Rho Cas Activity

[Christophe Boussin]

Hello all,

Here is my contribution to this very interesting monitoring of the Rho Cas activity.

I obtained previously a high resolution spectrum around the Halpha line of Rho Cas on July 8 at 1 h 20 TU (resolution of 17942, JJ = 2459403.5552, 6 x 600s) and recently two new spectra on October 19 at 20 h 19 TU (resolution of 19325, JJ = 2459507.3467, 7 x 600s), and on October 27 at 18 h 35 TU (resolution of 18778, JJ = 2459515.435, 6 x 600s) with my LHIRES III (grating of 2400 lines / mm).

Here is the comparison between these three spectra (the positions of the telluric lines are indicated using the PlotSpectra software) :

Spectral domain around the Halpha line of Rho Cas on July 8th and October 19th and 27th 2021

As reported by Ernst Pollmann in the previous post, the profile of Rho Cas Halpha line has clearly evolved in recent months. This evolution is well visible between my spectra of July 8 and October 19 but I don't notice any significant change between those of October 19 and 27.

Here is a more detailed view around the Halpha line of Rho Cas :

Spectral domain around the Halpha line of Rho Cas on July 8th and October 19th and 27th 2021 (zoom)

rhocas_20210708_20211027_Halpha_zoom_Christophe Boussin.png (23.82 KiB) Viewed 14743 times

Please note that the spectra are not corrected for heliocentric radial velocity (according to the ISIS software, the values are as follows : 17.880 km/s on July 8 ; 1.408 km/s on October 19 (the movement of the Earth brings us closer to Rho Cas for these 2 dates) and -1.192 km/s on October 27 (the movement of the Earth takes us away from Rho Cas for this last date).

Zero velocity is on Halpha 6562.801 A at rest, and, according to Klochkova et al. (2014), https://arxiv.org/pdf/1312.6922v1.pdf, the systemic velocity is −47 km/s (which means here that Rho Cas and the Sun are moving towards each other) and due to low amplitude pulsations of the atmospheric layers near the photosphere, the radial velocity varies with an amplitude of about 7 km/s around this value.

Clear skies to all !!

Christophe BOUSSIN

[Ernst Pollmann]

Monitoring of the ejection behavior of Rho Cas; Line flux and radial velocity of the Hα double peak emission

Our previous observation efforts to describe scientifically relevant radial velocities and emission fluxes in the Hα range do not seem to me from today's point of view and especially in view of our previous monitoring, to correspond to the research goals of professional astronomy.
According to Klochkova et al. we have also concentrated on the ejection process in the Hα range, because photospherical ejections are evidently particularly easy to detect in this spectral range. As before, our main focus is therefore still on the intensity behavior of the blue- and red-shifted Hα emissions, but now is supplemented by their radial velocity behavior (RV), which is why all the spectra provided by all observers involved in the Hα emission line profile have been re-evaluated. See:

https://astrospectroscopy.de/.cm4all/up ... 7db86c476b

Ernst Pollmann

[Ernst Pollmann]

Dear colleagues,
our rho Cas monitoring, particularly the behavior of the red emission component seems to reveal as monthly average time behavior a cyclical variability of its radial velocity with a period of 216 days (see the attached plot).
If I am informed right, such a cyclical property of the radial velocity of the red emission component has been unknow so far.
Against that background it makes sense to continue the observations of the star.
Ernst Pollmann

Radial-Velocity Red Emission.png (142.03 KiB) Viewed 14088 times

[Joan Guarro Flo]

Hallo Ernst,

I'm stopped due at bad weather..

Cheers, Joan.

[Robin Leadbeater]

Where can I find the spectra of Rho Cas please? I can see the ones in the BAA database but there are none in the ARAS database so there must be more I think

Thanks
Robin

[Ernst Pollmann]

... at the AAVSO data base:

https://app.aavso.org/avspec/search

Ernst

[Robin Leadbeater]

... at the AAVSO data base:

https://app.aavso.org/avspec/search

Ernst

Thanks