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Re: Pictures from Celestia

Posted: 28.02.2013, 21:39
by Cham
Deep inside the galaxy NGC 404 ...
neb1.jpg


... there's an Orion-like nebula, where newborn stars are growing :
neb2.jpg


(this is experimental sprites-only stuff. Pretty heavy on the frame rate and not yet satisfying from all points of view).

Re: Pictures from Celestia

Posted: 02.03.2013, 16:09
by Cham
Two stellar black holes...
bh1.jpg

bh2.jpg


Just for fun, here's my first black hole, made in 2004. She's still pretty :mrgreen:
the_old_one.jpg

This relic doesn't exist anymore on my computer. Since its creation, it evaporated ! :lol:

Re: Pictures from Celestia

Posted: 02.03.2013, 16:57
by Goofy
Cham wrote:Two stellar black holes...
Just for fun, here's my first black hole, made in 2004. She's still pretty :mrgreen:
This relic doesn't exist anymore on my computer. Since its creation, it evaporated ! :lol:
Martin, is it possible to mix the two, I mean the 2004 one plus the 2013 one? 8O
Just curious.

Goofy :D

Re: Pictures from Celestia

Posted: 02.03.2013, 17:04
by Cham
Goofy wrote:is it possible to mix the two, I mean the 2004 one plus the 2013 one? 8O

Of course, it's possible. But the marriage will not be very happy. A sprite is a sprite, and a mesh is a mesh. They don't like each other ! :wink:

Re: Pictures from Celestia

Posted: 02.03.2013, 18:31
by Goofy
Cham wrote:
Goofy wrote:is it possible to mix the two, I mean the 2004 one plus the 2013 one? 8O
Of course, it's possible. But the marriage will not be very happy. A sprite is a sprite, and a mesh is a mesh. They don't like each other ! :wink:
Well, probably it's a matter of opinions, and I respect your one, but I don't agree.
Look at this Io vulcan eruption.
And, believe me, looking it in motion is truly real. 8O
Bye

Goofy :D

Re: Pictures from Celestia

Posted: 03.03.2013, 09:49
by Guckytos
Cham wrote:
Goofy wrote:is it possible to mix the two, I mean the 2004 one plus the 2013 one? 8O

Of course, it's possible. But the marriage will not be very happy. A sprite is a sprite, and a mesh is a mesh. They don't like each other ! :wink:

I must say that I also would like to see how a merge of the old and the new one would look like.

The new one has in my opinion the better jets, but the accedition disk could perhpas gain from the old model.

Just my 2 cents.

Re: Pictures from Celestia

Posted: 03.03.2013, 15:52
by Cham
A star bursts its balloon !

jets3.jpg

jets2.jpg

jets1.jpg

New jets model made while eating my breakfast...

Re: Pictures from Celestia

Posted: 04.03.2013, 02:28
by Cham
Bloody Apocalypse !
apo1.jpg

apo2.jpg

apo3.jpg

Re: Pictures from Celestia

Posted: 05.03.2013, 04:50
by Cham
I made a mistake that turned into something funny.
I'm wondering if this effect could be used for something nice...

Looks like an easter egg in a basket. :o
mistake1.jpg

mistake2.jpg

Re: Pictures from Celestia

Posted: 05.03.2013, 13:04
by Hungry4info
I don't see why you couldn't have a disk of gas within the Roche lobe. It would be short-lived, but I don't think it would be impossible.

Re: Pictures from Celestia

Posted: 05.03.2013, 19:38
by Hungry4info
Your understanding of the Roche limit is not accurate. The International Space Station orbits well below the Roche limit of the Moon without being destroyed, for example, do you know why this is?

The Roche limit is simply the volume of space around a body where the tidal stress tends to destroy a body of a given density.

This distinction is important. The Roche limit is dependent on the density of the other body, as you see here:
Image
Where ?_M is the density of the primary, and ?_m is the density of the secondary. Indeed several moons of Jupiter and Saturn orbit the planet close enough where they would be inside the Roche limit if they had lower densities.

An unbound mass of gas is not governed by quite the same mechanics that governs tidal disintegration of rigid bodies.

You are correct that a gas disk close to the planet would be unstable, but not for the reason you think. The reason a gas disc very near a planetary body would be unstable is due to the disc's self-interaction - particles collide with each other causing them to trade orbital momentum around. Particles that surrender too much orbital momentum over the course of this find themselves falling onto the planet. If there were far fewer particles, then they could freely orbit the planet without having to worry about being accreted -- they would be in a normal orbit. The Roche limit is simply the distance from the primary that the secondary would be tidally disrupted.
(Note for obvious reasons I'm excluding effects of stellar radiation pressure and other external influences).

can you give us an example in the solar system or elsewhere ?
All the giant planets have rings within their Roche limits. But they are small particles, like a gas would be, and thus are free to orbit the planet without Roche limit -related tidal disruption.

