Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: [1] 2 3 4 5   Go Down

Author Topic: Kepler mission adds more weight to our solar system not being the norm.  (Read 24063 times)

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,515
  • Location: Thornton Cleveleys

The much vaunted Kepler mission continues to provide evidence that our solar system is tending towards uniqueness rather than the norm.

Prior to Kepler's launch, virtually every exoplanetary system and exoplanets, were hot jupiters. That is, massive planets the size of jupiter or larger and, orbiting their parent star in a matter of days since they were so close to it.

Simulations have shown that where a hot jupiter planet exists very close to its parent star, it must have migrated in from further out. Hot jupiters cannot form close in to a star as there just isnt enough material for them to form. Instead, they must form further out in a system where there is more gas, elements and material required to form planets of their size.

The simulations show where hot jupiters migrate inwards, smaller terrestrial sized planets, if they existed in the system, would be ejected from that solar system.


http://www.telegraph.co.uk/science/space/7966992/Three-vast-planets-found-orbiting-distant-star.html
Logged

Martin [Admin]

  • Administrator
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 20,331
  • Location: Peterborough, UK
    • Model Boat Mayhem
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #1 on: August 29, 2010, 12:59:50 pm »

Re:  "our solar system is tending towards uniqueness rather than the norm"

Yes that does increasingly seem to be the considered opinion amongst astronomers.
 Obviously the universe it a big place but of the know planetary systems, most have vary large planets.


Logged
"This is my firm opinion, but what do I know?!"    -   Mayhem FaceBook Group!

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,898
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #2 on: August 29, 2010, 02:11:24 pm »

Again, I'm not so sure that this is the case. Here's why:

Kepler is attempting to spot planets transitting across the disks of distant stars. From Kepler, all the target stars occupy less than a pixel on the ccd. That is, we can't resolve the disks. The software records the brightness of the target stars' pixel against time, and a dip in the brightness corresponds to a transit. A typical dip is about a 1/10000th drop in brightness, and a transit lasts for just a few hours.

Now, to be long-term-stable, multiple planets orbit their stars in a more-or-less 2d plane. Since a planetary system's orbital plane can lie at any angle relative to Kepler, it is only a tiny fraction of the 100000 target stars that Kepler's monitoring, that will display any transits. Think about the dynamics here, and you'll see that transits are more likely to be seen in those systems where the planets are large (they might just clip the edge of the target star), and more likely to be seen at all when they orbit close to the target star (there's a better chance of a transit) - this is exactly the same bias for those hot-Jupiter systems that have been reported from previous doppler studies.

That said, Kepler's only just got going. There's another three years or so of observations to be made (disregarding any mission extension), a length of time that would (if the angles are right) eventually spot a planet in a Mars-like orbit, and allow for repeated observations of a planet in an Earth-like orbit.

So, over time, Kepler might well discover more Sun-like systems, but in these early days, hot Jupiters are more likely.

Andy, taking off his astronomy hat.

Logged
Enjoying every minute sailing W9465 Mertensia

dodgy geezer

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,920
  • Location: London
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #3 on: August 29, 2010, 07:02:18 pm »


...

The simulations show where hot jupiters migrate inwards, smaller terrestrial sized planets, if they existed in the system, would be ejected from that solar system.

...


Mandell and Sigurdsson would disagree with you - Mandell, Raymond and Sigurdsson (2007) refers http://iopscience.iop.org/0004-637X/660/1/823/70644.text.html

Their simulations find that, rather than ejection, resonant shepherding occurs, with accretion at the relevent Legrange points. Note the comment under 3.4 - Final Configurations:

"... Potentially habitable planets survive in almost all of the simulations. In the eight simulations with drag, seven planets larger than 0.2 M (including two in simulation JSD-4) formed in the habitable zone, the orbital region where the stellar flux is sufficient to maintain liquid water on the surface of a planet (assumed to lie between 0.8 and 1.5 AU for these simulations; Kasting et al. 1993). Five planets with masses from 0.13 to 0.4 M formed in the habitable zone in the four simulations without drag..."

In the Conclusion the suggestion is made that our system may have evolved after an earlier Hot Jupiter transit phase, and suggestions are made for further work which may reveal this.

