If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Bad Astronomy and Universe Today Forum > Universe Today > Astronomy Cast
Register FAQ Members List Calendar Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old 16-November-2007, 03:52 PM
clint's Avatar
clint clint is offline
Senior Member
 
Join Date: Apr 2007
Posts: 433
Default 5 Planets in 55CancriA system

You have probably all heard of the discovery of a fifth planet around 55CancriA:
http://www.jpl.nasa.gov/news/news.cfm?release=2007-128

What confuses me:
How is it possible that 3 (three!!) planets of that size (similar in size to Jupiter, Saturn and Neptune, respectively)
all orbit that star much closer than Mercury does in our system?

Shouldn't they interfere with each others' orbits, making them highly unstable?
Reply With Quote
  #2 (permalink)  
Old 05-December-2007, 09:25 AM
Quarkus Quarkus is offline
Junior Member
 
Join Date: Dec 2007
Location: Verwood, Dorset, UK.
Posts: 12
Smile

Is it possible that we are only seeing a snapshot of a very transient phase in this particular system? Perhaps within a few thousand years the instability of this arrangement will become apparent with, say, two of the planets colliding, or one being absorbed by the star?
Another possibility is that as we look around the universe we find arrangements that throw our notions of sytem 'normality' out the window. For example, perhaps these planets have a synchronised or 'locked' orbit similar to the inner moons of Jupiter....

Questions I would also ask:
- what's the mass of the star? If it's small, perhaps the collected mass of the planets works in some sort of binary way, with the centre of gravity lying between the star and the inner planet, or on the outside edge of the star?

- and, finally, if it really is a highly unstable arrangement, are we 99% sure the data is being interpreted correctly?

This is all just idle speculation, but it's fun eh...! With a bit of luck a professional astronomer (perhaps one from this show) will provide an answer now... :-)
Reply With Quote
  #3 (permalink)  
Old 05-December-2007, 01:20 PM
banquo's_bumble_puppy's Avatar
banquo's_bumble_puppy banquo's_bumble_puppy is offline
Senior Member
 
Join Date: May 2003
Location: Alpha III
Posts: 1,900
Default

I think that there's a flaw in the detection method. I'm betting that in a few years that they'll discover that many of these super-giants that orbit close to there paernt stars are just phantoms?
__________________
The world breaks everyone and afterward many are strong in the broken places. ~ Ernest Hemingway ...
Reply With Quote
  #4 (permalink)  
Old 05-December-2007, 05:25 PM
Ilya's Avatar
Ilya Ilya is offline
Senior Member
 
Join Date: Nov 2001
Location: Boston
Posts: 2,893
Default

Quote:
Originally Posted by banquo's_bumble_puppy View Post
I think that there's a flaw in the detection method. I'm betting that in a few years that they'll discover that many of these super-giants that orbit close to there paernt stars are just phantoms?
Considering that in some of the multiple-planet systems the planets' mutual gravitational influence has been detected, not to mention several of them had been seen transiting the face of their star, I am willing to take on your bet.
__________________
Fiction has to be plausible. Reality is under no such constraint.
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
How Many Star Systems Might Contain Inhabited Planets? filrabat Astronomy 47 25-December-2007 12:46 AM
1 Year Without Pluto - & 12 reasons to reinstate it! Mungascr Astronomy 56 02-September-2007 07:09 PM
Prospective planets in the solar system who are enrich with minerals? suntrack2 Questions and Answers 5 24-September-2006 06:21 PM
There is no Nibiru Zap Against the Mainstream 172 26-February-2003 02:57 AM


All times are GMT. The time now is 10:26 PM.


Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2008, Jelsoft Enterprises Ltd.
LinkBacks Enabled by vBSEO 3.0.0
©  2006 Bad Astronomy and Universe Today