Could fast orbiting extra-solar planets be the result of orbital decay?

[jmilsom]

<font size="2"><p>I had a funny dream last night. I dreamt I was setting up a new telescope at the South Pole and was looking for extra-solar planets. In the dream I was disappointed in finding yet another super massive gas giant orbiting at high speed close to its parent star. My dream then dwelt on whether this could happen in our own system (perhaps due to massive collision with Jupiter aginst its direction of orbit), and whether it would orbit faster as it neared our sun (like a marble in a parabolic dish).</p><p>So I woke up wondering whether these fast orbiting super gas giants could be the result of orbital decay on a massive scale. I realise that these are the easiest extra-solar planets to detect, but must admit to be being surprised how many we are finding. It seems to be a common solar system configuration.</p><p>So questions:</p><p>Is current thinking that these super massive fast orbiting gas giants have formed in&nbsp;close proximity to their parent stars&nbsp;or perhaps that they are the result of decaying orbits? The latter would seem to be better in explaining the extraorindary speeds with which they orbit their parent stars. i.e do bodies orbit faster as their orbit decays / tightens? (and a side thought, why do we always think about crossing event horizons in straight lines?)</p><p>Have many papers been published yet postulating how these fast orbiting super giants have come to be?</p><p>Also if these are the result of decaying orbits, what could cause this? I understand that common sense says that they can only decay through the influence of gravitational waves and for most systems like our own, this is too weak to have any influence - so in the morning out of my dream world, I realise this is not really possible for our system. Could massive plantary impacts cause this? Are there other forces at work that we can only speculate on?</p><p>One would expect that these tight orbit supergiants will have swept their solar systems clean - could this be a common fate for solar systems?</p></font> <div class="Discussion_UserSignature"> </div>

 

[willpittenger]

Do we have a way to measure the rotational speed of a distant star?&nbsp; If so, we could compare that with the length of the planet's year. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I had a funny dream last night. I dreamt I was setting up a new telescope at the South Pole and was looking for extra-solar planets. In the dream I was disappointed in finding yet another super massive gas giant orbiting at high speed close to its parent star. My dream then dwelt on whether this could happen in our own system (perhaps due to massive collision with Jupiter aginst its direction of orbit), and whether it would orbit faster as it neared our sun (like a marble in a parabolic dish).So I woke up wondering whether these fast orbiting super gas giants could be the result of orbital decay on a massive scale. I realise that these are the easiest extra-solar planets to detect, but must admit to be being surprised how many we are finding. It seems to be a common solar system configuration.So questions:Is current thinking that these super massive fast orbiting gas giants have formed in&nbsp;close proximity to their parent stars&nbsp;or perhaps that they are the result of decaying orbits? The latter would seem to be better in explaining the extraorindary speeds with which they orbit their parent stars. i.e do bodies orbit faster as their orbit decays / tightens? (and a side thought, why do we always think about crossing event horizons in straight lines?)Have many papers been published yet postulating how these fast orbiting super giants have come to be?Also if these are the result of decaying orbits, what could cause this? I understand that common sense says that they can only decay through the influence of gravitational waves and for most systems like our own, this is too weak to have any influence - so in the morning out of my dream world, I realise this is not really possible for our system. Could massive plantary impacts cause this? Are there other forces at work that we can only speculate on?One would expect that these tight orbit supergiants will have swept their solar systems clean - could this be a common fate for solar systems? <br />Posted by jmilsom</DIV><br /><br />I think the consensus is that most of these fast rotators formed further away and orbits decayed as you suspect. The mechanism for the orbital decay is drag induced by gas and dust remaining after the planet formed. The trick is to get the planet to stop before it spirals all the way into the star. I don't recall reading too many papers about it in Science or Nature, there probably are some in some of the other stronomical journals though.</p><p>MW</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[jmilsom]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I think the consensus is that most of these fast rotators formed further away and orbits decayed as you suspect. The mechanism for the orbital decay is drag induced by gas and dust remaining after the planet formed. The trick is to get the planet to stop before it spirals all the way into the star. I don't recall reading too many papers about it in Science or Nature, there probably are some in some of the other stronomical journals though.MW <br />Posted by MeteorWayne</DIV></p><p>Ah. Yes. That makes sense. I'll hunt for some papers. I'm intrigued by this question now!<br /></p> <div class="Discussion_UserSignature"> </div>