CH Cygni: still surprizing

[Francois Teyssier]

After a short flare (recorded also by ARAS spectra) CH Cyg is now at a low luminosity.

CHCyg.PNG (53.76 KiB) Viewed 7568 times

Message from Margarita Karovska:
CH Cyg seems to be doing a very interesting things (at least photometrically).
When will be able to continue with the observations?

Spectroscopic monitoring at high cadency is strongly recommended. CH Cyg is now an easy target during mid-night

François

[Francois Teyssier]

Very low luminosity V ~ 8.6
Impressive changes in a few days.

Na I D emission lines are increasing (very low ionization level)

chcyg_1.png (23.01 KiB) Viewed 7527 times

[OIII] region, with He I 5016 and Fe II 5018:

chcyg_2.png (19.52 KiB) Viewed 7527 times

H beta in almost pure emission

chcyg_3.png (17.8 KiB) Viewed 7527 times

Comments from Margarita Karovska:
the interesting thing is that CH Cyg (V and B) its getting fainter (abruptly) and in a relatively short time period; When this happened in the past, it indicated a jet ejection and dimming of the LC by the ejecta/dust in the inner circumbinary environment. So close spectral and photometric monitoring in the next few months would be of a great interest.

Monitoring of the event at high cadency is strongly recommended

François

[Forrest Sims]

Here is my low resolution contribution on CH Cyg from last night using the Shelyak LISA. I have exaggerated the vertical scale. I have attempted to identify the Oxygen, Fe and Nitrogen lines. Do these look correct?

Woody

[Francois Teyssier]

Hi Woody,
Correct, unless high ionization Fe lines.
CH Cyg is a peculiar symbiotic, powered by accretion and temperature of the hot component ~ 50 000 K (only!).
Most of the lines are low ionized lines (allowed and forbidden) such as Fe, Ti, ...
Cheers,
François

[Francois Teyssier]

Hi Woody,
Here's an identification on your spectrum

I used your spectrum of RX Lep to detect the lines which appears at that resolution

More lines could be identified in the range 5000-5500

[Christophe Boussin]

Hello all,

Here is my contribution to the monitoring of CH Cyg.
I obtained the following spectrum the 12th of May at 00 h 03 TU with my Alpy 600 (resolution of 503, JJ = 2458615.5027) and an acquisition time of 27 min :

CH Cyg on May 12th, 2019

_chcyg_20190512_003_Christophe Boussin_3700_7570.png (104.14 KiB) Viewed 7427 times

Just to highlight the effect of the resolution on the detection of spectral lines, here is a comparison of the Forrest Sims spectrum (LISA) of CH Cyg with mine (Alpy).
I indicated the position of the same lines identified by François.

CH Cyg on May 12th and 15th, 2019 (comparison)

CH Cyg on May 12th and 15th, 2019 (comparison, zoom)

Clear skies,

Christophe BOUSSIN

[Christian Buil]

The blue part of CH Cyg spectrum the 15.99/06/2019 at moderate reslolution (UVEX 1200 l/mm) :



Possible significant evolution is I compare to a 16/03/05/2109 spectrum (but a low resolution spectrum, comparison is not easy) :



A tentative for adjust resolution (with caution) :



Christian Buil