10 replies to this topic

[lwbehney]

A bright Moon and a mildly hazy sky is made for double star hunting. I observed the Winter Albireo for the first time tonight. Sky Safari made that a bit difficult, because you won't find it typing in h 3945. You have to write Herschel 3945 or you can search the internet while your fingers chill until you find someone kind enough to have listed the SAO number, which is 173349.  

 

In any case, the  4.82 magnitude primary of the Winter Albireo has a striking orange color. It is a K3 bright giant star. The 5.84 magnitude companion is spectral class F0, but has a blue cast to it. I viewed it with my six inch refractor with the ES 17 mm and with the 13 mm T6 Nagler eyepieces. I felt that the companion star had a deeper blue color in the 13 mm at 92X vs 70X.  Is that due to the eyepieces themselves or just due to the magnifications used?  I'm curious to know if there exists a general rule regarding the ideal range of separation for appreciating the color contrast of binary stars.

 

I have viewed the Summer Albireo with my five inch refractor and the components are brighter. My recollection of the colors are that the the B9 spectral class companion of the Summer Albireo is a more pronounced blue color, but the Winter Albireo has a deeper orange color to the primary star. Some call it red orange in color.  Aesthetically, I would call it a tie at the moment, but I believe that if the Winter Albireo companion was also a B9 spectral class instead of F0, the Winter Albireo would be the winner. 

[Rick-T137]

I'm not sure which is prettier, but Summer Albireo is a lot nicer to view from my location as it gets much higher in the sky and is viewed during much nicer weather.

 

Still, this is a lovely place to stop and hang out in the winter months. Thank you for sharing!

 

Other catalog numbers I have from Stellarium for this star are (for those searching in their apps/programs):

 

145 CMa

HJ 3945

HIP 35210 A

HR 2764

HD 56577

WDS J07166-2319

 

Clear skies!

 

Rick

[JoeFaz]

You won't find h 3945 because "h" is an outdated reference to John Herschel's catalog, which now uses the discoverer code "HJ". HJ 3945 will get a result in SkySafari. It is the same idea as "Σ" for FGW Struve, which now uses the discoverer "STF." SkySafari uses the current discoverer codes where there is an outdated one, but also responds to at least some proper names "Herschel", "Struve", and surely some others.

 

If you want really amazing color contrast take a look at WZ Cassiopeiae. Carbon (orange-red) star and blue companion, and my personal favorite double star.

[Dave Mitsky]

HJ 3945 would fare better from a more southerly location, but I have to agree with what Joe said about the optical double star WZ Cassiopeiae.

 

https://gardenastron...-gold-and-blue/

 

https://cosmicpursui...he-perseus-arm/

 

Iota Cancri is another colorful binary star worthy of observation.

 

https://www.havastro.co.uk/iota-cancri

 

https://stargazerslo...inter-albireos/

Edited by Dave Mitsky, 12 March 2025 - 01:55 PM.

[Dave Mitsky]

The famous variable star Delta Cephei is another colorful binary star.
 

Delta Cephei R.A. 22h 29.20m Dec. +58d 25'

Prmary: mag. 4.07 (variable) sp. F5-G3 Secondary: mag. 6.27 sp. B7
Sep. 40.8" arc P.A. 191 deg.
Colors seen in 10 inch: Yellowish-white and light blue.
 

http://www.midnightk...aspx?URL=Visual
 

https://app.astrobin.com/i/ybcorf?r=0

[lwbehney]

Thank you for all of these replies.  I will have to put these new options in my notes lists. 

[Tony Flanders]

You won't find h 3945 because "h" is an outdated reference to John Herschel's catalog, which now uses the discoverer code "HJ". HJ 3945 will get a result in SkySafari.

Yes, I was thinking the same thing when I read the base note. As luck would have it, I didn't remember exactly the Winter Alberio was, and surprisingly, it wasn't labeled on the paper atlas I was using at the time. So I typed HJ 3945 into Sky Safari (yes, I remembered the number) and voila ...

But I don't really agree that the h notation is outdated -- and the capital Sigma for Struve is still very much alive and well. What we have now is an annoying bifurcation between the world of paper, which still uses the traditional designations, and the computer world, which uses the Washington Double Star Catalog designations because they're easier for a computer to handle.

Edited by Tony Flanders, 12 March 2025 - 02:28 PM.

[Jon Isaacs]

I know this double as the colorful double about 1.7 degrees north of the tau Canis major Cluster, NGC 2362.   It is visible as a double in my 50mm RACI Finder.

 

It is interesting enough that when I am in the area, I will take a look but even from my more southerly location, it is no competition for it's much brighter, better placed (from the northern hemisphere) name sake.  

 

I find the "Jumping Bean Cluster" NGC2362 more interesting and the visibility of the cluster around Tau Canis Majoris is a good indication of the transparency down near the horizon. 

 

Jon

[Astro-Master]

While it's not an orange and blue double, I've always like taking a look at Eta Cass, a bright yellow star, 3.5 Mag. and a 7.4 Mag. companion that looks purple to my eye at the right power in my 4" APO.  RA 00 49.1'   Dec +57* 49'

[lwbehney]

I know this double as the colorful double about 1.7 degrees north of the tau Canis major Cluster, NGC 2362.   It is visible as a double in my 50mm RACI Finder.

 

It is interesting enough that when I am in the area, I will take a look but even from my more southerly location, it is no competition for it's much brighter, better placed (from the northern hemisphere) name sake.  

 

I find the "Jumping Bean Cluster" NGC2362 more interesting and the visibility of the cluster around Tau Canis Majoris is a good indication of the transparency down near the horizon. 

 

Jon

NGC 2362 has to be one of my favorite open star clusters. Jerry Oltion of Sky & Telescope mentioned this cluster in his Big, Bold, Bright, and Beautiful article regarding  his look at old favorites. 

[justfred]

 I took a peek at HJ3945 last night as I was waiting on the Lunar eclipse. And thanks for the info on HJ instead of just H. 

 

The double was moving through the tree limbs and passing clouds to our South. It's a nice one. The colors were obvious. 

 

This was the first time I had ever seen it. Not many pastimes can offer you something new after almost 70 years in the hobby. Astronomy does this time and time again.

 

... and the skies cleared for the eclipse. And closed back up around 4AM.  :-)     

 

Fred