Stage Spectro - OHP 2016
Posted: Tue Jul 26, 2016 11:05 pm
Hello,
the OHP spectroscopy workshop will take place on august 9th to 14th of 2016. The workshop is already a success with a lot of attendies including astrophysics students and new comers.
Here is a list of possible interesting targets that we sent to the attendies; but I felt it would be nice for those not attending to have the list and maybe try some of those from home... so here it is! Thank you for François Teyssier & Steve Shore for participating to this target list.
BEGINERS
If you are starting in spectroscopy, make sure to get a copy of Richard Walker spectroscopy atlas (specially the section 33 : spectral classes of important stars ; and section 35 : bright nebulae sorted by excitation classes) :
http://www.ursusmajor.ch/downloads/spec ... nglish.pdf
and a copy of François Teyssier «low resolution spectroscopy observer's guide » :
http://www.astronomie-amateur.fr/Docume ... ion_En.pdf
Look also at Richard Gray atlas :
https://ned.ipac.caltech.edu/level5/Gra ... tents.html
For stellar classification, concentrate on the blue part of the spectrum to see the Ca II and Na I lines (ie : 3800-6000A). This is ideal for low resolution.
In general, WR stars are ideal for showing what you can do with lower resolutions:
V444 Cyg, WN-Wolf-Rayet star (binary) with LOTS of history and easy and well placed (V<9). CQ Cep: as a comparison with V444 Cyg, about the same magnitude.
OHP 2016 - MAIN TARGET
Our top target for this year will be BF Cygni, a ~mag 10 symbiotic star which currently shows some jets.
See : http://www.spectro-aras.com/forum/viewt ... f=5&t=1466
EXERCISES
Spectral calibration in intensity, even in relative spectroscopy, is critical in low resolution. A good exercise is to observe a standard star as it rises and sets, one spectrum every hour, to obtain the transmission curve with wavelength *and* see what Rayleigh scattering really means (with a single star and standard star the absolute variations don't matter).
Also, use ESO standards :
http://www.eso.org/sci/observing/tools/ ... ectra.html
Cross calibrate a couple of those standards (using one to recover the other and then compare with the atlases) to check your data reduction method.
With spectrograph where you can easily remove the mirror slit, take a spectrum with the slit and one without inorder to compare the flux. Measure the total flux per column and calculate how much you loose at slit entrance (seeing, guiding and telescope optical quality).
OTHER INTERESTING (PRO/AM) TARGETS
Look for active stars with variable spectra, and stars to watch change in the source of a week's observation: RS CVn stars (active chromospheres, detached or semi-detached binaries) -- for these stars, the Ca II H,K lines arer the key observation, the rest of the spectrum is almost invariant: Z Her, RS CVn, lam And… del Cep is also important because it's a standard and you should will see variations in a few nights; 89 Her and UU Her are neat supergiant freaks and not too faint. The active sigma CrB can be observed too.
For the end of the night, WZ Cas, one of the best C stars in the sky, for low res.
For any active stars, the Ca II H and K are the most important lines, but anyone who can get the Ca II lines at 8664A would see a new world.
Spectrum variables, where the stars are strongly magnetic and there are line variations (absorption) over the rotational period. This is a good way to see how things change spectrophotometrically, and there has been very little work on that at moderate-high cadence: alpha2 CVn (12 53 41.49 +38 35 16.9), beta CrB (perhaps not as interesting but an old friend), eps UMa; alpha And (subtle)
Observation of a standard star: eta UMa. This is a very good one to practice on, it's the UV standard and also important for optical calibrations so one to use to practice calibrations. Of course, there's always Vega and 108Vir (an equatorial standard), A good exercise is cross calibration of several of these.
Take spectra of several pecular stars: alpha Sco (Antares), eta Aql…
* P Cygni : a really interesting star ; in high resolution try to mame an atlkas of all the lines and compare with lower resolution spectra…
* alpha Cyg: this is to provide comparisons of giant spectra, and a comparison with alpha Lyr to drive home how an A star illustrates luminosity class, it also emphasizes spectral classes.
* a spectrum of bet CrB would also be a very good idea since that's well placed and bright and also show an A-preculiar spectrum
* one interesting star, worth trying at high resolution with an echelle, is lambda Boo. This is an A Star (a true freak, one that isn't at all well understood and the prototype of a class). Even at low resolution it's interesting.
U Cep: eclipsing binary, since I mentioned it in the last issue, it's one of the better Algol-type systems available and if we time it right it should be possible to see the Rossiter-McLaughlin effect (see the latest ARAS newsletter No 5). For active binaries, WW Dra and Z Her are good targets.
Symbotics of importance: AG Dra (always, high velocity star as well), CH Cyg, one to try V1329 Cyg = HBV 475 (faint, use low resolution, but very very interesting and very high excitation), EG And (also an eclipsing system), V1016 Cyg (compare with a spectrum of a nebula) – see Francois Teyssier detailed list.