Logged

Bryan Young

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 6,893
  • Location: Whitley Bay
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #4 on: August 29, 2010, 07:21:59 pm »

Mandell and Sigurdsson would disagree with you - Mandell, Raymond and Sigurdsson (2007) refers http://iopscience.iop.org/0004-637X/660/1/823/70644.text.html

Their simulations find that, rather than ejection, resonant shepherding occurs, with accretion at the relevent Legrange points. Note the comment under 3.4 - Final Configurations:

"... Potentially habitable planets survive in almost all of the simulations. In the eight simulations with drag, seven planets larger than 0.2 M (including two in simulation JSD-4) formed in the habitable zone, the orbital region where the stellar flux is sufficient to maintain liquid water on the surface of a planet (assumed to lie between 0.8 and 1.5 AU for these simulations; Kasting et al. 1993). Five planets with masses from 0.13 to 0.4 M formed in the habitable zone in the four simulations without drag..."

In the Conclusion the suggestion is made that our system may have evolved after an earlier Hot Jupiter transit phase, and suggestions are made for further work which may reveal this.


Dodgy: you've done it again! Most erudite, and completely incomprehensible to us little earth-worms. I'm obviously going to have to give you a promotion from "a lowly legal clerk".
I was going to ask if you would put your post into a language that this particular primitive mammal could understand, but I'm a bit scared that you may (using only words) reduce my mentality to that of an amoeba. BY.
Logged
Notes from a simple seaman

dodgy geezer

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,920
  • Location: London
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #5 on: August 29, 2010, 09:07:05 pm »


I was going to ask if you would put your post into a language ....


hear -> obey!

It's reasonably straightforward. When cheap computer time started to become available to scientists, one thing they did quite early on was orbital simulations - projecting planetary orbits into the future. originally, Newton had provided the basic maths for this, which famously predicted a giant stable clockwork system going on to infinity. Given that history, it was quite a surprise to find that, if you allowed for various eccentricities, the planets could actually move about quite a bit, and many configurations were not stable over several billion years. Here is an example of the sort of thing which can come out of these simulations:

http://www.theregister.co.uk/2009/06/11/boffins_track_odds_of_planetary_smashup/

When we started looking for extraterrestrial planets the easiest ones to find were big ones close to their sun - these shade the sun well and cause it to wobble more than a small planet further away would. We were surprised to find quite a lot of these big, close-to-sun planets - our understanding of the Solar System suggested that big planets formed further away. But orbit simulations found that big planets could move nearer (planetary migration) - and that this could throw the smaller, nearer planets completely out of their system. It was suggested that, because of this mechanism, small watery planets might be very rare, making life as we know it rare as well. 

I have referenced a simulation where the big planets move nearer to the sun, but the smaller planets are not ejected, and, indeed, a lot of water ice and dust coalesces in the big planets wakes - building water-rich earth-sized planets in the habitable zone.   


Of course all these simulations may be right or wrong - different assumptions produce different results. Computer models frequently bear little relationship to the truth. But it is far too early to say that one model or another MUST be right. This is a science in its infancy - we are only just managing to see the biggest planets around other stars, and I believe that to say that because we have only seen big planets smaller ones cannot exist is theorising well in advance of the observed facts....
Logged

Bryan Young

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 6,893
  • Location: Whitley Bay
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #6 on: August 30, 2010, 03:14:02 pm »

Now why couldn't you have said that in the first place instead of giving me an incipient migraine? Thank you. Now I think I understand.
Being au-fait with celestial navigation doesn't quite cover those sort of astronomical mathematics. In fact, I actually learned a lot from Bill Brysons' "Short History Of Nearly Everything"! Thanks. BY.
Logged
Notes from a simple seaman

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,773
  • Location: Blackpool, Lancs, UK
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #7 on: August 30, 2010, 09:59:06 pm »

Is there any valid or sensible reason for the idea that our system might be the "norm" in the first place?  Apart from Star Trek and the Hitch-hikers Guide to the Galaxy and the Clangers and similar erudite scientific thinking?
Logged
"With the right tool, you can break anything" - Garfield

dodgy geezer

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,920
  • Location: London
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #8 on: August 30, 2010, 10:11:46 pm »

Is there any valid or sensible reason for the idea that our system might be the "norm" in the first place? 

Well, it's the only one that we've been able to examine, so we can understand how it evolved. So we go looking for similar planets - we even refer to the part of the Solar System that we live in as the 'habitable zone'. The only form of life we know is protoplasmic, so we go looking for that as well.

