Sirius

[Graeme]

Sirius, α Canis Majoris, is the brightest star in the sky. It's bright because it's very hot and also because it's quite close to us. It's a binary pair, Sirius A is a Main Sequence type A star and Sirius B is a White Dwarf. They orbit each other every 50 years. At the moment they are just past greatest separation as seen from Earth. Canis Major is the Great Dog constellation that follows Orion the Hunter across the sky and Sirius is known as the Dog Star. So I thought I would have a go at imaging Sirius B, the Pup!

Sirius was at the meridian at 20:51 and here at 51° north that's only 21° altitude. I only get down to 25° in most directions but I can just get down to 20° towards the SSE. I captured seven minutes of 10 second luminance exposures.

Sirius_EL.jpg

Not sure about the off centre, top right donut and the nebulosity but there was no sign of the pup! I might have a go at using a foil strip over the sensor to dim the A star in the hope of catching some photons from the B star! It was a fun experiment though. It's a brilliant craic being retired!

Regards

Graeme

[HansV]

A good try. Keep us updated.

[stuck]

...It's a brilliant craic being retired!...

I'll second that!

Ken

[ChrisGreaves]

A good try. Keep us updated.

A siriously good try, surely?
Cheers, Chris

[GeoffW]

Come on Chris. How can anybody Sirius B?

[ChrisGreaves]

Come on Chris. How can anybody Sirius B?

Well, anyone who is vertically-challenged!
Here is but one example of a vertically-challenged star.
Cheers, Chris

[ChrisGreaves]

... I might have a go at using a foil strip over the sensor to dim the A star ...

A question of precision from Bonavista:-
"foil strip" as in a piece of aluminium cooking foil?
How small a strip?
And how do you physically place it to "blot out" as it were, Sirius A?

I think of a binary stars as a pair of stars that orbit a common centre outside the peripheral surface of both stars. So two separate stars. But the separation distance must be exceeding small compared to their distance from our Solar system (and hence our Earth)

Will you be nudging a 1 mm strip of cooking foil over parts of your lens/filter assembly with a pair of tweezers?
Thanks, Chris
P.S. I do admire your sere humour! "Its name is derived from the Greek word Σείριος (Latin script: Seirios), meaning lit. 'glowing' or 'scorching'" C.

[PaulB]

Thanks for introducing me to the word craic, although it does not pass the spell check! I'll try to work it into a conversation sometime with my fellow retirees. IIRC, you also introduced me to the astronomical meaning of Subaru.

[Graeme]

I'll try to work it into a conversation sometime with my fellow retirees.

That would be a right craic!

[Graeme]

... I might have a go at using a foil strip over the sensor to dim the A star ...

A question of precision from Bonavista:-
"foil strip" as in a piece of aluminium cooking foil?
How small a strip?
And how do you physically place it to "blot out" as it were, Sirius A?

Please see the 7th paragraph

[ChrisGreaves]

Please see the 7th paragraph

Thank you Graeme.
"The second essential device for seeing Sirius B tonight was an occulting bar. I took an old Kellner eyepiece and fitted a narrow strip of aluminum foil onto the field lens. Kellners are helpful in this regard since the internal eyepiece focus is normally very close to the exterior surface of the field lens: this makes attaching an aluminum strip (occulting bar) easy. Glue it onto the lens surface! I have an old 12 mm Kellner with such a bar."
So the procedure is indeed GLUING a very narrow strip of regular foil on to the exterior of the lens assembly.
I am amazed that this can blot out Sirius A, which is I believe the larger and brighter of the pair of stars.
Thanks again, Chris