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Re: 28 Tau ARAS monitoring

PostPosted: Sun Nov 26, 2017 10:52 am
by James Foster
To: Olivier,

Its mostly because Procyon very bright and well situated in a good part (end) of night. Before I do an IR curve, I take out H2O lines in Ha.

RE:".....you can take for exemple Gam Aur (a B7III)"
Do you mean Beta Tau? Got confused because according to Wikipedia Gam Aur was recently named Beta Tau; see:
https://en.wikipedia.org/wiki/Beta_Tauri

I'll try to use this star next time...........


James

Re: 28 Tau ARAS monitoring

PostPosted: Sun Nov 26, 2017 11:11 am
by Olivier GARDE
Yes you're right, Gam Aur and Bet Tau is the same star :
http://simbad.u-strasbg.fr/simbad/sim-i ... =submit+id

I think it's better to take this kind of star for instrumental response (better to match the continuum).

You spectra are welcome in bess data base and you can upload here (both H beta and H Alpha)
http://basebe.obspm.fr/basebe/

Re: 28 Tau ARAS monitoring

PostPosted: Sun Nov 26, 2017 3:39 pm
by Ernst Pollmann
James,
would you be so friendly to send me your Halpha spectra for monitoring of RV, V/R and EW ?

Ernst

Re: 28 Tau ARAS monitoring

PostPosted: Sun Jan 28, 2018 4:56 pm
by Ernst Pollmann
Dear colleagues,
it seems that the next periastron passage of 28 Tau is coming somewhat earlier than the ephemerides says.
Normaly we should to expect it around February 18th (this year), but current spectra of Alun Halsey and Joan Guarro are showing a quick change of radial velocity as indicator for that event (see attachment).
28tau_RV.png

It would be great, if further observers could dedicate to this event too.
Ernst Pollmann

Re: 28 Tau ARAS monitoring

PostPosted: Mon Jan 29, 2018 4:33 pm
by Olivier GARDE
It seems to have a reversal in the intensity of the V/R peaks in fifteen days.
Image

Re: 28 Tau ARAS monitoring

PostPosted: Mon Jan 29, 2018 6:45 pm
by Ernst Pollmann
... yes, Olivier, this could be an indicator for the periastron passage.
Question is, has this already taken place or not?
Further observations will be required urgently!!

Ernst

Re: 28 Tau ARAS monitoring

PostPosted: Tue Jan 30, 2018 3:22 pm
by Ernst Pollmann
Congratulation Alun Halsey & Olivier Garde !
Obviously you was able to catch the last "very sharp" periastron passage of 28 Tau with the V/R ratio and radial velocity in your spectra.
A really great result which enables to calculate the next periastron passage now with new precisely time reference.
28tau_VtoR.png

28tau_RV1.png

28tau_RV2.png

Ernst Pollmann

Re: 28 Tau ARAS monitoring

PostPosted: Tue Jan 30, 2018 7:46 pm
by Ernst Pollmann
Dear colleagues,
during an observation period of about 6 years, we always observed in the community a synchronous variation of the V/R ratio with the radial velocity RV. Within this period, 10 periastron passages have occurred with an orbital period of 218 days (Nemravova et al., A & A, 2010), of which we can document 6 passages with our observations.
28tau.jpg
28tau.jpg (90.46 KiB) Viewed 2676 times

The observed V/R variation correspond to a deformation of the central absorption core as it also to see in Fig. 6 of Nemravova et al. 2010. This systematic V/R variation during each minimum of radial velocity might confirm new aspects of the structure of the growing disk. Is striking that the V/R period is somewhat smaller (approx. 2 days).
The next periastron passage will take place at the beginning of September this year and should be observable.
Ernst Pollmann

Re: 28 Tau ARAS monitoring

PostPosted: Wed Jan 31, 2018 10:52 pm
by James Foster
I was able to squeeze in spectra observations of 28 Tau (Plenione) in CaK, Hb, & Ha bands with the LhiresIII with 2400 l/mm grating:
CaK:
Image
Hb:
Image
Ha:
Image

I don't see any obvious changes from spectra taken 1 month ago (orbital velocities increasing?)....but I haven't been following this object that long in high resolution.
Ernst (Took these 28 Tau spectra from your request in Spectro-L Yahoo)...let me know if you need the BeSS formatted spectra of these emailed......

James

Re: 28 Tau ARAS monitoring

PostPosted: Thu Feb 01, 2018 1:39 pm
by Ernst Pollmann
James,
yes, please send my your spectrum for evaluation.

Ernst