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The Ruby Star

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#1 Frisky

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Posted 29 February 2020 - 01:40 AM

119 Tauri, A.K.A. The Ruby Star, is a variable star near Orion that is said to be the 2nd reddest star in the night sky, behind the Garnet Star. Since most of us scope around Orion this time of year, the Ruby Star is something different to look at and is close at hand. Look between Betelgeuse and Bellatrix. Now draw an imaginary line straight upward from them. This assumes Orion is upright when you view. Off to the right of Orion, you’ll see the red star Aldebaran. Stop just before you go higher than this star. Start looking around with a low power eyepiece and you’ll see 119 Tauri. For me, it was more of a peach or reddish orange. Maybe not even as red as Betelgeuse has looked of late, but it’s clearly a red star! In fact, it’s a red supergiant. Give it a shot the next time you’re viewing around Orion.

 

Joe


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#2 Dave Mitsky

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Posted 29 February 2020 - 01:50 AM

119 Tauri is the second reddest naked-eye star.  
 

http://adsabs.harvar...JBAA..119...50A

Carbon stars are too faint to be seen without optical aid and have much higher B-V color indices.  R Leporis, which is currently visible early in the night, is one of the very best.

https://skyandtelesc...-red1203201401/

 


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#3 Frisky

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Posted 29 February 2020 - 01:56 AM

Right! I forgot to write that. Carbons are redder. I'll check out R. Leporis. I haven't looked for it and need to add a carbon. I only have 2 of them on my list. Great article! I read it before and didn't save it.

 

Joe


Edited by Frisky, 29 February 2020 - 01:59 AM.


#4 Frisky

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Posted 29 February 2020 - 02:03 AM

Here's a nice page that shows how to find R. Leporis:

 

http://wasociety.us/SJAstro/R-Lep.htm


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#5 NorthernlatAK

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Posted 29 February 2020 - 02:12 AM

Early mornings you can find t Lyra, another very red carbon star close to Vega. Easy to find. Very red.
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#6 Dave Mitsky

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Posted 29 February 2020 - 02:55 AM

Here are some carbon star articles and lists to consult: 

 

https://skyandtelesc...g-carbon-stars/

 

https://www.go-astro...arbon-stars.php

 

https://www.astrolea...bonStarLog3.pdf

 

http://www.astrosurf...iar2/carbon.htm

 

https://sites.google...me/carbon-stars


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#7 Frisky

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Posted 29 February 2020 - 03:56 AM

So far, I only have T Lyra and WZCas in my carbon list. I plan to start working on it.

 

Joe


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#8 chrysalis

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Posted 29 February 2020 - 04:25 AM

R Leporis (Hind's Crimson Star) from CdC:

 

HR 1607 HD 31996

Visual Magnitude:  7.71
Color Index:  5.74
Spectral Class:   C6IIe             
Annual Proper Motion:  0.021  0.020

J2000 RA:   4h59m36.50s   DE:-14°48'21.0"
Date  RA:   5h00m31.63s   DE:-14°46'36.5"


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#9 Allan Wade

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Posted 29 February 2020 - 07:58 AM

I enjoy carbon stars. I built a nice list that covers all the seasons with 131 stars. 
 

My favourite carbon star is DY Crucis because it is almost the reddest star in the sky and just 2 arc minutes from Beta Crucis.

 

TW Horologii is another great example, with PGC11984 just 4 arc minutes away.


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#10 flt158

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Posted 29 February 2020 - 09:22 AM

There are at least 4 more carbon stars in Taurus some people might check out. 

 

They are:

1. TT Tauri, 

2. TU Tauri. 

3. Y Tauri. 

4. SU Tauri. 

 

That last one I have not yet observed. 

 

Clear skies, 

 

Aubrey. 


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#11 Rich (RLTYS)

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Posted 29 February 2020 - 02:35 PM

So far, I only have T Lyra and WZCas in my carbon list. I plan to start working on it.

 

Joe

Have you looked into the Astronomical League's Carbon Star Program? They have a list of 100 Carbon Stars to observe.


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#12 Starman1

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Posted 29 February 2020 - 03:34 PM

Go here:

https://www.saguaroa.../sac-downloads/

Go down the page to red stars and download the version 2.0 of red stars.

333 extremely red stars.

One visible this time of year that's a favorite: V Hydrae.


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#13 Frisky

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Posted 29 February 2020 - 03:57 PM

Thanks folks for the info. I'll check out the links now. I have around 20 objects to go to get to 300 on my list. Only 2 carbons stars and a few other red giants is a crime!

 

Joe


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#14 Dave Mitsky

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Posted 29 February 2020 - 05:11 PM

My favorite carbon stars are V Aquilae, S Cephei, DY Crucis, V Hydrae, R Leporis, and T Lyrae.  DY Crucis is the ruddiest star that I've ever seen.


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#15 tchandler

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Posted 29 February 2020 - 06:04 PM

Y CnV (La Superba) is a naked eye carbon star. It’s around 5th magnitude but ranges from 4.8 to 6.3.  Its a beautiful sight and a pleasant change of pace after observing springtime galaxies.

