Astro fantasy league.

[cotterless45]

Sometimes it adds a lot of interest to find out about that fuzz or star that you're looking at. There's some amazing physics going on out there. My favourites are:

1.0 M87. In Virgo. A massive super black hole is at the heart from which a plasma jet extends 500 light years.The diameter of this is equivalent to the orbit of Pluto, rotating at 1000 k/s.There are 1200 globular clusters.

2.0 Epsilon Aurigae. A binary system with a dying double solar mass combined with a companion and a dust disc. This produces a 27 cycle with a 2 year dimming period.

3.0 Gamma Trianguli. A spheroid star with a debris disc. Dwarf star just over double the Sun's radius , but spinning at 208 k/s ( x140 that of the Sun) . rotating in 12 hours. The accretion disc is separated by 80AU.

4.0 Kappa Geminorum: visually orange and pale blue,the giant A is being orbited by a Sun like dwarf. Very lovely visually.

5.0 Lambda Bootis. The original in a class of only 50 rare stars which have their outer layers mostly depleted of chromium,barium, nickel and titanium. Thought to be caused by an early dusty gas depleting by absorption, starlight pressure pushed the dust away and the gas settled to become part of the star.

These are objects that you can turn your scope , you won't see what's happening ! I 've stuck to visuals as there's a lot more happening further out.

I'm not a physicist , just a simple observer, so I apologise if I've misunderstood what I've written.

Any others to look at in wonder ?

Nick.

[badgerchap]

I like VY Canis Majoris for its sheer size - 236 (I think) solar masses! Nobody understands how a star can reach this mass as it should have blown most of the material away when it first began to fuse H. I also like Eta Carinae, just because it looks so malevolently violent.

[Stargazer_00]

VY Canis Majoris is quite a bit more than 236 solar masses.

If you imagine the Sun's diameter to be 1cm then VY Canis Majoris would have a diameter of 2km. Or 200,000cm

It's literally insanely big, so big in fact that it broke the model for what physicists thoughts was the maximum size a thing could be. It is a hyper star. Incredibly dim object from earth, if it were closer I dont think I'd sleep well at night

EDIT: Sure everyone has seen this but on the off chance someone hasn't its a real eye opener!

[Knight of Clear Skies]

1.0 M87. In Virgo. A massive super black hole is at the heart from which a plasma jet extends 500 light years.The diameter of this is equivalent to the orbit of Pluto, rotating at 1000 k/s.There are 1200 globular clusters.

In a similar vein, the Death Star Galaxy is worth a mention. The jet from its central black hole's accretion disc is impinging on another galaxy. Even at a range of 20,000 light years, it's powerful enough to damage the atmosphere of any planets in it's path. However, it could literally be a jet of both life and death. It could potentially kill off life on the surface of planets, but it is also compressing gas and triggering star formation.

[DazC]

VY Canis Majoris is quite a bit more than 236 solar masses.

If you imagine the Sun's diameter to be 1cm then VY Canis Majoris would have a diameter of 2km. Or 200,000cm

It's literally insanely big, so big in fact that it broke the model for what physicists thoughts was the maximum size a thing could be. It is a hyper star. Incredibly dim object from earth, if it were closer I dont think I'd sleep well at night

EDIT: Sure everyone has seen this but on the off chance someone hasn't its a real eye opener!

Thanks for posting this link Stargazing00, i had not seen that bofore.

I t really puts things into perspective.

D.C

[badgerchap]

That's stellar radius - not mass. Depending on thhe type of star, you can have a solar mass star witha a greater / lower radius, depending on the stage of its life. Also, the higher the mass of a star, the bigger it is - the bigger it is, the more distant the outer layers from the centre and the lower the magnitude of the gravitational field at that point. Because gravity follows an inverse square (1/r^2) law, even though the mass is greater, there is a point at which radius outdoes gravity. This means that as stars increase in mass, they will increase faster in radius. So although VY Canis Majoris is indeed >1000 times the radius of the sun, its mass is not nearly as high (though still huge). This relationship between mass and radius is what makes this star particularly interesting. It shouldn't exist - at the mass it is it should be blasting its loosly assosciated layers clean off, or at least should have done before it formed. VY Canis Majoris is an example of a star that is contradicting current theories of star formation for this reason.

[badgerchap]

Just reread that and noticed how terribly I have explained all that. Apologies.

[Knight of Clear Skies]

The relationship between mass and the size of a body can be quite complicated.

In the case of Jupiter, if you added more mass, it would actually get smaller. This is because it's mostly composed of gas, which is highly compressible. The increased strength of the gravitational field would shrink it. Jupiter is about as big as a planet of it's temperature can be. There are planets larger than Jupiter, but only only because they orbit close to their parent star. Gas expands as it is heated.

The factors which determine the the size of a star are mass, which compresses it under the force of gravity, and rate of energy production, which causes it to expand under radiation pressure.

In the case of a main-sequence hydrogen-burning star, adding mass increases the pressure on the core, compressing it and makes it more dense. However, his increases the rate of nuclear fusion as nuclei are jammed together with increased force, which releases more energy, causing the outer layers of the star to expand due to radiation pressure.

Red Giants are far larger than main sequence stars. This is because the core has (mostly) run out of fuel, causing it to collapse and the density and pressure to greatly increase. Hydrogen fusion now occurs in a zone between the core and the outer layers, at a far higher rate than before due to the increased pressure and size of the fusion zone. The increased radiation pressure causes the outer layers of the star to expand. The outer layers of a Red Giant can be very tenuous, closer in density to vacuum than the Earth's stratosphere.

In the case of VY Canis Majoris, please bear in mind there are very large uncertainties in it's estimated size.

[badgerchap]

Thanks - much more eloquently put than I could manage.

[DaveS]

3C 273

It's just within the visual grasp of an 8" from a dark site.

2 billion LY away, probably the most distant thing you're likely to see AND the brightest / closest quasar.

something to think about.

[Scott]

OK, I'm going to be a tad boring here but the more I see, the more it makes me think the most incredible thing I've seen is our own piece of rock. Alright, so it's probably almost definately not the only planet in the universe to sustain intelligent life (?) or even in our own galaxy, but for everything to be just right at just the right time to me is pretty amazing. Ok, so it's probably not going to have any affect on the scheme of things but it's still pretty cool.

[Stargazer_00]

Indeed. And How precious life actually is.

[Pig]

I found this on you tube - it puts the size of stars etc into perspective