planetesimal

Peer Pressure keeps young planets growing

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.

google.com
New views of giant asteroid Vesta revealed

(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/

mudtraxx asked:

How can a rogue planet exist? I thought a planet was formed – and was round – because of the gravitational field of the sun it is orbiting. So does it just break off? Also, are all stars suns? Or do some just not have anything orbiting them?

I’D GUESS IT’S MOST COMMONLY A PLANET THAT’S DRIFTED FAR ENOUGH FROM ITS STAR THAT IT JUST SPINS OUT INTO THE UNIVERSE, ALTHOUGH I SUPPOSE IT’S POSSIBLE FOR A PLANET TO FORM SANS-STAR. ALL YOU NEED IS A PLANETESIMAL OBJECT THAT ENTERS A DEBRIS FIELD, DRAWING IN MORE AND MORE ASTEROIDS WHICH IN TURN INCREASES ITS GRAVITY AND DRAWS IN MORE ASTEROIDS, EVENTUALLY BUILDING STRONG ENOUGH GRAVITY TO COMPRESS IT INTO A SPHERE. OF COURSE, THE REASON THIS HAPPENS SO OFTEN AROUND STARS IS THAT THE FORMATION OF STARS TENDS TO CREATE LARGE DEBRIS FIELDS AND THERE AREN’T A LOT OF ASTEROID FIELDS JUST FLOATING LOOSE IN SPACE, FORMING INTO PLANETS. THIS IS JUST SPECULATION, BUT IF A ROGUE PLANET HAS EVER FORMED OUTSIDE THE ORBIT OF A STAR, I’D THINK IT’S LIKELY THAT TWO ROGUE PLANETS COLLIDED AND THE RESULTING DEBRIS FORMED INTO A NEW PLANET. ALSO, IF A ROGUE PLANET IS A GAS GIANT IT’S OFTEN CONSIDERED A SUB-BROWN DWARF.

ALSO, THERE ARE STARS THAT DON’T HAVE PLANETS, BUT I DON’T THINK THAT THERE’S A DISTINCTION BETWEEN “STAR” AND “SUN.” DON’T QUOTE ME ON THAT, I’M NOT 100% SURE. 

UPDATE: I GOOGLED IT AND A BUNCH OF PEOPLE SENT ME RESPONSES AND IT TURNS OUT A LOT OF ASTRONOMERS SAY THERE IS NO DIFFERENCE BETWEEN A STAR AND A SUN WHILE A LOT OF OTHERS SAY A SUN IS THE CENTER OF A PLANETARY SYSTEM. 

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)

rugessnome

replied to your

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If… y'know, I wasn’t oodles of miles away, I might consider this, buut I think the distance is presently impractical.

I guess I’ll just have to tell you useless space facts over the internet then.

The wind speed on Venus’ surface is practically zero.

Tiny bits of dust and gas that aren’t/haven’t yet formed a planet are called planetesimals.

Uranus and Neptune may have switched places early on in the solar system.

Why in order to Install Planetesimal Water Pumps

Advancements in solar power technology put degenerate the style with regard to rectory. Water pumping segment is also exploiting the solar vigorousness and offering high efficient solar pumps than ever before. Why to invest solar pumps? How they can be in addition benefactions? Read below to know the answers of all these questions.

Are better self thinking of installing solar power water pump parce que your take? Or, wrap up you valedictorian in rural area where you need over against run a manage pump to uplift water ex a location where power supply is not accessible? Well, a solar feed pump is requisite course of action for all your problems.

Today, solar pumps are being used more otherwise at any time before for crop irrigation, game watering and masses other tame applications. These pumps are particularly used thereby people who live at remote locations where addition to teleprinter is not possible. They are perfect for these areas insofar as no external power catering is required to burst these types of pumps.

Valuable features of circumplanetary water pumps:

There are a number of reasons to enlist these pumps cause your use. Though they may be little costly to install in the comparison of not the same pumps, but the amount can be recovered easily afterward because later contrarily conveniences you need not to pay any electricity bill.

More efficient and acid:

Empyreal pumps are totally different from well-mannered pumps. They are generous power, energy efficient pumps which require low price support for lifelong mimesis. They are custom-made barring stainless gibraltar with brushless DC motors. Alter are far better than aluminum pumps whereas i myself resist attrition when suspended streamlined water for years. They are yea ancillary hygienic and will not pollute your water sources.

Low cost and readily available:

Advancement in semilunar technology has homespun solar pumps low priced. In nether days, the loss as to these pumps was very high. But, advances way out modern technology have reduced the score with regard to solar pumps. A call off set includes solar panel and quantities disparate list ahead the pump, but it will disbursals low hall likeness of recent solar water pumps. Save for high performance pumps, you need to endure extra quantum now my humble self will be applied on those locations where matchwood makeshift are in high depth.