 

It used to be of spectral class N. It is a rarer class of carbon star (Class J) and the brightest in the sky of its type according to Sky Safari. Well worth a look! 


Edited by tchandler, 29 February 2020 - 06:05 PM.

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#16 flt158

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Posted 29 February 2020 - 06:12 PM

It always a thrill to learn from you, T Chandler. 

 

But I do have one question:

Why do professional astronomers change spectral classes of carbon stars?

 

Why change Y CnV from class N to class J?

What's the difference?

 

Just wondering. 

 

Aubrey.  


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#17 tchandler

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Posted 29 February 2020 - 06:25 PM

Good day Aubrey. And Good question. Probably something to do with our ever evolving understanding of stars.. 
 

The Sun and moon were once considered to be planets. Then their designation changed as our understanding evolved. The first asteroids were also considered to be planets, then they were reclassified as “asteroids” after Neptune was discovered.

 

Stars evolve. So to does our understanding of them.


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#18 Starman1

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Posted 29 February 2020 - 06:43 PM

As they learn more about the chemistry of red giant stars' atmospheres, it becomes obvious that the chemical evolution of one may be very different than another.

Spectral classes are not only determined by temperature, but also by their chemistry.

The chemistry indicates age, different origin conditions, different constitutions of elements, probable future evolution and fate and possible variability.

Once the mass and chemistry is known, it can also lead to a determination of distance and the amount of material lying between us and the star.

If the distance is known exactly, from parallax, then the probable size and surface temperature can be calibrated against our knowledge of the chemistry.

 

Red stars were once in classes R & N, but are now split into several sub classes of C based on all those factors.

See: https://en.wikipedia...C:_carbon_stars

If you have not followed this for a few years, just know that the old classes of OBAFGKM have all been further divided into sub classes and new classes

as our knowledge of stellar evolution and chemistry has evolved.

 

One thing to be aware of as an observer is that carbon stars tend to get much redder as their atmospheres expand (a lowering of surface temperature)

and get more orange as their atmospheres shrink (a raising of surface temperature).  Carbon stars are much more dramatic, color-wise, on the down cycle of their variability.

As one example: in October, Omicron Ceti (Mira) was at its brightest.  It's now on the way down.

I noticed it was a yellow-orange when I observed it late last Fall.  I caught it near minimum a few years ago and it was quite red.

The visible light shifted into the infrared, leaving mostly the deep red visible.  It was cool to not only see the range of variability, but also the color change.

V Hydrae, visible now, is like that as well--on its way down, it gets redder and redder.


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#19 Dave Mitsky

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Posted 29 February 2020 - 07:39 PM

Yes, once upon a time the mnemonic was Oh Be A Fine Girl (Gal/Guy) Kiss Me Right Now Smack (Sweetheart).  There was also an S class then.

http://adsabs.harvar...ApJ...120..484K

 

Many variations have been proposed.

 

http://www.star.ucl....obafgkmrns.html


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#20 Migwan

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Posted 29 February 2020 - 07:51 PM

I looked at a dozen carbons stars recently.   Of those, here are three I favored;   UU Aurigae  SAO59280,  SAO12874, S Cep  SAO10100.   jd


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#21 tchandler

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Posted 29 February 2020 - 09:07 PM

I had no idea there were so many version of that mnemonic. Yowza! Oh Bring A Fully Grown Kangaroo My Recipe Needs Some? Really?

 

Did some sleuthing. The J type star is not quite as rare as I thought, representing 10-15% of carbon stars according to this article. The J stars have higher amounts of 13C, relative to the typically more abundant 12C.

 

I’m curious to check out the Ruby Star, being as it’s close to the blue star 120 Tauri. 
 


Edited by tchandler, 29 February 2020 - 09:08 PM.

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#22 Frisky

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Posted 29 February 2020 - 09:58 PM

So far, my favorite carbon is WZ Cas, but I've only seen two, lol! Tonight, I showed my sister the Ruby Star and Orion Nebula. Moon too. The Ruby looked peach again. 

 

Joe


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#23 chrysalis

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Posted 01 March 2020 - 04:50 AM

119 Tau Color Index = 2.07

R Lep Color Index = 5.74

 

R Lep far redder, looks like an ember.


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#24 sanbai

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Posted 01 March 2020 - 08:48 AM

For Skysafari users:
Go to Observe -> Observing lists -> Import from online repository.

There you can import a list with 30 carbon stars (among other lists)

You can highlight them in the map and GoTo with one click. Great for beginners like me. Useful when the moon and street light make other stuff difficult.

Edited by sanbai, 01 March 2020 - 08:49 AM.

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#25 Frisky

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Posted 01 March 2020 - 10:24 PM

I found R. Leporis (Hind’s Crimson Star) and R. Sculptoris. Also Epsilon Leporis, a red giant orange hued star. I added the first two to my list of carbons and doubled it. 

 

Joe


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