pi Aqr V/R and EW monitoring

[jack martin]

Followup observation 2 nights apart.

Any comments ?

Jack

Essex UK

piaqr2nightsapart.JPG (55.5 KiB) Viewed 5283 times

[jack martin]

Here are the differences in 5 H alpha line observations from 20201102 to 20201227.

Jack

Essex UK

piaqr5.JPG (65.09 KiB) Viewed 5283 times

[jack martin]

Further to my previous question, I would like to ask the following in order to better understand the bigger picture;

1. What is the ultimate purpose of this study ? Is it to accurately determine the V/R period of Pi Aqr or is it for another purpose ?

2. The V/R period was 84 days, then it was 42 days and now it appears to be 24 days. Is the period actually getting shorter or is it fact that the data is producing a more accurate period determination ? i.e. is there a real physical change in periodicity, or is just better accuracy of data interpolation ?

3. If there is a dramatic change in periodicity, what is causing this ?

4.The larger star is a main sequence type B1III-IVe. But what is spectral type of the smaller binary companion ?

5. Do we know the masses of the 2 stars ? If so what are they ?

6.What is the distance from one star to the other ? And how far are the stars from the Roche limit ?

Jack

Essex UK

[Ernst Pollmann]

Hi Jack,
in the literature compilation on my website, all of your questions are largely answered:
https://astrospectroscopy.de/Projects See: 4. π Aqrii
It would be idle to reproduce all of this here again.
Only the question about the "real" causes of the V/R period changes (86d> 43d> 24d) cannot be answered seriously at the moment.
But let's wait and see how the expected analysis of spectra taken by Anatoly Miroshnichenko will contribute to an increase in knowledge.

Ernst

[jack martin]

Ernst,

Thank you for the link, I will read all about it.

Wishing you an Happy New Year.

Jack

Essex UK

[Ernst Pollmann]

Dear colleagues,
the comparison of the Fourier analysis of Prof. Dr. Anatoly Miroshnichenko to my analysis of the V/R data before the increase (JD 2453280) and after them did yield almost a perfect accordance (see attachment).

The recent data (JD 2459057 to JD 2459227) don´t show such a strong peak in the power spectrum and the phase curve for the 42-day period is not as good. This is probably partially due to the 84.3-day orbital period and a lack of data, because this data set covers only 150 days which is not even 2 orbital periods.

Anatoly commented:
we need more time coverage before making any conclusions. I think that as the disk becomes larger and accumulates more matter, its structure may change and we may see a single-peak Halpha profile in the nearest future. This kind of profile was observed in the spectrum of Pi Aqr in the 1980's (K. Gosh_1988, A&AS) when the Halpha line EW was about 40 A.
It is questionable whether we get a seccond opportunity to observe such a V/R event again.
Unfortunately the observation season of the star is almost finished, so there is no chance to observe further the 42 day period.

summary 28.1.21 (84 Tage Periode).png (222.79 KiB) Viewed 4972 times

summary 28.1.21 (40 Tage Periode).png (162.74 KiB) Viewed 4972 times

Ernst

[Ernst Pollmann]

It is well known that most Be stars are photometric long-term variables, and that at least two characteristic behaviours can be recognized when simultaneous photometry and optical spectroscopy are available: positive and inverse (negative) correlation between the Balmer emission strengths and the stellar brightness (Harmanec, 1983). Indeed, a positive correlation has been observed in several Be stars as their Hα emission gets stronger when their photometric V magnitude increases:

Harmanec, P., 1983, Hvar Observatory Bulletin, 7, 55
Juza, K., et al, Astrononmy and Astrophysics Suppl., Vol. 107, p.403-411 (1994)
Koubsky et al., Astronomy and Astrophysics, v.328, p.551-564 (1997)
http://www.bav-astro.de/rb/rb2011-1/5.pdf
http://www.bav-astro.de/rb/rb2014-2/89.pdf
http://www.bav-astro.de/rb/rb2012-1/20.pdf
https://konkoly.hu/pub/ibvs/6101/6109.pdf

Obviously this is also applicable for pi Aqr. The attached plot (top) shows the Hα EW developement from JD 2456868 (2014/07/29). The plot bottom shows simultaneous V data (AAVSO data base) versus Hα EW (BeSS spectra) from Oct. 2014 to Oct. 2021.

Vmag versus Halpha EW.png (86.38 KiB) Viewed 3342 times

The current visibility of pi Aqr invites to take spectra in order to complete the correlation.
Ernst Pollmann

[James Foster]

To: Ernst,

This is great work! When I have my eShel fully operational, I'll take spectra and concurrent photometry with my ST-8xe.

James

[Ernst Pollmann]

Hi James,
that would be a welcome input to our monitoring.

Ernst