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Symbiotic Star CH Cyg

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18 replies to this topic

#1 old_frankland

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Posted 11 July 2014 - 01:55 AM

CH Cyg is a spectroscopic binary containing a Be type giant star with a decretion disk (circumstellar matter ring thrown off by, and orbiting the Be star) and a late M class giant star. In the spectra you can see evidence of both stars. The red end of the spectra shows primarily the cooler red M7 star with it's TiO bands. The H-alpha emission peak is generated in the decretion disk of the Be star and not representative of the M star. The blue end of the spectra contains mostly emission lines from the B type star and ionized decretion disk. Fascinating mix of early and late type stellar classes.

http://www.lafterhal...-0635ut_001.jpg
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#2 nytecam

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Posted 17 July 2014 - 02:30 PM

Very nice Jim - Be+ M7 unusual :-)

#3 Rich (RLTYS)

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Posted 18 July 2014 - 05:26 AM

A most interesting star that I've been following for years.

Rich (RLTYS)

#4 old_frankland

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Posted 20 July 2014 - 11:11 AM

A most interesting star that I've been following for years.

Rich (RLTYS)


Rich, have you been monitoring for outbursts or variation of CH Cyg visually or photometrically? The Symbiotics look to be an interesting lot.
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#5 Rich (RLTYS)

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Posted 22 July 2014 - 05:32 AM

I've been monitoring CH visually. Over the years I've seen it brighten to almost 5th mag and fade down to 10th mag.

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#6 robin_astro

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Posted 22 July 2014 - 09:10 PM

Hi Jim,

There have been a couple of spectroscopic surveys of CH Cyg in recent years in support of some work being done by Dr Margarita Karovska (Harvard-Smithsonian Center for Astrophysics)

http://www.astrosurf.../surveys/chcyg/
http://www.astrosurf...CHCyg_2013.html

I am sure your spectrum would welcome if you would like to submit it.

Cheers
Robin

#7 BrooksObs

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Posted 28 July 2014 - 09:20 AM

Like Rich, I've been following CH Cygni for a loooong time (about 50 years!). It's always been a favorite and one of those objects that really does absolutely what it wants! I've seen it attain its all-time record brightness (bright enough to be estimated with the unaided eye at a dark-site) in the 1980's, then progressively but irregularly fade to its all-time record low (magnitude ~11) a decade, or so, later. Its spectrum varies even more wildly than its photometric behavior and many attempts at explaining just what's going on with this bizarre object have arisen over the years, only to fall by the wayside.

BrooksObs

#8 Rich (RLTYS)

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Posted 29 July 2014 - 08:36 AM

I remember CH brightening to about mag 5.4 in the late 70's. I continue to observe CH in the hope it will brighten that much again. So far no luck but will keep looking.

Rich (RLTYS)

#9 DHEB

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Posted 12 July 2018 - 02:03 PM

I use this old thread on CH Cyg to spread the message that AAVSO has recently issued an alert on this star as it has started fading fairly abruptly. As it appears in the alert:

 

 

July 3, 2018: The symbiotic variable CH Cyg is undergoing a fade that began on June 25. Multicolor photometry is requested; V and particularly B should take priority over Rc and Ic. Observations made two to three times a week are sufficient; time series observations are not needed. Visual observations are also requested and encouraged. Spectroscopy would be very welcome and appreciated. Coverage should continue throughout the observing season.

 

https://www.aavso.or...lert-notice-639

 

Interestingly, it seems that there has been some rebrightening in the last couple of days:

CH-Cyg_Screenshot.png

 

Northern observers will find CH Cyg at or very close to the zenith these days. It should be easy to find and observe.

 

Happy observing!


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#10 OJS

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Posted 15 July 2018 - 04:09 PM

Thanks for pointing this variable out. I've added it to my list of regulars in Cyg (with SS, RT and U). I got a visual estimate of 7.5 on 7/14 using an AAVSO chart.


