Struve 1657: The Spring Albireo

[Nightspore]

The combination of the blue and yellow stars of Albireo or Beta Cygni is arguably the most famous double star in the night sky. The almost as well known 'Winter Albireo' aka 145 G Canis Majoris is often viewed as a winter time version. However, there is a candidate for a spring equivalent. Regularly overlooked, Struve 1657 aka 24 Comae Berenices, is often referred to as ‘The Spring Albireo’. Quite widely spaced at just over twenty arc seconds, '24 Coma’ is a variable double of spectral types K0 and A3. With magnitudes of 5.2 and 6.7 respectively. It can be observed with the naked eye, and anywhere between around 20x to well over 100x with optical instruments. 

 

 

Technically it is a triple star system probably about three hundred light years distant. The primary star has a deep yellow hue that borders an intense orange. It is classified as a Bright Giant that has exhausted its hydrogen supply and is approximately twenty times the diameter of the Sun. The secondary companion star is a sumptuous blue colour. It is about three times the radius of the Sun and twenty four times its luminosity. This stunning double easily compares with Beta Cygni (Albireo) even though it isn’t as bright.

 

 

It isn’t particularly difficult to find, although there are a lot of stars of similar magnitude in the immediate vicinity.

 

 

I draw an imaginary line from Alpha Leonis (Regulus) to Theta Leonis, also known as Chertan. 

 

 

Regulus, at magnitude 1.35 is the brightest star in Leo, and apparently the twenty first brightest star in the night sky. Theta Leonis, also known as Coxa or Chertan, is magnitude 3.34. ‘Coxa’ means hip in Latin and refers to the ‘hip of the lion’.

 

 

If the line is then continued underneath Berenice’s Hair a low magnification sweep should reveal the beautiful 'Spring Albireo'. 

 

Screenshots by courtesy of Stellarium, SkySafari Pro, Ksnip & Pinta

Edited April 25, 2022 by Nightspore

[+Bino-viewer]

Thanks : i'll chase that one down next time i'm out 👍🏼🔭

[Nightspore]

1 hour ago, Bino-viewer said:

Thanks : i'll chase that one down next time i'm out 👍🏼🔭

 

You're welcome. I just saw the real Albireo. Unfortunately cloud prevented me from seeing both 'Albireos' in the same night.

[+Glafnazur]

I've looked at 24 Coma a few times recently, it is a beautiful double. I've just checked my notes and I've described it as red/orange and blue and I noted that the colours were best in my ES 6.7.

[Nightspore]

1 hour ago, Glafnazur said:

I've looked at 24 Coma a few times recently, it is a beautiful double. I've just checked my notes and I've described it as red/orange and blue and I noted that the colours were best in my ES 6.7.

 

Interestingly, I use my ES 6.7mm a lot with my 72ED for 24 Coma. It gives me about 63x. I've read that the colours are often richer with larger apertures.

[+Glafnazur]

10 hours ago, Nightspore said:

 

Interestingly, I use my ES 6.7mm a lot with my 72ED for 24 Coma. It gives me about 63x. I've read that the colours are often richer with larger apertures.

I was using my Esprit 100, it gives me about 82x. I'll have to try it with my 150 Evostar or maybe I'll root out my 8" OO Europa and see what the colours are like.

[Nightspore]

2 hours ago, Glafnazur said:

I was using my Esprit 100, it gives me about 82x. I'll have to try it with my 150 Evostar or maybe I'll root out my 8" OO Europa and see what the colours are like.

 

Probably also best when it's at transit.