An O star is about _______ degrees surface temperature. ?

O stars: 30,000 -60,000 Kelvin

B stars: 10,000–30,000 Kelvin

A stars: 7,500–10,000 Kelvin

F stars: 6,000–7,500 Kelvin

G stars: 5,000–6,000 Kelvin

K stars: 3,500–5,000 Kelvin

M stars: 2,000–3,500 Kelvin

Notes:

(1) these are surface temperature. Internal temperatures are much hotter

(2) the Sun is a G star.

(3) 273 Kelvin = 0 degree Celsius

It a main sequence star type. It is a strong super angrily ultra hot star that ripps trough its hydrogen like it is going out of style so thay are short lived from just intantly exploding to just a few million years. They are objects so hot that thay glow blue and give extremely huge amounts of light and radiation. Their temperature is betweem 85,000. degrees F to 125,000. degrees F. These stars are actually very rare as to how many stars are out there. there is another type just above this star but thay are extremely rare because most just collect too much mass and get over loaded with energy and go nova. there is only 3 of them easily observed in our sky. they can have a surface temperature up to 175,000. degrees F. As for our sun it is so cold only a surface temp of 9,800. degrees F making it look yellow to a trace of orange and giving us just the right amount of heat and light to live off of.

Main Sequence Stars:

Once a protostar starts burning hydrogen in its core, it quickly passes through the T-Tauri stage (in a few million years) and becomes a main sequence star where its total mass determines all its structural properties. The three divisions in a stellar interior are the nuclear burning core, convective zone and radiative zone. Energy, in the form of gamma-rays, is generated solely in the nuclear burning core. Energy is transfered towards the surface either in a radiative manner or convection depending on which is more efficient at the temperatures, densities and opacities.

The interior of three stellar types are shown below. Note that an O star is about 15 larger than a G star, and a M star is about 1/10 the size of a G star, this scale is shown below the interiors.

Notice how the nuclear burning regions takes up a larger percentage of the stellar interior as one goes to low mass stars. High mass stars have a very small core surrounded by a large envelope. The energy released from the stellar core heats the stellar interior producing the pressure that holds a star up.

If stars were like cars, then they would burn their core hydrogen until they ran out and the star would fade out. But fusion converts hydrogen into helium. So the core does not become empty, it fills with helium `ash'.

As the helium ash builds up, energy generation stops in the core. The fusion process moves outward into a shell surrounding the hot helium core. Helium can also undergo fusion but, since it is a larger atom, it requires over a 100 million degrees of temperature to overcome its electrostatic repulsion (the helium nuclei has two protons, double the hydrogen nuclei). For small stars, this temperature is never reached and the helium core remains inert.

Stars begin their lives as 74% hydrogen, 25% helium and 1% everything else on the periodic table (by mass). Fusion has been ongoing in the core of the Sun for 5 billion years, and its core is now about 29% hydrogen, 70% helium and 1% everything else. Fusion alters the chemical composition of stellar interiors.

Note that since the cores of stars are so large and massive, it takes anywhere from 100's of thousands to billions of years to run out of hydrogen fuel. Clearly, stars that burn brightest, burn fastest and, thus, have the shortest lifetimes.

We can use Einstein's famous E=mc2 to find out how long before a star evolves into a red giant star. The total energy released by a star in its lifetime is, E*, such that:

E* = Lt

where L is the luminosity of the star (energy per sec) and t is the lifetime of the star. The total energy produced by a star is how much of the star's mass is converted into energy. Assuming that about 1/2 mass of the star is passed through the fusion reaction in the core, which converts 0.71% of the mass of four protons into energy. Thus, with E=mc2, we get:

Lt = (0.0071/4)(M/2)c2

where M is the mass of the star. So the lifetime of a star, t, in seconds is

t = 8.9x10-4Mc2/L

Now we know from the mass-luminosity relation for stars that L α M3.5 so:

t α Mc2/M3.5

t α c2/M2.5

in terms of solar units we have

t/to = 1/(M/Mo)2.5

where Mo is the mass of the Sun and to is the lifetime of the Sun, 1010 years. So we see that a massive, hot star burns fast (short lifetime) and a low mass, cool star burns slow.

I cant remember but as a O star it the hottest in the sequence, O,B,A,F,G,K,M,R,N,S.

30,000 to 50,000 Kelvin