Supernova and SW planetary shield

Omega-13 · Post by **Omega-13** » 2004-03-23 11:48pm

If a planetary shield (something the strength of Coruscant) was erected on a planet the same distance from the sun as Earth, and the star was the same size as our own sun

would the shield hold?

And if it does, what size of star would it require? or maybe even our sun is too much

just curious
thanks

Omega-13 · Post by **Omega-13** » 2004-03-23 11:48pm

I just realized, heh

And the star goes Nova (in our case) or supernova for a larger star

Post by **Darth Wong** » 2004-03-23 11:55pm

It is impossible to estimate the energy content of a nova-like event in sci-fi, for the simple reason that it is obviously not a natural nova, nor can it possibly function as advertised (residual heat and conversion of GPE to heat would make the collapse of a star from the cessation of core fusion take millions of years). Any attempt to derive energy estimates from assumption of identical behaviour to natural novae is an clear fallacy. You need to estimate the density and velocity of surface ejecta in order to determine the energy content of the blast.

Omega-13 · Post by **Omega-13** » 2004-03-23 11:57pm

Darth Wong wrote:It is impossible to estimate the energy content of a nova-like event in sci-fi, for the simple reason that it is obviously not a natural nova, nor can it possibly function as advertised (residual heat and conversion of GPE to heat would make the collapse of a star from the cessation of core fusion take millions of years). Any attempt to derive energy estimates from assumption of identical behaviour to natural novae is an clear fallacy. You need to estimate the density and velocity of surface ejecta in order to determine the energy content of the blast.

I hadn't realized a supernova takes millions of years, i was always under the impression that its leading to a REdGiant takes millions of years, but its actual collapse only takes a matter of days,

I wonder if surface ejecta would be planet sized, i don't know enough about the subject

Elheru Aran · Post by **Elheru Aran** » 2004-03-24 12:40am

Supernovae take a very long time, believe me... they do appear suddenly and then fade away, but y'know-- it's just like that cause of a minor fact about space; distances are HUGE. the light of a supernova explosion takes a very long time indeed to reach us; in fact, by the time it gets to us, it's long over.

As for the situation you postulated, well... a red giant, sad to say, would be so big that its diameter would be greater than that of Earth's orbit! or at least Betelgeuse is that big-- not sure, the picture I saw was pretty old; it was of the inner planets of the Solar System, with a red circle depicting the circumference of the red giant, and it was definitely bigger than Earth's orbit.

I fear that, alas, the planet would be destroyed long before any supernova occurred...

HRogge · Post by **HRogge** » 2004-03-24 05:12am

Supernova's don't take long...

Within ~40 days they reach their maximum energy output. Within a few years they are completely gone.

( Source: "Introduction into Astronomy 1, University of Bonn, Pr. Klaas S. de Boer )

Post by **Darth Wong** » 2004-03-24 06:22am

Omega-13 wrote:I hadn't realized a supernova takes millions of years, i was always under the impression that its leading to a REdGiant takes millions of years, but its actual collapse only takes a matter of days,

The collapse would take a long time (it's been estimated that our Sun would take 10 million years to collapse if nuclear fusion was not holding it out), but when you reach critical point and fusion re-ignites, the blast outwards is much quicker.

HRogge · Post by **HRogge** » 2004-03-24 06:34am

Darth Wong wrote:
Omega-13 wrote:I hadn't realized a supernova takes millions of years, i was always under the impression that its leading to a REdGiant takes millions of years, but its actual collapse only takes a matter of days,
The collapse would take a long time (it's been estimated that our Sun would take 10 million years to collapse if nuclear fusion was not holding it out), but when you reach critical point and fusion re-ignites, the blast outwards is much quicker.

Another problem is that the collapse of the rest of a supernova has not much to do with the collapse of a red giant.

A supernova is started by the collapse of the core and only a few seconds later a shockwave starts propagating outwards from the core. Most of the mass of the star is thrown away, the rest forms a neutron star/pulsar or a black hole.

Murazor · Post by **Murazor** » 2004-03-24 06:47am

The planetary shield on Coruscant isn't representative of planetary shields. However, a supernova takes a non trivial amount of time to deliver its energy and the blast is omnidirectional so only a small fraction will hit the shield. Finally, an AU is quite a distance. Enough to lessen to some degree the energy of the blast.
IMO an strong shield would resist a supernova shockwave, but the planet would suffer great damage anyway.

HRogge · Post by **HRogge** » 2004-03-24 06:50am

Murazor wrote:The planetary shield on Coruscant isn't representative of planetary shields. However, a supernova takes a non trivial amount of time to deliver its energy and the blast is omnidirectional so only a small fraction will hit the shield. Finally, an AU is quite a distance. Enough to lessen to some degree the energy of the blast.
IMO an strong shield would resist a supernova shockwave, but the planet would suffer great damage anyway.

If you take ALL energy of a supernova into one "shot" and distribute it over a sphere of 1 AU radius, Earth would get enough energy to be destroyed ( a little bit larger than the grav. binding energy )... have done the calculations some time ago.
The Coruscant shield might be able to block it if they can switch it to "block ALL wavelengths"... but it's not clear if it could block the incoming plasma wave.

Murazor · Post by **Murazor** » 2004-03-24 06:58am

HRogge wrote: If you take ALL energy of a supernova into one "shot" and distribute it over a sphere of 1 AU radius, Earth would get enough energy to be destroyed ( a little bit larger than the grav. binding energy )... have done the calculations some time ago.
The Coruscant shield might be able to block it if they can switch it to "block ALL wavelengths"... but it's not clear if it could block the incoming plasma wave.

"Block ALL wavelengths". That was what I was trying to say. It would basically require turning the shield opaque, something we don't know if they are able to.

Dave · Post by **Dave** » 2004-03-24 11:31am

Coruscant's shields are actualy a double-layered shield (Source: X-wing: Rogue Squadron), so IMHO Coruscant's shields are not a standered configuation.

Also, perhaps the shields could take the plasma wave, as the Vong could not shoot plasma balls thru the starship shiels (and assuming that Planetary shields are the same principle on a large scale)

As for X-rays and comic rays and all the other crud, perhaps the people who live in the underground and foundations of buildings on Coruscant would survive with all that Ferrocrete over their head.