Death of the sun. - Page 2

lazserus · #31 (**permalink**) 05-January-2004, 07:02 PM

A nova is when a star's luminosity significantly increases and then it fades back to normal. Normally that happens within a span of a few months to a few years.

A supernova is when a star blows off it's outer layers in an explosive manner, expelling large quantities of high frequency radiation. Typically supernovae happen in stars with 5 solar masses or more.

From what I know, stars don't end in novae, just supernovae. Considering the star returns to its original luminosity after a nova and within a short period of time, it tends to happen during a life cycle as opposed to the end of one. When our sun expands to a red giant, it's goin to eventually collapse to a white dwarf - I guess you could say it will go nova, but it won't return to the red dwarf luminosity.

Littlemews · #32 (**permalink**) 05-January-2004, 07:53 PM

Our sun will go supernova(White Dwarf)..hmm that's ture, but what happen next? White Dwarf Supernova (Nothing)? or Nutron Star or Black Hole (Massive White Dwarf)? I think the chance for our sun to become a neutron Star is high.

Sun's Mass : 2*1020 kilograms
Luminosity : 111.16 (I think)

Hmm probably our sun wont turn into Neutron Star, or black hole, but leave Main Sequence and become a red giant...

damienpaul · #33 (**permalink**) 05-January-2004, 11:28 PM

and generally be a nuisance for earth

lazserus · #34 (**permalink**) 05-January-2004, 11:46 PM

Quote:

Our sun will go supernova(White Dwarf)..

Yes, it will end in a white dwarf, but it surely won't go supernova. In order for a star to explode into a supernova it has to be a minimal of 5 solar masses. That means 5 times the mass of our sun.

Our sun is not massive enough to collapse into a black hole. We're considered a yellow medium. It would take a much more massive star than our own to collapse into a black hole. The fate of our sun is simple - brief red giant expansion, collapse to white dwarf. No black holes and no neutron stars. Our sun isn't massive enough to collapse that far. We're well within the Chandrasekhar limit.

damienpaul · #35 (**permalink**) 05-January-2004, 11:52 PM

1. what is the ultimate fate of the sun

2. what is the Chandrasekhar limit?

lazserus · #36 (**permalink**) 06-January-2004, 12:13 AM

Quote:

1. what is the ultimate fate of the sun

white dwarf status

Quote:

2. what is the Chandrasekhar limit?

The Chandrasekhar limit is the maximum mass of a white dwarf, and is approximately 3 × 1030 kg, around 1.44 times the mass of the Sun. This is the limit before it will collapse into a neutron star or black hole.

damienpaul · #37 (**permalink**) 06-January-2004, 12:15 AM

a further silly question - when white dwarfs use up their fuel, what then?

lazserus · #38 (**permalink**) 06-January-2004, 12:34 AM

Actually, that's not a silly question. There is no fuel to use up at this point. The only thing that keeps a white dwarf intact is electron degeneracy pressure. If the mass is still above the Chandrasekhar limit then it will collapse further into a neutron star.

damienpaul · #39 (**permalink**) 06-January-2004, 12:38 AM

neutron stars fascinate me, but i know so little, can someone please explain?

TheThorn · #40 (**permalink**) 06-January-2004, 12:44 AM

White dwarfs have already used up their fuel. Before they use up their hydrogen they are main sequence stars, then as they "burn" heavier elements they are red giants. When that runs out, they become white dwarfs and then just slowly cool off, eventually becoming black dwarfs.

White Dwarfs

No one here has mentioned the brief but spectacular "planetary nebula" phase that appears to come with the transition from red giant to white dwarf. That will probably be more fun to watch from a couple of light years away than it will be from here.

lazserus · #41 (**permalink**) 06-January-2004, 12:44 AM

A neutron star is basically the next step below a white dwarf. Super dense, but very small in radius. A neutron star is typically the same density as the Sun, yet only has a radius of 10km, where a white dwarf's radius is roughly 25km. Neutron stars are held together by neutron degeneracy pressure as opposed to electron degeneracy.

damienpaul · #42 (**permalink**) 06-January-2004, 12:46 AM

that is unbelievably small!!! can i assume the gravity would be the same? or will earth likely be a piece of burnt toast by then anyways?

lazserus · #43 (**permalink**) 06-January-2004, 12:48 AM

The Sun probably would never collapse as far as a neutron star considering it's not massive enough. The Earth will definitely be sense long gone. The gravity stays the same.

Littlemews · #44 (**permalink**) 06-January-2004, 12:49 AM

A neutron Star is the ball of neutrons created by the collapse of the iron core in a massive star supernova, high massive than the sun. Neutron stars are essentially giant atomic nuclei, with 2 important differences :
1. They made almost entirely of neutrons.
2. Gravity, not the strong froce, is what binds them together.

---------------------
If the earth were visited by a N.star, it would be squashed into a shell no thicker than your thumb on the surface of the N.star.

damienpaul · #45 (**permalink**) 06-January-2004, 12:50 AM

so to a black dwarf it'll go? what is a black dwarf and have they ever been detected?

lazserus · #46 (**permalink**) 06-January-2004, 01:07 AM

I've never heard of a black dwarf, but I've heard of a brown dwarf.

damienpaul · #47 (**permalink**) 06-January-2004, 01:12 AM

ok, but would the sun fizzle into a brown dwarf... leading to another question...what of jupiter?

Littlemews · #48 (**permalink**) 06-January-2004, 01:20 AM

Quote:

Originally posted by damienpaul@Jan 6 2004, 01:12 AM
ok, but would the sun fizzle into a brown dwarf... leading to another question...what of jupiter?

No, Our sun wont fizzle into BD, because our sun is not a fail star while forming...

damienpaul · #49 (**permalink**) 06-January-2004, 01:21 AM

please explain...i am intrigued

Littlemews · #50 (**permalink**) 06-January-2004, 01:23 AM

Quote:

Originally posted by lazserus@Jan 6 2004, 01:07 AM
I've never heard of a black dwarf, but I've heard of a brown dwarf.

When a WD cool down (Dark), eventually they turn into Black Dwarf..

Littlemews · #51 (**permalink**) 06-January-2004, 01:26 AM

BD : an object too samll to become a ordinary star because of the D.Pressure, so it collapse before fusion becomes self-sustaining. Other word, a Fail Star