Planet forming dust disk imaged - wow!
Discussion
friction and impacts?
two very small object have similar mass collide and the friction or force of impact is enough to stop them from pulling apart again, this happens many many times and you get small rocks, same process happens and eventually it gets bigger etc....
why it ends up being spherical is something I don't understand - maybe a mind far superior to mine on here wcan advise??
two very small object have similar mass collide and the friction or force of impact is enough to stop them from pulling apart again, this happens many many times and you get small rocks, same process happens and eventually it gets bigger etc....
why it ends up being spherical is something I don't understand - maybe a mind far superior to mine on here wcan advise??
Wonderful image.
As far as my understanding goes, you have the ISM (interstellar medium) and when enough of it is in a cloud, some clumps together through gravity. That attracts more and so on, as it all attracts it will start to rotate and spin out the disc as the image is seen. Other clumps form and they will become planets or more fuel for the core clump depending on how fast it is spinning, as the core clump reaches a certain size, the reaction starts that results in a sun. When that blows off the centripetal force keeps the other clumps where they are and they hoover up their orbits getting bigger and forming planets. There is a name for this lighting up bit that escapes me and other effects associated with it.
I am probably wrong, been a year or six since I read that book. What I am not sure about is what decided a gas vs rocky planet if there is enough in the system for both.
As far as my understanding goes, you have the ISM (interstellar medium) and when enough of it is in a cloud, some clumps together through gravity. That attracts more and so on, as it all attracts it will start to rotate and spin out the disc as the image is seen. Other clumps form and they will become planets or more fuel for the core clump depending on how fast it is spinning, as the core clump reaches a certain size, the reaction starts that results in a sun. When that blows off the centripetal force keeps the other clumps where they are and they hoover up their orbits getting bigger and forming planets. There is a name for this lighting up bit that escapes me and other effects associated with it.
I am probably wrong, been a year or six since I read that book. What I am not sure about is what decided a gas vs rocky planet if there is enough in the system for both.
Moonhawk said:
AA999 said:
Is that a true colour image?
I'm guessing that the 'dust' and small elements towards the extent of the discs are not 'hot' per say?
No - it's at millimetre/submillimetre wavelengths (radio astronomy).I'm guessing that the 'dust' and small elements towards the extent of the discs are not 'hot' per say?
Revolutionary ALMA Image Reveals Planetary Genesis
Nom de ploom said:
why it ends up being spherical is something I don't understand - maybe a mind far superior to mine on here wcan advise??
If an object with mass is attracting material towards it, the matter will accumulate around the gravitational centre of the object. As the object grows bigger, the gravitation pull increases, attracting more material - and so on.When the object has increased beyond a certain size, the gravitational pull is sufficient to start smoothing out the surface until it forms a sphere around the gravitational centre, the greater the mass, the more spherical the shape.
That's why small objects such as asteroids or comets, which have low gravitational fields, are lumpy and irregular. Larger objects, with their stronger gravitational fields, are more spherical.
Nom de ploom said:
why it ends up being spherical is something I don't understand - maybe a mind far superior to mine on here wcan advise??
Just wanted to add to this reply already given above.Every system will have a 'resultant' angular momentum, even though some objects individually may not be moving in the same direction, the overall system itself will have a singular angular momentum and resultant direction.
Over time this overall effect will enact on all objects within that system. Giving rise to the typical spherical shapes seen all over the universe and in more established systems they are often flattened as gravity acts to bring things in to a plane.
Edited by AA999 on Tuesday 11th November 09:04
I think the question was why planets end up ball shaped rather than some other shape
Solar systems aren't "spherical" as such but more in the shape of a disk with the planets rotating around the central star more or less on the same plane. This is natural as they form from the accretion disks that surrounds many (if not all) young stars.
Having said that, it is highly likely that far out from the central star, there actually is a spherical "ball" of cometary material - known as the "Oort Cloud".
Solar systems aren't "spherical" as such but more in the shape of a disk with the planets rotating around the central star more or less on the same plane. This is natural as they form from the accretion disks that surrounds many (if not all) young stars.
Having said that, it is highly likely that far out from the central star, there actually is a spherical "ball" of cometary material - known as the "Oort Cloud".
Re the ALMA telescope - it was covered on a Horizon episode a couple of years back. Available on iPlayer and certainly worth a watch.
http://www.bbc.co.uk/iplayer/episode/b013pnv4/hori...
http://www.bbc.co.uk/iplayer/episode/b013pnv4/hori...
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