Thursday Thirteen

Since a star led the Wise Men to Bethlehem, I thought I'd do some star theory today.

1. Our sun is a star! It took it 50 million years to mature to adulthood, which is where it is now. It will stay in this phase for 10 billion years.

2. Stars are fueled by the nuclear fusion of hydrogen, which forms helium deep in their interiors.

3. The smallest stars are called red dwarfs. They may contain as little as 10% the mass of the Sun and emit only 0.01% as much energy, glowing feebly at temperatures between 3000-4000K. Red dwarfs are the most numerous stars in the Universe and have lifespans of tens of billions of years.

4. The most massive stars are called hypergiants. They may be 100 or more times more massive than the Sun, and have surface temperatures of more than 30,000 K. Hypergiants emit hundreds of thousands of times more energy than the Sun but have lifetimes of only a few million years. 

5. When a star has fused all the hydrogen in its core, nuclear reactions cease. Deprived of the energy production needed to support it, the core begins to collapse into itself and becomes much hotter. Hydrogen is still available outside the core, so hydrogen fusion continues in a shell surrounding the core. The increasingly hot core also pushes the outer layers of the star outward, causing them to expand and cool, transforming the star into a red giant.

6. Stars are the most widely recognized astronomical objects and represent the most fundamental building blocks of galaxies.

7. Stars are responsible for the manufacture and distribution of heavy elements such as carbon, nitrogen, and oxygen,

8. The majority the stars in the Milky Way are paired or in groups of multiple stars.

9. For average stars like the Sun, the process of ejecting its outer layers continues until the stellar core is exposed. This dead, but still ferociously hot stellar cinder is called a White Dwarf.

10. If a white dwarf forms in a binary or multiple star system, it may experience a more eventful demise as a nova.

11. Main sequence stars over eight solar masses are destined to die in a titanic explosion called a supernova.

12. In a supernova, the star's core collapses and then explodes. In massive stars, a complex series of nuclear reactions leads to the production of iron in the core. Having achieved iron, the star has wrung all the energy it can out of nuclear fusion - fusion reactions that form elements heavier than iron actually consume energy rather than produce it. The star no longer has any way to support its own mass, and the iron core collapses.

13. Some astronomers think The Star of Bethlehem was an alignment of Jupiter, Saturn, the moon and the sun in the constellation of Aries on April 17, 6 B.C. This conjunction fits with the story for a few reasons. First, this conjunction happened in the early morning hours, which aligns with the Gospel's description of the Star of Bethlehem as a rising morning star. The Magi also lost sight of the star, before seeing it come to rest in the place where baby Jesus lay in the stable. This could have been the result of the retrograde motion of Jupiter, which means that it appears to change direction in the night sky as Earth's orbit overtakes it. 

Check out NASA's site for more information on stars.

Check out space.com for more information on space stuff, including the proposed explanation for The Star of Bethlehem.

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Thursday Thirteen is played by lots of people; there is a list here if you want to read other Thursday Thirteens and/or play along. I've been playing for a while, and this is my 787th time to do a list of 13 on a Thursday. Or so sayth the Blogger counter, anyway.