Author Archives: rootcoruja

A star is born (Part 3 cont.: Evidence of a protostar in a Bok globule)

Bok globules are small interstellar clouds of very cold gas and dust that are nearly totally opaque to visible light as we’ve already seen in a previous post. Although they can be studied with infrared and radio techniques. They were … Continue reading

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A star is born (Part 3: The Virial Theorem, Jeans mass and Bok globules)

In this article I will try to show by skipping calculations and focus on the process on how to get to the result, that from a theorem called the Virial theorem, given a molecular cloud composition (mostly hydrogen), known density … Continue reading

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How bright is a star? Introducing apparent and absolute magnitude

In ancient Greece, for approx 2000 years ago, the Greek astronomer Hipparchus was the first to make a catalog of stars according to their brightness. The brightest stars were ‘magnitude 1’, the next brightest were ‘magnitude 2’, etc., down to … Continue reading

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How bright is a star? Introducing luminosity and its use for calculating distances

If we have a detector on earth of 1 m^2, one can measure something called the “solar constant” or “apparent brightness” which is called “b_sun” ‘b’ as in brightness, a measure of the flux of energy per square meter of … Continue reading

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How far from earth is a star? What is Parallax?

This short intro on the concept of parallax is required in order to understand how brightness can be measured for NEARBY stars. The problem is that distances are useful to calculate many astronomical features of stars like luminosity, mass, motion/velocity … Continue reading

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A star is born (Part 2: H-alpha emission nebula)

In this post I will write about a special type of light produced by hydrogen atoms which is extremely important for astronomers in quest of finding star forming regions and newly born stars. By observing the star formation process at … Continue reading

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A star is born (Part 1: The Inter-Stellar Medium and dust clouds/nebulae)

In this series of post, I will try to understand how a star is created until it reaches the so-called “main sequence”. Another series of post will look at what is happening after the star leaves the main sequence. In … Continue reading

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