How many kinds of stars are there?

1. Brown Dwarfs
2. Neutron and Pulsar
3. Yellow White
3. Blue White
4. White Dwarf
5. Red Giant
6. Super Red Giant
7. Red Dwarf
8. Blue Giant
9. Possibly Quark Stars

Are there green stars to? What other kinds and what does G2, G3 and other things like this mean? What does class M planet and stuff like this mean?

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Probably some of the stuff you're looking for is here.

Or possibly here.

Enjoy. 8)

Or here about spectra and spectral classes.

How about black holes? :-?

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Pre Main Sequence

Proto Stars (Thermal Output)
T-Tauri Stars (Gravitational/Thermal Output)
Brown Dwarfs (Thermal Output)
Red Dwarfs (Thermal/Nuclear Output, Deterium Fusion only)

Main Sequence

Blue Dwarfs (Nuclear Output, Hydrogen Burning)
Yellow Dwarfs (Nuclear Output, Hydrogen Burning)
Yellow Sub-Giants (Nuclear Output, Hydrogen Burning)
Blue Sub-Giants (Nuclear Output, Hydrogen Burning)

Post Main Sequence
Red Giants (Nuclear Output, Helium Burning)
[i]Blue Giants (Nuclear Output, Carbon Burning)
Wolf-Rayet (Nuclear Output, Carbon Burning?, High Mass Loss)
Yellow Giants (Nuclear Output, Oxygen Burning)
Blue Supergiants (Nuclear Output, H, He, and Carbon Burning)
Yellow Supergiants (Nuclear Output, H, He, C, and Oxygen Burning)
Red Supergiants (Nuclear Output, H, He, C, O, Sulfer and Silicon Burning)
Hypergiants (Colors as supergiants, mass of star is at theroretical maximum limit and is on last stages of evolution. Only 7 known Hypergiants in milkway, these stars so massive they may have spent as little as 10000 years in main sequence (hydrogen burning) stage)

Dead Stars
White Dwarfs (Thermal Output)
Black Dwarfs (No Output)
Nutron/Pulsars (Gravitational Output)
Magnatars(Gravitational/EM Output)
Black Holes
Supermassive BH/AGN/Quasars (No Visiable Output, expect when in Outburst stages)
White Holes (Theroretical, Disproven)
Quark Stars (Theroretical)

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"Main sequence star" is a synonym for "dwarf". So a blue O main sequence star is much brighter than the Sun in its red gianthood but still it is technically a "blue dwarf". Blue giants and supergiants have given up hydrogen fusion in their cores and started to evolve.

Red (spectral class M), orange (K), yellow (G), yellow-white (F), white (A), blue-white (B), blue (O) dwarfs (V), subgiants (luminosity class IV), giants (III), bright giants (II), lesser supergiants (Ib), bright supergiants (Ia), hypergiants (0)...
Also there are carbon stars (C, S, N) and Wolf-Rayet stars (W).
There are also number of unusual stars like peculiar A stars or shell stars.

Quasars are not stars, but distant active galaxy cores powered by supermassive black holes (millions to billions of solar masses).
Among neutron stars there are also magnetars.

There are also great variety of variable stars and close binary stars.

How big is a blue super giant? They sound like a neat star to create a hard SF world around. I'm into that sort of thing.

__________________
If we don't play god, who will?-James Watson
I never think of the future, it comes soon enough.-Albert Einstein
The large print giveth and the small print taketh away.-Tom Waits
Any sufficiently advanced technology is indistinguishable from a yo-yo.-Enoch Root, The Confusion
When I was a kid, if someone brandished a shrink gun he'd get a little bit of respect!-Myron Reducto, Harvey Birdman

Let's see... Jim Kaler has arranged his star articles according to their spectral classes. For example, O5 Ia (blue supergiant) Naos (Zeta Puppis) is a star some 50 times more massive than the Sun and has a radius of 20 times solar. It is 20,000 times more luminous than the Sun in visible light. Note that its surface as a O star is much more hotter than red star's so it does not have to be very large to be very bright (but because it is hot, it shines mostly in UV light: total radiation output is million times greater than Sun's). (The very brightest stars like Eta Carinae are both hot and large.)

Wow They'd be fried if they were like most of the life on Earth. They'd need to be able to paste their DNA(or their version of genetic material) back together like some bacteria can. The planet would probably have to be about as far from the star as Saturn is wouldn't it to keep from cooking? Unless the life also can live at 500+C. Wow!

