Rho Cas Activity

[Andrew Smith]

I found the following paper A New outburst of the Yellow Hypergiant Star Rho Cas available here https://arxiv.org/pdf/1611.04493.pdf

I attach its Figure 1 which shows the development of the Fe I and Fe II lines at 6431 and 6433 respectively. I also attach my recent observation which shows it continues to develop.

Figure1 From Aret, Kraus, Kolka and Maravelias

Rho Cas Paper.png (111.73 KiB) Viewed 29692 times

Rho Cas SAJB

rhocas_20171211_861_SAJB.png (15.24 KiB) Viewed 29684 times

While all spectrographs have pros and cons the wide range and medium resolution of my MRes R ~ 10000 allows the following of several sets lines - even unplanned ones!

Regards Andrew

PS Re uploaded my file has I had shifted the spectra the wrong way to remove net RV of star of - 47Km/s

[Olivier GARDE]

HI Andrew,

Interesting study of this star.
I Will try as soon as possible (but actually, the weather is very bad here in south east of France...)

[etienne bertrand]

Ha is interested for this outburst ?

[Andrew Smith]

Hi Etienne, I am not an expert on these stars having only just started to study them. H alpha is studied in these stars but mainly metal lines sensitive to the changing effective temperature.

There is a large literature on Rho Cas and the other bright yellow hypergiants as they suit the smaller observatories and PhD students. I have a pile of papers to read.

It looks like this outburst maybe coming to an end.

Regards Andrew

[Ernst Pollmann]

Dear colleagues,
from 2011 to 2019 the yellow hyper giant rho Cas has been investigated by several ARAS observers.
Are there any unpublished summarises that has been not published in this forum?

Ernst Pollmann

[Ernst Pollmann]

... once again my question:
are there any summaries of the amateur observations relating to the several observations presented here?

Ernst Pollmann

[Ernst Pollmann]

According Klochkova et al. (Astronomy Reports, 2018, vol. 62, No. 9)
“Thus, the ejections in rho Cas are becoming more frequent. According: Astrophys. J, 583.923 and ASP conf. Ser. 508, 357, this may indicate that the star is approaching a crossing of the Yellow Void. This fact suggests the urgent need of further monitoring of rho Cas”
I tried by use spectra of the BAA data base (A. Smith, F. Sims, D. Boyd, J. Paraskeva) to find out something of the Hα radial velocity and the Hα equivalent width during Nov. 2017 to Sept. 2018 (see Fig. below).

The spectra have been evaluated for the Hα absorption and its blue-shifted PCyg-component.
By considering the RV and EW, it seems there has been an ejection within that time section. Both parameter of the Hα absorption seems to be confirmed to each other. Also the RV of the blue-shifted PCyg-component seems to confirm the ejection. Only its EW behavior do not fit to that event. Unfortunately there is a large gap of observations between Jan. to July 2018. If there further spectra of other observers available, it would be nice if I could receive these for further analysis.

Zusammenfassung.png (112.82 KiB) Viewed 26728 times

[Ernst Pollmann]

Newest observation of the star:

Zusammenfassung.png (93.19 KiB) Viewed 26613 times

Ernst Pollmann

[Ernst Pollmann]

For interested observers:

https://www.aavso.org/aavso-alert-notice-746

Ernst Pollmann

[Ernst Pollmann]

After more observation experience in the meantime, the focus of the evaluation of the monitoring has been changed.
Above all, the behavior of the red and blue emission components has now come into focus. In the course of the previous spectra, their flux has clearly increased.

rhocas_Halpha monitoring.png (79.53 KiB) Viewed 25055 times

In addition, the radial velocity of the central Halpha absorption and the blue-shifted P Cygni component are further monitored. It is currently not clear whether the scatter is real or is due to inaccuracies in the wavelength calibration. This will continue to be monitored.

rhocas_Halpha_radial velocity.png (38.61 KiB) Viewed 25055 times

Ernst Pollmann