The Biggest Star in the Heavens

--------- #1395 - The Most Massive Star in the Heavens?

- Attachments : Tarantula Nebula

- I have 2 astronomy textbooks and each states that the theoretical maximum size that a star can get without exploding is 150 Solar Mass. That is 150 times the mass of our Sun.

- The bigger the star, the more intense the compression of gravity, the brighter the luminosity, the faster the star burns all its fuel, the shorter its lifetime before it explodes as a supernova.

- The life expectancy of our Sun is 10 billion years. Here is the formula used to calculate the lifetime of a star:

----------------------- Lifetime = 10 billion years / ( mass ) ^2.5

----------------------- 1 Solar Mass = 10^10 / 1 = 10 billion years

---------------------- 10 Solar Mass = 10^10 / (10)^2.5 = 32 million years

--------------------- 150 Solar Mass = 10^10 / (150)^2.5 = 36,000 years

- A 150 Solar Mass star would only live 36,000 years. Therefore over 1,000,000 of these massive stars would come and go during our Sun’s lifetime.

- Astronomers are astonished to find a 350 Solar Mass star in the Tarantula Nebula in the Large Megellanic Cloud Galaxy. It is named R136a1 and it is 165,000 lightyears away. The star is 9,000,000 times brighter that our Sun and has a surface temperature of 95,000 Fahrenheit ( 53,000 Kelvin). If that were our Sun the Earth would be vaporized at 15,000 Kelvin. Thankfully R136 is 165,000 lightyears away.

- Here is a table of the most massive stars found to date:

---------------------------------------------Times ------------Times ----------Times
---------------------------------------------Solar ------------ Sun’s ---------- Sun’s
------------------------------------------- Mass ----------- Diameter -------Luminosity

--------------- R136a1 ------------------ 350 ------------- 35 ------------10,000,000
--------------- Eta Carina -------------- 250 ------------- 195 ------------5,000,000
--------------- Peony Nebula ---------- 175 ------------- 100 ------------3,200,000
--------------- Piatol Star -------------- 150 ------------- 340 ------------6,300,000
-------------- HD269810 -------------- 150 ------------- 19 --------------2,200,000
--------------- LBV1806 -------------- 130 ------------- 200 ------------10,000,000
--------------- HD93129a ----------------- 120 ------------- 25 ------------5,500,000
--------------- HD93250 ------------------ 118 ------------- 18 ------------5,000,000
--------------- S Doradus ------------------ 100 ------------ 380 ------------600,000

- Eta Carina is the second most massive star and it is the next supernova expected to go Booom! ( see Review #1346 and #775 and #49 to learn about this binary star system). This 2 star system has a primary Luminous Blue Variable Star that is 250 Solar mass. Its companion star is a Main Sequence Secondary Star that is 80 Solar Mass. the Blue Variable s 5,000,000 times more luminous that our Sun.

- There is some debate about R136 mass, still 265 Solar Mass is the minimum, because the mass has not been measured directly. It calculated based on its temperature and the solar wind it is ejecting. The star is loosing one Solar Mass every 20,000 years.

- The reason a star is not expected get this big before exploding is that the calculations tell us that over 150 Solar Mass anti-matter would be created at the core. Electrons and anti-electron pairs would be created. This would cause the star to explode sooner and to completely vaporize sending 10 Solar Mass of iron into interstellar space.

- Iron is the last element to be fused in a star because it is the heaviest element in the Periodic Table that requires adding energy to continue the fusion process. All the lighter elements than iron actually release energy when they fuse. That is what opposes gravity and keeps the star from collapsing. Once iron is created there is no release of energy and the star collapses to the core, rebounds into a supernova explosion.

- Our Sun will die differently. It will not fuse elements above carbon and when it runs out of fuel it will expand into a Red Giant. This Red Giant will pulsate creating a Planetary Nebula with a White Dwarf star left at its core. That will happen 5 billion years from now. An announcement will be made shortly, stay tuned.

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707-536-3272, Thursday, February 2, 2012