The point is that we could probably recognise our kind of planet and our kind of life. If there were gas or dust-particle based intelligences living in interstellar space, or electro-magnetic based intelligences living inside stars we would probably be completely unable to recognise them. That might make it difficult to get a research grant... 
Logged

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,515
  • Location: Thornton Cleveleys
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #9 on: August 30, 2010, 10:48:57 pm »

Different people have different opinions. However, the question of hot jupiters ejecting terrestrial placed planets is dependent on when the hot jupiter forms and how quickly it migrates closer to its star through the stellar disk. If the migration occurs during the first million years or so, the planetary disk, planetesimals have time to reform. If later, well hasta lavista baby!

http://casa.colorado.edu/~raymonsn/hotjup.pdf

"The survival rate of terrestrial planets depends on the rate of migration (faster migration means higher survival rate) and ranges from 1540% (Mandell and Sigurdsson, 2003)." and "Only a very small fraction (14%) of terrestrial planets survive the migration event without significant alteration to their orbits."

So, in any event, the end result is a system that doesnt resemble ours.

The reason, originally, that our solar system was normal was based on, our solar system! It has an average star. Not too big and not too small. It had 9 now 8 planets and in the absence of anything else, was just considered the 'norm.'

as I've said before, the evidence mounts almost daily, that our solar system isnt the norm. Kepler should find many terrestrial sized planets but, although early in its mission, the suggestion is that of a lot of further planets found, the small ones are very close to their star.

Cannot lay my hands on the relevant link yet but, in a test of hot jupiter migration, 2500 simulations resulted in the terrestrial planets being ejected from the system.
Logged

dodgy geezer

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,920
  • Location: London
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #10 on: August 31, 2010, 11:42:20 am »

Different people have different opinions. However, the question of hot jupiters ejecting terrestrial placed planets is dependent on when the hot jupiter forms and how quickly it migrates closer to its star through the stellar disk. If the migration occurs during the first million years or so, the planetary disk, planetesimals have time to reform. If later, well hasta lavista baby!

http://casa.colorado.edu/~raymonsn/hotjup.pdf

"The survival rate of terrestrial planets depends on the rate of migration (faster migration means higher survival rate) and ranges from 1540% (Mandell and Sigurdsson, 2003)." and "Only a very small fraction (14%) of terrestrial planets survive the migration event without significant alteration to their orbits."



Umm, Umm and thrice Umm...

Why do you cite this paper? It strongly supports the idea that earth-like planets can form in the presence of a hot jupiter, which, I understand, you do not believe. Look at its conclusions:


"..based on the above arguments, we expect that terrestrial planets can form in a standard bottom-up fashion in the presence of a hot jupiter, and survive for the lifetime of the parent star...

We have argued that terrestrial planets can form in the presence of hot jupiters. we have shown that potentially habitable planets can form in such conditions. ...

...we suggest that stars with hot jupiters may be a good place to look for extra-solar terrestrial planets....Our result, that potentially habitable planets can exist around stars with hot jupiters, effectively widens the Galactic Habitable Zone...."


The background to these papers is that there is a bit of a problem seeing how earth-like planets can form. When a disc of material round a sun solidifies, there should be a lot of iron in the earth-type orbits, then rock, and all the gas and water should be further out. So an earth-position planet should be mainly made of iron.

If a giant planet from further out migrates inwards, and eventually falls into the star, this migration will stir up the ingredients. Specifically, it will bring water and gas inwards and eject some of the internal iron. So you end up with earth-type habitable planets, made of a mix of iron, rock, gas and water, in a liquid-water zone.

All large planets eject mass from a system. That is not an issue. In fact, outer gas giants eject more mass. From your paper:

"An outer giant planet ejects approximately one half of the total terrestrial mass in the system, while a hot jupiter can remove up to one third of the total mass."

What matters is the mix of materials left. You will note that the paper I cited earlier suggested that our solar system might have experienced an earlier migrating giant planet, a suggestion which this paper also supports. In fact, migrating gas giants may be the norm, and it may be that habitable planets composed of an iron core with a rocky outside and water on the surface can only form in this way.



