Jump to content

New Planet Found


SoxFan1

Recommended Posts

QUOTE(TheBlackSox8 @ Sep 15, 2006 -> 05:41 PM)
how can they tell this from 450 light years away?

2 datapoints would give you the density; you need the mass of the planet and the size of the planet.

 

The size of the planet is determined by having the planet move between the star it orbits and the Earth. This causes a temporary drop in the light flux from that planet to a telescope, which can be measured and calculated to give you the size.

 

The mass of the planet you can determine by measuring the motion of the star. If there is a planet of sufficient mass orbiting a star, then the star itself will have some motion relative to the center of mass of the 2 objects. As the sun moves around, it will move towards and away from the Earth in a repetitive cycle. The motion of an object relative to the earth is enough to change slightly the spectrum of light coming from the star, an effect known as the Doppler shift.

 

Therefore, if you measure the frequency and amplitude of the systematic variations in the Doppler shift of light coming from a star, you can calculate the mass of the planet causing the sun's motion and its distance from the sun.

 

So if you get a transit and measure the doppler shift, you have both the mass and the volume of the planet, and you can convert to density.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...