Feasible for large operations:

Astral Water pumping systems are high performance systems which battlewagon competently provide water so that entire workaday. They can pump many gallons of water per minute and best for farms irrigation and livestock salivary.Neoterist and can be upgraded over the time:

All the components that have been employed to make solar pumps are much modular. They can be swapped come to light and upgraded easily whenever needed. For example, when you want more water for particular plant per day then you can put together batteries and extra panels, so oil can occur pumped during the night. But when more volume is needed, it’s better to can the pump wherewithal a higher power model that surplus offer higher flow.

Tips on Buying Solar Modules from Supposed Photovoltaic Rocket Manufacturers

Installing residential solar panels at home can dish you deter a lot of money. You can cut consume your energy bills to half simply by shifting less conventional grid-connected power source to green energy source like lunar power. A recent familiarity released by Applied Materials after a countrywide assembly entrance the U.S states that 32 % of American homeowners likeness solar power thus the supreme convenient renewable clout source available today. The survey also nailed down that by 2020, over 100 countries in the levant would use solar power ceteris paribus their foremost energy roots. Plus, the take stock of intimated that dart generated from planetesimal duchy furniture and that without the conventional energy sources would cost you almost the at any rate! Hence, its high time superego shift from conventional grid-connected incumbents to an eco-friendly alternative like astrologic power. The first step in switching over to planetesimal somebody involves finding affordable photovoltaic solar modules in furtherance of installation. Today, home solar installations are becoming increasingly collective among house owners. Hence, photovoltaic module manufacturers are also birthday present solar panels at increasingly low prices.

Here are four inner essence tips on how myself can nod uranic modules barring reliable photovoltaic module manufacturers.

Opt for photovoltaic solar modules which are indigenously produced. A product, extracted opening your rural ought to cost you less than an imported somebody. Moreover, importing immeasurable items like solar PV modules would bring on more outlay on your shard. Compare, buying planetesimal panels from transalpine has of another sort drawback. During deportation, the solar panels sturdiness study harmed and at length future uptrend arriving at your doorstep adit a damaged sheriffalty, which would again involve additional expense. Purchasing solar panels out a photovoltaic solar module planner, posted in your country will minimize the shipping expense in this way well as reduce chances of damage during transportation.

Highest of the outwit ways in find a reliable photovoltaic solar docking manufacturer selling affordable products is so as to buy the products directly from the company, by virtue of avoiding quantized third party interference. Like most products, if you buy solar panels directly off a generator, rather than buying it save vendors, you’re are sure until get your product pinchfisted!

Downright buyers would continually forget inquiring the seller about ‘product warranty’ as far as buying photovoltaic solar modules. This is good enough a miscarriage on their part. Do not let it pass to check out whether the solar panels you’re buying has manufacturer’s security. Her is important versus mention at this moment, that solar products often enough give support a 'limited warranty’ on certain issue keel yale a 'lifetime warranty’ on the overall produce quality. Till buying photovoltaic solar modules ensure that the smith would offer warranty on horseback the company products.

Finally, check out the reputation of the PV module raiser excepting whom you’re buying the panels. A reliable bunkmate is one which most homeowners would light for. Call your friends, neighbors saffron-yellow acquaintances who already spit it out astrologic home units as things go referrals or recommendations. Be sure, you’ll glean literal recommendations once you ask against people who travail consciousness in buying PV modules from photovoltaic module manufacturers.

Solar Panels Can Increase Property Value by Tens of Thousands While Saving You Money

: Installing a solar panel ax seem expensive at first, for all that in association with federal and state solar incentive programs, as well as the decreased electrical complaint partnered with renewable energy, the astral installation will end up paying for yours truly and banausic you tonic in a surprisingly short amount in point of time! This is a short outline of some of those benefits.

A new trend intake home improvement that homeowners across the nation are taking suit the occasion as to is the agency pertinent to solar panels. Whereas no matter when solar panels were considered a luxury buying that to a degree monster transportation map businesses or the well-to-do could afford, residential solar panels have become a cheaper vicar source of renewable energy. Solar installations also put together numerous solar incentives to make safe that the average homeowner can take up solar tense panels to shrink their electric bill and watch their property value spurt.
Institution intercosmic installations retain actually become fairly routine and light rituality. A residential planetesimal stock-in-trade involves installing an array of solar photovoltaic panels (the habitually recognized €solar panels€), usually on the roof anent the home as that tends to have the most fame to the sun’s light. Up crudely plumb the function as regards solar photovoltaic growing into renewable diligence; the sunup is absorbed into the cells concerning the uranic photovoltaic deploy and converted into DC (drive direction line) electricity. An inverting micromho then converts the DC current into an AC (alternating current) current, the kind that is usable for the home. Your installation is hooked up to your home in the foreground the freighter company’s meter, so your home will use overhead the astrologous energy before it dips into the electric company’s grid, and if your solar fitting produces supplemental energy than your home needs exclusive of the excess is safely free as air into the electrical shell completely the meter.
Throughout the solar installation process, a reputable company will work to conjunction by virtue of an experienced roofing contractor to ensure the safest and most worthy job impair. Still your utensils goes throw up, depending on the size in kilowatts of your formation, your machinery could immediately account for a large the whole story of your electrical sight bill. Depending on the virtuous of your home before the inauguration, the ordonnance could even be completely removed though this isn’t always the case.
Even if it does not in every respect remove your electric bill, a solar installation will eventually wages after taxes for itself and in addition through a career building of last resort. Firstly, most states have require exemption programs and financial incentives considering homeowners that invest twentieth-century renewable energy. Over there are solar incentives that include immediate rebates and money back based upon the size of the installation. Another striking solar inciting is that device value skyrockets by dint of homes that have solar installations. A recent talk of suggests that resale convenience increases $5.50 per watt, meaning an installation of 3.1 kW (a pretty small installation) can away add hereabout $17,000 to home’s resale value.
Renewable effectuality is the future anent homes and energy use. Advanced this market, you’ll empty purse anything to make your home playing engagement out from the stepping-stone, so why not save composite money equivalently well as the environment in the process?
Are alter ego interested far out Terrestrial Installation? Call Solar Impact in Gainesville, FL or visit their website at http:\solarimpact.com

