THE LIFE OF A STAR: CLASSIFICATION
THE LIFE OF A STAR: CLASSIFICATION
In order to understand the life of a star, we must understand star classification.
And there are SO many different ways to classify a star.
In star classification, understanding the relationship between color and temperature is crucial. The greater the temperature of the star, the bluer they are (at their hottest, around 50,000 degrees Celcius), while red stars are cooler (at their coolest, around 3,000 degrees Celcius). This occurs on a wide range (fun fact: stars only come in red, orange, yellow, white, and blue, because stars are approximately something called a "black body"). For example, our Sun is a yellow star with a surface temperature of 5,500 degrees Celcius (The Life of a Star).
But why is this so? In order to understand that, I'm going to tell you about how stars live at all. This is what will determine the entire life of a star - something we'll be focusing on throughout this series. Two words: nuclear fusion.
Nuclear fusion is "a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifested as either the release or absorption of energy." (Wikipedia) And this is where nuclear fusion gets REALLY important to stars. Throughout their lives, stars undergo nuclear fusion in their core. This is mostly in the form of fusing two or more hydrogen atoms into one or more helium atoms. This releases energy in the form of light (the pressure of nuclear fusion in the core also prevents the star from collapsing under the weight of gravity, something we'll get to later). The energy transports to the surface of the star and then radiates at an "effective temperature." (Britannica)
Stars are different colors due to differing amounts of energy. This is best explained by Einstein's e=mc2 or the mass-energy equivalence. In other words, the more mass something has, the more energy, and vice versa. Stars with greater mass undergo more nuclear fusion - and as such - emit more energy/temperature. And so, the bigger the star, the greater the temperature, the bluer the star; and the smaller the star, the lower the temperature, the redder the star (Universe Today). Another way to think about this is this: the hotter something is, the shorter frequency of energy it emits. Blue light has a shorter frequency than red light, and so, higher energy/temperature stars are bluer.
Another important classification of a star is its luminosity (or the brightness, or the magnitude of the star). (The Life of a Star)
The most famous diagram classifying stars is the Herzsprung Russell Diagram, shown in this article's picture. The x-axis of the diagram shows surface temperature, hottest left, and coolest right. The y-axis shows brightness, brighter higher, and dimmer lower. There are main groups on the diagram.
Most stars fall in a long band stretching diagonally, starting in the upper left corner and ending in the right lower corner, this is called the main sequence. The main sequence shows stars which mostly use their life going through nuclear fusion. This process takes up most of a star's life. Most stars which are hotter and more luminous fall in the upper left corner of the main sequence and are blue in color. Most stars that have lower-masses are cooler, and redder falls in the lower right. Yellow stars like our Sun fall in the middle.
The group located in the lower-left corner are smaller, fainter, and bluer (hotter) and are called White Dwarfs. These stars are a result of a star like our Sun one day running out of Hydrogen.
The group located right above the righter's main sequence is larger, cooler, brighter, and a more orange-red or red, are called Red Giants. They are also part of the dying process of a star like our sun. Above them in the upper right corner are Red Super Giants, massive, bright, cooler, and much more luminous. To the left of the Red Super Giants are similar stars which are just hotter and bluer and are called the Blue Super Giants.
That explains the most famous star classifying diagram. The important thing to remember is the data on the chart is not what a star will be like it's whole life. A star's position on the chart will change like our Sun will one day do.
In a ThoughtCo. article on the Hertzsprung Russell Diagram, Carolyn Collins Petersen wrote: "One thing to keep in mind is that the H-R diagram is not an evolutionary chart. At its heart, the diagram is simply a chart of stellar characteristics at a given time in their lives (and when we observed them). It can show us what stellar type a star can become, but it doesn't necessarily predict the changes in a star." ( The Hertzsprung-Russell Diagram and the Lives of Stars)
And this will continue to be important in the next chapters. Stars don't just stay in the same position their entire lives: they change in their color, luminosity, and temperature. In this series, we'll be tracking how stars form, live and die - all dependent on these three factors - and nuclear fusion - again - super important :)
Previous - Chapter 1: An Introduction
Next - Chapter 3: Star Nurseries
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More Posts from Acosmicgeek and Others
Okay, that is really funny lol
Also - I’m back from my self-imposed vacation! I’m drafting the next chapter and starting my post schedule tomorrow, so look forward to new content coming soon!
I hope you’re all doing well :)
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Here’s some physics.
Aw heck yeah let’s go
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List of extrasolar candidates for liquid water
The following list contains candidates from the list of confirmed objects that meet the following criteria:
Confirmed object orbiting within a circumstellar habitable zone of Earth mass or greater (because smaller objects may not have the gravitational means to retain water) but not a star
Has been studied for more than a year
Confirmed surface with strong evidence for it being either solid or liquid
Water vapour detected in its atmosphere
Gravitational, radio or differentation models that predict a wet stratum
55 Cancri f
With a mass half that of Saturn, 55 Cancri f is likely to be a gas giant with no solid surface. It orbits in the so-called “habitable zone,” which means that liquid water could exist on the surface of a possible moon. ]
Proxima Centauri b
Proxima Centauri b is an exoplanet orbiting in the habitable zone of the red dwarfstar Proxima Centauri, which is the closest star to the Sun and part of a triple star system. It is located about 4.2 light-years from Earth in the constellation of Centaurus, making it the closest known exoplanet to the Solar System.
