In: Physics
A certain red giant star has a luminosity of 100,000 times that of the Sun and is located 600 light-years from Earth. If the apparent magnitude of the star is observed to be m=0, calculate the rate of interstellar extinction in the direction of the star.
If someone could show me step by step how to solve this I would
be appreciative.
Measuring Extinction - The Star Counting Method:
The images have been previously processed, so the contrast should
already be at a good
setting for counting purposes. If you do feel you need to alter the
images settings to allow
you to make better counts, you can adjust this by using the `screen
stretch' window.
Choose an area within a cloud of conspicuous obscuration on one of
the photographs.
The area should be as large as possible to maximize the accuracy of
the count, but its shape is irrelevant. Choose a window
of a convenient size and shape and outline it over the area
youwant to
count. Now decide on the faintness to which you think you can count
and choose alimit by the size of the
images. The fainter you count, the better the accuracy of the
countsfrom
the statistical point of view; however it is also essential that
you are able to recognizethe limit consistently (It may
take a minute or so to get used to counting the stars on
theseimages).Outline the window on the cloud
and count all the stars to the chosen limit. Move
thewindow to
a comparison