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# If Both Saturn And Jupiter Were Red Dwarves.....

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While we're speculating......

I think that I read somewhere that Jupiter would have to be about 12x its current size to be even the Smallest of Red Dwarves.....

Be that as it may.

Assume that both Jupiter and Saturn were just above the minimum size to become Red Dwarves.

Sure, having that much extra mass in the Solar System would completely change everything--but lets imagine, just for Phun--that the inner Planets: Mercury, Venus, Earth, Moon and Mars; and the outer Planets--Uranus, Neptune and Pluto, all ended up pretty much exactly as they are today.....

What would the apparent Size and Magnitude of Jupiter and Saturn be in the Night Sky? Would either ever be visible in daytime?

{Obviously, sometimes they would be much closer than others.....}

Would enough heat and light reach Earth to have any but the most trivial effects on our Climate?

Does anyone know where the "Goldilock's Zone" would be, on a minimal-sized Red Dwarf?

{They used to believe that there couldn't be Any Goldilock's Zone for Red Dwarves. Current theory believes that there could be--a curious planet with one face turned perpetually toward its Sun.

I don't know that this is possible with the Smallest possible Red Dwarf--someone else may know.

What would be the Smallest Red Dwarf that could support a Goldilock's Zone?

Plug it into the Earlier Questions.....}

Why do I ask?

Well, just because it is Phun to Speculate.....

But I also was reflecting on the old SF Stories from the 30's, 40's and '50's--where as one commentator put it--"Explorers travelled the Solar System in their Shirt Sleeves".

Some of the old stories sure were Phun--with a capital "F"--but they're really dated.....

But how could we get several "Shirt Sleeved" Worlds into our Solar System?

{If there were Astronomical Numbers of Universes in our Multiverse, conceivably one of them might have a Solar System that just happened to Evolve exactly like the Hypothetical Solar System that I described.....

Well.....Probably not.....But as a Story Premise.....

And to make for more Phun, make the Protagonist a Man from our Universe who fell into some Phreak Wormhole.....

But my Cosmology isn't Strong Enough to work out some of the Nuts and Bolts.}

Saxon Violence

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I think that I read somewhere that Jupiter would have to be about 12x its current size to be even the Smallest of Red Dwarves.....

I suspect you’re confusing red dwarfs and brown dwarfs, SV.

The minimum mass for a red dwarf – a mass of mostly hydrogen-1 large enough to fuse it into into helium-4 – is about 1.5 x 1027 kg, about 80 Jupiter masses. Below about 80 but above about 12 MJ are brown dwarfs – which can only fuse 2H into 3He.

Below 12 MJ, bodies can’t fuse much hydrogen of any kind.

Be that as it may.

Assume that both Jupiter and Saturn were just above the minimum size to become Red Dwarves.

Sure, having that much extra mass in the Solar System would completely change everything--but lets imagine, just for Phun--that the inner Planets: Mercury, Venus, Earth, Moon and Mars; and the outer Planets--Uranus, Neptune and Pluto, all ended up pretty much exactly as they are today.....

What would the apparent Size and Magnitude of Jupiter and Saturn be in the Night Sky? Would either ever be visible in daytime?

The smallest brown dwarves are believed to have almost no radiation in the visible spectrum, so a 12 times or massive Jupiter (or an 80 time more massive Saturn) brown dwarf wouldn’t be much brighter than they currently are, getting their visible brightness from reflected sunlight. Brown dwarfs compress their gasses more than gas giants, so are only slightly larger, so there’d be little increased brightness due to a larger disk. I can’t guess what making a brown dwarf of Jupiter would do to its albedo (reflectivity), so it’s possible that a brown dwarf Jupiter would be dimmer to the naked eye.

To an infrared telescope, on the other hand, the difference between a gas giant and a brown dwarf would be pretty dramatic.

Would enough heat and light reach Earth to have any but the most trivial effects on our Climate?

From the above, we can see that radiation effects on Earth of a brown dwarf in Jupiter’s orbit would be very minor.

The gravitational effects of a much larger body there, however, would have a dramatic effect on the formation of the solar system, which I’m pretty sure would have significantly effected Earth and the other inner planets’ present-day orbits, sizes, and even existences.

Does anyone know where the "Goldilock's Zone" would be, on a minimal-sized Red Dwarf?

As luck would have it, a nearby brown dwarf of about 12 MJ, WISE 1541-2250 was just discovered, so we have an idea what temperature such a body would have, about 370 K, pretty close to the boiling point of water.

