planetesimal

Mysterious and Well-Preserved Oort Cloud Object Heading Into Our Solar System

What if we could journey to the outer edge of the Solar System – beyond the familiar rocky planets and the gas giants, past the orbits of asteroids and comets – one thousand times further still – to the spherical shell of icy particles that enshrouds the Solar System. This shell, more commonly known as the Oort cloud, is believed to be a remnant of the early Solar System.

Imagine what astronomers could learn about the early Solar System by sending a probe to the Oort cloud! Unfortunately 1-2 light years is more than a little beyond our reach. But we’re not entirely out of luck. 2010 WG9 – a trans-Neptunian object — is actually an Oort Cloud object in disguise. It has been kicked out of its orbit, and is heading closer towards us so we can get an unprecedented look.

But it gets even better! 2010 WG9 won’t get close to the Sun, meaning that its icy surface will remain well-preserved. Dr. David Rabinowitz, lead author of a paper about the ongoing observations of this object told Universe Today, “This is one of the Holy Grails of Planetary Science – to observe an unaltered planetesimal left over from the time of Solar System formation.”

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Peer Pressure keeps young planets growing

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Why don’t young planets get pushed into their companion stars before they have a chance to grow? Astronomers believe that planets form in a disk of gas and dust surrounding a young star. The first step towards planet formation is the planetesimal – a small rocky body with radius of roughly 1–10 km. As the dust condenses into planetesimals during the first few million years of a star’s life, larger rocks begin to emerge that grow much more rapidly than the rest. These bodies, termed oligarchs, are on their way to young planethood, using their gravitational pull to attract and pack on more planetesimals.

In addition to providing a means for growth, planetesimals can also push an oligarch towards its doom in the central star. A lone oligarch orbiting through the disk of planetesimals clears a path much like a stick being dragged through sand. The planetesimals on either side of the trench press on the oligarch, and as the outer ring has more mass, the planetesimals deliver a net inward push.

In the past, magnetic fields, turbulence and thermodynamics have been used to explain how rocky planets are prevented from falling into their stars. However, a new study by Bromley and Kenyon say that the wake patterns created by multiple oligarchs circling a star are enough to prevent structures from forming in the planetesimal disk that would push the young planets in.

Once the oligarchs account for about half of the material in the disk, a few tens of millions of years after the birth of the star, they begin making even more material gains by combining with one another. Rather than hollowing out a series of trenches, the oligarchs are now randomly scrawling in the planetesimal “sand”, which also prevents the planetesimals from settling into patterns that would feed the oligarchs to the star.

Jupiter a "failed star"

   astronomy has developed a lot.scientists have studied almost all planets.they are trying to figure out the formation of the planets.by doing so the came to know that the formation of  jupiter, “the king of all planets” was a little bit different. jupiter’s  formation initially, likely to be a star but a very different manner than stars form.thus it was called a “failed star”.

formation of stars

  Stars form directly from the collapse of dense clouds of interstellar gas and dust. Because of rotation, these clouds form flattened disks that surround the central, growing stars. After the star has nearly reached its final mass, by accreting gas from the disk, the leftover matter in the disk is free to form planets.  

a different jupiter

Jupiter is generally believed to have formed in a two-step process. First, a vast swarm of ice and rock ‘planetesimals’ formed. These comet-sized bodies collided and accumulated into ever-larger planetary embryos. Once an embryo became about as massive as ten Earths, its self-gravity became strong enough to pull in gas directly from the disk. During this second step, the proto-Jupiter gained most of its present mass (a total of 318 times the mass of the Earth). Soon thereafter, the disk gas was removed by the intense early solar wind, before Saturn could grow to a similar size.          

brown dwarf      

 brown dwarfs may look like planets but they form like stars–that is, they collapse directly from a gas cloud, rather than building up in the disk around a star. Brown dwarfs lack sufficient mass to shine, so they might more fairly be described as “failed stars.“   

why jupiter?

                jupiter is formed  of same elements such as hydrogen,helium as of the sun,but it is not massive enough pressure and temperature to fuse hydrogens to form helium ,which is the power source of stars. 

binary star system

if jupiter had become a star,our solar system would have become a binary star system.a binary star system is those systems having two stars.they both revolve around themselves in their own orbits.it is interesting to note that most of the solar systems in the universe are binary,triple or higher multiple star systems but our sun is rather unusual.it is the sun which grabbed most of the mass during the formation of solar system.this made jupiter a failed star while in other systems the masses are more equitably distributed
thus its still mysterious, scientists are trying to fathom these mysterious details of the birth process.

source:scientific american

pc :nasa,wikipedia

#science#space#astronomy#nasa
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New views of giant asteroid Vesta revealed

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(This image released Monday, Dec. 5, 2011, by the Dawn spacecraft shows the surface of the massive asteroid Vesta. Credit: AP Photo/NASA)

“New views of the massive asteroid Vesta reveal it is more like a planet than an asteroid, scientists said Monday.”

