Star types/Classes

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Acknowledgements

Data as from:

United Confederation of Interstellar Planets Science Academy Guide
Stardate 239802.26 Ver1.0
Author: Lieutenant Commander Ma'bor Jetrel
Stardate 239808.03 Ver2.0
Updated and compiled by Ensign Ryukanden Suwada
Stardate 239907.14 Ver3.0
Updated by Henrich VonKraus
Stardate 241309.22 LCARS Version
Formatted by: Arcos


Types and Timelines of Stars:

Spectral Types: There are seven major spectral types of stars, forming a continuous band of types from O through M: O B A F G K M
These are divided into ten numbered subtypes, for example: A0 A1 A2 A3 A4 A5 A6 A7 A9 F0

Stars at the "0" end of this band are hotter (around 50,000 degrees K), bluer in color and more massive; those at the other end are cooler (around 2,000 degrees K), redder in color and less massive.

A conventional code for star color is: (lighting order)

Type Color Temperature Mass Radius
O Violet-white 30,000-50,000K 10-30 solar masses 2.5-3.0 solar radii
B Blue-white 10,000-30,000K 3-5 solar masses 2.0-3.5 solar radii
A White 7,500-10,000K 2-3 solar masses 1.5-2.0 solar radii
F Yellow-white 6,000-7,500K 1-2 solar masses 1.0-1.5 solar radii
G Yellow 4,500-6,000K .8-1 solar masses 0.8-1.0 solar radii
K Orange 3,500-4,500K .5-.8 solar masses 0.5-0.8 solar radii
M Red 2,000-3,500K .02-.5 solar masses0.1-.5 solar radii

While a "Giant" star may have a radius of up to 1,000 times that of Sol and be up to 100,000 times as luminous, most stars are in the "main sequence" portion of their lifetimes and have values near the typical main sequence ones for their type. Type O stars may live for as little as a few hundred million years, while it is believed that type M stars may live for as long as 30 or 40 billion years. Sol, Earth's sun, is type G. Its spectrum, as filtered by Earth's atmosphere, is the basis for standard illumination in Human quarters.

Chronicalstardiagram.png

POPULATION:

Population 1 stars are old stars well down the main sequence (class F, G, K, and M stars) and short on heavier elements. Planetary systems accompanying Population 1 stars primarily consist of gas giants without accompanying satellites.

Population 2 stars are younger stars showing traces of heavier elements, hydrogen and helium. Planetary systems accompanying Population 2 stars include gas giants, stony worlds, satellite companions and planetoid and comet shells.

STAR PHASES:


Dwarfs:(White/Red/Brown/Black)

Dwarfs are relatively classified as the small dim-lit stars because they have gone through two gravitational collapses. "Dwarf" is a category comprising various small and dim energy-radiating or formerly energy-radiating celestial objects.
White Dwarf: Whitedwarf.jpg


Primarily degenerate matter, this main sequence star, usually of type G-late A, has completed nuclear burning processes and has
collapsed into a configuration roughly the size of a small planet which takes a very long significant time.
White dwarfs radiate at various levels of intensity through self-gravitational collapse.
Nuclear burning occurs only on the surface through accretion of unburned matter from other sources;
in such cases, nuclear ignition can regularly occur and is the source of the "recurrent nova" effect.
The spectral class of white dwarf stars is usually prefixed with a D.


Red Dwarf:Reddwarf.jpg


A red dwarf is a main sequence star of a type M. A red dwarf is a small star which was able to ignite.
However, these stars usually have very low solar masses, and, as a result, burn for a very long time.
Also, these stars, due to the slow burn rate and low temperature, tend to burn with a red color, hence the label red.


Brown Dwarf:Browndwarf.jpg


A brown dwarf is a gaseous body producing much more energy through self-gravitation than it receives from the ambient medium,


but which may not be massive enough to initiate internal fusion reaction and, therefore, not truly a star.
These stars are usually only hot enough to produce infrared emissions, or a very deep red light.
Brown dwarfs hot enough to produce visible light ("substellar objects") are listed as Class S planets.
Those producing infrared ("thermal edens") are listed as Class T planets.
They are both also known as supergiant gas planets.
Some gas giant planets (Class A) may produce slightly more energy than they receive, but they are not generally considered to be brown dwarfs.
Black Dwarf:Blackdwarf.gif

A black dwarf is the remains of a white dwarf once it has cooled down to the point that it is no-longer radiating.
As the white dwarf cools, it finally cools to the point that it is no longer radiating in the visible spectrum, and at that point, is designated a black dwarf.


