V711 Tau - a RS CVn star

V711 Tauri is a RS CVn star. It is a binary system with a late evolved chromospherically active star and a main-sequence or sub-giant companion. With a magnitude V=5.64, it is fairly bright and within reach of 0.28m telescope with the echelle instrument. The binary period is 2.8 days.

A key article on this system and why to observe it is there:
https://arxiv.org/abs/astro-ph/0303154

telescope inside the dome with optical fibers

On the night of october 9th, I woke up around 1am to check the sky and it cleared up from cloudy evening. I started acquisition of 10 min exposures, signal seemed ok.

 first spectrum of the serie, quickly reduced in ISIS

The signal went up at the beginning as the star was rsing high in the sky but after few hours I noticed the signal was getting poor - a quick check outisde confirmed that clouds were coming back. Oh well, I got 20 spectra covering around 4 hours of time.

observatory control computer screen shot at the end of the acquisitions

I reduced the 20 spectra together to obtain a high signal-to-noise spectrum but I also looked at the individual spectra over time around Halpha, no significant change nor shift seems to appear (maybe a small shift, to be confirmed).

merged spectrum (over the visual domain)

Halpha (order 34) 

spectrogram over 4 hours (Y axis is time, X axis is wavelength); bright line is H alpha

Olivier Garde observed it on october 3rd and I was able to observe it again night of october 11th.

PRISM control screen at the end of the observing run on V711 Tau on october 11th

with Gemini hand controler & telescope camera also visible

Here is a comparison of those three observations, there are some radial velocities involved due to the binarity of this system (Doppler effect):

and the code in MAtLab using my scripts to obtain this graph (modified for the Y legend & title full text):

otz_plot -600 800 0 1 '_v711tau_20161003_966_34.fit' -f '_v711tau_20161009_987_34.fits' -f '_v711tau_20161011_950_34.fits' -y p 1 2451142.943 2.83774 -w Ha -s 6549 6550 -x RVH -t s 'V711 Tauri (RS CVn star) - Halpha - Olivier Garde & Olivier Thizy' -l Doi -p png

Here is the spectrogram obtained in ISIS with the one from october 9th (on top) as a comparison:

On can see that Halpha emission (but not only) is actually shifting toward the blue during the approximatly 5 hours total exposure. A graph showing the first and last exposure show a shift of about 40km/s in about 5 hours:

This is promising for the future and more observations are required!...