Category: planeta

ALMA Discovers Trio of Infant Planets around N…

Novel technique to find youngest planets in our galaxy.

The Atacama Large Millimeter/submillimeter Array (ALMA) has transformed our understanding of protoplanetary discs — the gas- and dust-filled planet factories that encircle young stars. The rings and gaps in these discs provide intriguing circumstantial evidence for the presence of protoplanets. Other phenomena, however, could also account for these tantalising features.

But now, using a novel planet-hunting technique that identifies unusual patterns in the flow of gas within a planet-forming disc around a young star, two teams of astronomers have each confirmed distinct, telltale hallmarks of newly formed planets orbiting an infant star.

Measuring the flow of gas within a protoplanetary disc gives us much more certainty that planets are present around a young star,” said Christophe Pinte of Monash University in Australia and Institut de Planétologie et d’Astrophysique de Grenoble (Université de Grenoble-Alpes/CNRS) in France, and lead author on one of the two papers. “This technique offers a promising new direction to understand how planetary systems form.”

“We looked at the localised, small-scale motion of gas in the star’s protoplanetary disc. This entirely new approach could uncover some of the youngest planets in our galaxy, all thanks to the high-resolution images from ALMA,” said Richard Teague, an astronomer at the University of Michigan and principal author on the other paper.

Rather than focusing on the dust within the disc, which was clearly imaged in earlier ALMA observations, the astronomers instead studied carbon monoxide (CO) gas spread throughout the disc. Molecules of CO emit a very distinctive millimetre-wavelength light that ALMA can observe in great detail. Subtle changes in the wavelength of this light due to the Doppler effect reveal the motions of the gas in the disc.

The team led by Teague identified two planets located approximately 12 billion and 21 billion kilometres from the star. The other team, led by Pinte, identified a planet at about 39 billion kilometres from the star.

The two teams used variations on the same technique, which looks for anomalies in the flow of gas — as evidenced by the shifting wavelengths of the CO emission — that indicate the gas is interacting with a massive object [5].

The technique used by Teague, which derived averaged variations in the flow of the gas as small as a few percent, revealed the impact of multiple planets on the gas motions nearer to the star. The technique used by Pinte, which more directly measured the flow of the gas, is better suited to studying the outer portion of the disc. It allowed the authors to more accurately locate the third planet, but is restricted to larger deviations of the flow, greater than about 10%.

In both cases, the researchers identified areas where the flow of the gas did not match its surroundings — a bit like eddies around a rock in a river. By carefully analysing this motion, they could clearly see the influence of planetary bodies similar in mass to Jupiter.

This new technique allows astronomers to more precisely estimate protoplanetary masses and is less likely to produce false positives. “We are now bringing ALMA front and centre into the realm of planet detection,” said coauthor Ted Bergin of the University of Michigan.

Both teams will continue refining this method and will apply it to other discs, where they hope to better understand how atmospheres are formed and which elements and molecules are delivered to a planet at its birth.

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High-resolution images of Pluto taken by NAS…

High-resolution images of Pluto taken by NASA’s New Horizons spacecraft.

The plains on Pluto’s surface are composed of more than 98 percent nitrogen ice, with traces of methane and carbon monoxide. Nitrogen and carbon monoxide are most abundant on the anti-Charon face of Pluto (around 180° longitude, where Tombaugh Regio’s western lobe, Sputnik Planitia, is located), whereas methane is most abundant near 300° east. The mountains are made of water ice. Pluto’s surface is quite varied, with large differences in both brightness and color. Pluto is one of the most contrastive bodies in the Solar System, with as much contrast as Saturn’s moon Iapetus. The color varies from charcoal black, to dark orange and white. Pluto’s color is more similar to that of Io with slightly more orange and significantly less red than Mars. Notable geographical features include Tombaugh Regio, or the “Heart” (a large bright area on the side opposite Charon), Cthulhu Macula, or the “Whale” (a large dark area on the trailing hemisphere), and the “Brass Knuckles” (a series of equatorial dark areas on the leading hemisphere). Sputnik Planitia, the western lobe of the “Heart”, is a 1,000 km-wide basin of frozen nitrogen and carbon monoxide ices, divided into polygonal cells, which are interpreted as convection cells that carry floating blocks of water ice crust and sublimation pits towards their margins; there are obvious signs of glacial flows both into and out of the basin. It has no craters that were visible to New Horizons, indicating that its surface is less than 10 million years old.

source | images: NASA/JPL

The Moon is lit by the golden colours of sunse…

The Moon is lit by the golden colours of sunset and Venus is just about to get occulted disappearing behind the dark limb of the Moon.

Image credit: Luis Argerich

What’s Your favorite space object?

What’s Your favorite space object?

