28 Tau ARAS monitoring

[Ernst Pollmann]

James,
all the evaluated parameter, RV, V/R, CA and EW in your spectrum fits perfectly into the corresponding monitorings.
Thanks!

Ernst

[Ernst Pollmann]

Dear colleagues,
I want to remind at the periastron passage of 28 Tau on November 13th this year. Halpha spectra are urgend required.

Ernst Pollmann

[Ernst Pollmann]

Dear colleagues,
the so far high cadence of spectra enables very well the determination of the exact time of the last periastron (important to determine the orbital period of the companion). Thanks a lot to all the colleagues who contributed so far!!
But in order to evaluate the total character of the periastron passage with parameter EW, V/R, RV and CA (= central absorption core) of the Halpha line profile, further spectra are urgently required.
Please try it, if it is possible ...

Ernst Pollmann

[James Foster]

Hope you got the 28 Tau data I submitted to BeSS!

James

[Ernst Pollmann]

Yes, James, I used all your BeSS spectra for the monitoring.

Ernst

[Ernst Pollmann]

Dear colleagues,
I want to introduce results of the extraordinary successful ARAS periastron passage campaign of 28 Tau from November 2019 to February 2020.
Here the link the the report:

https://www.astrospectroscopy.de/.cm4al ... 8020&cdp=a

Ernst Pollmann

[Ernst Pollmann]

The observation period of 28 Tau has began.
A wonderful opportunity to complement our monitorings of the central depth (1), EW (2), radial velocity (3) and V/R (4) of Halpha.

conclusion_25.9.20.png (179.72 KiB) Viewed 20190 times

Ernst Pollmann

[Ernst Pollmann]

Dear colleagues,
don´t forget to observe the next periastron passage on February 1th 2021!!
This time there are very good opportunities to observe totally the rise and the descent of the parameters EW, V/R, RV and CA.

Ernst Pollmann

[Ernst Pollmann]

Dear colleagues,
don´t forget to observe the next periastron passage on February 1th 2021!!
This time there are very good opportunities to observe totally the rise and the descent of the parameters EW, V/R, RV and CA.
Attached you can see the current state of observations.

Ernst Pollmann

[J Labadie Bartz]

Hi Ernst,

I'm looking ahead at interesting Be star targets that are being observed by TESS over the next ~1.5 years. 28 Tau ( = Pleione) is one of them- it is being observed by TESS for three months between 2021-Aug-20 - 2021-Nov-06. I believe this window also includes a periastron passage. Going by the ephemeris published in BLANK (...actually I can't find the paper now... will update when found), there is a periastron passage very late in August 2021

Ernst, do you expect periastron on/near this time?

Pleione (and the other bright members of the Pleiades) was observed by K2, as shown in the Fig. below (from White et al. 2017; 2017MNRAS.471.2882W). Pleione has photometric signals similar to other Be stars of relatively late spectral type (probably mostly SPB pulsation).

However, I think the TESS data will be even more interesting, especially if the September 2021 periastron is well observed with spectroscopy. For the K2 data, it was extracted and processed in a way that removed low frequency signals, so it got rid of any signals that may arise from tidal changes in the disk (like probably what causes the observed spectroscopic behavior). The TESS data can be processed more carefully to keep these longer-term signals intact. Especially since Pleione is in a shell phase, tidally-induced disk variability near periastron, should, I expect, cause photometric variability.

This next plot shows data from Halpha on BeSS over the past few years (similar to Ernst's plots), and the shaded rectangles show the TESS observing window (but propagated back in time according to orbital phase). The point is, the shaded rectangle shows the sort of spectroscopic activity that will probably happen during TESS observing. The horizontal black bar shows the orbital phase that K2 observed.

Pleione_Pleione_H-alpha_2.png (124.13 KiB) Viewed 19130 times

Also, I am very many years late to the party for 28 Tau, but is it perhaps interesting that in the plot of V/R, there seems to be 'extra' structure shortly after periastron? I mean that there seems to be a first quick spike (like near 8800 in my plot) on top of the bigger and slightly slower signal. I must caution that I haven't looked at the data very closely.

-Jon