Supernovae vs. Planets

[PlutonianEmpire]

Is it possible that for a planet orbiting a massive star that goes supernova, the force of the supernova is strong enough to overcome the planet's gravitational pull enough to destroy it?

If so, how?

For some reason, I remain skeptical that a supernova is strong enough to blow up planets, even though plenty of people say it is.

[Hungry4info]

Supernovae are sweet, but not that much. The result of a supernova, lots of radiation and particles flying everywhere, isn't going to destroy a planet. It might evaporate away its atmosphere and reduce gas giants to their cores, but the solid part of a planet will remain.

[t00fri]

Supernovae are sweet, but not that much. The result of a supernova, lots of radiation and particles flying everywhere, isn't going to destroy a planet. ...

Except the star's own planets (if existing). One day, when our Sun goes "Bang", also Celestia will die

Fridger

[ajtribick]

Assuming circular orbits it is easy to show that if the mass loss of the primary exceeds half of the total mass of the system, the orbit becomes unbound, i.e. the planets fly off into outer space even if they survive.

On the other hand supernovae are not symmetrical and the central remnant appears to get a "kick", which might if you are lucky save the planet. This would almost certainly result in a planet on an eccentric orbit, so this cannot be the explanation for the system of terrestrial-mass planets around PSR B1257+12 - these planets probably formed after the supernova, likely from a fallback disc.

As for destroying planets, approximating binding energy of the planet as [tex]\frac{GM^2}{r}[/tex] (uniform sphere has a factor of 3/5 in front but planets are not uniform spheres), taking the total energy output of the supernova as [tex]10^{44}[/tex] joules and calculating the fraction of this that is intercepted by the planet (roughly [tex]\frac{r^2}{4d^2}[/tex]), the distance at which the total energy intercepted equals binding energy of the planet is about ~1 AU for Jupiter and ~10 AU for Earth (provided the recent excesses of Christmas time haven't killed off my mathematical ability...). This does of course neglect various processes that would occur during such an event which would modify the actual region in which a planet would get destroyed, but it does at least seem plausible that planets (assuming they can form in the first place) can be destroyed or severely eroded by a supernova.

[Chuft-Captain]

Nice analysis Andrew,

That's an impressive amount of energy if it can exceed the gravitational forces holding the Earth together at a distance of 10 au... makes the mind boggle !!

I guess your analysis is basically correct, however, doesn't it depend also on just how this energy is expended? ie. I guess it would be a mixture of light radiation, heat, and exploded plasma.
I would think that the consideration should whether the net result is able to exert sufficient "force" to overcome the binding energy of the planet.

Intuitively, it seems to me that whilst the light pressure and heat may well strip off any atmosphere and lighter materials, they may not exert enough force to damage the "hard" stuff.
It's only the physical material of the explosion (gases etc) which might exert enough force to actually overcome the binding gravitational force of the planet.

So it depends on what proportion of the SN's energy output is energy, and what proportion is matter... does it not?

CC

[ajtribick]

Sure as I said, the actual processes involved are going to modify the exact numbers of how close a planet needs to be to the supernova to get completely destroyed. E.g. neutrinos may pass right through the planet; the atmosphere will expand, increasing the cross sectional area, etc. The analysis I posted is a quick bit of "back-of-an-envelope" scribbling, should certainly not be taken as gospel!

[t00fri]

Sure as I said, the actual processes involved are going to modify the exact numbers of how close a planet needs to be to the supernova to get completely destroyed. E.g. neutrinos may pass right through the planet; the atmosphere will expand, increasing the cross sectional area, etc. The analysis I posted is a quick bit of "back-of-an-envelope" scribbling, should certainly not be taken as gospel!

Right

I was about to mention neutrinos, but you did it already...

Fridger

[Reiko]

Supernovae are sweet, but not that much. The result of a supernova, lots of radiation and particles flying everywhere, isn't going to destroy a planet. ...

Except the star's own planets (if existing). One day, when our Sun goes "Bang", also Celestia will die

Fridger

No worries! We'll have warp drive then and Celestia will be able to escape.

[Hungry4info]

So let me see if I understand...

If the energy received by the planet exceeds the binding energy of the planet, its atoms get up and leave?

[Chuft-Captain]

So let me see if I understand...

If the energy received by the planet exceeds the binding energy of the planet, its atoms get up and leave?

It's not so simple as that Hungry. All Andrew's saying is that there's enough energy involved to make it "possible" to destroy the planet, but it all depends on how and where that energy manifests itself as destructive forces.

For a more down to earth example...

Scenario One:
You're in a car traveling at 60mph and you are NOT wearing a seatbelt. You hit a brick wall and your head hits the windscreen cracking your skull and mulching your brain, resulting in your untimely death.
(The binding energy of your skull and brain was exceeded)

Scenario Two:
You're in a car traveling at 60mph and you ARE wearing a seatbelt. You hit an identical brick wall but this time your seatbelt arrests your flight towards the windscreen, preventing your head from impacting on the windscreen and spreads the force of the impact across your chest and hip bones, thus saving your life. You walk away from the crash.
(The resultant forces did not exceed the binding energy of any part of your body)

In both scenarios the amount of kinetic "energy" was exactlly the same, but the processes in which it was converted into forces on your body was completely different, resulting in 2 quite different outcomes.

