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Red Giant
2009-Feb-05, 08:15 PM
Ok, let's say there is a trinary star system with a distance of 1000 AUs (more or less) and that one sun is much like the Earth's out to Jupiter. The other one is a Nova system, going nova once every 100 years or so. What effects would this have on Earth 2?

Hornblower
2009-Feb-06, 03:48 AM
Ok, let's say there is a trinary star system with a distance of 1000 AUs (more or less) and that one sun is much like the Earth's out to Jupiter. The other one is a Nova system, going nova once every 100 years or so. What effects would this have on Earth 2?

At 1000AU, an ordinary nova might rival the Sun in brightness for a short time and then fade away in a few days or weeks. Since the warmup from the increased heating is slow, we might survive. Just an educated guess on my part.

Red Giant
2009-Feb-06, 05:11 PM
Well, it had been like this for centuries, I guess. So, these people probably would expect it.

antoniseb
2009-Feb-06, 05:20 PM
Well, it had been like this for centuries, I guess. So, these people probably would expect it.

Hi Red Giant,

Are you writing a science fiction story? or creating a world for a role-playing game? or just asking, concerning a story you read some place? I'm asking because those of us who are chronic answerers like to know why we're answering things like this.

BTW, Hornblower is right, but it would also be *very* hot on said planet during the bright time.

Red Giant
2009-Feb-07, 01:13 AM
I just spotted the idea on another site, and just wanted to know if it would work. Might use it in a sci-fi story latter, but I'm working on a different idea right now.

mugaliens
2009-Feb-07, 03:55 PM
Let's examine this a bit further. Our sun shining on our Earth, rotating as it does every 24 hours, keeps the mean temp hovering around 65 deg, with 95% of all variations occurring between -60 and 120 deg F (these are estimates, but they're close enough to make my point). In C, it's -51 and 49. For convenience sake, we'll call it -50 and 50 C, with a mean of 18 C (the distribution is not centered around the average of the extremes).

If we were to double that influx, just how much would the temperature increase?

To examine that, let's look at these temps in Kelvin:

Min: -50 C = 223 K
Median: 18 C = 291 K
Max: 50 C = 323 K

On the Moon, the daytime temps averages 107 C, or 380 K, and the nighttime temperature drops to -153 C, which is 120 K. On Earth, however, when conditions are just right (no sun for several months, weather patterns conducive to super-cooling), the minimum temp gets down to -89 C, which is 184 K, and a maximum (super-heating) of 137 F = 58 C = 331 K

Since an earlier post mentioned "a few days to a couple of weeks," and the lunar night is two weeks, the duration is roughly the same to what we might expect of the duration of a supernova, and we can use that to our advantage.

The bottom line is that due to the attenuating effects of Earth's atmosphere, the maximum temp we might expect from twice the influx would be 1.41 * average(Earth max, Moon max), or 441 K, which is a whopping 167 C, or 334 F.

I think things would get a little toasty...

This assumes, of course, that the supernova would be in the solar ecliptic. If it instead shone down on Earth's North of South pole, things would be different, particularly if it hit a pole during that pole's dead of winter. In that case, say, for Antarctica, you'd have some temporary warming, possibly some slight melting, then after it faded into night, the temporary influx would be re-radiated back to space, and a year later there'd be little to show for it.

A supernova in the plane of the solar ecliptic, however, would result in massive overheating, burning, destruction of grasslands and forest, starvation, millions, if not billions of heat deaths.

Not pretty.

Tom Mazanec
2009-Feb-07, 04:40 PM
Don't recurrent novae reach lower maxima than classical novae?
I am probably the poster mentioned. I suggested this scenario on an alternate history website forum. I said it would get too hot in most places to do work for a week or two, maybe bad sunburn from UV. Perhaps I underestimated it. I figured that the nova would be somewhat dimmer than the sun, but still a significant fraction.

cjameshuff
2009-Feb-07, 05:49 PM
Doubling the input power doubles the radiated power once equilibrium is reached. Radiation increases with the fourth power of temperature, so, approximating the planet as a black body with albedo independent of temperature, Tnew = 2^(1/4)*Told = 1.19*Told

