[Aavso-photometry] Aavso-photometry Digest, Vol 46, Issue 7

[Laszlo Kiss]

Hi,

> Ref:
> Smith, H, A., "RR Lyrae Stars". Cambridge University Press; New Ed edition
> (September 16, 2004) ISBN-10: 0521548179
>
> Jones, R. V., Carney, B. W., Latham, D. W., "The Baade-Wesselink method and
> the distances to RR Lyrae stars. VI - The field stars RS Bootis, TW
> Herculis, VY Serpentis, and UU Virginis, and the absolute magnitudes of RR
> Lyrae stars".1988ApJ 332, 206.
>
>> I was typing up some notes on the archetype
>> short-period (13 hours) variable RR Lyr.  Assuming
>> that the variable does expand and contract across the
>> period, is there a stellar model estimate or an
>> empirical estimate of how much the diameter of the
>> star changes across its cycle and the velocity at
>> which the star's surface moves? - Kurt
> ***********************************************

In addition to Don's suggestions, I would also recall the
Fokin & Gillet (1997), A&A, 325, 1013 paper, in which both models and 
observations of RR Lyr itself were presented and the real complexity of
atmospheric motions is revealed. The paper is freely available through 
ADS:

http://adsabs.harvard.edu/abs/1997A%26A...325.1013F

A close-match model in Fig. 2 shows about 1 R_sun variation at a mean 
surface value of about 6 R_sun (double the values for diameter).

Cheers,
    Laszlo Kiss