Edit: These pictures are amazing, Cham :o
Cham wrote:I'm wondering if this effect could be used for something nice...
You could probably use it for Be stars.

Re: Pictures from Celestia

Posted: 05.03.2013, 20:25
by Cham
Hungry4info wrote:
Cham wrote:I'm wondering if this effect could be used for something nice...
You could probably use it for Be stars.

Hmmm, this may be interesting indeed.

Or maybe a star with many flares...

The sprites may be usefull for the surface of some stars. I'll have to investigate this idea, one day.
For the moment, I'm still trying to create irregular nebulae.

Re: Pictures from Celestia

Posted: 06.03.2013, 11:45
by BrianJ
Couldn't resist posting this creenshot of comet SidingSpring C2013A1, seen from the foothills of Olympus Mons aprox.12hrs before closest approach to Mars on 19 Oct. 2014.
c2013a1_1.jpg

Would be cool if it really was this spectacular!!

.ssc and .xyzv for C2013A1 available here (735kb)
http://myweb.tiscali.co.uk/briansutilit ... 2013A1.zip
.xyzv runs from Oct 2013 to Oct 2015
Unzip into your "extras" folder

Cheers,
BrianJ

Re: Pictures from Celestia

Posted: 07.03.2013, 09:59
by BrianJ
Ola!
olyv wrote:but, the same comet near our planet would have serious consequences ?
dust destroy all satellites and toxic gases would be deadly to life on earth, right ?

I'm not sure about the toxic gases - I know comet comas contain such gases as ammonia, methane, carbon monoxide,etc. but I don't know if the quantities would be enough to cause a problem with Earth's atmosphere.

But a flyby of ~50,000km near Earth would certainly be a problem for geostationary satellites, I would think!

Although, apparently the trajectory of Siding Spring / C2013A1 means Mars will avoid most of the cometary debris, I'm surprised there is not more concern for Mars satellites such as MRO,MEX.

Cheers,
Brian

Re: Pictures from Celestia

Posted: 07.03.2013, 15:16
by Cham
Another sprites sculpture...

sculp1.jpg

sculp2.jpg

Re: Pictures from Celestia

Posted: 09.03.2013, 16:13
by kristoffer
C/2013 A1 comet

Re: Pictures from Celestia

Posted: 12.03.2013, 02:04
by Goofy
argelesmer wrote:a beautiful rose nebula with blue stars in its heart. :)
Hey, argelesmer, this too looks very nice.
Will you upload it?
Will you try to insert real stars within the nebula?
Believe me, it's a very different thing.
Look at the below shown celestia images, where I used mneme's Star Generator found here
viewtopic.php?f=6&t=17072&hilit=star+cluster
to obtain the stars, and your Red Nebula from here
viewtopic.php?f=2&t=17034&hilit=red+nebula&start=60
that you very kindly allowed me to test.
Moreover there is not one but three nebula models, like three shells, each one with its texture rotated more or less to give a more complex structure, and with different densities/contrast.
Personally I love it, and my students too, when we fly internally from one star to another one, among whisps of surounding nebulosity.
I suggest all of you to click on the image to see it larger.
Bye and thank you for your very nice nebulae.

Goofy :D

Re: Pictures from Celestia

Posted: 12.03.2013, 02:31
by Cham
Wait to see what I have in my pocket !

During the following weeks (or months?), I'll drop some large Orion-Like nebulae full of stars, with Pillars of Creation... Hehehee !

Re: Pictures from Celestia

Posted: 12.03.2013, 10:09
by Goofy
Cham wrote:Wait to see what I have in my pocket!
During the following weeks (or months?), I'll drop some large Orion-Like nebulae full of stars, with Pillars of Creation... Hehehee !
I'll wait eagerly, Martin, but actually I'll use argelesmer's one, because "something is always better than nothing", do you agree? :wink:
Bye soon

Goofy :D

Re: Pictures from Celestia

Posted: 12.03.2013, 10:13
by Goofy
argelesmer wrote:
Goofy wrote:Hey, argelesmer, this too looks very nice.
Bye and thank you for your very nice nebulae.
Goofy :D
Thanks Goofy.
I used the same mesh with another texture.
Rendering you've done is amazing... :)
I understand that you and your students love it. :)
There are still several more brains than one...
It is teamwork. :)
Happy you like it. :blue:
Could you please share your last texture, so I'll make some more tests?
You have my email.
Thanks a lot once again.
Bye

Goofy :D