Such a body wouldn’t have much of a Goldilocks zone – an orbital distance where liquid water could exist on a roughly Earth-size planet – but to say for sure, we'd have to do some black body/bolometric luminosity calculations. Maybe it would be enough to have liquid water on one of the present-day large moons of Jupiter.

The problem, then, would be having an orbiting body large enough to keep its liquid water. Jupiter’s present largest moon, Ganymede, is only about 2 times the mass of Earth’s moon, far too small to prevent liquid water from escaping into space.

So, just because a planet/moon is within its primary’s Goldilocks zone doesn’t guarantee it’ll be “Goldilocks size”, large enough to have liquid water and a life-friendly atmosphere.

Terrestrial biology shows us, though, that life is startlingly adaptive, so I wouldn’t rule out something living on a Ganymede or Europa-size moon of a brown dwarf. I wouldn’t even rule out the possibility that there’s something living in liquid water under the frozen surface of present day Europa.

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While we're speculating......

I think that I read somewhere that Jupiter would have to be about 12x its current size to be even the Smallest of Red Dwarves.....

Be that as it may.

Assume that both Jupiter and Saturn were just above the minimum size to become Red Dwarves.

Sure, having that much extra mass in the Solar System would completely change everything--but lets imagine, just for Phun--that the inner Planets: Mercury, Venus, Earth, Moon and Mars; and the outer Planets--Uranus, Neptune and Pluto, all ended up pretty much exactly as they are today.....

What would the apparent Size and Magnitude of Jupiter and Saturn be in the Night Sky? Would either ever be visible in daytime?

I put the words in italics above as a constraint would in the likely make it that we would never had been. This would be because you are requiring the orbits of these two new stellar additions to our system that would likely change the dynamics of our solar system. Were these two planets more than 12x larger yet in the same orbit. This would cause orbital instabilities in all the planets and cause so many collisions that our pleasant environment on Earth would never have survived.

Now if I were allowed to equivalently moved the orbits out in proportion to their mass, then you would likely have the equivalent kind of star system to our closest neighbor Alpha Centauri (a trinary star system). It is thought that from a planet in that system that all three stars would be visible in daylight (thus 3 suns).

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Actually, I was thinking of Red Dwarves--Just got my Numbers crossed.

Been fascinated by Red Dwarves ever since I saw that Speculation about life on a Planet Circling a Red Dwarf with one face perpetually toward its Sun on one of the Educational Channels.

I'll try to find a Link--I know they wrote the show up on "Wikipedia" {Yes, I know that Wikipedia is not on parr with The Holy Gospels as far as Unerring Accuracy...}

If I Understand maddog correctly, even if we somehow get four inner Planets just like ours (and our Moon)--They won't be able to find stable orbits.....

Thus, if we want Four inner Planets very similar to our own, we'll need to move our Red Dwarves much Farther away.

Cool.

Like I said--My Cosmology is weak.

http://en.wikipedia.org/wiki/Aurelia_and_Blue_Moon

http://en.wikipedia.org/wiki/Habitability_of_red_dwarf_systems

Saxon Violence

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I suspect you’re confusing red dwarfs and brown dwarfs, SV.

The minimum mass for a red dwarf – a mass of mostly hydrogen-1 large enough to fuse it into into helium-4 – is about 1.5 x 1027 kg, about 80 Jupiter masses. Below about 80 but above about 12 MJ are brown dwarfs – which can only fuse 2H into 3He.

Below 12 MJ, bodies can’t fuse much hydrogen of any kind.

I appreciate the clarification. Had I seen this, I might not have even posted (in my mind I was thinking more on order of 10^2 jupiter masses).

In the 50's or so, it was thought planets would not be stable around multiple star systems. Now it is when the perturbations are insignificant enough to have long term stability. There was a paper from the 70's that ran through stability models of stars. This was all before the new data about exoplanets and all. In stellar systems with brown dwarfs and one of the planets could later produce life. Once this life could rise to sentience with a culture to study astronomy. These budding scientist would theorize about flaws in their data (movement of the planets) as though one or more unseen companions are in their system.

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Interesting speculation, I believe some red dwarfs would have a goldilocks zone at some distance much closer to the primary. So just for fun lets take our solar system and plug in a large red dwarf for our sun and relocate all the current planets into closer orbits so that Earth would be in the new goldilocks zone.

How would that affect life on Earth?