So, in any event, the end result is a system that doesnt resemble ours.

as I've said before, the evidence mounts almost daily, that our solar system isnt the norm. Kepler should find many terrestrial sized planets but, although early in its mission, the suggestion is that of a lot of further planets found, the small ones are very close to their star.



The paper you have cited is in agreement with  Mandell, Raymond and Sigurdsson (2007) ( http://iopscience.iop.org/0004-637X/660/1/823/70644.text.html ) which says:

"If planetary systems that suffer the migration of a gas giant to small distances can eventually form terrestrial planets similar to those in our own system, and the migration of young giant planets is a common result of interactions with the gaseous disk, then it is appropriate to consider the possibility that our own planetary system could have formed earlier generations of giant planets prior to those in the outer solar system.


It is early days yet, as I have often said, but it looks to me as if the migrating hot jupiter theory provides a good explanation of how inner habitable planets can be formed, and may well be the norm for our kind of system....
Logged

PMK

  • Guest
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #11 on: August 31, 2010, 02:40:25 pm »

Just as an aside, I wonder why it is that Humankind are so hellbent on trying to discover life as we know it on other planets.
For eons we human have looked towards the stars and wondered how it might be if there may actually exist planets abundantly sustained with the same air that we breathe, the same foodstuffs that we eat, etc, etc. Already we are sending unmanned probes into the heavens, and likewise, already we are being told that the possibility of another planet capable if sustaining human life is pretty much a foregone conclusion.
So what is the deal with this ongoing obsession of trying to colonise other planets which doesn't even belong to us? The question is, what would we do if we were indeed to stumble upon such a life-sustaining planet? And how would WE, the human race, how would we feel if we knew that any particular lifeform from some distant galaxy were intent upon doing the very same thing as us? Could we be trusted not to make the same mess of things as we have to planet Earth. Or indeed, could any alien lifeform be trusted not to make a mess of things once they have found their way here?

Most humans don't even greet their next-door neighbours' with a cheery "Good morning". Indeed, most humans don't even have the foggiest idea of how their neighbours look like. So how in watney would we react should we ever be greeted with a form from a far-distant planet? Or how are we to be trusted, giving that most humans are bent on screwing-up what should be a perfectly good planet anyway? Would our first contact with alien life be a bit of a shocker should it turn out that aliens have the same average mentality of an X-Factor contestant?
Logged

Bryan Young

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 6,893
  • Location: Whitley Bay
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #12 on: August 31, 2010, 06:33:37 pm »

I think I'm rather pleased that this discussion has descended down to the level of the "Red Tops".
But although I subscribe to the notion that "it's in our genes" to search for and push the boundaries of knowledge, I've come to the conclusion that the entire study and search for extra-terrestrial life (as we know it) is a waste of time and money.
When distances are measured in terms of light years we don't even know if what we are seeing still exists, never mind communicating with anybody.
I'm all in favour of attempting to discover more about the actual cosmos and the extent of the Universe and so on, but I really do believe that we should at least try to understand our own bit of rock a lot better than we do at present. BY.
Logged
Notes from a simple seaman

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,515
  • Location: Thornton Cleveleys
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #13 on: August 31, 2010, 10:13:05 pm »


Umm, Umm and thrice Umm...

Why do you cite this paper? It strongly supports the idea that earth-like planets can form in the presence of a hot jupiter, which, I understand, you do not believe. Look at its conclusions:


"..based on the above arguments, we expect that terrestrial planets can form in a standard bottom-up fashion in the presence of a hot jupiter, and survive for the lifetime of the parent star...

We have argued that terrestrial planets can form in the presence of hot jupiters. we have shown that potentially habitable planets can form in such conditions. ...

...we suggest that stars with hot jupiters may be a good place to look for extra-solar terrestrial planets....Our result, that potentially habitable planets can exist around stars with hot jupiters, effectively widens the Galactic Habitable Zone...."


The background to these papers is that there is a bit of a problem seeing how earth-like planets can form. When a disc of material round a sun solidifies, there should be a lot of iron in the earth-type orbits, then rock, and all the gas and water should be further out. So an earth-position planet should be mainly made of iron.

If a giant planet from further out migrates inwards, and eventually falls into the star, this migration will stir up the ingredients. Specifically, it will bring water and gas inwards and eject some of the internal iron. So you end up with earth-type habitable planets, made of a mix of iron, rock, gas and water, in a liquid-water zone.