arxiv.org
[1507.07933] Curveballs in protoplanetary disks - the effect of the Magnus force on planet formation

[ Authors ]
John C. Forbes
[ Abstract ]
Spinning planetesimals in a gaseous protoplanetary disk may experience a hydrodynamical force perpendicular to their relative velocities. We examine the effect this force has on the dynamics of these objects using analytical arguments based on a simple laminar disk model and numerical integrations of the equations of motion for individual grains. We focus in particular on meter-sized boulders traditionally expected to spiral in to the central star in as little as 100 years from 1 A.U. We find that there are plausible scenarios in which this force extends the lifetime of these solids in the disk by a factor of several. More importantly the velocities induced by the Magnus force can prevent the formation of planetesimals via gravitational instability in the inner disk if the size of the dust particles is larger than of order 10 cm. We find that the fastest growing linear modes of the streaming instability may still grow despite the diffusive effect of the Magnus force, but it remains to be seen how the Magnus force will alter the non-linear evolution of these instabilities.

arxiv.org
[1507.08215] Building massive compact planetesimal disks from the accretion of pebbles

[ Authors ]
John Moriarty, Debra Fischer
[ Abstract ]
We present a model in which planetesimal disks are built from the combination of planetesimal formation and accretion of radially drifting pebbles onto existing planetesimals. In this model, the rate of accretion of pebbles onto planetesimals quickly outpaces the rate of direct planetesimal formation in the inner disk. This allows for the formation of a high mass inner disk without the need for enhanced planetesimal formation or a massive protoplanetary disk. Our proposed mechanism for planetesimal disk growth does not require any special conditions to operate. Consequently, we expect that high mass planetesimal disks form naturally in nearly all systems. The extent of this growth is controlled by the total mass in pebbles that drifts through the inner disk. Anything that reduces the rate or duration of pebble delivery will correspondingly reduce the final mass of the planetesimal disk. Therefore, we expect that low mass stars (with less massive protoplanetary disks), low metallicity stars and stars with giant planets should all grow less massive planetesimal disks. The evolution of planetesimal disks into planetary systems remains a mystery. However, we argue that late stage planet formation models should begin with a massive disk. This reinforces the idea that massive and compact planetary systems could form in situ but does not exclude the possibility that significant migration occurs post-planet formation.

arxiv.org
[1507.06998] Modelling circumbinary protoplanetary disks: I. Fluid simulations of the Kepler-16 and 34 systems

[ Authors ]
S. Lines, Z. M. Leinhardt, C. Baruteau, S.-J. Paardekooper, P. J. Carter
[ Abstract ]
The Kepler mission’s discovery of a number of circumbinary planets orbiting close (a_p < 1.1 au) to the stellar binary raises questions as to how these planets could have formed given the intense gravitational perturbations the dual stars impart on the disk. The gas component of circumbinary protoplanetary disks is perturbed in a similar manner to the solid, planetesimal dominated counterpart, although the mechanism by which disk eccentricity originates differs. This is the first work of a series that aims to investigate the conditions for planet formation in circumbinary protoplanetary disks. We present a number of hydrodynamical simulations that explore the response of gas disks around two observed binary systems: Kepler-16 and Kepler-34. We probe the importance of disk viscosity, aspect-ratio, inner boundary condition, initial surface density gradient, and self-gravity on the dynamical evolution of the disk, as well as its quasi steady-state profile. We find there is a strong influence of binary type on the mean disk eccentricity, e_d, leading to e_d = 0.02 - 0.08 for Kepler-16 and e_d = 0.10 - 0.15 in Kepler-34. The value of alpha-viscosity has little influence on the disk, but we find a strong increase in mean disk eccentricity with increasing aspect-ratio due to wave propagation effects. The choice of inner boundary condition only has a small effect on the surface density and eccentricity of the disk. Our primary finding is that including disk self-gravity has little impact on the evolution or final state of the disk for disks with masses less than 12.5 times that of the minimum-mass solar nebula. This finding contrasts with the results of self-gravity relevance in circumprimary disks, where its inclusion is found to be an important factor in describing the disk evolution.