Cataclysmics : SS Cyg a dwarf nova prototype, to compare with U Gem in the winter; see latest ARAS newsletter for more targets and current brightness.
zeta Aur types: 31 Cyg, 32 Cyg
* eps Aur : for very late birds, just before sunrise)
* VV Cep : a must do, one to follow, ; use broad coverage even if nothing seems to be happening ; long awaited eclipse is approaching !
novae: low resolution to medium,. broad coverage, on any you feel like doing! For old novae, it would be worth a try to get (low resolution, slits wide open, broad coverage) HR Del, V339 Del (faint), DQ Her; if you try any of these, be sure to take multiple shorter spectra and co-add. They're faint and you'll see mainly the peaks of the strongest emission ([OIII] usually).
Look at symbiotic nova HM Sge whic is nice at the moment.
Planetaries: Cat's eye nebulae (NGC6543, 151 years after Sir William Huggins !), NGC 7027, M 97 an comparisons with H II regions and supernovae (remember, M1 -- the Crab -- will be visible in the winter for comparison).
Look at ARAS newsletter N°2 of 2015 and Françoys Teyssier web for how to measure & calculate electronic temperatures and densities.
Look at some bright Be stars :
* beta Lyr: take one spectrum each night ; it shows what different parts of the spectrum show you about a system. Compare spectra of beta Lyr and and W Ser, the latter is still high enough (dec=-15 but that's not terrible).
* delta Sco and gamma Cas. Do *time series* with one or two spectra per night. Try to cooperate between different observing posts (say one in Hbeta, another in Halpha, another in He I 5876).
RR Lyr: this would be ideal to follow at different resolutions, each group taking spectra every hour. In two nights it will be possible to reconstruct the changes in profiles and radial velocities.
BW Vul : a period of less than 5h. Continuously acquire spectra every 2 to 3 minutes, and built the 2D time spectrogram and the animation showing pulsations and shocks.
Missing ideas ? Look at any Be stars ; check latest Be star newsletter (on ARAS web site) and look for targets on ARASBeAm web site :
http://arasbeam.free.fr/
Look also at ARAS web site, forum (well, this is where you are!) & database for ideas & latest news :
http://www.astrosurf.com/aras/
http://www.spectro-aras.com/forum/
http://www.astrosurf.com/aras/Aras_Data ... taBase.htm
Cordialement,
Olivier Thizy
the OHP spectroscopy workshop will take place on august 9th to 14th of 2016. The workshop is already a success with a lot of attendies including astrophysics students and new comers.
Here is a list of possible interesting targets that we sent to the attendies; but I felt it would be nice for those not attending to have the list and maybe try some of those from home... so here it is! Thank you for François Teyssier & Steve Shore for participating to this target list.
BEGINERS
If you are starting in spectroscopy, make sure to get a copy of Richard Walker spectroscopy atlas (specially the section 33 : spectral classes of important stars ; and section 35 : bright nebulae sorted by excitation classes) :
http://www.ursusmajor.ch/downloads/spec ... nglish.pdf
and a copy of François Teyssier «low resolution spectroscopy observer's guide » :
http://www.astronomie-amateur.fr/Docume ... ion_En.pdf
Look also at Richard Gray atlas :
https://ned.ipac.caltech.edu/level5/Gra ... tents.html
For stellar classification, concentrate on the blue part of the spectrum to see the Ca II and Na I lines (ie : 3800-6000A). This is ideal for low resolution.
In general, WR stars are ideal for showing what you can do with lower resolutions:
V444 Cyg, WN-Wolf-Rayet star (binary) with LOTS of history and easy and well placed (V<9). CQ Cep: as a comparison with V444 Cyg, about the same magnitude.
OHP 2016 - MAIN TARGET
Our top target for this year will be BF Cygni, a ~mag 10 symbiotic star which currently shows some jets.
See : http://www.spectro-aras.com/forum/viewt ... f=5&t=1466
EXERCISES
Spectral calibration in intensity, even in relative spectroscopy, is critical in low resolution. A good exercise is to observe a standard star as it rises and sets, one spectrum every hour, to obtain the transmission curve with wavelength *and* see what Rayleigh scattering really means (with a single star and standard star the absolute variations don't matter).
Also, use ESO standards :
http://www.eso.org/sci/observing/tools/ ... ectra.html
Cross calibrate a couple of those standards (using one to recover the other and then compare with the atlases) to check your data reduction method.
With spectrograph where you can easily remove the mirror slit, take a spectrum with the slit and one without inorder to compare the flux. Measure the total flux per column and calculate how much you loose at slit entrance (seeing, guiding and telescope optical quality).