All large planets eject mass from a system. That is not an issue. In fact, outer gas giants eject more mass. From your paper:

"An outer giant planet ejects approximately one half of the total terrestrial mass in the system, while a hot jupiter can remove up to one third of the total mass."

What matters is the mix of materials left. You will note that the paper I cited earlier suggested that our solar system might have experienced an earlier migrating giant planet, a suggestion which this paper also supports. In fact, migrating gas giants may be the norm, and it may be that habitable planets composed of an iron core with a rocky outside and water on the surface can only form in this way.


The paper you have cited is in agreement with  Mandell, Raymond and Sigurdsson (2007) ( http://iopscience.iop.org/0004-637X/660/1/823/70644.text.html ) which says:

"If planetary systems that suffer the migration of a gas giant to small distances can eventually form terrestrial planets similar to those in our own system, and the migration of young giant planets is a common result of interactions with the gaseous disk, then it is appropriate to consider the possibility that our own planetary system could have formed earlier generations of giant planets prior to those in the outer solar system.


It is early days yet, as I have often said, but it looks to me as if the migrating hot jupiter theory provides a good explanation of how inner habitable planets can be formed, and may well be the norm for our kind of system....

Do you try and get things wrong deliberately? The evidence suggests you must do. Of course while just posting in a forum, I forgot there are always some people around who expect a science paper to be provided to support every post.

You state "........hot jupiter, which, I understand, you do not believe. Look at its conclusions:"

To correct you once again, I have never said I do not believe hot jupiters will always prevent terrestrial planets forming or that they will always eject terrestrial planets from forming in the habitable zone. I do believe it is very likely this will be the case but as most of us are prepared to acknowledge, there will always be exceptions to the rule especially in a galaxy with billions of stars.

But. you carry on misrepresenting what people post if that lights your candle.

I have said and will say again, that research of 2500 simulations showed in every case migrating hot jupiters caused terrestrial planets to be ejected from an exo solar system. I've acknowledge I cannot find the link to this but I could trawl through the 'There's no one out there' thread to find it. If I had time and wanted to take every poster to task as you do, I dare say I could find it again.

You provided a paper that suggested otherwise. In response, I posted a link to another paper which stated clearly although you appear to have ignored, that HJ's can and will disrupt the planeeisimal matter as they migrate inwards. The article also stated that if this migration happens in the first million or so years of the exo systems existence, the planetesimal matter has chance to re form and allow terrestrial planets to form after the migration.

The article also states that if the HJ's migrate later than this, the results are very different. Of course at the moment, even the paper you alude to is not supported by all the evidence so far gathered. And this is that where an exo solar system has HJ's the information to date is that terrestrial planets in the habital zone are virtually non existeant. We could concur this is because the HJ have ejected or prevent terrestrial planets from forming.

Oh and just so we are clear, when I mention terrestrial planets, I mean terrestrial sized planets in the habitable zone. Rocky terrestrial planets may form in closer to the parent star even with HJ's but so what? I gather one dataset from Kepler alludes to such a scenario http://www.telegraph.co.uk/science/space/7966992/Three-vast-planets-found-orbiting-distant-star.html.

So I guess you could triumphantly claim that even with an HJ in an exo solar system, we now have evidence that terrestrial planets can still form. Whoopee- do!

Despite this, the premise still holds. That is Kepler's
Logged

dodgy geezer

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,920
  • Location: London
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #14 on: September 01, 2010, 01:02:56 am »



... I forgot there are always some people around who expect a science paper to be provided to support every post. ...I have said and will say again, that research of 2500 simulations showed in every case migrating hot jupiters caused terrestrial planets to be ejected from an exo solar system. I've acknowledge I cannot find the link to this ...


If you are making a scientific claim it is an absolute requirement to provide the research evidence.



"You provided a paper that suggested otherwise. In response, I posted a link to another paper which stated clearly although you appear to have ignored, that HJ's can and will disrupt the planeeisimal matter as they migrate inwards. The article also stated that if this migration happens in the first million or so years of the exo systems existence, the planetesimal matter has chance to re form and allow terrestrial planets to form after the migration.

The article also states that if the HJ's migrate later than this, the results are very different. "



Indeed. The paper goes on to state that creation and migration of HJs is typically rapid, within 1.1 Myr.

