Re: Number of low eccentricity distant planets

Crown-Horned Snorkack wrote:

> On 29 veebr, 22:35, Erik Max Francis <m...@[EMAIL PROTECTED]
> wrote:
>> Crown-Horned Snorkack wrote:
>>> Except that you do not see the velocity - it is fundamentally
>>> impossible to distinguish from overall peculiar motion of the star
>>> itself.
>>> You can only see the acceleration.
>> No, what is seen is the _change_ in velocity of the star due to the
>> orbiting planet.  Change in velocity isn't acceleration; acceleration
is
>> the time rate of change on velocity.
>>
>> The star has some peculiar radial velocity.  You look for changes in
>> that radial velocity for evidence of planets.  The changes center
around
>> the peculiar velocity itself, so you can factor that out.
>>
> Which you cannot do if you do not see the changes over your period of
> observations.

The observable is the instantaneous radial velocity.  It is not the 
acceleration.  What you look for is changes in that radial velocity. 
Those are changes in velocity, not accelerations.

You were "correcting" something that Steve Willner said that was 
perfectly correct; your correction was wrong.

-- 
Erik Max Francis && max@[EMAIL PROTECTED]
 && http://www.alcyone.com/max/
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