Observations - 16/03/21

Hello, everyone. 

These are the celestial objects I observed on Tuesday night 16th March 2021 with my William Optics 158 mm F/7 apochromatic refractor: 2 doubles, I triple and I carbon star. 

However I noticed they are completely new to me and my William Optics 158 mm F/7 apochromatic refractor. 

At the beginning of my 2 hours 15 minutes observing session on Tuesday night 16th March, I had a major problem with high cloud which www.clearoutside.com had forewarned me about. But that high cloud was less of a problem at a later stage as Taurus became lower in the western sky. 

There was an 8 km/h breeze, but it wasn't too cold. The air temperature was 6 degrees Celsius. 

Each of these systems can be checked out on www.stelledoppie.it  

I began with M45 (Pleiades) and sought out these 2 true binaries. 

1. STTA 40 is in the north eastern side of M45. Magnitudes: A = 6.6. B = 7.5. Sep = 85.6". PA = 308 degrees. Of course I had an easy split at 40X. But to check out the colours I increased up to 112X. The spectral class of the primary is B9; and sure enough I did notice a blue-white hue. The secondary is supposed to be A0 white, but I kept seeing it as orange-white.  However I know many of us can see all sorts of different colours when we are at the eyepiece. Therefore please feel free to disagree with me. STTA stands for Otto Struve Supplement. 

2. STF 449 is near the centre north of M45. Magnitudes: A = 8.8. B = 11.3. Sep = 6.8". PA = 330 decrees. This binary is thankfully more of a challenge - but still quite easy. I could see the faint secondary at 112X. 140X produced a bigger black gap. But I found it more pleasing at the former magnification. Both stars appeared white to yours truly. 

3. Finally, east of M45, we have the triple star STF 479. Magnitudes: A = 6.9. B = 7.8. C = 9.5. Sep's = 7.5" and 57.8". PA's = 126 and 243 degrees. What a real beauty this triple is. I got a stunning tight split at a mere 40X. And what colours I saw! A was blue-white, B was dark orange and C was cherry. Another strange fact I discovered on www.stelledoppie.it was that A and B are an uncertain double. And yet, A and C are a definite true binary - even though they have such a wide separation. I tried to imagine that when I was observing STF 479. Is the secondary nearer or further away from us?

4. I set out to find my 7th observed observed in Taurus which has the strange designation BD+23 601. 
BD is definitely a German designation.
It stands for Bonner Durchmusterung which is an astrometric star catalogue and was compiled by Bonn Observatory between 1859 to 1903. 
BD+23 601 also has other alternative designations. 
These include TYC 1813 1139, GSC 1813 1139 and HIP 18696. 
This carbon star's spectral class is R3 of C3. 

It does vary in magnitude slightly from +10.3 to 10.6. 
And its Johnson B-V colour is somewhere between 1.39 to 1.5. 

To find BD+23 601 I used my Guide 9.1 DVD.       
I was soon to discover there are 3 stars to its east which are shaped like a gentle and evenly spread curve. 
These were: TYC 1813 771 (10.1 mag). TYC 1813 812 (10.9) and TYC 1813 1043 (11.0)
Once I could see these 3 stars I was certain I could figure where BD+23 601 was, i.e., directly to their west. 

But initially at first I had a major problem to overcome: high cloud!
And it was moving extremely slowly. 

Therefore there was no sign of BD+23 601 at all. 

Thankfully as time went on, the high cloud moved up away from this area of Taurus. 

And the constellation was descending out of that same cloud.

Eventually I could only see the carbon star at 167X. 
But the sky conditions were improving. 
At 112X I could see those same 3 stars and BD+23 601 in the same field of view - 4 stars in a row. 
At the end of the night the star was perfectly visible at a mere 40X. 
And that made perfect sense as it is of 11th magnitude.
At 225X I could see that it has a good orange colour with a hint of tangerine about it. 

BD+23 601 is my 7th carbon star in Taurus. 
And it is my 99th observed carbon star overall. 

Thank you for reading my report. 

Comments and corrections are very welcome. 

All that's left is to ask the question: which carbon star is going to be my 100th?  

Clear skies, everyone,

Aubrey.  

 

  

 
 

Hello Aubrey,

Very many thanks for sharing your wonderful observations with us. I remember seeing some of that high cloud on Tuesday. Thankfully, it lifted towards the latter part of the night.

STF 479 sounds delightful, and I reckon with your fine scope your take on the colours is spot on. Is it always the case that the closer the star is to the primary it assigned the 'B' value?

Also, BIG congratulations on observing your 99th Carbon star. Have you decided what star will be 100 - actually don't tell me, I'll like suprises?

I'm really looking forward to reading that you reached triple figures.

Clear skies to you,

Darren.

 

Hello again, Darren. 

Yes. You're right what you said about the B star. 
And the C star is further away again. 

Generally speaking the B star (secondary) is fainter that the A star primary 99% of the time.
And B can have a different spectral class than A.
For instance, Izar's 2 components definitely have 2 different spectral classes because the 2 stars have different colours.

Very best regards, 

Aubrey. 

 

Hi Aubrey,

Very many thanks for clarifying that for me. 

And on the topic of distance between double stars, I managed to have a look at Kappa Bootis last night. There was a larger space between the A and B stars than there was with the A and B stars of Iota Bootis. So, thanks for bringing that to my attention too.

Kindest regards,

Darren.