Had an epiphany regarding the poor resolution on Vega back on 8/2. The filter box setup for imaging and the filter box setup for spectroscopy are very different. I’d dropped the grating into the filter box when the box was positioned and configured for M16. The short spacing resulted in a resolution of only 15 Ao per pixel
The night is calm and the moon is down Cloud’s coming in but spectro works when imaging would be out of the question. And since long exposure’s not necessary I can beat the cloud while taking another run at spectroscopy.
Vega (Alpha Lyrae) is a Blue/White Main Sequence (type A0Va) star that’s only halfway through its one billion-year lifetime, and still in the process of fusing hydrogen into helium. It is about 40 times more luminous than the Sun, as it is using up its hydrogen fuel about ten times faster. Vega is also about 2.1 times more massive than our sun, but only 0.54% of its total mass consists of elements heavier than helium. 25 LY from Earth. It’s a very hot 10,060° K. With a visual magnitude of +0.03 Vega is the fifth brightest star in the night sky.
And here’s the final star profile at my refractor’s maximum resolution of 3.5 Ao per pixel:
- Vega calibrated profile vs library type a0v curve 3800A - 6800A.jpg (229.92 KiB) Viewed 1199 times
For comparison, here’s the comparative low resolution results from 8/2: The data falls off below 4350 Ao and the absorption lines are shallow.
- Vega calibrated profile vs A0v std profile.jpg (75.44 KiB) Viewed 1199 times
The sky is holding. And the resolution is optimized for the first time. Can’t stretch grating distance more than another 5mm before the scope runs out of focus.
Playing around with camera settings while observing video of the spectrum it’s observed that gain settings over 100 result in very noisy curves.
Etamin imaged at 8 seconds, 100 gain, - 5° C with no guiding.
Etamin (Gamma Draco) is an evolved giant star with a visual magnitude of 2.2 This orange type K5 III star is located in the right eye of the Dragon It has 72% more mass than the Sun and it has expanded to around 48 times the Sun's girth. It is radiating about 471 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 3,930 K. This is cooler than the Sun, giving this star the orange-hued glow of a K-type star. 154 LY distant.
- Etamin calibrated profile vs F5 library profile.jpg (84.05 KiB) Viewed 1199 times
- Sadr calibrated profile.jpg (163.43 KiB) Viewed 1199 times
I was fascinated to learn that there is no relationship between color and size. For example, a red star can be large or small. Small stars are more energy efficient than larger stars and live longer.
Rasalhague is a blue-white giant star - spectral type of A5III. It’s 46 LY distant and has avisual magnitude of 2.08 At 7,960 Kelvin it’s hotter than our Sun (5,777 Kelvin). And with only twice the mass of Sol it has 25 times the luminosity. Distance is 46 LY and age is estimated at 910 million years.
- Rasalhague calibrated profile.jpg (87.56 KiB) Viewed 1199 times
-5°C, RGB24 color, PNG format and 3120 X 2088 pixel capture area used for all work tonight. I believe that the gain setting on Vega was 0 and on the rest it was 100.
Now that I’ve got things working the question is what, if anything, I’m going to do with this technology.
hgp