View Full Version : What's the range of EMP from Kappa Ceti-like Superflares?

2010-Jul-03, 04:56 PM
We know that big solar flares and CMEs can cause EMP on Earth, knocking out power grids and frying electronics.

We also know that some sun-like stars (e.g. Kappa Ceti, Groombridge 1830) can erupt into "superflares", which makes the biggest CME Sol's ever had look like a popgun. Fortunately these don't seem to have happened at Sol (it's effects would show up in the historical record and/or on the surfaces of the other planets and moons). If they happened at Sol, these superflares would destroy Earth's ozone layer completely, wipe out all our electronics, and melt the surfaces of the icy moons of Jupiter and Saturn.

What I'd like to know is whether there's a way to figure out the maximum effective range of the EMP that results from a Kappa Ceti-like superflare. Would it knock out electronics beyond say, 50 AU from the star? Could it knock them out from a range of several lightyears? I know that a superflare was observed at Groombridge 1830 in 1968, and that didn't have any effect here (it's about 30 lightyears away), so presumably the EMP generally wouldn't have any effect at that range, but what about closer?

See these links for more info:
More about superflares:
http://www.tmgnow.com/repository/solar/superflares.html (which says that they affect the whole star, and are not directional)

2010-Jul-03, 05:10 PM
It would be extremely dependent on the configuration of the fields involved. I would imagine that once you hit the heliopause the plasma would start coming apart pretty quick. Prolly tens of AU, but not light years of range.

I do find it interesting that the wiki talks about the ozone layer getting destroyed if a superflare happened on the sun. I think I would be far more concerned with my skin bursting into flames than wether I was getting a bit more UV


2010-Jul-03, 05:36 PM
Yeah, it seemed rather unlikely that EMP would affect electronics much farther than the range of the outside of the planetary system. Though I'm not sure what part of the EMP does the most damage to electronics. From the wiki article about it (http://en.wikipedia.org/wiki/Electromagnetic_pulse#Characteristics_of_nuclear_E MP ) it looks like it'd mostly be caused by geomagnetically induced currents?

2010-Jul-03, 09:03 PM
There seems to be facts as yet unknown... to me. What frequency range does what damage ?
Obviously large networks of transmission lines are like antennas for this type of radiation impact.
The duration and impact strength./ distance. ? I like graphs... :eh:
Obviously over distance the strength will fall away with dispersement.
Like the Gamma ray burst this Electro Magnetic Pulse could easily be a extinction event.
We can be aware of a risk without any ability to hide... This is just one of the many risks to humanity.
Fortunately these events are rare and compiling accurate information is dodgy .... I still want the graph...
Adding a layer of tinfoil to my sun hat might just push me over the edge... now where's that umbrella ? ;)

2010-Jul-03, 09:15 PM
Hard to say...if the inverse square law is equally applicable to solar flares, then a hypothetical superflare 1 million times more powerful than the Sun's strongest known ones would fry the Earth's electronics at a distance of ~1000 AUs. If we up that to 10 million times, then the distance goes out to ~3200 AUs. That sounds like a lot, but even the most powerful superflare would be negligible at a distance of one light-year (~63,240 AUs), where it would be only about 1/400th as disruptive.

2010-Jul-03, 10:12 PM
[...] That sounds like a lot, but even the most powerful superflare would be negligible at a distance of one light-year (~63,240 AUs), where it would be only about 1/400th as disruptive.

Glad you finished strong. I was wondering how you would move a star just 1000 AU away.

2010-Jul-04, 04:04 AM
I agree that it seems very unlikely (if not impossible) for the superflare to be able to affect any electronics beyond the star's own planetary system.

I guess it's really down to whether any GICs (geomagnetically induced currents) can be created by the flare. Say you had a moonbase or something - could currents be induced directly in the cables and pipes and conducting materials in the base itself? (essentially, do you need to have a magnetic field around the planet in order to create the EMP effect?)

The wiki page on GICs (http://en.wikipedia.org/wiki/Geomagnetically_induced_current) says this:

A time-varying magnetic field external to the Earth induces electric currents in the conducting ground. These currents create a secondary (internal) magnetic field. As a consequence of Faraday's law of induction, an electric field at the surface of the Earth is induced associated with time variations of the magnetic field. The surface electric field causes electrical currents, known as geomagnetically induced currents (GIC), to flow in any conducting structure, for example, a power or pipeline grid grounded in the Earth. This electric field, measured in V/km, acts as a voltage source across networks.

So I guess that means you don't necessarily need a planetary magnetic field for GICs to be created at all? (That said, I guess you need a planetary magnetic field to cause the E1 pulse, as described here (http://en.wikipedia.org/wiki/Electromagnetic_pulse)?

2010-Jul-04, 04:19 AM
What about a full-blown supernova? Would that be able to cause an EMP at a range of several lightyears?

And presumably the flares that happen at some Type M (red dwarfs) stars would have a similar effect as superflares on any local planetary system orbiting those stars?

2010-Jul-04, 05:05 AM

Not that my abilaty to understand is so sharp but, it would seem that from the wiki site a great deal is known of this sort of weaponry.

Tests and methods of delivering such a EMP have been known and used. Regarding a space born EMP or one born from a Gama ray burst.

We can only be observant and vigilante in detection of abnormal star energy outputs...

I recall a edge on galactic core that might release a Gama burst is of little concern., but the few that are lining us up with a polar view, full frontal are a far more serious issue... Its not the EMP that travels the distance... Its the GRB that becomes a EMP only after reaching our upper atmosphere. But as with all things... lets not get too bogged down with our inhalation... its not like we can stop it a ?

2010-Jul-04, 05:09 AM
This site's got a ton of (rather fascinating) info about EMP on it too - http://www.futurescience.com/X5DNA/X5DNA.html#EMP

Yeah, it seems like a supernova would do the trick at a range of several lightyears. But superflares would just affect their own systems.