"...recent results show that giant planets can form on very short timescales (Boss 1997; Mayer et al 2002; Rice et al 2003). New simulations of the standard core-accretion scenario (Pollack et al  1996) including turbulence (Rice and Armitage 2003) and migration during formation (Alibert et al 2004) have shown that giant planets can form via this mechanism in 1,000,000 years or less....

The timescale for the inward migration of a giant planet depends on the mass of the planet and the mass and viscosity of the gaseous disk, and is typically less than 100,000 years for Saturn and Jupiter-mass planets. Migration begins immediately after, even during, the formation of the giant planet....


So a 'normal' HJ system migrates rapidly, and WILL retain the building blocks of a terrestrial planet within the habitable zone, after they have been carried there by the migrating HJ. If this has happened here, it would explain why we have a rocky AND gaseous planet. The distribution of water and other volatiles in the inner Solar System is still not well understood, and it looks to me as if migrating HJs, rather than being a threat to terrestrial-type planets, could in fact be the creators of them.   

Despite this, the premise still holds. That is Kepler's

It is hard to tell what premise you refer to in your final sentence, which is incoherent. Is a part missing? However, given your title of 'Keppler mission adds more weight to our solar system not being the norm', I would suggest that a system showing HJs which have migrated close to their sun is exactly what you would expect to see during the early stages of a system which will have terrestrial type planets in the habitable zone.

Logged

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,898
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #15 on: September 01, 2010, 08:59:10 am »

So I guess you could triumphantly claim that even with an HJ in an exo solar system, we now have evidence that terrestrial planets can still form. Whoopee- do!

In this case: not necessarily!

That terrestrial (sized) planet is in a day-and-a-bit orbit, inside two Saturn-type planets in 19 and 38 day orbits. All going around a star very much like the sun. In our system, Mercury (in an 88-day orbit) has a surface temperature of up to 700K.

So the terrestrial planet there could be no more than the rocky remnant core of a former hot Jupiter.

Andy
Logged
Enjoying every minute sailing W9465 Mertensia

dodgy geezer

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,920
  • Location: London
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #16 on: September 01, 2010, 09:57:55 am »


So the terrestrial planet there could be no more than the rocky remnant core of a former hot Jupiter.

Andy

Indeed. At that range from the sun (around 1.86 million miles?) I would agree that this is the most likely possibility. I suspect that it is being ablated, and experiencing drag from the solar wind, so will probably disappear entirely in a short time.

Logged

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,898
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #17 on: September 01, 2010, 12:36:16 pm »

A quick play with Excel suggests the surface temparture there must be around the 2200K mark. Well over the temperature of molten rock. Even titanium would be a puddle.
Logged
Enjoying every minute sailing W9465 Mertensia

dodgy geezer

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,920
  • Location: London
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #18 on: September 01, 2010, 03:35:38 pm »

Interesting calculation! I wonder what G is there...

If it's boiling away and losing mass I suspect that will tend to make it fly away from the sun, while the drag from the solar wind will slow it down and make it tend to fall into the sun. That effect might stabilise its orbit for a while, but I would guess that in a 100k years or so it will be completely vaporised.....   
Logged

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,515
  • Location: Thornton Cleveleys
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #19 on: September 03, 2010, 11:28:55 pm »

If you are making a scientific claim it is an absolute requirement to provide the research evidence.

Absolute tosh. This is a general chat forum for subjects to be discussed in a matter of fact way. So most people wouldnt expect or demand scientific papers. You continually spoil perfectly reasonable debate by requiring scientific papers to support a debate or, as is usually your want, to stifle debate.

You just troll threads trying to make your self look important.


Quote
Indeed. The paper goes on to state that creation and migration of HJs is typically rapid, within 1.1 Myr.

"...recent results show that giant planets can form on very short timescales (Boss 1997; Mayer et al 2002; Rice et al 2003). New simulations of the standard core-accretion scenario (Pollack et al  1996) including turbulence (Rice and Armitage 2003) and migration during formation (Alibert et al 2004) have shown that giant planets can form via this mechanism in 1,000,000 years or less....

The timescale for the inward migration of a giant planet depends on the mass of the planet and the mass and viscosity of the gaseous disk, and is typically less than 100,000 years for Saturn and Jupiter-mass planets. Migration begins immediately after, even during, the formation of the giant planet....