“Since slipping into orbit around Vesta in July, NASA’s Dawn spacecraft has beamed back stunning images of the second largest object residing in the asteroid belt.”

“Vesta’s rugged surface is unique compared to the solar system’s much smaller and lightweight asteroids. Impact craters dot Vesta’s surface along with grooves, troughs and a variety of minerals.”

“‘Vesta is unlike any other asteroid,’ said mission co-scientist Vishnu Reddy of the Max Planck Institute for Solar System Research in Germany. The new findings were presented at a meeting of the American Geophysical Union in San Francisco.”

2010 WG9 & The Oort Cloud

Somewhere beyond the orbit of Neptune is a treasure-trove just waiting to be opened – and I’m not talking about Pluto. Astronomers have identified the trans-Neptunian object 2010 WG9; it’s certainly an awesome find. Dr. David Rabinowitz believes 2010 WG9 isn’t any regular trans-Neptunian object, but rather an object from the Oort cloud that has ventured closer to home.

To read the full article, see: http://www.fromquarkstoquasars.com/2010-wg9-the-oort-cloud/

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Asteroids, Comets and Meteors: What’s what? 

Asteroids, comets and meteors are all rocky bodies within our solar system but significantly smaller than planets. We hear the terms all the time but what’s the difference between them? 

Asteroids are composed of rock, nickel and iron, and range from a few metres to 900 kilometres in diameter. Some have molten cores and thin crusts like the Earth, and we think they’re most likely failed planetesimals—rocks that didn’t quite stick together into large planets. They orbit the Sun in a large belt in the gap between Mars and Jupiter, whose strong gravity disrupts the belt all the time; it may have prevented the belt from accreting into a planet early in the solar system’s history. But there actually isn’t a whole lot of material in the asteroid belt—if they formed a planet, it would be smaller than the Moon. 

Comets, on the other hand, originate outside the solar system. Long period comets (with orbits of more than 200 years) come from the Oort Cloud, which is a spherical halo of matter surrounding the solar system 50,000 AU away. Short period comets (with orbits of less than 200 years) come from the Kuiper Belt, a ring of icy objects beyond Neptune, 30-100 AU away. Comets can be as big as a small town and consist of frozen rock, gas and dust, with a hard nucleus of rock surrounded by water, methane, ammonia, and carbon dioxide. When their orbits veer close to the sun, their frozen nucleus begins thaw, throwing out gas and dust. This forms a coma, the fuzzy outline, and a tail, which can trail out for millions of kilometres. (Note: the tail of a comet doesn’t point directly behind the comet; rather, directly away from the sun because it’s blown by the solar wind.) As comets continue to orbit over many years they lose more and more of their icy material, until eventually they’re just hunks of rock. 

Finally, meteoroids are rocky bodies significantly smaller than asteroids or comets, only up to 1 metre across, composed of rocks and dust grains. They’re actually debris, commonly formed when asteroids collide or when comets leave material behind them in their wake. When meteoroids pass by the Earth, our gravity can pull them into the atmosphere where they burn up at high speeds, letting off flashes of light. In this case they’re called meteors. If they’re large enough to reach the Earth’s surface, we call them meteorites. We have annual, predictable meteor showers because Earth regularly passes through the debris left behind by comets, sending showers of glittering rock and dust through our atmosphere. 

So to sum up: 

  • Asteroids are failed planetesimals, orbiting within the asteroid belt except when thrown off course by larger planets. 
  • Comets are icy objects from the outer reaches of the solar system, and take a long time to orbit the Sun. 
  • Meteoroids are much smaller debris, left over from collisions. 

Bam. Science.

(Image Credit)

NASA Astronomy Picture of the Day 2016 May 7 

Three Worlds for TRAPPIST-1 

Three new found worlds orbit the ultracool dwarf star TRAPPIST-1, a mere 40 light-years away. Their transits were first detected by the Belgian robotic TRAnsiting Planets and Planetesimals Small Telescope, TRAPPIST, at ESO’s La Silla Observatory in Chile. The newly discovered exoplanets are all similar in size to Earth. Because they orbit very close to their faint, tiny star they could also have regions where surface temperatures allow for the presence of liquid water, a key ingredient for life. Their tantalizing proximity to Earth makes them prime candidates for future telescopic explorations of the atmospheres of these potentially habitable planets. All three worlds appear in this artist’s vision, an imagined scene near the horizon of the system’s outermost planet. Of course, the inner planet is transiting the dim, red, nearly Jupiter-sized parent star.