__________________
If we don't play god, who will?-James Watson
I never think of the future, it comes soon enough.-Albert Einstein
The large print giveth and the small print taketh away.-Tom Waits
Any sufficiently advanced technology is indistinguishable from a yo-yo.-Enoch Root, The Confusion
When I was a kid, if someone brandished a shrink gun he'd get a little bit of respect!-Myron Reducto, Harvey Birdman

UV radiation is rather nasty thing: it not just lethal to life but wrecks planetary formation too!

Well what's a yellow supergiant like and if they do exist what would a yellow hypergiant be like? That could get interesting, a Sol sized yellow- white could orbit the super or hypergiant from a very far distance and this smaller star could have a system of planets around it? Trippy hard SF.

__________________
If we don't play god, who will?-James Watson
I never think of the future, it comes soon enough.-Albert Einstein
The large print giveth and the small print taketh away.-Tom Waits
Any sufficiently advanced technology is indistinguishable from a yo-yo.-Enoch Root, The Confusion
When I was a kid, if someone brandished a shrink gun he'd get a little bit of respect!-Myron Reducto, Harvey Birdman

You are not going to have life evolving on a planet orbiting a giant, supergiant or hypergiant star (of any color). They (the stars) just don't live long enough (tens to hundreds of millions of years) for life to evolve. In fact, an Earth sized planet would barely have time to solidify befor the star went blooey (technical term :wink: ).

If you are going to use one in a Sci-Fi story, you'll be better off having observers/explorers arriving from outside.

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Blue Stragglers -- result of two main sequence stars merging

Is there a name for a still-fusing core of a red giant, stripped bare by a companion star? I know such exist.

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Yes, they are called the Wolf-Rayet stars. But on the other hand some WR stars lose their hydrogen envelopes by themselves.

Ultraviolet radiation from these stars is so immense that it probably prevents any formation of planets around them or in neighboring stars. There are good examples in the Orion Nebula how the brightest stars of Trapezium Cluster destroy protoplanetary disks (proplyds) around smaller stars.

Yellow supergiants (class F, G) (they're evolving to red supergiants) often become unstable and star to pulsate. Bright cepheids are such stars. Example: Polaris.

I know only one yellow hypergiant, and it is called Rho Cassiopeiae.

I think this one deserves an answer too: Class M planets etc. are Star Trek stuff.

In reality there are following types of planets:

In the Solar System:

Terrestrial planets (rocky, thin atmosphere, few or no moons): Mercury, Venus, Earth, and Mars
Jovian (gas giant) planets (no solid surface, very thick atmosphere, many moons, rings): Jupiter and Saturn.
Uranus and Neptune are often classified as ice giants since their composition and structure is different from Jupiter and Saturn.
Pluto is sometimes classified as an ice dwarf. The reason why it is called a planet and not a Kuiper Belt object is historical.

Extrasolar planets (this is more or less unofficial classification):

Super-hot Jupiters: Jovian planets that orbit their parent stars in extremely short orbits (in less than 2 days). All of them have been found using the transit method. Example: OGLE-TR-56 b.
Hot Jupiters (Pegasids): Jovian planets that orbit their parent stars in every few days. Example: First extrasolar planet around a sunlike star, 51 Pegasi b.
Eccentric Jupiters: Jovian planets that orbit in very oval orbits. Currently the most common type of planets. Example: 70 Virginis b.
Classic Jovians: Jovian planets that resemble the Jovian planets in the Solar System. Example: 47 Ursae Majoris b and c.
Hot Neptunes or hot super-Earths: Neptune-mass planets that orbit in orbits similar to hot Jupiters. They may be rocky planets with relatively thin atmosphere. Example: Mu Arae d.
Pulsar planets: these planets have mass similar to the terrestrial planets. First extrasolar planets that were discovered were pulsar planets orbiting the pulsar PSR 1257+10. There are three of them, mass ranging from lunar to 3 Earths. Likely a very rare class of planets.
There are also so-called free-floating or rogue planets, planetary-mass bodies that don't orbit any star. It is not clear if they're real planets but sub-brown dwarfs instead. Probably bona fide planets that have escaped their systems exist, but they are very difficult to detect. Example: S Ori 70.
Recently imaged brown dwarf planet 2M1207 b doesn't fit any of these categories. It likely formed different way than normal Jovian planets.

Some hypothetical planet classes:

Cthonian planets: hot Jupiters that have lost their atmosphere and are now massive molten balls of rock.
Oceanic planets: warmed-up ice giants that have lost their atmosphere and are covered with global deep oceans.
Trojan planets: planets that are located in binary star systems' trojan points.

