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Carbon Stars

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#26 Chris K

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Posted 26 September 2020 - 09:22 AM

Hey gang, my curiosity about Spectral Class and the cryptic codes they have led me to find this late last night.

 

Check it out:  https://www.cfa.harv...htmls/note.html

 

Hope it helps... enjoy.

 

Chris


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#27 flt158

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Posted 26 September 2020 - 09:38 AM

Thank you, Chris. 

It's always good to be reminded about spectral classes, luminosities and  peculiarities- especially for new beginners. 

 

Clear skies, 

 

Aubrey. 



#28 KMAO

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Posted 27 September 2020 - 09:11 AM

Hi Aubrey

interestingly

RASC list for RV Cyg

lists  magnitude 7.8 - 8.4.

Checking aavso LCG1

it does have indeed rather low amplitude....

Typo ?

 

Best regards

KMA


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#29 hambone20

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Posted 10 November 2020 - 11:49 PM

Just wanted to report here that I've observed v aquilae a few times since that origninal observation and I now see more orange in it.  Not just red.  Maybe there is a learning curve to color identification.


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#30 Rich (RLTYS)

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Posted 12 November 2020 - 04:30 PM

My own observations suggest V Aql is a reddish/orange color. What you see also depends on the size of your scope and how bright the star is.


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#31 hambone20

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Posted 21 November 2020 - 12:01 AM

Got out last night for a 3 hour session and observed 5 carbon stars which I thought might be worth sharing.  At each star I stayed at the EP for five or more minutes and cupped the focuser with my hand to really keep it dark.  I wanted to get a good grasp on the color and in four out of five I agree with the description on the AL observing program guide.  S Cephius was first and I thought it was also the best of the bunch.  Vivid orange with a tinge of red.  RZ Pegasus was next and was smaller and described as dusky orange.  I sat on that star for a long time but finally agreed with that description.  Next up was V460 in Cygnus.  This star was larger and brighter and described as a lovely orange yellow.  This is the one that I would have called a lovely yellow orange.  Not really either of those colors but kind of a blend of the two.  I couldn't really see yellow or orange but probably right in the middle.  RV Cygnus was smaller again and dark orange.  This one looked alot like the final star which was RX Pegasus.  About the same size and color as RV Cygnus it is orange with a reddish tinge. 

 

I was using my Obsession 18 Classic with a TV 32mm Smoothie which gives about 65x mag.  Sky was dark.  Probably about a 9.3 or 4 with the meter.  All the objects were peppered around the Zenith as I was standing for everything.

 

I mixed in some other nice objects to keep it fun:  M39, M15, NGC 6939, NGC 752

 

The dew got bad and we had to give up at 10:00 pm.


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#32 flt158

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Posted 21 November 2020 - 06:00 AM

Great report, Hambone. Thank you. 

5 carbon stars in one session is truly remarkable! Well done. waytogo.gif

 

RZ Pegasi and V460 Cygni are 2 carbon stars I have observed in the past. 

I'm sorry to say we have had nothing but cloudy nights over Ireland for the last 14 nights. bawling.gif

 

And I still have some more of these amazing orange stars to observe in Cassiopeia. 

 

Thank you again from Aubrey.  



#33 dhkaiser

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Posted 21 November 2020 - 08:46 AM

Anyone observe V666 Cas, a carbon star that I independently discovered back in the 1980's?  Simbad lists it as V 9.61 with a B-V 6.35.



#34 flt158

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Posted 21 November 2020 - 10:57 AM

I haven't observed V666 Cassiopeiae, Dan.

I see it has an alternative designation GSC 03697-00241 or Case 538.    

It appears to vary quite a bit in magnitude from 9.6 down to 13.8. 

I see it's near the Double Cluster in Perseus. 

 

Apart from you saying it was only discovered in the 1980's, can I ask you why you are drawing our attention to it?

Just wondering. waytogo.gif 

 

Clear skies from Aubrey.  



#35 dhkaiser

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Posted 21 November 2020 - 11:18 AM

Apart from you saying it was only discovered in the 1980's, can I ask you why you are drawing our attention to it?

Just wondering. waytogo.gif

 

Clear skies from Aubrey.  

Hi Aubrey,

 

I draw your attention to it simply because it is a favorite of mine, the first of some 3 dozen variable stars I discovered.  And it is very red and indeed a carbon star.  Other carbon stars on my list are BK CMi and V1060 Tau.  The rest are eclipsing binaries and long period variables.  

 

Keep looking up!