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The Oort Cloud
TOP:  Graphic from NASA
BOTTOM:  Still image from Neil Tyson's Cosmos [Fox / National Geographic]

Frozen rocks and dust (“planetesimals”) that remained after the solar system formed, the Oort Cloud is a sphere of comets that surrounds us - at a distance of about 1 light year from the sun - in all directions.   [WP]

Fortunately for our aspirations to become interstellar travelers, the planetesimals are not very near one another.

Phoebe was on her way to becoming a planet

NASA’s Cassini probe has recently revealed that Saturn’s moon Phoebe may be more like a planet than previously expected. The moon is likely a planetesimal – a body that evolved quickly and actively during the early life of the solar system; that has chemical, geological, and geophysical properties similar to planets; and that may have evolved into a planet, had its development not stalled out.

(Image from Science Daily)

cosmic witchcraft 101: jovian magick ♃

Jupiter is the fifth planet from the Sun. Due to its massive size, there are multiple ways the planet could have formed. Regardless of its formation process, some scientists believe that Jupiter migrated inward right up to the orbit of Mars after its initial formation. This is referred to as the Grand Tack Hypothesis. In the early solar system, Neptune and the other outer planets may have begun interacting with icy planetesimals, sending comets from one planet to the next, causing Uranus, Neptune, and Saturn to move outwards as the comets moved inwards. When the comets reached Jupiter, the planet’s massive gravity flung the comets into highly elliptical orbits or out of the solar system entirely and Jupiter migrated inwards to conserve angular momentum.

As it made its way towards the Sun, Jupiter’s gravity would have prevented the asteroid belt material from forming into planets and swept away large amounts of material that may have made Mars more massive. Thanks to Saturn, Jupiter stopped its inward migration and turned around, settling approximately where we see it today. As Jupiter moved inward and Saturn moved outward, it’s theorized that they became locked in a 3:2 orbital resonance, with Saturn finishing 3 orbits around the Sun for Jupiter’s 2. Jupiter’s migration may have also brought icy and gaseous material into the inner solar system, helping the inner planets form their atmospheres and perhaps even providing those vital life-giving compounds we can thank for our existence today.

Facts:

  • Jupiter produces more heat than it receives from the Sun.
  • Jupiter is more than twice as massive as all the other planets combined.
  • The planet has at least 67 moons.
  • Jupiter is NOT a failed star. The smallest stars in the observable universe have about 1/12 of the Sun’s mass, and Jupiter has about 1/1000th of the Sun’s mass. Jupiter is simply a colossal planet.
  • The Great Red Spot is larger than Earth. It’s a colossal hurricane that’s been going on since the 17th century, maybe even before that.
  • Jupiter rotates faster than any of the other planets; a Jovian day is only about 10 Earth hours. It takes 11.86 years to orbit around the Sun.
  • Lighter stripes along the planet are called zones and darker stripes are called belts. They flow in opposite directions and turbulence between regions causes the Jupiter’s storms.

Magickal Correspondences*

Colors: red, white, yellow, brown, purple

Intents: growth, expansion, prosperity, justice, exploration, freedom, protection, spiritual evolution, success, meditation, psychic development, confidence, storm magick

Herbs: frankincense, rosemary, oak, cedar, nutmeg, sage, anise, catnip, sandalwood, rosehips, dandelion, fennel, tansy

Crystals: tin, amethyst, lepidolite, sugilite, lapis lazuli, sapphire, diamond, agate, antimony, rhodocrosite, aragonite, jasper, onyx, amber

*some of these correspondences are based on traditional associations and some are based on my personal associations

universetoday.com
Three New Earth-sized Planets Found Just 40 Light-Years Away
“With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun,” said Michael Gillon, lead author of the research paper.

Three more potentially Earthlike worlds have been discovered in our galactic backyard, announced online today by the European Southern Observatory. Researchers using the 60-cm TRAPPIST telescope at ESO’s La Silla observatory in Chile have identified three Earth-sized exoplanets orbiting a star just 40 light-years away.

The star, originally classified as 2MASS J23062928-0502285 but now known as TRAPPIST-1, is a dim “ultracool” brown dwarf only .05% as bright as our Sun . Located in the constellation Aquarius, it’s now the 37th-farthest star known to host orbiting exoplanets.

