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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-1828
DTSTART:20100420T203000Z
DTEND:20100420T220000Z
DTSTAMP:20260506T161457Z
LAST-MODIFIED:20100412T145539Z
LOCATION:3425 Sterling Hall
SUMMARY:Modeling surface velocity fields from tidal interactions: the 
 one-layer approximation\, Astronomy Colloquium\, Gloria Konigsberger\,
  UNAM
DESCRIPTION:Binary stars in eccentric orbits are the clearest example 
 of stars whose equatorial rotation velocity is not synchronized with  
 orbital motion. Under these conditions\,  the surface  velocity field 
 is perturbed from its purely rotational nature\, thus modifying the sh
 ape of the  observationally-detectable photospheric absorption lines o
 n a variety of timescales.   Absorption lines are used to derive basic
  stellar  parameters<br>
\nand to gain a better physical understanding
  of  stars.  Although their variability is often interpreted in terms 
 of non-radial pulsation theory\, it is important to understand the nat
 ure of the surface velocity fields that are induced by the tidal inter
 actions alone\, especially under conditions of rapid rotation and  lar
 ge orbital eccentricity where the perturbations can become highly non-
 linear. We use a time-marching numerical calculation from first princi
 ples to compute the surface velocity field due to the tidal interactio
 n  (Moreno &amp\;amp\;amp\; Koenigsberger 1999\; Toledano et al. 2007)
 .  This velocity field is then projected along the line-of-sight to th
 e observer to predict the orbital phase-dependent line-profile variabi
 lity (Moreno et al. 2005). In this talk\, the general characteristics 
 of our model will be described  and we'll discuss its predictions for 
 synchronization timescales in very eccentric binaries. In addition\, w
 e will show that the general characteristics of the theoretical photos
 pheric line-profiles compare favorably with observational data of the 
 short-period B-type binary system Spica (Harrington et al. 2009).  It 
 is interesting to note that because tidal flows are associated with  v
 iscous shear energy dissipation\, the atmospheric structure of an asyn
 chronously rotating binary star could differ significantly from that o
 f a single star.<br>
\n
URL:https://www.physics.wisc.edu/events/?id=1828
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