Gliese 581c
Gliese 581c gained interest from astronomers because it was reported to be the first potentially Earth-like planet in the habitable zone of its star, with a temperature right for liquid water on its surface, and by extension, potentially capable of supporting extremophile forms of Earth-like life.
Gliese 667 Cc
Gliese 667 Cc is an exoplanet orbiting within the habitable zone of the red dwarf star Gliese 667 C, which is a member of the Gliese 667 triple star system, approximately 23.62 light-years away in the constellation of Scorpius.
Gliese 1214 b
Gliese 1214 b is an exoplanet that orbits the star Gliese 1214, and was discovered in December 2009. Its parent star is 48 light-years from the Sun, in the constellation Ophiuchus. As of 2017, GJ 1214 b is the most likely known candidate for being an ocean planet. For that reason, scientists have nicknamed the planet “the waterworld”.
HD 85512 b
HD 85512 b is an exoplanet orbiting HD 85512, a K-type main-sequence star approximately 36 light-years from Earth in the constellation of Vela.
Due to its mass of at least 3.6 times the mass of Earth, HD 85512 b is classified as a rocky Earth-size exoplanet (<5M⊕) and is one of the smallest exoplanets discovered to be just outside the inner edge of the habitable zone.
MOA-2007-BLG-192Lb
MOA-2007-BLG-192Lb, occasionally shortened to MOA-192 b, is an extrasolar planet approximately 3,000 light-years away in the constellation of Sagittarius. The planet was discovered orbiting the brown dwarf or low-mass star MOA-2007-BLG-192L. At a mass of approximately 3.3 times Earth, it is one of the lowest-mass extrasolar planets at the time of discovery. It was found when it caused a gravitational microlensing event on May 24, 2007, which was detected as part of the MOA-II microlensing survey at the Mount John University Observatory in New Zealand.
Kepler-22b
Kepler-22b, also known by its Kepler object of interest designation KOI-087.01, is an extrasolar planet orbiting within the habitable zone of the Sun-like star Kepler-22. It is located about 587 light-years (180 pc) from Earth in the constellation of Cygnus. source
Update on The Life of a Star, Chapter 7
So I’m a little over halfway done (I should be ready for some editing on Saturday) with this chapter and I think this might be my one longest yet! My current longest is Chapter 6, with 1,245 words. I’m currently at around 700 words with this one, and I’ve got at least 400 more to go. Anyway, I’m really excited for this one. We’ll be touching on nebulae again, and finally addressing our first ending for a star.
We’ve only got three more chapters left, plus a possible one for additional topics. I’ll be sad to end this one, but I’m starting to gather ideas for the next book. Maybe on the methods of observing the universe? Maybe on random astrophysics topics? Perhaps one on galaxies? Cosmology? The Four Fundamental Forces? Haven’t decided yet xD
I think you’ll all really like these last chapters I have planned, or at least I hope you do. Thanks for reading :)
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This isn’t family friendly but its darn funny xD
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They haven’t figured it out
Wow, Mars is one of the closest planets to us xD
Just shows you how massive space really is
(Maybe even infinitely so)
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This is what the Earth looks like from the surface of our red neighbour, Mars!
Happy Earth day everyone 🌎🌍🌏 Hope you’re all staying safe!!
Image Credit: NASA’s Curiosity Mars Rover
Okay I know that I love black holes but buddy why don’t you not come here?
I wonder if falling into a black hole would hurt? If I could choose any way to go out, it’d probably be by black holes. Might as well be killed by the love of my life.
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OJ287 is one of the largest black holes in the known universe. If it were placed at the center of our solar system, its event horizon would swallow nearly everything is our Sun’s sphere of influence. All the planets, the asteroid belt, and (obviously) us. This beast is an estimated 18 billion solar masses and drifts through the cosmos some.
Image credit: Jaime Trosper/FQTQ
Tonight’s a New Moon!
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Honestly I don’t really understand why they didn’t call the APOLLO missions the ARTEMIS missions! Artemis is the greek goddess of the moon, not Apollo xD
Dat rocket does look cool though. I prefer posting about astrophysics, but I’m having a lazy day and rockets are easy to find and cool to look at. Apologies for anyone expecting another post on stars or memes.
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NASA Attaches First of 4 RS-25 Engines to Artemis I Rocket Stage : Engineers and technicians at NASA’s Michoud Assembly Facility in New Orleans have structurally mated the first of four RS-25 engines to the core stage for NASA’s Space Launch System (SLS) rocket that will help power the first Artemis mission to the Moon. (via NASA)
Woah :o
So, basically, like the Mission Space ride at Epcot (that one is my favoriteeeee)?
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Testing and Training on the Boeing Starliner : NASA astronaut Mike Fincke works through a check list inside a mockup of Boeing’s CST-100 Starliner during a simulation at NASA’s Johnson Space Center on Aug. 21, 2019. (via NASA)
Poor, poor moon :(
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“boy, girl, time for dinner!”
