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EB's With Significan Spectral Changes (?)

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B.P.Vietje
B.P.Vietje's picture
EB's With Significan Spectral Changes (?)

I've observed a few EB's, mostly to have some "fast moover" data for students to analyze, since they get much more excited when the curve is showing more "action".

Now I have a student who wants to learn photometry, but also spectroscopy.  I'm hoping to ID a few really interesting targets that can be used for both.  Not out of laziness, but to get the most bang for the buck in terms of imaging time, the hours of clear sky available during the winter, and her college schedule.

A perfect target would be visible from Jan - June (say 4h to 12h in RA), and in the northern hemisphere.  If there are some EB's that would show significant spectral changes as one star eclipsed the other, that would be most interesting.

17" f/6.8 with a Star Analyzer in the filter wheel, so we can get good low-rez spectra down to about 12th mag, and reasonable/readable/usable spectra down to 14th - 15th with careful stacking and a magic wand from Olivander's shop on Diagon Alley.

I'll reda up on the EB Zoo, but any good suggestions will be most appreciated -- thanks!

Brad Vietje, VBPA

Newbury, VT

www.nkaf.org

 

bpablo
Hey Brad,

Hey Brad,

I could possibly help you out (I'd have to look at my target list), but can I get a little more info? I do a lot with binary stars, and there are plenty which will show significant movement (doppler shifts), but I have a feeling you are looking for more. Do you want stars where the lines themselves will change significantly as a function of orbital phase (this is a bit harder, but probably doable). Also, what kind of magnitude limit do you have for spectroscopy?

Thanks,

Bert
Staff Astronomer
AAVSO

B.P.Vietje
B.P.Vietje's picture
EB's With Significant Spectral Changes

Hey Bert (seeing Ernie for SOME reason!),

Thanks for your kind offer.  Our resolution is only 11A/px when unbinned, so any line shifts would probably need to be in the 30 - 50 Angstrom range to measure -- pretty big shifts!  I just don;t see us doing any RV measures without a lot more resolution.

We can reach ~14th mag pretty reliably with the Star Analyzer.

I was thinking an interesting pair with two very different star types might show the presence or absence of some broad feature that could be detected with our system?  The most obvious spectral features we can see are probably emission lines from Wolf-Rayet stars, but they tend to be pretty big stars, so probably less likely to be eclipsed by an unseen companion(?)  Maybe an EB pair involving a Be star?

Even if we get a blend of 2 star types that appears to be one distinct type during an eclipse/transit, and then returns to a blended spectrum would be pretty interesting to work on.

If I can get decent spectra of any of the brighter supernovae, they would be excellent targets, and the photometric data could be useful, but an EB could go through its gyrations in a single night, so they would be better if we just can't find enough clear nights.

Thank you kindly,

 

Brad

 

bpablo
Hey Brad,

Hey Brad,

Sorry for not responding back sooner. Wolf Rayet Stars are out. I have played with a lot of them and the secondary is almost always much much smaller and almost indistinguishable in the spectra. Even an O star would barely be noticed. You would need two WR stars and that would show the differences you would want. I would say a Be star binary might be your best bet. However, I am not sure I know of any close Be star binaries, but I can ask around.

Thanks,

Bert

TCB168
TCB168's picture
EB Spectra

Brad

Unfortunately the SA will not give you enough resolution to see the doppler shift.

I have been taking losts of spectra of EB stars as part of my own research. I use a LHIRES with a resolution of R=15000 or about 0.2A/pixel. This works well. I also have a LISA spectrograph with a R=1500 ie 10 fold less. I have not been able to detect a shift consistently with the lower resolution spectrograph. Your SA has a  ~R=300 so much lower still so I don't think that you will find much.

Explore here http://sb9.astro.ulb.ac.be/mainform.cgi

Find a star high in your sky with a short period - up to 2 days and a velocity change of 150 and try.

Terry

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