Using that approximation, Earth's average temperature would rise from 287 K, 13.9 C, to 342 K, 68.4 C. More specifically, it'll rise toward that over time, and I highly doubt a few days or weeks will be enough time to reach it. There's a great deal of thermal mass to warm up. Ocean evaporation will absorb a lot of heat as equilibrium shifts toward a more humid atmosphere, and there's ice caps to melt...phase changes and shifts in equilibrium points like these will increase the time constant of the system considerably over a bald rock like the moon. I suspect the water vapor would also produce a thick cloud layer that greatly increases albedo and decreases the equilibrium temperature...unless the structure of our atmosphere gets disturbed enough that it starts trapping more heat as a greenhouse gas than it reflects as clouds. The particularly high amounts of ionizing radiation hitting the atmosphere might increase cloud formation.

It would greatly disrupt ocean and temperate zone ecologies. A thick global cloud layer and other weather disruptions would probably disrupt crops. It would likely cause mass extinctions, but while it would certainly strongly impact us, I don't think it would threaten human civilization. If it's periodic and survivable, the native life will have adapted to it (long-lived species possibly even depending on it), and the civilization might be able to predict it well enough to plan for the disruption...or even take actions to mitigate the effects through artificially increasing the planet's albedo or manipulating its weather.

Red Giant
2009-Feb-07, 06:12 PM
Keep in mind that this planet has been going through this for centuries, so any native life is very well adapted. Tom was the one who gave me the idea, but i do think he underestimated the effects.

mugaliens
2009-Feb-07, 09:37 PM
Doubling the input power doubles the radiated power once equilibrium is reached. Radiation increases with the fourth power of temperature, so, approximating the planet as a black body with albedo independent of temperature, Tnew = 2^(1/4)*Told = 1.19*Told

Using that approximation, Earth's average temperature would rise from 287 K, 13.9 C, to 342 K, 68.4 C. More specifically, it'll rise toward that over time, and I highly doubt a few days or weeks will be enough time to reach it.

You're errantly assuming even heating. Just as the equator is hotter than the poles, whatever latitude becomes the subpoint will swelter while the further the angular distance from that latitude one gets, the less effect it will have. In other words, the subpoint will be significantly hotter than your average calculation (closer to mine), while the angularly distant regions will be significantly cooler than your average calculation.

Red Giant
2009-Feb-08, 03:16 PM
Just for simplicity the subpoint is the equator.

mugaliens
2009-Feb-08, 10:32 PM
You mean it's assumed? Or are you saying that a subpoint is always on the equator?

You're probably aware, but the subpoint is the spot on Earth where the star is directly overhead, at zenith.

Red Giant
2009-Feb-09, 10:03 PM
Yes, i know. But it will always be somewhere on the equator in this scenario just for simplicity.

mugaliens
2009-Feb-10, 09:36 PM
Yes, i know. But it will always be somewhere on the equator in this scenario just for simplicity.

Then we're doomed! Doomed, I tell 'ya!

Seriously, all vegetation in the tropics would dry up and burn.

However, since it's only for 2 weeks... In a year or two, lots of vegetation would have grown up to replace it, and at the end of 100 years, much of the jungles would have been restored so far as the vegetation goes, but it would take many times longer for the fauna to return.

cjameshuff
2009-Feb-12, 03:25 AM
You're errantly assuming even heating. Just as the equator is hotter than the poles, whatever latitude becomes the subpoint will swelter while the further the angular distance from that latitude one gets, the less effect it will have. In other words, the subpoint will be significantly hotter than your average calculation (closer to mine), while the angularly distant regions will be significantly cooler than your average calculation.

I'm not convinced it's such an errant assumption. Hotter portions of the planet will radiate more, and cloudcover and storm systems from increased evaporation will tend to reflect, absorb, and spread the heat. Taking a typical temperature for the tropics of around 303 K (30 C), using this approximation they would warm to around 361 K (87 C)...and again, that's equilibrium, and I doubt it would be reached in 2 weeks. Things would wilt and get a bit steamed, lots of things would die, some places might get dry and experience wildfires.

An equatorial event may actually be ideal. No portion of the planet would be exposed to the nova radiation for longer than it is facing away from it. The high albedo of ice covered poles might compensate for the continuous exposure from a polar event, however.