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#11 quality guy

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Posted 02 August 2018 - 12:04 PM

Observed CH CYG. last night using V band PEP and measured a mag. 9.521, I am going to observe again tonight. I have never observed it so faint. Plotted on the AAVSO LCG and to my surprise my observation was the only one recently that faint, the AAVSO has issued and alert notice # 639 to monitor the fading of CH CYG. I always plot my observations on LCG (light curve generator) to perform a simple QC check of my observations, quite a surprise about this one from last night.

#12 BrooksObs

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Posted 02 August 2018 - 10:18 PM

Puzzling. I too had a look at CH Cyg yesterday evening (August 2.1 UT), but clouds halted my observing session before I could manage a solid magnitude determination for the star. However...it was certainly around 7.0 in my binoculars .

 

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#13 quality guy

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Posted 03 August 2018 - 01:03 AM

Not puzzling, I made a mistake in the star field and measured the wrong star -my bad. I re-observed CH tonight and confirmed the correct star field and obtained higher numbers, I have removed my data entry for JD 58332 and will enter new data for JD 58333. So call back the hounds, lower the flags and stand down the troops. LOL
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#14 quality guy

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Posted 04 August 2018 - 10:00 PM

The readings from JD 58333 indicate a mag. of 6.805, looking at AAVSO LCG it appears the fading was around JD 58300 at 8.4 mag. My weather was horrible all of July, soooo I just keep on a weekly cadence (weather permitting).

#15 DHEB

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Posted 24 September 2018 - 12:43 PM

CH Cygni has been showing some awesomely strange behavior lately:

 

Cyg-CH.png

 

Keep looking! Who knows what we will see next smile.gif


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#16 BrooksObs

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Posted 02 October 2018 - 03:51 PM

Yup, CH CYG is a fun variable to follow. I've been monitoring its strange fluctuations since about 1965 and seen it as bright as the mid 5's and as faint as the mid 10's, so spanning from naked eye visibility to strictly telescopic in overall range. Following it over the course of a full observing season never fails to disappoint the observer and sometimes can reveal amazingly abrupt changes in brightness in just days. Over the years I've seen this star get moved from one classification to another and I'm still not sure that the professional community has a really good handle on it. It spectrum can be a bit wild, too! Often listed with the Z AND-type stars, its variations are much too rapid to easily be included in that group, the observation of which I am highly familiar with. I note that from time to time it has been relegated to the "Unique" class of variable stars and to my mind I think that such is the most logical and accurate classification for it.

 

BrooksObs


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#17 KMA

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Posted 03 May 2019 - 04:58 AM

CH CYG  latest.jpg

 

A few days of visual observations 

using AAVSO LCG1

best regards

KMA


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#18 Rich (RLTYS)

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Posted 03 May 2019 - 06:29 AM

Yup, CH CYG is a fun variable to follow. I've been monitoring its strange fluctuations since about 1965 and seen it as bright as the mid 5's and as faint as the mid 10's, so spanning from naked eye visibility to strictly telescopic in overall range. Following it over the course of a full observing season never fails to disappoint the observer and sometimes can reveal amazingly abrupt changes in brightness in just days. Over the years I've seen this star get moved from one classification to another and I'm still not sure that the professional community has a really good handle on it. It spectrum can be a bit wild, too! Often listed with the Z AND-type stars, its variations are much too rapid to easily be included in that group, the observation of which I am highly familiar with. I note that from time to time it has been relegated to the "Unique" class of variable stars and to my mind I think that such is the most logical and accurate classification for it.

 

BrooksObs

I remember CH Cyg brightening to about mag 5.5 back in the mid to late 70's. Haven't seen it as bright since.


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#19 DHEB

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Posted 21 August 2019 - 07:04 AM

Back again after the summer (twilight) pause. The saga continues at CH Cyg.

Cyg-CH.png

 

 


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