OTHER INTERESTING (PRO/AM) TARGETS
Look for active stars with variable spectra, and stars to watch change in the source of a week's observation: RS CVn stars (active chromospheres, detached or semi-detached binaries) -- for these stars, the Ca II H,K lines arer the key observation, the rest of the spectrum is almost invariant: Z Her, RS CVn, lam And… del Cep is also important because it's a standard and you should will see variations in a few nights; 89 Her and UU Her are neat supergiant freaks and not too faint. The active sigma CrB can be observed too.
For the end of the night, WZ Cas, one of the best C stars in the sky, for low res.
For any active stars, the Ca II H and K are the most important lines, but anyone who can get the Ca II lines at 8664A would see a new world.
Spectrum variables, where the stars are strongly magnetic and there are line variations (absorption) over the rotational period. This is a good way to see how things change spectrophotometrically, and there has been very little work on that at moderate-high cadence: alpha2 CVn (12 53 41.49 +38 35 16.9), beta CrB (perhaps not as interesting but an old friend), eps UMa; alpha And (subtle)
Observation of a standard star: eta UMa. This is a very good one to practice on, it's the UV standard and also important for optical calibrations so one to use to practice calibrations. Of course, there's always Vega and 108Vir (an equatorial standard), A good exercise is cross calibration of several of these.
Take spectra of several pecular stars: alpha Sco (Antares), eta Aql…
* P Cygni : a really interesting star ; in high resolution try to mame an atlkas of all the lines and compare with lower resolution spectra…
* alpha Cyg: this is to provide comparisons of giant spectra, and a comparison with alpha Lyr to drive home how an A star illustrates luminosity class, it also emphasizes spectral classes.
* a spectrum of bet CrB would also be a very good idea since that's well placed and bright and also show an A-preculiar spectrum
* one interesting star, worth trying at high resolution with an echelle, is lambda Boo. This is an A Star (a true freak, one that isn't at all well understood and the prototype of a class). Even at low resolution it's interesting.
U Cep: eclipsing binary, since I mentioned it in the last issue, it's one of the better Algol-type systems available and if we time it right it should be possible to see the Rossiter-McLaughlin effect (see the latest ARAS newsletter No 5). For active binaries, WW Dra and Z Her are good targets.
Symbotics of importance: AG Dra (always, high velocity star as well), CH Cyg, one to try V1329 Cyg = HBV 475 (faint, use low resolution, but very very interesting and very high excitation), EG And (also an eclipsing system), V1016 Cyg (compare with a spectrum of a nebula) – see Francois Teyssier detailed list.
Cataclysmics : SS Cyg a dwarf nova prototype, to compare with U Gem in the winter; see latest ARAS newsletter for more targets and current brightness.
zeta Aur types: 31 Cyg, 32 Cyg
* eps Aur : for very late birds, just before sunrise)
* VV Cep : a must do, one to follow, ; use broad coverage even if nothing seems to be happening ; long awaited eclipse is approaching !
novae: low resolution to medium,. broad coverage, on any you feel like doing! For old novae, it would be worth a try to get (low resolution, slits wide open, broad coverage) HR Del, V339 Del (faint), DQ Her; if you try any of these, be sure to take multiple shorter spectra and co-add. They're faint and you'll see mainly the peaks of the strongest emission ([OIII] usually).
Look at symbiotic nova HM Sge whic is nice at the moment.
Planetaries: Cat's eye nebulae (NGC6543, 151 years after Sir William Huggins !), NGC 7027, M 97 an comparisons with H II regions and supernovae (remember, M1 -- the Crab -- will be visible in the winter for comparison).
Look at ARAS newsletter N°2 of 2015 and Françoys Teyssier web for how to measure & calculate electronic temperatures and densities.
Look at some bright Be stars :
* beta Lyr: take one spectrum each night ; it shows what different parts of the spectrum show you about a system. Compare spectra of beta Lyr and and W Ser, the latter is still high enough (dec=-15 but that's not terrible).
* delta Sco and gamma Cas. Do *time series* with one or two spectra per night. Try to cooperate between different observing posts (say one in Hbeta, another in Halpha, another in He I 5876).
RR Lyr: this would be ideal to follow at different resolutions, each group taking spectra every hour. In two nights it will be possible to reconstruct the changes in profiles and radial velocities.
BW Vul : a period of less than 5h. Continuously acquire spectra every 2 to 3 minutes, and built the 2D time spectrogram and the animation showing pulsations and shocks.
Missing ideas ? Look at any Be stars ; check latest Be star newsletter (on ARAS web site) and look for targets on ARASBeAm web site :
http://arasbeam.free.fr/
Look also at ARAS web site, forum (well, this is where you are!) & database for ideas & latest news :
http://www.astrosurf.com/aras/
http://www.spectro-aras.com/forum/
http://www.astrosurf.com/aras/Aras_Data ... taBase.htm
Cordialement,
Olivier Thizy