Hmmm-never heard of supergiant or hypergiant stars. Time to do some reading.

8)

Are there any stars whose maximum emission peaks in the X-ray portion of the EM spectrum? UV stars are common, but I haven't heard much about an X-ray star. Oh yeah, not including black holes, neutron stars/pulsars, and "special" stars.

No (as far as I know). There are stars whose emission peaks in the far-UV range, the piece of spectrum that's hard to see because of interstellar hydrogen absorption (between about 50-912 Angstroms). Most O stars come in this category - their intensity is still rising to short wavelengths when we reach the hydrogen absorption edge, and one must rely on models and what little we can see through the gas for nearby stars. Some white dwarfs (like Sirius B) are hot enough that we do see the soft X-rays from their thermal surface emission, but it doesn't actually peak there. Strong stellar X-ray sources are all from accreting compact objects in binaries; weaker emission can come from stars with strong winds and magnetic fields, which is why one sees proto- and young stars preferentially. (There is a huge Chandra survey to look deeply at the young stars in the Orion Nebula, for example). Go deep enough with an X-ray telescope and you see normal coronae, for cooler stars.

Thanks for all the info, I learned alot. How long do yellow giants(not super or hyper) last? How do they compare with Sol as to what they'd do to an orbiting planet? Kind of stinks that there are no green stars at least that we can see, well that's our eyes for us. As an aside note: Is this the same reason why green fire doesn't work unless copper is being burned in there to? Why can't the heat be just right that only green light is given off when methane or other flamable gases are burned?

__________________
If we don't play god, who will?-James Watson
I never think of the future, it comes soon enough.-Albert Einstein
The large print giveth and the small print taketh away.-Tom Waits
Any sufficiently advanced technology is indistinguishable from a yo-yo.-Enoch Root, The Confusion
When I was a kid, if someone brandished a shrink gun he'd get a little bit of respect!-Myron Reducto, Harvey Birdman

Because the way a rising temperature gas emits light affects our eyes about like this: brown-red-orange-yellow-white-pastel blue.

Off-topic, but nice quote, SkepticJ! Another funny spin-off from the Guns don't kill people.

Here is some new info on the percentage of stars of different types in the Galaxy. It's a little old, and apparently counts only main sequence stars--brown and white dwarfs are fairly numerous--and not giants or supergiants. It's from The Search for Life in the Universe, by Donald Goldsmith and Tobias Owen (New York: Addison-Wesley, 1992).

from page 398:

Spectral Type / Percent of Total
O / 0.00002
B / 0.09
A / 0.6
F / 2.9
G / 7.3
K / 15.0
M / 73.0

You seem to be interested in yellow supergiant stars, SkepticJ;
There are three in the autumn sky; Enif, Sadalmelik and Sadalsuud.

They are only going to be yellow and hospitable for a short while, and seem to be subject to flare-ups- but they could hold an artificial solar system for a short while. I've put colonies around Sadalmelik and Enif myself.

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Isnt there just two kinds of planets.....terrestrial and gas giant?

Different flavors within that.

Jupiter and Neptune are both gas giants, but they are very different animals from one another.

By the same token, a 14 mass terrestrial planet is going to be a very different animal than Earth.

Though Pluto is a solid planet, its unlike anything that formed in the inner solar system.

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Don't forget the Magnetar-Stars described as a type of neutronstar with a super-strong magnetic field, the magnetic fields get so powerful that the solid neutron star crust buckles and power the mysterious soft gamma repeaters into space

As far as planets go, I'v been working on a classification scheme for some time:

http://j.dollan.home.bresnan.net/ARCpclindex.html

A revision currently underway is here:

http://j.dollan.home.bresnan.net/ARCPCLIndex4ed.html

Pleae note that this is a fictional list. But in the revision, I am trying to make it as realistic as possible.

...John...

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First, even within our Solar system there are at least three kinds, and possibly four. Uranus and Neptune are NOT "gas giants", they are "ice giants" (hydrogen and helium make up only 10-20% of their mass). And if you consider Pluto a planet (not everyone does), then it is in a class by itself -- Pluto is very unlike the four inner planets.

And second, with only none examples you can not define a lot of "classes". As time goes by and detection techniques improve, we will find more planets completely unlike anything in the Solar system, as well as some "in-between". A planet with 8 Earth masses will not be just Earth writ large -- it will be something between Earth and Uranus in properties other than size.

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