Astronomy Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!?
So I m a freshman at high school and tommorrow is my finals :/
Im currently doing my study guide but I came across questions that I just dont know how I can answer those. I tried finding the answers but failed so I would appreciate anyone who will help me
1) How do you calculate distance based on parallax? (plz use simpler language if u can)
2) How do you tell if one star is brighter than the other?
3) How do we measure apparent and real magnitude?
Thx
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1. Read the following article, THEN ask MORE SPECIFIC questions:
http://en.wikipedia.org/wiki/Stellar_parallax
2. "Brighter" in what sense? "Brighter" in the seen from Earth sense? Or "brighter" in the intrinsically a more luminous object sense?
For brighter in the seen from Earth sense...just look at them.
3. The "magnitudes" aren't really real physical concepts anyway. They are just a logarithmic scale make-up artificially to make for convenience of visual ranking of the stars we see in the sky. More suitable for "just eyeballing it" than actually making a measurement.
What the REAL CONCEPT is, is intensity. All that must be done, is to use irradiance measurements to measure illumination power per unit area...and then you got the intensity of the star's light at Earth's location. Now, if you want apparent magnitude, just translate through the arbitrary logarithmic scaling formula.
The REAL CONCEPT of absolute magnitude is luminosity. As in, how much actual power does the star emit. To get this, we first need distance, and then we use the inverse square law of the distance.
To get absolute magnitude from luminosity, what you must do is calculate the intensity observed by a hypothetical observer at a distance of 10 parsecs from that star via inverse square law (the STANDARD observer point...not, Earth isn't necessarily at the place of this hypothetical observer)...and then, crunch it through the apparent magnitude formula.