Well for one thing a red dwarf will have a 3 to 5 times longer life than our current sun, not that we are very worried about that at this time. Any animal life would most likely have eyes that see in the lower range of the spectrum. So who knows maybe that dim red dwarf would still look very bright to any life that developed under it. Possibly we wouldn't have to worry about ultraviolet radiation or even CME's due to a smaller less active sun. Can anybody else think of anything else to add?

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i think it would have an effect depending on the spectum signature of each star

where life on earth reacts to the moon

life would react to the stars also

mabe unique flower blooms

or mabe a flower only bloom when all 3 stars shine during the day, and all 3 can be seen

or mabe a cascading long season, where similar to grashoppers turning to locust

when the days are constant, the spectrum changes for each star and time

it triggers an effect on the " grasshopper" - new type grasscooker

at this time, the grasscooker makes instinctually makes a lens from its mucus

and puts grass seeds under it, after the cooking occurs

they feast, and go to hybernate

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Interesting speculation, I believe some red dwarfs would have a goldilocks zone at some distance much closer to the primary. So just for fun lets take our solar system and plug in a large red dwarf for our sun and relocate all the current planets into closer orbits so that Earth would be in the new goldilocks zone.

How would that affect life on Earth?

Well for one thing a red dwarf will have a 3 to 5 times longer life than our current sun, not that we are very worried about that at this time. Any animal life would most likely have eyes that see in the lower range of the spectrum. So who knows maybe that dim red dwarf would still look very bright to any life that developed under it. Possibly we wouldn't have to worry about ultraviolet radiation or even CME's due to a smaller less active sun. Can anybody else think of anything else to add?

Yes, seasonal variation. In our case is due to two reasons:

1. Inclination of Earth to ecliptic (orbit of Earth around sun).
2. Ellipticity of Earth's orbit (ratio of Earth's closest approach to sun - to the farthest = eccentricity).

This produces the seasons we see.

So if the eccentricity of Earth's orbit were much beyond what it is now, season would be radically more pronounced. This may not be a problem if say the habitable zone were about Mercury's orbit.

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i think it would have an effect depending on the spectum signature of each star

where life on earth reacts to the moon

life would react to the stars also

mabe unique flower blooms

or mabe a flower only bloom when all 3 stars shine during the day, and all 3 can be seen

or mabe a cascading long season, where similar to grashoppers turning to locust

when the days are constant, the spectrum changes for each star and time

it triggers an effect on the " grasshopper" - new type grasscooker

at this time, the grasscooker makes instinctually makes a lens from its mucus

and puts grass seeds under it, after the cooking occurs

they feast, and go to hybernate

Gosh and Gollies!

Back to our original Premise:

Minimal-Sized Red Dwarves in Jupiter and Saturn's orbit.

{"Minimal" meaning as small as they can be, and still be Red Dwarves.}

Maddog tells us that the orbits would not be stable--but lets just pretend momentarily.

Earth's Sun warms the Moons of Jupiter very little.

I'm not sure what the Ambient Temperature would be without the Tidal Warming, and minimal heat that Jupiter provides.....

But probably, the Sun raises the temperature no more than a very few degrees.

A Red Dwarf would be putting out much less light and heat than our Sun.

When we could see Jupiter in the Night sky, it would be one AU (93 Million Miles) closer to Earth than our Sun would be to Jupiter--that is rather inconsequential.

When Jupiter was in the Daytime sky, it would be 93 million Miles Farther Away from Earth, than Jupiter is to our Sun.

Saturn is noticeably farther away than Jupiter.

Still, If the distant Red Dwarves caused Earth's average yearly temperature to be even a half degree warmer, the cumulative effect on Earth's climate might be dramatic.

Just for argument's sake, we're going to stipulate that this didn't happen (Large-Scale Climate Change).

But the amount of Heat/Light reaching Earth would be minimal--certainly not enough to spur a "Super-Growing-Season".....

I don't think.

The questions that remain are:

How brightly would Jupiter and Saturn shine in the Night Sky?

What would the apparent size of each be be?

Could we see them in the daylight sky?

Now more informed people have told me that Jupiter would have to be 80x its current Mass, to become a Red Dwarf--and not the 12x figure that I was using.

If Jupiter was 80 times as massive, and since Gravitation is inversely proportioned to distance: The Square Root of 80 is about 9. Red Dwarf Jupiter would have to be about nine times as far out.

Saturn as a Twin Red Dwarf would be far less of a concern--but we'd better multiply the distance between Jupiter and Saturn by about 9 if we don't want them to destabilize each other.