[t00fri]

In both scenarios the amount of kinetic "energy" was exactlly the same, but the processes in which it was converted into forces on your body was completely different, resulting in 2 quite different outcomes.

... except that a star's "Bang" includes other most dangerous effects besides an outburst of kinetic energy. Just to mention: HEAT and other devastating radiation! Seat belts won't help here and that part of the story spreads rather isotropically...

Fridger

[Chuft-Captain]

In both scenarios the amount of kinetic "energy" was exactlly the same, but the processes in which it was converted into forces on your body was completely different, resulting in 2 quite different outcomes.

... except that a star's "Bang" includes other most dangerous effects besides an outburst of kinetic energy. Just to mention: HEAT and other devastating radiation! Seat belts won't help here and that part of the story spreads rather isotropically...

Fridger

Well, it WAS an analogy!
They'd have to be the "best seatbelts in the world" and made by Carlsberg.

Explanation: --- Carlsberg Beer runs a series of TV Ads here based on the premise that it's the "Best Beer in the World", using the catch-phrase "best XXXX in the world"
(eg. "If Carlsberg did rescues, they'd be the best rescues in the world", "If Carlsberg did flatmates, they'd be the best flatmatesin the world", etc...)

[t00fri]

In both scenarios the amount of kinetic "energy" was exactlly the same, but the processes in which it was converted into forces on your body was completely different, resulting in 2 quite different outcomes.

... except that a star's "Bang" includes other most dangerous effects besides an outburst of kinetic energy. Just to mention: HEAT and other devastating radiation! Seat belts won't help here and that part of the story spreads rather isotropically...

Fridger

Well, it WAS an analogy!

obviously but my additionally mentioned isotropic sources of devastation (HEAT, other ratiation from within particle physics) were NOT analogies!

They'd have to be the "best seatbelts in the world" and made by Carlsberg.

Explanation: --- Carlsberg Beer runs a series of TV Ads here based on the premise that it's the "Best Beer in the World", using the catch-phrase "best XXXX in the world"
(eg. "If Carlsberg did rescues, they'd be the best rescues in the world", "If Carlsberg did flatmates, they'd be the best flatmatesin the world", etc...)

Asking once more: which continent are you located in? Australia?

Fridger

[Fenerit]

In all these concerns the importance of the electromagnetic theory of the HEAT and the LIGHT or of the LIGHT and the HEAT is out of question. Same thing about Van der Waals forces and so on. BUT now I wonder about the dusts that ram the planet down. How speed should be the erosion of the rocks? Supposed either strong and fast or light and slow, what about the internal heat of the planet?

[Chuft-Captain]

Asking once more:

???

which continent are you located in? Australia?

Close. ...NZ.

[t00fri]

Asking once more:

???

Well, it is Friday night / Sat morning here...

vive de largo la revoluci?n !!!

Oha! Since here it's just Friday afternoon, you must be located in the EAST of me!! Sorry I always placed you to the WEST of me (US) because of your native pleasure with your English mother tongue .

Hence, do I have to locate you to Australia, perhaps??

Fridger

which continent are you located in? Australia?

Close. ...NZ.[/quote]

Aha, thanks I just guessed on the basis on your "appearance habits" in the forum.
So for you the New Year has started since quite a while already . Anyway...all the best!

Fridger

[MKruer]

This sounds like the discussion I had before. viewtopic.php?f=7&t=10337

If you had a space ship that had FTL drive that was damaged but still had conventional thrusters and given that the ship was made of high strength carbon fiber composite. in orbit around a ~10 Solar masses (forms a Type II supernova) The red giant phase should have a max radius of roughly 2.6AU if I did my math right.

Could you use a Jupiter sized planet at 10AU to shied yourself at least for a while in order to fix your FTL system and escape?

My guess would be that you could use the planet to shield yourself from the initial radiation/light surge, then then at 10 AU, be about about another 200-530 minutes (3.3 - 8.8hrs) before expanding shell hits the planet and starts striping it.

Is this correct?

[Hungry4info]

if I did my math right

And

If you had a space ship that had FTL drive

Do not mix.

[MKruer]

Ok let me try this again.

You have a really really fast ship orbiting around a star, you detect that the star may go supernova, the closest object that my afford you some protection is a Jupiter sized planet. The people on the ship would rather die hiding behind a planet waiting for the big shock wave then be subject to radiation of the initial flash, so they opt to hide behind said planet.

Other then being delusional suicidal and having a really really fast ship. would this trick delay the inevitable?

[selden]

Maybe.

Planets have been detected around pulsars. Maybe they';re the cores of super-jovians that survived.
Pulsars are the neutron stars left after a supernova has happened.

I doubt they'd have time to get there, though.
I don't know the details of the symptoms of an immanent supernova, but they're likely to be very quick.