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In 40 million years, Mars may have a ring (a…

In 40 million years, Mars may have a ring (and one fewer moon)

Nothing lasts forever – especially Phobos, one of the two small moons orbiting Mars. The moonlet is spiraling closer and closer to the Red Planet on its way toward an inevitable collision with its host. But a new study suggests that pieces of Phobos will get a second life as a ring around the rocky planet.

A moon – or moonlet – in orbit around a planet has three possible destinies. If it is just the right distance from its host, it will stay in orbit indefinitely. If it’s beyond that point of equilibrium, it will slowly drift away. (This is the situation with the moon; as it gradually pulls away from Earth, its orbit is growing by about 1.5 inches per year.) And if a moon starts out on the too-close side, its orbit will keep shrinking until there is no distance left between it and its host planet.

The Martian ring will last for at least 1 million years – and perhaps for as long as 100 million years, according to the study.

The rest of Phobos will probably remain intact, until it hits the Martian surface. But it won’t be a direct impact; instead, the moonlet’s remains will strike at an oblique angle, skipping along the surface like a smooth stone on a calm lake.

This has probably happened before – scientists believe a group of elliptical craters on the Martian surface were caused by a small moon that skidded to its demise. (If this were to happen on Earth, our planet’s greater mass would produce a crash as big as the one that wiped out the dinosaurs, the researchers noted as an aside.)

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images: NASA/JPL,

Tushar Mittal using Celestia 2001-2010, Celestia Development Team.

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The diversity of worlds in our solar system (climate and geology)…

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The Great Red Spot is a persistent high-pressure region in the atmosphere of Jupiter, producing an anticyclonic storm 22° south of the planet’s equator. It has been continuously observed for 188 years, since 1830. Earlier observations from 1665 to 1713 are believed to be of the same storm; if this is correct, it has existed for at least 350 years. Such storms are not uncommon within the turbulent atmospheres of gas giants.

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With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io’s interior as it is pulled between Jupiter and the other Galilean satellites—Europa, Ganymede and Callisto.

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Europa has the smoothest surface of any known solid object in the Solar System. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably harbor extraterrestrial life.

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Neptune, the eighth and farthest planet from the sun, has the strongest winds in the solar system. At high altitudes speeds can exceed 1,100 mph. That is 1.5 times faster than the speed of sound. In 1989, NASA’s Voyager 2 spacecraft made the first and only close-up observations of Neptune.

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Ganymede  is the largest and most massive moon of Jupiter and in the Solar System.

Possessing a metallic core, it has the lowest moment of inertia factor of any solid body in the Solar System and is the only moon known to have a magnetic field. (Sounds of Ganymede’s magnetosphere).

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Saturn’s hexagon is a persisting hexagonal cloud pattern around the north pole of Saturn, located at about 78°N. The sides of the hexagon are about 13,800 km (8,600 mi) long, which is more than the diameter of Earth (about 12,700 km (7,900 mi)).

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Miranda’s surface has patchwork regions of broken terrain indicating intense geological activity in Miranda’s past, and is criss-crossed by huge canyons. It also has the largest known cliff in the Solar System, Verona Rupes, which has a height of over 5 km (3.1 mi). 

Some of Miranda’s terrain is possibly less than 100 million years old based on crater counts, which suggests that Miranda may still be geologically active today.

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Enceladus is the sixth-largest moon of Saturn. It is about 500 kilometers (310 mi) in diameter, about a tenth of that of Saturn’s largest moon, Titan. 

Evidence of liquid water on Enceladus began to accumulate in 2005, when scientists observed plumes containing water vapor spewing from its south polar surface, with jets moving 250 kg of water vapor every second at up to 2,189 km/h (1,360 mph) into space.

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Titan is the largest moon of Saturn. It is the only moon known to have a dense atmosphere, and the only object in space, other than Earth, where clear evidence of stable bodies of surface liquid has been found.

Triton is one of the few moons in the Solar System known to be geologically active (the others being Jupiter’s Io and Europa, and Saturn’s Enceladus and Titan). As a consequence, its surface is relatively young with few obvious impact craters, and a complex geological history revealed in intricate cryovolcanic and tectonic terrains. Part of its surface has geysers erupting sublimated nitrogen gas, contributing to a tenuous nitrogen atmosphere less than 1/70,000 the pressure of Earth’s atmosphere at sea level.

source: wikipedia~

image credit: data and images from NASA

Rhea and Saturn by Gordan Ugarkovic

Rhea and Saturn by Gordan Ugarkovic

This picture of Mercury was taken by NASA&rs…

This picture of Mercury was taken by NASA’s MESSENGER spacecraft.

Credits: NASA

Hubble’s Jupiter and the Shrinking Gre…

Hubble’s Jupiter and the Shrinking Great Red Spot 

Image Credit: NASA, ESA, Hubble, OPAL Program, STScI; Processing: Karol Masztalerz