 

Dan


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#36 hambone20

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Posted 21 November 2020 - 12:24 PM

Dan, can you provide RA and Dec for V666 Cas?


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#37 flt158

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Posted 21 November 2020 - 02:13 PM

I can provide that information, Hambone. 

 

RA: 02 hours 02 minutes 40.29 seconds. 

 

Dec: +61 degrees 06 minutes 11.52 seconds. 

 

I wonder what magnitude V666 Cas is at now. 

 

Clear skies from Aubrey. 



#38 dhkaiser

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Posted 21 November 2020 - 03:04 PM

AAVSO latest mag estimate was around 11th visual, trending up.


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#39 KMAO

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Posted 22 November 2020 - 12:47 AM

Dan

congratulation for discovery of V666 Cas.

Here are my few obs.

Best wishes for more discoveries

KMA

Attached Thumbnails

  • V666 CAS  h.jpg

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#40 dhkaiser

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Posted 22 November 2020 - 07:45 AM

Dan

congratulation for discovery of V666 Cas.

Here are my few obs.

Best wishes for more discoveries

KMA

Thank you KMA!



#41 Paul Sweeney

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Posted 24 November 2020 - 04:30 AM

Last Friday and Saturday, an amazing thing happened and we had two consecutive clear nights. So, I decided to have a look at some carbon stars. The temperature was just below freezing, the moon was in the west and the sky was slightly hazy and milky. The list that I was working from is called "The 'Coolest' Stars" by Jack Kramer that I found at www.bpccs.com. I am not certain if all the stars listed here are carbon stars, so if I list a non-carbon star, please excuse my bumbling.

 

I started Friday night with a Vixen 80L, mainly because I was first observing Mars. Later, I switched to a Vixen VC200L. Despite its many vices, this scope has the virtue of being color free, even at high powers. For eyepieces I used a Celestron Halloween 40mm and various Vixen LVs. Most observations were made at 45x because the color was more concentrated. I went up to 90 and 150x to confirm the colors. On Friday I covered the eastern half of the sky and quit about 2AM when the fog rolled in. Saturday I covered the western half and had a bit of trouble with the moon and haze, since I was star hopping to the targets.

 

VX AND          Bit of a disappointment. Listed as "very red", I found it to be a bright orange

 

AQ AND         This was a bright yellow-orange

 

V ARI              Yellow-orange. Too dim for the listed 8-8.6 mag. 19 ARI was much redder. I searched the area for anything red, in case the chart was wrong. This needs more investigation.

 

UU AUR          A deep, rich orange. A real beauty!

 

ST CAS          Bright yellow-orange, tending towards yellow

 

WW CAS        Deep red-orange. It was dim, so I assume it is near minumum.

 

TU GEM          Deep burnt orange, with a touch of purple

 

R LEP             Bright copper color, not as red as I remember it

 

W ORI             Deep subdued orange, tending towards red

 

BL ORI            Dark orange, dim. I had real problems finding this one. I ended up using setting circles.

 

GK ORI            Couldn't find it. Gave up after a while and moved on.

 

RX PEG           Deep orange. Dim.

 

TW PEG          Deep, rich orange. Dim.

 

Y PER              Too dark for orange, not quite red. The color of glowing embers.

 

Z PSC               Nice orange with a hint of red

 

TX PSC             Obviously red through the finder (50mm), deep "fire" red. Great color!

 

Y TAU                 Bright rich orange

 

On reviewing my notes, a few questions pop up. Did the bright milky sky change my color perception? Did it cause me to call stars "dim" that otherwise should have appeared brighter?

 

That's all for this time. If anyone has comments or suggestions, I'd be glad to hear them.


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#42 Astrolog

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Posted 24 November 2020 - 09:08 AM

Paul

 

Good report. You really took advantage of the two nights of opportunity. 

 

To date, I have only observed UU AUR from your list above but I recognize many of the stars listed as carbons (on my to do list).

 

V ARI shows as having a magnitude range from approximately 8.3 to 10.8 in one of my guides, so perhaps it is currently near minimum.

I note that the last visual estimate for this in AAVSO database was in January 2020.

 

All the best


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#43 Paul Sweeney

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Posted 24 November 2020 - 10:33 AM

Astrolog,
Thanks for the feedback. As I was writing this, I was wondering how much aperture has to do with color perception. I go through this list seasonally, with 60, 88, 120 and 200 mm scopes. So what I was thinking was to set a few up next to each other, and compare some bright and dim stars to see how the colors come out. Does the red star in an 80mm scope become an orange star in a 200 mm scope? I'll have to check that out.
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#44 flt158

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Posted 24 November 2020 - 10:56 AM

Hello Paul. 

