Here I present my summary of parallax formula, magnitudes and cepheid variable star, for more info visit my website Neocities.
Parallax is a method of using two observation points to measure the distance of an object by looking at how it appears to move against the background. One way to understand parallax in our everyday life is to look at a close object and observe its position against a background. If you look with one eye and then the other, the object will appear to move against the background. In astronomy, the closer an object is, the more the object will appear to move relative to the background on a grand scale. Between the two apparent locations of the star, where one side is the distance between the sun and the other star. We can use 1AU to find the distance to that star. D Astronomical units are not very convenient to work with, so we define a parsec as the distance to a star showing 1 arcsec of the parallax angle (1pc= 3.6 ly).
Here you can see an image:
Hipporchus observed the magnitudes of the stars and said that there were different types of magnitudes in the stars. Pogson said that stars with magnitudes had a difference in illumination between the magnitudes. 1 →6 x100. Negative values are more illuminated than a star. For example, most stars are brighter than the sun, but the sun is much closer. They found a relationship between luminosity and period (Period luminisity Relation).
From the light curve and the photometric data, two values can be determined; the average apparent magnitude, m , of the star and its period in days. Knowing the period of the Cepheid, we can now determine its mean absolute magnitude, M , by interpolating on the period-luminosity graph. The vertical axis shows the absolute magnitude, while the period is shown as a logarithmic value on the horizontal axes. Once both the apparent magnitude, m , and the absolute magnitude, M , are known, we can simply substitute the distance modulus formula and rework it to give a value for d , the distance to the cepheid.
Here you can see an image:
