BF Cygni

Excellent night tonight, with very good seeing (well, for the site; estimated around 3") and sky magnitude (with SQM) around 20.6.

I started with some known friends such as VV Cep and P Cygni and switched to a star of interest at the moment, the primary target scheduled for the coming OHP spectroscopy workshop: BF Cygni. This is a classical symbiotic binary star but the shape of some emission line (H beta for exemple) has the signature of strong jets emitted from the system.

Here is the observatory computer screen copy showing the guiding image, the spectrum (H alpha is very strong), the two CCD control (acquisition camera & guiding camera), the skymap area (around BF Cygni) and the telescope control:

Here is a view inside the dome, telescope pointed toward the target:

And the guiding camera long exposure (Atik Titan, 10sec) to see the field of view around BF Cygni:

BW Vul, a pulsating star

BW Vul is a variable star whose brightness changes every 4h50min. Spectroscopic study such as the one I did last night shows that the atmospheric absorption lines shift over the same period. This is due to the star pulsating radially, same as other beta Cephei - and BW Vul is the largest amplitude beta Cep stars ever observed.

The following graphs shows two spectra taken at different times, around sodium doublet:

 When you look over time, one can see that the two sodium lines are fixed (as well as several other ones). The small ones are absorption lines from our own atmosphere (vapor lines), and are of course stable (ie: no radial velocity) over the 6h observing time. The two sodium are the signature of interstellar sodium material which resides somewhere between us and the star, they are also not changing velocities relative to us.

The large absorption line around 5876 Angstroems is helium in BW Vul atmosphere which first shifts toward the red (ie: toward the right of the graph) as the stellar atmosphere compresses itself... up to a point when it bounces back - and does it twice with line doubling phenomenon, due to shocks inside this atmosphere:

 The following graph shows the evolution of the spectrum (dispersion = horizontal axis) over time (vertical axis, time going up when you go up), one can clearly see the star pulsating over the observing time:

You may notice a small absorption line between the two sodium lines; this is nickel which also moves (as the atmosphere moves) but as the temperature of the BW Vul atmosphere changes due to the compression (density) changing, there are moment when the line is not visible; nickel atoms are always there, but temperature is too high for the transition (ie: absorption) to take place.

BW Vul spectra acquisition (PRISM v10)

Night picture taken during spectra acquisition (see previous blog post)

Observatory by night

Clear night tonight. Full moon is illuminating the dome and the observatory so I took that opportunity to take some shots...

Short observing session

I slept early and set the alarm just after midnight and finally got some clear night... well, at the begining!

First a calibration star hd173648 (airmass 1.2; elevation 56°).

Good results on the calibration (I slightly changed my focus from previous sessions) :
Ordre #31 :  FWHM = 4.31  -  Dispersion = .195 A/pixel  -  R = 8605.3
Ordre #32 :  FWHM = 3.94  -  Dispersion = .188 A/pixel  -  R = 9481.3
Ordre #33 :  FWHM = 3.68  -  Dispersion = .185 A/pixel  -  R = 9981.2
Ordre #34 :  FWHM = 3.52  -  Dispersion = .180 A/pixel  -  R = 10422.7
Ordre #35 :  FWHM = 3.49  -  Dispersion = .175 A/pixel  -  R = 10530.4
Ordre #36 :  FWHM = 3.18  -  Dispersion = .169 A/pixel  -  R = 11587.2
Ordre #37 :  FWHM = 3.38  -  Dispersion = .164 A/pixel  -  R = 10988.6
Ordre #38 :  FWHM = 3.35  -  Dispersion = .160 A/pixel  -  R = 10992.9
Ordre #39 :  FWHM = 3.18  -  Dispersion = .158 A/pixel  -  R = 11444.1
Ordre #40 :  FWHM = 3.41  -  Dispersion = .153 A/pixel  -  R = 10764.6
Ordre #41 :  FWHM = 3.50  -  Dispersion = .148 A/pixel  -  R = 10557.6
Ordre #42 :  FWHM = 3.67  -  Dispersion = .145 A/pixel  -  R = 10011.2
Ordre #43 :  FWHM = 3.17  -  Dispersion = .145 A/pixel  -  R = 11325.5
Ordre #44 :  FWHM = 3.34  -  Dispersion = .140 A/pixel  -  R = 10921.9
Ordre #45 :  FWHM = 3.34  -  Dispersion = .136 A/pixel  -  R = 11009.6
Ordre #46 :  FWHM = 3.40  -  Dispersion = .133 A/pixel  -  R = 10751.2
Ordre #47 :  FWHM = 3.24  -  Dispersion = .129 A/pixel  -  R = 11454.3
Ordre #48 :  FWHM = 3.26  -  Dispersion = .126 A/pixel  -  R = 11359.8
Ordre #49 :  FWHM = 3.60  -  Dispersion = .125 A/pixel  -  R = 10157.6
Ordre #50 :  FWHM = 3.84  -  Dispersion = .123 A/pixel  -  R = 9531.4
Ordre #51 :  FWHM = 4.21  -  Dispersion = .115 A/pixel  -  R = 9063.9
Ordre #52 :  FWHM = 4.86  -  Dispersion = .115 A/pixel  -  R = 7739.0
Ordre #53 :  FWHM = 5.36  -  Dispersion = .113 A/pixel  -  R = 7012.1


Then beta Lyrae for a quick run.

CH Cygni after, but clouds are coming and with the bad seeing of the night, I am loosing lot of flux.

A run on P Cygni (great target) and ups Cyg (Be star) before going to my main target: VV Cep.

Here is a quick profile for 3x2min exposures on VV Cep while other acquisition are progressing:

May 21-22 at OHP - Pulsating Stars workshop

On may 21st (my 50th birthday!) and may 22nd, a french workshop with around 20 participants was organized at Observatory of Haute Provence. Subject was pulsating stars, with a focus on RR Lyrae and technics such as photometry and spectroscopy.

I traveled with Olivier Garde and as pleased to meet again lot of friends sharing the same passion about Astronomy!

Group Picture (T. de France)

Part of the workshop was on design of spectrograph, including fiber fed technics, image slicers, echelle spectroscopy, how to reach R=50000 for large telescopes, etc... Jean-Sebastien Devaux presented SARDINE R~10000 spectrograph and Pierre Valvin the design of echelle spectrograph and the search for higher resolution with R~50000. Olivier Garde showed first result of his echelle R~30000 spectrograph.

Another part was about results achieved so far with a great talk by our moroccan friends Benhida & Sefyani showing the results with their echelle spectrograph and new mount at the Oukaimeden observatory, specifically 40 observing sessions on RR Lyrae.

Benjamin Mauclaire showed also the results of the pro/am campaign on RR Lyrae, showing Halpha emission at phase ~0.91 but also third red shifted Halpha emission at phase ~0.30.

HeI 5875 emission has been clearly observed around phase ~0.91. He I 6678 has also been observed at the same time. There has been discussion if He II 4686 emission around phase ~0.91 was also visible or not - it was not obvious but could be suspected!


I recorded some talks in video - not high quality and some bugs during recording with Open Broadcaster; but it could interest some people and it should be made available through the Pulsating Stars web site:
http://www.pulsating-stars.org/

More information on openware SARDINE spectrograph(s) can be found on the following web site:
http://open-astronomy.org/sardine/


Here are the slidesets in PDF format that you can download (45MB total):
http://thizy.free.fr/Slides/20160521a_Spectrographe-Sardine_Devaux.pdf
http://thizy.free.fr/Slides/20160521b_ConceptionEchelle_Valvin.pdf
http://thizy.free.fr/Slides/20160521c_ESP_Garde.pdf
http://thizy.free.fr/Slides/20160522a_Bilan-campagne-spectrophotometrie_Benhida&DeFrance.pdf
http://thizy.free.fr/Slides/20160522b_Spectroscopie-RRLyr-Maroc_Sefyani&Benhida.pdf
http://thizy.free.fr/Slides/20160522c_Resultats-RRLyr_Mauclaire.pdf
http://thizy.free.fr/Slides/20160522d_Interpretations-of-the-Blazhko-effect_Gillet.pdf
http://thizy.free.fr/Slides/20160522e_Introduction_Polarimetrie_Matthias.pdf

Anyway, it was a great week-end and I was excited to be at this great OHP observatory again, looking for future time there! :-)

ESPRESSO - a new revolutionary spectrograph

On april 11th, I had the great opportunity to visit the Observatory of Geneva and the assembling/testing site for the new very high Radial Velocity accuracy spectrograph: ESPRESSO. Organised by Alexandre Santerne (we just learned he succeeded the exam to be an astronomer at the LAM astronomycal lab in Marseille, France), the visit was led by Francesco Pepe who worked on HAPRS and now his successor - ESPRESSO.

The new facility is impressive and we learned a lot on how professional astronomers and engineers are designing the spectrograph that will search for exo-Earth exoplanets. The spectrograph will be used by one or the four VLT telescopes. More on ESPRESSO can be found there:
https://www.eso.org/sci/facilities/develop/instruments/espresso.html

OK.. let's go for a selfie there... :-)

Francesco presenting the overall ESPRESO goals & design

View from above

The old Geneva observatory dome in a field near-by...

it may become a famous bar place in the future! :-)

Special clothing to get into the clean ESPRESSO integration room

A second selfie for me... :-)

Francesco Pepe and Thierry Lemoult during the tour

The structure inside

Waiting the the camera?

Some first parts in place

Continuous lamp (plasma excited by laser)

Wavelength calibration

Alexandre Santerne & the director of the Geneva Observatory

Pisa

With my wife Rachel, I had a great opportunity to travel to Pisa (Italy) and visit Steve Shore, profesor at the Univeristy of Pisa, and some of his students in Astrophysics. We went through the concept of Astronomical Spectroscopy, spectrograph design & finetuning. We were able to observe one night with the observatory & spectrograph at the top of the roof of the university. The following day, we could talk about data reduction algorithms.

Pisa is also a beautiful city with some very nice place to eat and lot of History. But most importantly, people are so nice!!! :-)

 in Steve Shore's office...

Observing at night

Rachel & I at Donati's square