This is a very excellent report. 

It has been a real joy to read it through. 

 

I can tell you that each and every one of these stars are carbon -all except TW Pegasi. 

That star has a spectral class of M6. 

Please feel free to check out Simbad if you have the desire. 

 

Maybe some time when you are not observing so many carbon stars you will successfully find GK Orionis. 

I last observed it in 2011 and I did find it very faint. It must have been near minimum. 

 

Some I haven't observed at all. 

These are UU Aurigae, RX Pegasi and Y Persei. 

 

But I must say your descriptions of the colours are first class. 

 

So a huge thank you to you. 

Your telescopes are very good too. 

 

Clear skies from Aubrey. 


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#45 Rich (RLTYS)

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Posted 24 November 2020 - 04:37 PM

I haven't observed V666 Cassiopeiae, Dan.

I see it has an alternative designation GSC 03697-00241 or Case 538.    

It appears to vary quite a bit in magnitude from 9.6 down to 13.8. 

I see it's near the Double Cluster in Perseus. 

 

Apart from you saying it was only discovered in the 1980's, can I ask you why you are drawing our attention to it?

Just wondering. waytogo.gif

 

Clear skies from Aubrey.  

If I can get a clear night I'll try to image V666 Cas. bow.gif


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#46 dhkaiser

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Posted 24 November 2020 - 06:04 PM

If I can get a clear night I'll try to image V666 Cas. bow.gif

Hey Rich, I would be very interested to see that!  Thanks.


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#47 star drop

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Posted 24 November 2020 - 06:49 PM

Astrolog,
Thanks for the feedback. As I was writing this, I was wondering how much aperture has to do with color perception. I go through this list seasonally, with 60, 88, 120 and 200 mm scopes. So what I was thinking was to set a few up next to each other, and compare some bright and dim stars to see how the colors come out. Does the red star in an 80mm scope become an orange star in a 200 mm scope? I'll have to check that out.

I perceive a change in star colors when switching from a 332mm aperture to a 635mm aperture. Red tends toward orange and orange becomes slightly yellower.  


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#48 ssmith

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Posted 25 November 2020 - 08:55 AM

Here is a photo of V666 Cas I took Last year - about at the midway point of its magnitude variation.

 

Aperture has a great deal to do with color perception.  Much like the saturation of a camera sensor, colors can be softened by flooding the eye with more light not to mention the Purkinje Effect when perceiving colors (especially reds) at low illumination levels.

 

Look at the color recorded in the wide field image of my photo (15s ISO 640) compared to the Star Trail image where the exposure time on any given pixel is much shorter. 

 

I much prefer to view Albireo with my 5" refractor than through my C9.25 SCT.

 

V666 Cass C9 11-8-19 640 15s 4fr.jpg  


Edited by ssmith, 25 November 2020 - 09:30 AM.

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#49 dhkaiser

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Posted 25 November 2020 - 10:06 AM

 

 

Here is a photo of V666 Cas I took Last year - about at the midway point of its magnitude variation.

 

Aperture has a great deal to do with color perception.  Much like the saturation of a camera sensor, colors can be softened by flooding the eye with more light not to mention the Purkinje Effect when perceiving colors (especially reds) at low illumination levels.

 

Look at the color recorded in the wide field image of my photo (15s ISO 640) compared to the Star Trail image where the exposure time on any given pixel is much shorter. 

 

I much prefer to view Albireo with my 5" refractor than through my C9.25 SCT.

 

attachicon.gifV666 Cass C9 11-8-19 640 15s 4fr.jpg

Thank you Steve for the recent image of V666 Cas.  I can see the close (companion?) star near V666.  Actually the reason I discovered this star is because it is so red.  I was using a 135mm lens and red sensitive color slide film.  V666 stood out in my 5 min exposures due to it's color even at fainter magnitudes, as your explanation tells us why.  Thanks again Steve!


Edited by dhkaiser, 25 November 2020 - 10:07 AM.

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#50 Paul Sweeney

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Posted 25 November 2020 - 10:14 AM

Great photo and a point well made. I remember many moons ago there was a chart showing various red tones to help estimate the color of carbon stars. There were some really dark reds, like Burgundy. At the time, I couldn't understand why such a color was included, but the Purkinje Effect explains it.

Is there an " official" chart with standardized names for the various hues?
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