Southern Doubles

[TiTanecd]

Hey guys

After my last 2 topics First Lunar / Solar Images, I felt like doing a few more firsts

I looked on Stellarium and the net for some good Doubles to look at in the Southern Hemisphere. 

I decided to look at one that's unique to the south and always up.

I chose Alpha Cruis (Acrux). It is the southern star in the Souther Cross (Crux).

I waited until around 9:30pm, about 3 hours after the sun set, didn't align perfectly, just winged it, and turned out perfect.

Started with my 32mm Skywatcher to centre the star and get an idea of the stars I will magnifying. I then went to a 15mm with still no split.

I decided to just go for it. I have a 6mm and the stock Celestron 10mm. I decided to 2x barlow the 10mm for better eye relief.

This gave me a power of 130x.

With this power I was about to split the 2 stars a¹ and a². I did make out the figure 8 that the stars made and could visually see the difference in flicker rate. I didn't know if I would be about to do it, but I did

It give me a really good baseline for the future also.

See first Double: tick

Stats on the double:

a¹ = mag of 1.40

a² = mag of 2.09

Seperated by 4 arcsec (1 AU)

a¹ is 10-14x the mass of the sun

Alpha Cruis C is a 3^rd star that seems to be gravitationally bound, which is 90 arcsec (can see separation with 32mm)

Picture:

(Picture not mine, only reference)

[mjpfc]

Nice report, it's 20-odd years since I have seen Crux and the Jewel box.

Must look to get down to the south sometime in the future

Mick

[timwetherell]

Another cool southern double very close to the southern cross is beta-Muscae. Sub arc second so pretty tight but resolvable in a 6"+ on a good night

all the best

Tim

[TiTanecd]

Thanx I'll check it out with 8" thats coming soon