Re: [Phys-l] stellar distance measurement

[Mark Sylvester <mark.sylvester@spin.it>]

That's very cool about measuring the diameter of Antares directly. How 
does the interferometry work? The optical path changes across the 
disk... how is the interference observed?

John Denker wrote:
> On 05/20/2009 06:31 AM, mark.sylvester@spin.it wrote:
>   
> > How is the distance to a star like Antares measured? It's too far for
> > trigonometrical parallax and not being a main sequence star is not a
> > candidate for spectroscopic parallax... so how is it done?
> >     
>
> 1) Parallax works.
>
> The Hipparcos astrometry satellite is good to 10% at 100 pc
>    http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit1/distances.html
>
>
> 2) Antares is so big and so close that its diameter (!) can be
>  measured by interferometry or occultation.  If you know the 
>  diameter you don't need the HR diagram to get absolute brightness
>  from color;  all you need is the black-body law.
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