RR Lyrae

RR Lyrae is a pulsating star. It is the prototype of this "RR Lyrae" class of variable star with short period radial pulsations. It is part of the instability strip on the HR diagram.

There is a group of amateur astronomers who are actively monitoring this star spectroscopically (note that it is also actively monitored photometrically).

Couple of workshop took place at Observatory of Haute Provence (OHP) under the lead of the professional astronomer Denis Gillet with the participation of Philippe Matthias and astronomers from Marrakech & Oukamaiden observatory in the moroccan Atlas mountains.


Here are the video & the slides from april 2013 workshop at OHP:

* Spectroscopy with small telescopes (myself): Viméo (PDF)

* Shock waves (Guillaume Mathias): Viméo (PDF)

* Spectroscopy of variable stars (Philippe Mathias): Viméo (PDF)

* Spectroscopy and pulsating stars (Denis Gillet): Viméo (PDF)

* Principles of spectra data reduction (Benjamin Mauclaire): PDF

* Astronomy at Oukamaiden (Adbelmjid Benhida): Viméo (PDF)

* Spectroscopy with a LISA spectrograph (Thierry Lemoult): Viméo (PDF)

* Understanding the Blazhko effect (Denis Gillet): Viméo (PDF)


See also my previous post on this blog about may 2016 workshop with video and PDF of the talks:
http://observatoire-belle-etoile.blogspot.fr/2016/05/may-21-22-at-ohp-pulsating-stars.html


The group is described in this web site:
http://www.pulsating-stars.org/

On this web site one can see the ephemeris of the events, for exemple with tonight event on top line:

The spectroscopi event tonight was scheduled at photometric phase 0.91, around 25/08/2016T20h54m58s UT, so around 22h55 Legal Time and occurs during 10-20 minutes.

Because of uncertainty and in order to capture before and after the event, it is recommended to start 40 min before the scheduled time, so around 20h15 UT (22h15 TL). I started my observations of RR Lyrae at 19h45 (21h45) so well in advance...

Because the events is short in time (10-20min), I decided to take a continuous serie of 3min exposures. This led to a dynamic around 1500 ADU.


Here is one screen taken during the exposures. It is captured on my main PC at home as I observed remotely! :-)

I took two 3-min spectra and reduced them; dividing them gives a 'flat' curve which I measured the standard deviation giving me a Signal/Noise ratio around 22:

The Halpha is well in emission during the event but the interesting feature is the He I 5876 line which is seen in emission on four 3-min exposures:

HeI 6678 emission seems to be detected on 20h57 UT spectrum but it is very faint:

Nothing concluding at 4686A:

Note that the last three graphs have been done with MatLab and a script that I currently working on: otz_plot.m (it also use another important function called rfitsinfo.m). More to come on this later... But here are the three commands I used in MatLab console to plot those graphs - very convenient to use for me (ie: saves me lot of time!):
otz_plot 6520 6700 0 5 '@pro34-13.fits' -f '@pro34-14.fits' -f '@pro34-15.fits'  -f '@pro34-16.fits' -f '@pro34-17.fits' -f '@pro34-18.fits' -y 6620 6640 -t short -s 0.5 -c kbgrm -d s -p png

otz_plot 5840 5980 0 5 '@pro38-13.fits' -f '@pro38-14.fits' -f '@pro38-15.fits'  -f '@pro38-16.fits' -f '@pro38-17.fits' -f '@pro38-18.fits' -y 5655 5665 -t short -s 0.5 -c kbgrm -d s -p png
 
otz_plot 4680 4710 0 5 '@pro48-13.fits' -f '@pro48-14.fits' -f '@pro48-15.fits'  -f '@pro48-16.fits' -f '@pro48-17.fits' -f '@pro48-18.fits' -y 4685 4695 -t short -s 0.5 -c kbgrm -d s -p png