changes in both objects. In some cases the two can merge — but in others, they are ripped apart.

Just below the center of this image is the blue, twisted form of galaxy NGC 2936, one of the two interacting galaxies that form Arp 142 in the constellation of Hydra. Nicknamed “the Penguin” or “the Porpoise” by amateur astronomers, NGC 2936 used to be a standard spiral galaxy before being torn apart by the gravity of its cosmic companion.

The remnants of its spiral structure can still be seen — the former galactic bulge now forms the “eye” of the penguin, around which it is still possible to see where the galaxy’s pinwheeling arms once were. These disrupted arms now shape the cosmic bird’s “body” as bright streaks of blue and red across the image. These streaks arch down towards NGC 2936’s nearby companion, the elliptical galaxy NGC 2937, visible here as a bright white oval. The pair show an uncanny resemblance to a penguin safeguarding its egg.

The effects of gravitational interaction between galaxies Continue reading No Gentle Galaxy Collision

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Super-Earths: New Planets Found!

Astronomers working at the European Southern Observatory (ESO) in Chile have discovered seven planets orbiting the star Gliese 667C.

Two exoplanets have been discovered in the star’s habitable zone, which has just the right range of distance where liquid water can exist on a planet’s surface.

A super-Earth is an extrasolar planet with a mass higher than Earth’s, but substantially below the mass of the Solar System’s smaller gas giants Uranus and Neptune, which are both more or less 15 Earth masses.

The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability.

Astronomers at the European Southern Observatory in Chile found out that 40 per cent of red dwarves are orbited by super-Earths. Red Dwarfs are by far the most common type of star in the Milky Way galaxy, so there might be tens of billions of such planets in our galaxy alone.

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Penetrating the Solar Surface

The Interface Region Imaging Spectrograph, or IRIS, has made it’s first major heliospheric discovery. Finding unprecedented temperature changes, we are gaining critical data about how heat travels from the sun’s core to its various destinations in our solar system.

IRIS is designed to provide significant new information to increase our understanding of energy transport into the corona and solar wind and provide an archetype for all stellar atmospheres. The unique instrument capabilities, coupled with state of the art 3-D modeling, will fill a large gap in our knowledge of this dynamic region of the solar atmosphere. The mission will extend the scientific output of existing heliophysics spacecraft that follow the effects of energy release processes from the sun to Earth.

IRIS will provide key insights into all these processes, and thereby advance our understanding of the solar drivers of space weather from the corona to the far heliosphere, by combining high-resolution imaging and spectroscopy for the entire chromosphere and adjacent regions. IRIS will resolve in space, time, and wavelength the dynamic geometry from the chromosphere to the low-temperature corona to shed much-needed light on the physics of this magnetic interface region.

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Cosmic Journeys – HyperEarth

Scientists are intensively tracking the workings of planet Earth with satellites that chart its winds, ocean currents, temperatures, plant growth, and more. They are constructing a new virtual Earth based on physical equations, satellite data, and computer codes that show the workings of our planet in whole new ways.

Our world, Earth, is changing before our eyes. Go back millions of years. Forests reached into polar regions, sea levels rose, and temperatures soared with high levels of the greenhouse gas, carbon dioxide in the atmosphere. A long cooling period followed. But now CO2 is on the rise again. What will happen? How will we live in the New World that’s now emerging?

Scientists are intensively tracking the workings of planet Earth with satellites that chart its winds, ocean currents, temperatures, plant growth, and more. And with a new virtual Earth, shrunk down and converted into physical equations, satellite data, and computer codes they are able to show the workings of our planet in whole new ways..

This other Earth, a mirror of the one in which we live, is designed to follow the flow of heat through the complex, dynamic engine known as the climate… and to predict its future evolution. Continue reading Cosmic Journeys – HyperEarth

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Titan: The Mystery of the Missing Waves

Titan (or Saturn VI) is the largest moon of Saturn. It is the only natural satellite known to have a dense atmosphere and the only object, other than Earth, for which clear evidence of stable bodies of surface liquid has been found. However, these bodies of liquid are incredibly still, with no sign of wave activity. What is causing this incredible phenomenon?

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The Incredible Sungrazing Comets

A sungrazing comet is a comet that passes extremely close to the Sun at perihelion — sometimes within a few thousand kilometers of the Sun’s surface. While small sungrazers can be completely evaporated during such a close approach to the Sun, larger sungrazers can survive many perihelion passages. However, the strong evaporation and tidal forces they experience often lead to their fragmentation.

What can these comets tell us about our solar system? Perhaps they can even reveal some of the mysteries of the sun itself…

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Meteor Explodes Over Russia

From NASA’s Scientific Visualization Studio. Analysis of the meteor that flew in over Russia tells a surprising tale. Shortly after dawn on Feb. 15, 2013, a bolide measuring 18 meters across and weighing 11,000 metric tons, screamed into Earth’s atmosphere at 18.6 kilometers per second. Burning from the friction with Earth’s thin air, the space rock exploded 23.3 kilometers above Chelyabinsk, Russia.

The event led to the formation of a new dust belt in Earth’s stratosphere. Scientists used data from the NASA-NOAA Suomi NPP satellite along with the GEOS-5 computational atmospheric model to achieve the first space-based observation the long-term evolution of a bolide plume.

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Black Holes and Exploding Stars: FERMI at Five

From NASA’s Scientific Visualization Studio. In only five short years, the FERMI Space Telescope has observed and catalogued an astounding amount of phenomena, including some of the most high-energy events in our galaxy.

The Fermi Gamma-ray Space Telescope (FGST), formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor (GBM; formerly GLAST Burst Monitor), is being used to study gamma-ray bursts.

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