On Earth, it would be an ecological catastrophe. On another world...I wonder about the likelihood of such events happening enough times for any real adaptations to be made. It would select pretty rapidly for organisms that can survive the events and rapidly recover afterward, but I doubt there'd be anything that is particularly specific to the nova event...nothing like animals hibernating in deep burrows and plants producing underground sucker nodes every 100 years.

mugaliens
2009-Feb-14, 11:07 AM
I'm not convinced it's such an errant assumption. Hotter portions of the planet will radiate more, and cloudcover and storm systems from increased evaporation will tend to reflect, absorb, and spread the heat.

Now this is an errant assumption. I've found that hotter portions of the planet most definately radiate a lot more. But, because of the dryness of the air, there is no cloud cover (reflective layer) or humidity (refractive layer) which acts as a warm blanket. The daily cyclical temperature swings over the deserts (the hotter portions of the planet) are the largest.

It's errant to assume that more heat means more cloud cover. More heat does mean more humidity as a function of water mass / air mass. However, the warmer the air, the more humidity it can hold. It's the dew point which determines condensation and cloudcover.

Also, while they're great at blanketing the Earth's surface heat, storm systems are also great at reflecting solar heating. It's the thn, whispy clouds during the day which provide the better daytime blanket, and the overcast sky at night which provides the better nighttime blanket.

The best blanket by far, however, is simple humdity. And this is relative humidity, not absolute. Thus, if you increase the temperature a few degrees, you might increase the water mass in the air, but you'll also increase the air's capacity to hold water - the relative humidy will remain relatively unchanged.

As for the hotter = more cloud cover theory...

I've flown all over the world. The hottest or most humid parts of our planet have the least cloud cover! By that, I mean the deserts and the open equatorial oceans. For jungle areas such as the Amazon river basin, or the Congo, you find some thunderstorms, but not many. Typically it's all convective heating, so there are a lot of what we pilots call "puffies" out there, from small spots a couple hundred feet high to spots a mile wide and extending upwards of a couple of miles. Much larger stoms do exist, but they tend to be located around convergence zones, such as areas between land and water, or with mountainous activity (the Andes), or where colder polar area reaches in - but the latter almost never makes it to the tropics.

Move north a bit into the sub-tropics and you'll find more normal, and larger cloud cover, including both convective and convergent thunderstorms, as well as the brunt of the cyclonic systems (which are huge, but a small percentage of all cloud cover due to their infrequency).

An equatorial event may actually be ideal. No portion of the planet would be exposed to the nova radiation for longer than it is facing away from it. The high albedo of ice covered poles might compensate for the continuous exposure from a polar event, however.

Look at it this way - you're choosing to fry the tropics where the majority of life on this planet abounds, including human life, as opposed to frying the poles, which has but a tiny fraction of the tropical life. Melt the poles? Sure - beats decimating 90% of the life on this planet, and I'd caution you against AGW kjr-ing against rising waters eclipsing all else in it's importance.

When faced with a decision to fry or move inland 100 yads... Hmm... I guess it's time to pick up my mat and move.

On Earth, it would be an ecological catastrophe.

No doubt - and regardless of the subpoint of the event. I maintain that a polar subpoint would be preferable, and that an Antarctic subpoint would result in less loss of human life than an Arctic subpoint simply due to the population distribution on our planet (someone correct me if I'm wrong, as that may be a simple case of my being a Northern Hemi rather than a Southern Hemi...)

On another world...I wonder about the likelihood of such events happening enough times for any real adaptations to be made. It would select pretty rapidly for organisms that can survive the events and rapidly recover afterward, but I doubt there'd be anything that is particularly specific to the nova event...nothing like animals hibernating in deep burrows and plants producing underground sucker nodes every 100 years.

Now you're talking! Would it be possible for evolution to find a way to survive if the environmental stressor only peeked it's head out every 100 years? I would say, "yes, it's possible." It wouldn't be that flora and fauna would develop a way to keep track of 100 year cycles, but rather, something as simple as a dandylion's deep tap root which survives to spring up again whether it's topside part is pulled, cut, shredded, or burned, or, as you mention, animals such as the lungfish which can burrow ever deeper in the wet mud as the topside bakes itself bone dry under multi-year total droughts.

cjameshuff
2009-Feb-16, 12:12 AM
Now this is an errant assumption. I've found that hotter portions of the planet most definately radiate a lot more. But, because of the dryness of the air, there is no cloud cover (reflective layer) or humidity (refractive layer) which acts as a warm blanket. The daily cyclical temperature swings over the deserts (the hotter portions of the planet) are the largest.