So a 'normal' HJ system migrates rapidly, and WILL retain the building blocks of a terrestrial planet within the habitable zone, after they have been carried there by the migrating HJ. If this has happened here, it would explain why we have a rocky AND gaseous planet. The distribution of water and other volatiles in the inner Solar System is still not well understood, and it looks to me as if migrating HJs, rather than being a threat to terrestrial-type planets, could in fact be the creators of them.   

It is hard to tell what premise you refer to in your final sentence, which is incoherent. Is a part missing? However, given your title of 'Keppler mission adds more weight to our solar system not being the norm', I would suggest that a system showing HJs which have migrated close to their sun is exactly what you would expect to see during the early stages of a system which will have terrestrial type planets in the habitable zone.



And as with all these papers, they are theoretical until definitively proved otherwise. You appear to take them as gospel.

Still, when everyone else acknowledges SETI has been in existence for 50 years yet you state its more like 10 and, wasted what was it, 20 headless pc's crunching useless SETI data for 10+ years, one can begin to understand your frustrations.

Just for once, well, actually for the second time, why dont you let debate flow on an every day level instead of trying to bull yourself up? Dont bother answering that as it was a rhetorical question.
Logged

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,515
  • Location: Thornton Cleveleys
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #20 on: September 03, 2010, 11:43:49 pm »

Just as an aside, I wonder why it is that Humankind are so hellbent on trying to discover life as we know it on other planets.
For eons we human have looked towards the stars and wondered how it might be if there may actually exist planets abundantly sustained with the same air that we breathe, the same foodstuffs that we eat, etc, etc. Already we are sending unmanned probes into the heavens, and likewise, already we are being told that the possibility of another planet capable if sustaining human life is pretty much a foregone conclusion.
So what is the deal with this ongoing obsession of trying to colonise other planets which doesn't even belong to us? The question is, what would we do if we were indeed to stumble upon such a life-sustaining planet? And how would WE, the human race, how would we feel if we knew that any particular lifeform from some distant galaxy were intent upon doing the very same thing as us? Could we be trusted not to make the same mess of things as we have to planet Earth. Or indeed, could any alien lifeform be trusted not to make a mess of things once they have found their way here?

Most humans don't even greet their next-door neighbours' with a cheery "Good morning". Indeed, most humans don't even have the foggiest idea of how their neighbours look like. So how in watney would we react should we ever be greeted with a form from a far-distant planet? Or how are we to be trusted, giving that most humans are bent on screwing-up what should be a perfectly good planet anyway? Would our first contact with alien life be a bit of a shocker should it turn out that aliens have the same average mentality of an X-Factor contestant?

A very interesting post. Dont worry, I wont demand you provide links to scientific papers though!

I guess a large part of the answer is, we are as a species (although not the only one by any means) that is naturally inquisitive. We want knowledge, we want to explore and yes to a degree, we want to own.

Theories abound that when \ if we ever do find ETI, it would have a profound effect on most of us. Maybe it will, maybe it wont. I know people who say 'so what if ET contacts us. It wont change my life!'

Perhaps not. I think its a sad perspective of people to say since it would be a great discovery. And if we could talk to another species, maybe it might encourage us to talk to one another.

However, all this is looking more and more unlikely since even SETI observers are beginning to ask if the ways they are looking for ETI are flawed (well yes it is but well done for starting to wake up to that simple fact!). Add in the fact that virtually every one of the exo solar systems found to date are not like ours reduces even further to the very slim chance of ETI's being out there. But that's another thread!

Logged

dodgy geezer

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 3,920
  • Location: London
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #21 on: September 04, 2010, 12:22:42 am »


 You continually spoil perfectly reasonable debate by requiring scientific papers to support a debate or, as is usually your want, to stifle debate.



Are you having problems finding any data to support your assertions? You may find the Wiki to be of assistance: http://en.wikipedia.org/wiki/Hot_Jupiter refers...
Logged

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,898
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #22 on: September 04, 2010, 01:42:04 pm »

...virtually every one of the exo solar systems found to date are not like ours reduces even further to the very slim chance of ETI's being out there. But that's another thread!

I think your reasoning is incorrect, but your conclusion is right.

All the methods used to discover extrasolar planets introduce a bias towards finding systems that aren't like the solar system. At the moment they can only detect close in, large planets, which is not the model underlying our own solar system.

