Snow at McDonald Observatory

Todd Watson and the 82 inch telescope at McDonald Observatory

Target Stars Summary

Here's a quick summary of our target stars:

1)  HS0507+0434B has proven to be very much like EC14012-1446 and GD358.  We 
have identified multiplets associated with several of the modes, plus we have 
seen power grow as we have been observing:)  Take a look at the figure in the
blog. You can see how HS0507 has evolved during the run.
2) HL Tau 76 is always interesting.  Here we are seeing a wide range of 
pulsation frequencies - from 900 to 2500 microHz, some of which are 
multiplets. Some of these "modes" appear to comprise a series that is 
equally spaced in frequency, which is very interesting.  Many of these
frequencies also appear in Dolez 2005.  Of course, we also find 
numerous combination frequencies. Take a look at the web page under 
"Interesting Plots" to see the latest.  
3)G132-12 - this beginning of night target was chosen because of its 
temperature (reported as 12,800 K) and the fact that it only has one mode of 
pulsation (very low amplitude).  The idea is to gather enough cycles 
(period is about 212 s) to create a pulse shape which we can then use for 
convective light curve fitting.  Many of you might remember the figure 
from the EC14012 paper that shows our latest empirical relation.  We 
definitely need more hot stars, as G117-B15A is currently our only example.  
With the addition of WHT, Hawaii, and KPNO data, G132-12 has proven to be 
interesting.  Its pulsation mode is a multiplet with a splitting of 
around 4.1 microHz.  It may be an l=2 mode, but that is unclear. Of 
course, more data is needed:)
4)EC04207 - We have a beautiful FT of this star, thanks to contributions from 
Mt. John, SAAO, Prompt, and SOAR.  This is a large amplitude DB pulsator 
dominated by a single mode that is surprisingly stable. We are working 
towards an eventual pdot measurement.
5) EC05221 - very little is known about this fairly new DBV.  We now know
that it is the DB example of a type of white dwarf pulsator we like to call
the "soft and squishy" stars.  As we add more data to this star's light 
curve, the amplitudes in the FT continue to decrease.  This is a sign
of instability/amplitude modulation.  This star is very similar to R808
and G38-29.

Watch the Night Sky

Webcam at McDonald Observatory

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Greetings from Hawaii from Judi Provencal