The exoplanets were discovered via the transit method (TRAPPIST stands for Transiting Planets and Planetesimals Small Telescope) through which the light from a star is observed to dim slightly by planets passing in front of it from our point of view. This is the same method that NASA’s Kepler spacecraft has used to find over 1,000 confirmed exoplanets.

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Astronomical Centaurs 

So we know that asteroids and comets are distinct bodies: asteroids orbit in the belt between Mars and Jupiter, while comets are icier and originate from the very fringes of the solar system. 

But there’s a special class of astronomical objects that aren’t quite comets or asteroids—there are 250 known icy planetesimals orbiting between Jupiter and Neptune, with half-and-half characteristics. The first one detected, Chiron, was originally thought to be an asteroid until it developed a coma like a comet, hence the name Centaur for the half-human, half-horse of mythology. 

Centaurs cross the orbits of the larger planets and so their own orbits are pretty unstable, constantly changing as the planets’ gravity affects them. 

Astronomers were once unsure whether Centaurs were asteroids slowly being flung out of the solar system, or comets being drawn in. But evidence now suggests that at least two thirds of Centaurs are objects of cometary-origin, formed in the Kuiper Belt, and are in the process of either becoming much shorter-period comets near Jupiter or being ejected right out. This means they’re made of the same material as comets, but many are inactive—but they may have been active in the past or will be in the future. 

More data will help us classify the remaining third, and learn more about how they formed and how they reached their current orbits.

(Image Credit)

The key to forming a planet could be found in some of the tiniest pieces of space debris—glassy beads the size of grains of sand that are known as chondrules. According to simulations developed in part by researchers at the Museum, asteroid-like objects known as planetesimals sweep up these glassy grains, growing into planets as they accumulate more and more dusty particles. The results of the simulations, carried out with collaborators at Lund University in Sweden and elsewhere, were published today in the journal Science Advances

“The big question is, ‘How did the planets come to be?’” said Mordecai-Mark Mac Low, a curator in the American Museum of Natural History’s Department of Astrophysics and an author on the paper. “When the solar system first started forming, the largest solids were sub-micron dust. The challenge is to figure out how all of that dust was gathered up into planet-building objects that then formed the diversity of planets and other smaller bodies that we see today.”

Planets start out small, as dust particles in the disk of gas and dust surrounding a young star collide and stick together to form dust bunnies, then pebbles, then boulders. However, models show that when those boulders get larger than a person, they begin to orbit faster than the surrounding gas. The resulting headwind brakes them in their orbit, so that they drift into their parent star within about 100 orbits. In addition, fast-moving boulders break apart, rather than sticking together, when they collide. So how do some of these objects stick around long enough to grow into planets?

Learn more about this new research

New Insights into Debris Discs

Using 39 of the 66 antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), located 5000 metres up on the Chajnantor plateau in the Chilean Andes, astronomers have been able to detect carbon monoxide (CO) in the disc of debris around an F-type star. The star, named HD 181327, is a member of the Beta Pictoris moving group, located almost 170 light-years from Earth.

Until now, the presence of CO has been detected only around a few A-type stars, substantially more massive and luminous than HD 181327. Using the superb spatial resolution and sensitivity offered by the ALMA observatory astronomers were now able to capture this stunning ring of smoke and map the density of the CO within the disc.

The study of debris discs is one way to characterise planetary systems and the results of planet formation. The CO gas is found to be co-located with the dust grains in the ring of debris and to have been produced recently. Destructive collisions of icy planetesimals in the disc are possible sources for the continuous replenishment of the CO gas. Collisions in debris discs typically require the icy bodies to be gravitationally perturbed by larger objects in order to reach sufficient collisional velocities. Moreover, the derived CO composition of the icy planetesimals in the disc is consistent with the comets in our Solar System. This possible secondary origin for the CO gas suggests that icy comets could be common around stars similar to our Sun which has strong implications for life suitability in terrestrial exoplanets.

Credit: ESO/Marino et al.

The Wreckage of Creation

In the 550 million kilometres (340 million miles) of space between the orbits of Mars and Jupiter lies the asteroid belt, where a vast mass of rubble circles the Sun in a diffuse and chaotic band.

More worlds than we see today condensed out of the solar system’s accretion disc, but at least a few of them developed orbits around the Sun that were too elliptical for safety. At some point in the distant past, their paths intersected and they smashed together, creating a swarm of rubble. Each chunk is known as…….? You guessed it, asteroids. Some asteroids may be the remains of an ancient planetesimal that was unlucky enough to stray too close to Jupiter. Tidal forces from the mighty gas giant tore the smaller world apart.