I was not talking about deserts...they are more a result of the shaping of air currents by the land than of latitude.

It's errant to assume that more heat means more cloud cover. More heat does mean more humidity as a function of water mass / air mass. However, the warmer the air, the more humidity it can hold. It's the dew point which determines condensation and cloudcover.

Erm, monsoons? Air over land warms more quickly than that over deep ocean water. The end result is air with more water than it can hold, and very large amounts of thick clouds, typically dropping that water in copious quantities on the land below.

The best blanket by far, however, is simple humdity. And this is relative humidity, not absolute. Thus, if you increase the temperature a few degrees, you might increase the water mass in the air, but you'll also increase the air's capacity to hold water - the relative humidy will remain relatively unchanged.

I am fairly sure it is absolute, not relative humidity that matters for such things, at least until relative humidity reaches 100% and you get water droplets.

The desiccation and firestorms you describe really seem more likely to happen to temperate zones in the hemisphere of a polar nova. Unless it happens in the winter (assuming a planet with strong seasons like Earth), when it may just add up to a couple unseasonably warm weeks, and possibly frost kill of some plants that tried to come out too early.

Now you're talking! Would it be possible for evolution to find a way to survive if the environmental stressor only peeked it's head out every 100 years? I would say, "yes, it's possible." It wouldn't be that flora and fauna would develop a way to keep track of 100 year cycles, but rather, something as simple as a dandylion's deep tap root which survives to spring up again whether it's topside part is pulled, cut, shredded, or burned, or, as you mention, animals such as the lungfish which can burrow ever deeper in the wet mud as the topside bakes itself bone dry under multi-year total droughts.

Not just that...I wonder how many times the event will happen before the recurrent nova, well, stops recurring. How many times can that white dwarf build up a blanket of fuel and blow it off before it accretes too much and you get a type Ia supernova instead? Bringing a conclusive and rather sudden end to the attempts of life to adapt to the recurrent novas that preceded the big one...or what about the other star of the pair?

mugaliens
2009-Feb-16, 09:10 PM
I was not talking about deserts...they are more a result of the shaping of air currents by the land than of latitude.

Granted. But does that also hold for vast expanses of the oceans which are technically deserts due to their less than 10" of rainfall each year? I don't believe it does.

The desiccation and firestorms you describe really seem more likely to happen to temperate zones in the hemisphere of a polar nova. Unless it happens in the winter (assuming a planet with strong seasons like Earth), when it may just add up to a couple unseasonably warm weeks, and possibly frost kill of some plants that tried to come out too early.

We're talking tropical temps beyond the boiling point of water, not a few days warmer than usual.

Not just that...I wonder how many times the event will happen before the recurrent nova, well, stops recurring. How many times can that white dwarf build up a blanket of fuel and blow it off before it accretes too much and you get a type Ia supernova instead? Bringing a conclusive and rather sudden end to the attempts of life to adapt to the recurrent novas that preceded the big one...or what about the other star of the pair?

That's right... The OP did mention a trio, didn't it? I would think the first flash would seriously disrupt the other two stars, if not destroy them, as the explosion is symmetric only for the white dwarf. The other two stars are broadsided by the blast.

cjameshuff
2009-Feb-16, 10:26 PM
We're talking tropical temps beyond the boiling point of water, not a few days warmer than usual.

Not with double the power input. A black body under that increase will only reach a temperature 1.19 times higher than before...only areas that already reach 40 C would reach 100 C. And that's at equilibrium, which again, I strongly doubt will be reached in the timeframe given, and it's ignoring the changes to the surface and atmosphere that would result.

That's right... The OP did mention a trio, didn't it? I would think the first flash would seriously disrupt the other two stars, if not destroy them, as the explosion is symmetric only for the white dwarf. The other two stars are broadsided by the blast.

Well, recurrent novae do exist, and some repeat on much shorter timescales (decades). I was thinking more about the fact that the other in the pair is often a red giant...but they are apparently longer lived than I'd remembered. When not next door to and feeding a recurrent nova, that is.