That's not all bad news, because it does prove that planets are likely to be common - there's 490 extrasolar ones known right now. A few years ago we knew of none, but the fact is that the formation of just about any kind of a star is potentially able to create planetary systems (and dust rings) of a findable type.

Ok - so why don't we discover hot Jupiters around just every star that's looked at, if planet formation is not uncommon? I'd argue that it's precisely because our solar system isn't unique, and many stars might well have systems not unlike ours, that are currently undetectable.

As to "life" I strongly believe it's just chemistry, time and chance; and in those terms our kind of carbon-based life could well start all over the place. The right materials exist throughout our solar system, and we know of liquid water under Europa, in Enceladus, and there's a great chance of liquid brines under Mars, too. Toss in 100 billion stars in the galaxy, and I think we'll ultimately find that living things are ubiquitious. Look at it this way, our universe clearly has the physics, structure and age which make it life-friendly.

Intelligent, communicating life, on the other hand, I think is an extreme rarity - we're the outcome of some stupendously lucky breaks from our single-celled ancestors - and I'd point you to Fermi's Paradox for a likely proof of that rarity.

Andy
Logged
Enjoying every minute sailing W9465 Mertensia

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,515
  • Location: Thornton Cleveleys
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #23 on: September 05, 2010, 03:18:59 pm »

I think your reasoning is incorrect, but your conclusion is right.

All the methods used to discover extrasolar planets introduce a bias towards finding systems that aren't like the solar system. At the moment they can only detect close in, large planets, which is not the model underlying our own solar system.

That's not all bad news, because it does prove that planets are likely to be common - there's 490 extrasolar ones known right now. A few years ago we knew of none, but the fact is that the formation of just about any kind of a star is potentially able to create planetary systems (and dust rings) of a findable type.

Ok - so why don't we discover hot Jupiters around just every star that's looked at, if planet formation is not uncommon? I'd argue that it's precisely because our solar system isn't unique, and many stars might well have systems not unlike ours, that are currently undetectable.

As to "life" I strongly believe it's just chemistry, time and chance; and in those terms our kind of carbon-based life could well start all over the place. The right materials exist throughout our solar system, and we know of liquid water under Europa, in Enceladus, and there's a great chance of liquid brines under Mars, too. Toss in 100 billion stars in the galaxy, and I think we'll ultimately find that living things are ubiquitious. Look at it this way, our universe clearly has the physics, structure and age which make it life-friendly.

Intelligent, communicating life, on the other hand, I think is an extreme rarity - we're the outcome of some stupendously lucky breaks from our single-celled ancestors - and I'd point you to Fermi's Paradox for a likely proof of that rarity.

Andy

Clearly, our technology prior to kepler could, in the main, only detect planets close in to their parent star. Kepler has the ability to detect exo solar systems that match our own and time will tell if results from kepler start to swing the bias toward solar systems like ours. Im still not convinced this will be the case though. That which is easily found tend to be the most common. And planetary systems with HJ's close in are currently the most common. Even now, early in the mission, kepler is returning results of more systems with HJ's although it appears to have spotted smaller terrestrial sized planets even closer to the parent stars.

Therefore, in the time for kepler to positively spot planetary systems like ours, if they do exist, it will have undoubtedly have uncovered many more that aren't leading more weight to the fact that ours is tending towards uniqueness.

I dont disagree with your comments about the chances of intelligent life. I think it will be exceedingly rare in our galaxy. Fermi was correct, where are they all? The rare earth theory proves an insight to this but as I said before, that's another thread.
Logged

dreadnought72

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,898
  • Wood butcher with ten thumbs
  • Location: Airdrie, Scotland
Re: Kepler mission adds more weight to our solar system not being the norm.
« Reply #24 on: September 05, 2010, 04:58:02 pm »

That which is easily found tend to be the most common.

Not at all. If I wanted to do a survey of the UK's population, to determine general statistics of age and gender, and my search parameters only let me look in model boat clubs (for example!), I'd have biased results. As I mentioned earlier, Kepler's results currently have a bias similar to the previous methods of planet detection. Time (i.e. the chance to see longer-period transits) will tell, of course - and the good news is that Kepler's got years of life left in it.

Andy
Logged
Enjoying every minute sailing W9465 Mertensia
Pages: [1] 2 3 4 5   Go Up