Meteorites are strayed asteroids that collide with Earth for one, surviving their fiery decent and reach the ground intact. Some meteorites are made of iron, or a mix of stone and iron. The most common kind of meteorites are stony, very rich in silicate minerals, with only small flecks of metal. These are the wreckage from the outermost crusts of planetesimals. So, let us be introduced to just some of the more well known ones, or, not so well known.

Eros: The Near-Earth Asteroid Rendezvous probe (NEAR) achieved orbit around asteroid 433 Eros in February 2000, and spent the next thirteen months studying the drifting rock, whose weak gravity field was just sufficient to hold the visiting probe in a slow orbit. Eros circles the Sun once every 1.76 years.

Vesta: At 560km (348 miles) across, Vesta should have been large enough to pull itself into a spherical shape by virtue of its mass and gravity. Something must have prevented that from happening, an impact perhaps?

Mathilde: This asteroid is a fairly sizeable 66km (41 miles) in diameter, but is not as dense as might be expected from such a hefty lump of rock. Its gravity field is only as strong as the effect that that a similar volume of water would exert. It may be pepped on the inside with cavities.

Gaspra: This small lump of rock is an S-type asteroid, rich in silicate materials and metals. In the future, asteroids such as Gaspra may make tempting targets for commercial exploitation.

Ida and Dactyl: This pretty sounding couple were discovered by the Galileo probe. The probe found that Ida has its own miniature moon, a small, irregular shaped lump of rock about 45km (33.5 miles) long, and composed of carbon-rich materials.

Lutetia: The European probe Rosetta made its closest approach to asteroid 21 Lutetia on July 10, 2010, revealing a battered world with many craters (post image). Lutetia is probably a primitive survivor from the violent birth of the Solar System; some 4.5 billion years ago… give or take. An interesting feature on Lutetia shows that boulders have participated in a landslide, tumbling down the sides of a depression. This hollow was probably gouged by an impact, but its sides have become softer and more rounded than might be expected.

So there you have it folks, there was an introduction to just a few of those fascinating but ominous balls of rock hurtling through space. Now it’s your turn. Care to share any more interesting asteroids with us? then post below and let us continue sharing the awesomeness of these things.

~ JM

Image Credit: ESA / MPS / UPD / LAM / IAA / RSSD / INTA / UPM / DASP / IDA / Daniel Machacek. Sourced on 19/05/15.

More Info:
Asteroid Day-Join the Movement
Rosetta Fly’s by Lutetia-Video
Near Earth Object Program
JPL Small-Body Database Browser
List of Asteroids, NASA

Just 40 light years from Earth, three planets might host life forms adapted to infrared worlds

Is there life beyond our solar system? If there is, our best bet for finding it may lie in three nearby, Earth-like exoplanets.                                

For the first time, an international team of astronomers from MIT, the University of Liège in Belgium, and elsewhere have detected three planets orbiting an ultracool dwarf star, just 40 light years from Earth. The sizes and temperatures of these worlds are comparable to those of Earth and Venus, and are the best targets found so far for the search for life outside the solar system. The results are published today in the journal Nature.

The scientists discovered the planets using TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope), a 60-centimeter telescope operated by the University of Liège, based in Chile. TRAPPIST is designed to focus on 60 nearby dwarf stars—very small, cool stars that are so faint they are invisible to optical telescopes. Belgian scientists designed TRAPPIST to monitor dwarf stars at infrared wavelengths and search for planets around them.

The team focused the telescope on the ultracool dwarf star, 2MASS J23062928-0502285, now known as TRAPPIST-1, a Jupiter-sized star that is one-eighth the size of our sun and significantly cooler. Over several months starting in September 2015, the scientists observed the star’s infrared signal fade slightly at regular intervals, suggesting that several objects were passing in front of the star.

With further observations, the team confirmed the objects were indeed planets, with similar sizes to Earth and Venus. The two innermost planets orbit the star in 1.5 and 2.4 days, though they receive only four and two times the amount of radiation, respectively, as the Earth receives from the sun. The third planet may orbit the star in anywhere from four to 73 days, and may receive even less radiation than Earth. Given their size and proximity to their ultracool star, all three planets may have regions with temperatures well below 400 kelvins, within a range that is suitable for sustaining liquid water and life.

Because the system is just 40 light years from Earth, co-author Julien de Wit, a postdoc in the Department of Earth, Atmospheric, and Planetary Sciences, says scientists will soon be able to study the planets’ atmospheric compositions, as well as assess their habitability and whether life actually exists within this planetary system.

“These planets are so close, and their star so small, we can study their atmosphere and composition, and further down the road, which is within our generation, assess if they are actually inhabited,” de Wit says. “All of these things are achievable, and within reach now. This is a jackpot for the field.”

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