Sirius, also called Alpha Canis Majoris or the Dog Star is visual magnitude 1.44, lower than any other star.
At 8.6 light-years distance, Sirius is one of the nearest stars to us after the sun.
Classified by astronomers as an “A” type star. It is much hotter than our sun, with a surface temperature of about 17,000 degrees F (the sun is about 10,000 degrees F). It is slightly more than twice the mass of the sun and just less than twice its diameter.
Sirius still puts out 26 times as much energy as our sun and is considered a normal (main sequence) star similar to our sun, meaning that it produces most of its energy by converting hydrogen into helium through nuclear fusion
At 26 times more luminous than the Sun, it has a significantly lower luminosity than other bright stars such as Canopus or Rigel. It has a white dwarf star close to it making the star a binary system. The system is between 200 and 300 million years old.
The above photographs were taken with a Sony HX200V camera. This is a one piece camera with a 30 times zoom, similar to the Fuji HS10 which is the camera I took the photos of Betelgeuse.
But instead of a 12 mega pixel detector, this camera has 18.2 Megapixels enabling more detail to zoom into.
In addition the camera has an option switch to do 60 times going into the optical range. When this option is enabled, a unique software application starts to operate giving at 60 time the same resolution as at 30 times. That is amazing.
With the flick of another option switch, the camera will zoom even further, up to 120 times.
This picture was taken at this magnification.
In addition, the light sensitivity of the camera is out of this world. Normally a photograph might be taken at 100 ASA on film. The Fuji HS10 can be cranked out to 6200 ASA. This camera has a light sensitivity of 12500 ASA at a magnification of 30 times.
Practically for this star we needed the switch for 120 times zoom and at that magnification the camera will only deliver 3200 ASA at this setting.
However at that setting, if you can hold the camera on the star, you can take a still shot using the steady shot feature and a very high-speed shutter without a tripod. The brighter of the two shots was at about 1000 shutter speed at 320o ASA.
I found this too bright to see detail of the star so the second shot the next day, was taken at about 1600 ASA and about 250th of a second.
One of the most powerful features of this camera for this type of work is that it can zoom in up to 8 times once the shot has been take and take another shot within the first shot. This second shot can be taken at the full 18.2 megapixels. As long as the picture stays inside the camera, the definition is preserved to a high degree. This is because the picture is not a JPG format yet. It is a special Sony format.
With the above photographs, I took them at 120 times, zoomed and then 8 times and then 7 times on the second photo within the camera. By my calculations this is about a 7000 time zoom photo.
Once out of the camera, I then manipulated the exposure, saturation and shadow intensity on software standard to Apple OS.
By David Holland
- Sony Cyber-shot DSC-HX200V 18.2MP Exmor R CMOS Digital Camera with 30x Optical Zoom and 3.0-inch LCD + Sony 16GB SD Card + Sony Case + Replacement Battery Pack + Mini HDMI Cable + Accessory Kit@’ (bowiyb.wordpress.com)