I need to look at a List of Planetary distances--but I believe that a Red Dwarf 9 times the distance of Jupiter would be out around the Orbit of Uranus or Neptune--or farther.

Saxon Violence

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one interesting thing is we always measure earth things according to the spectrum of light that is most prevalent from the sun

if we got a spectruma analysis of jupiter and saturn, then the spike in intensity from the spectrum were recorded, and those wavelengths added to

different species,

especially any species that has rare occurances at times where they could be exposed to the spectrums from these planets,

then if the discrepanceies occur with the added spectrum, then we would know that its the effect of light from them that causes the occurance

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How brightly would Jupiter and Saturn shine in the Night Sky [if they were the smallest possible red dwarfs]?

Brightness, how well you can see a body and see by its illumination, is conventionally measured by apparent magnitude.

The smallest red dwarfs have absolute magnitudes of about +15

Jupiter orbits at about 5.2 AU, so the smallest red dwarf in Jupiter’s orbit would have an apparent magnitude of about

$+15 -5\left(1 -\log_{10}\left( \frac{5.2 -1 AU}{10 pc}\right) \right) \dot= -18.5$

to

$+15 -5\left(1 -\log_{10}\left( \frac{5.2 +1 AU}{10 pc}\right) \right) \dot= -17.6$

Saturn orbits at about 9.6 AU, so its red dwarf replacement would apparent magnitude about

$+15 -5\left(1 -\log_{10}\left( \frac{9.6-1 AU}{10 pc}\right) \right) \dot= -16.9$

to

$+15 -5\left(1 -\log_{10}\left( \frac{9.6+1 AU}{10 pc}\right) \right) \dot= -16.4$

The apparent magnitude of a full moon is about -12.7, so red dwarf Jupiter would be about [imath]2.512^{18.5-12.7} \dot= 203[/imath] to [imath]2.512^{17.6-12.7} \dot= 89[/imath] times brighter that the full moon, red dwarf Saturn, about [imath]2.512^{16.9-12.7} \dot= 47[/imath] to [imath]2.512^{16.4-12.7} \dot= 30[/imath].

The apparent magnitude of the Sun is about -26.7, about 1900 time brighter than RD Jupiter at its brightest.

How brilliant a body is – their radiative power per unit area – is roughly proportional to the fourth power of their absolute temperature, and not related to their distance. The smallest red dwarfs have temperatures of about 2300 K. The Sun’s is about 5780 K. So they’d be about [imath]\left( \frac{2300}{5780} \right)^4 = 0.023[/imath] times as brilliant as the sun

What would the apparent size of each be be?

The smallest red dwarfs aren’t much larger in diameter than Jupiter, so their disks wouldn’t appear much larger than Jupiter’s or Saturn’s do now. Like the planets, to a casual naked eye, they’d be point like, like stars.

Could we see them in the daylight sky?

Yes, as long as they weren’t too close to the Sun.

If Jupiter was 80 times as massive, and since Gravitation is inversely proportioned to distance: The Square Root of 80 is about 9. Red Dwarf Jupiter would have to be about nine times as far out.

Calculating the long-term stability of the red dwarf Jupiter and Saturn system would be complicated, requiring high-accuracy computer simulation, but short term, it shouldn’t be necessary to change their orbits very much.

Because the force of gravity between RD Jupiter and Saturn will be greater, I believe they’d need to be in closer orbital resonance, and the inner planets be in closer resonance with RD Jupiter – but again, I think you’d need to model the system to say with much confidence.

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CraigD

Nice work, from what you said, I have the impression that while the red dwarfs Jupiter & Saturn orbits would be brighter than the moon, they would not necessarily provide more light than the moon due to being farther away?

Whenever I think of being on a planet in a multi-star system, I always picture a SF view of a sky with two or three suns in it. But in this case that might not be the case as the red dwarfs would only appear in the sky as very bright stars.

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We know that Jupiter and Saturn hoovered up a lot of material in the early solar system and also sling shoted planets inwards and outwards.

If they were both brown dwarves with masses a dozen times their present mass we would see a vastly different solar system to the one we now live in, possibly without an Earth or a planet which was far closer to the sun so life could not exist on it. I doubt that gas giants Uranus and Neptune would exist as such, maybe instead being small bodies.

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http://www.space.com/16298-saturn-jet-streams-cassini-spacecraft.html

does anyone have a light spectum signature of the two planets, one from the opposite side of the sun, so the only signature is that which they emit themselves?

or do the objects we have orbiting not have the capability to get a true signature??

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