Sun Sun1a.jpg

Term describing the medium sized to medium small stars in the universe that normally has at least one Class-M planet.
Sol, the Earth's sun is a medium sized star.
They normally burn for five billion years,
at which point they move onto the next phase of star development.
At the point that the star uses up the hydrogen in the core,
it will begin to contract, re-igniting the shell around the core,
and creating a Red Giant. However, a nova is something completely different
and is unrelated to the actual lifecycle of a star.


Red Giant:Redgiant1.jpg

The red giant phase is common in the evolution of many less massive stars.
When core hydrogen is exhausted, gravitational collapse ignites hydrogen shell burning outside the core.
The star's envelope expands far beyond the photosphere limit.
The star's atmosphere is extremely tenuous and relatively cool.
Following Red Giant stage for stars less than 3 Solar masses,
the outer shell of the star will continue to cool and move out to form a ring around the remaining white dwarf star.
This ring is what is known as a Planetary Nebula.
For stars of 3 solar masses and greater, this stage is followed by a supernova.


Blue Straggler:Bluestraggler1.jpg


Hot, massive, bright blue stars found in the cores of a few globular clusters,
stragglers are formed by the head-on collision of two red giant stars.

The increase of mass and fresh hydrogen mixture from the envelope into the new star's core causes the star to behave like an extremely massive young star, no matter the age of its progenitors.
Red Supergiant:Redsupergiant1.jpg

If the shell outside the core is high enough in hydrogen, the envelope may expand even farther.


Supernova:Supernova1a.jpg

When a massive young star exhausts it's core hydrogen, it undergoes second-stage gravitational collapse.
The resulting core temperature increase leads to runaway nuclear burning. This causes the fusion of heavier and heavier elements(Helium, Carbon, Oxygen, up to Iron).
However, when the fusion gets to the point that Iron O's present in the core, it is no-longer able to fuse the atoms.
At this point, the star begins an irreversible collapse.
The mass of the star falls down onto the star, including the outer layers previously making the red giant.
Because of the violence of this collapse, as well as the abundance of lighter elements in the outer layers, fusion begins again, except that this time it cannot sustain the weight of the star.
This fusion causes the explosion of the star in an extremely powerful explosion.
If any planets exist around such a star, they now are dead, if they weren't already dead from the Red Giant stage.
Supernova explosions are the major source of metals and other heavy galactic elements.
Supernovae are also responsible for high neutrino emissions which can be detected from far away shortly after the explosion.


Neutron Star:Neutronstar1.jpg

A neutron star is usually type B-0 and measures only a few kilometers in diameter.
A neutron star is formed when a star of about 3 to about 5 solar masses undergoes gravitational collapse at the end of its lifetime.
During the gravitational collapse, the star begins the runaway fusion of elements as stated in the Supernova description, and continues until it reaches iron, since Iron cannot be fused.
At the point Iron is reached, the mass of the star collapses upon itself, and reignites in a spectacular explosion, thus causing a supernova.
This violent contraction forces the electrons of the Iron into the cores and drives them into the protons, thus creating neutrons.
As the nebula which is the remnants of the star disperses at high speed, the neutron core is left spinning at extremely high velocity.
This rate of spin is also what creates the radio waves which we are able to detect.


Black Hole:Blackwhole1.jpg

A black hole is the other possible result of a supernova.
A black hole forms in a similar fashion to a Neutron Star.
However, there are a few differences.
In the case of a black hole, what happens is that the star undergoes the violent gravitational collapse seen in the formation of a Neutron star.
However, in the rebounding explosion, there is sufficient implosion force due to the sheer mass involved that the atomic forces are overcome and all the matter is forced into a singularity.
Around this singularity is what is known as an Event Horizon.
At the Event Horizon, the escape velocity from the star is equal to the speed of light.
Anything travelling slower than the speed of light which passes through this horizon will be pulled into the black hole.
Additionally, the tidal forces across an object in the vicinity of a black hole are so extreme that a person falling toward the black hole feet-first would have their feet and legs ripped off before even reaching the event horizon.
Because it is nearly impossible to get close enough to one to conduct an exhaustive study, very little is known about them. However, we do know a few things.
Black holes are called black because of the fact that no light escapes from inside them, and because of the fact that they seem to be able to engulf an infinite amount of mass without filling up.
Further, we know that they exist because matter falling into them does radiate.
Matter falling into a black hole radiates X-rays in large amounts, which are detectible.
Additionally, black holes can also be detected because of the "lensing effect".
This is an effect which is found near large gravity wells.
If a large gravity well is placed between a light source and an observer, that light source will appear to form a ring around the gravity well.
Additionally, if the observer or the light source moves one way or the other, the light source will appear as if it were being viewed through a lens.
The deeper the gravity well, the greater the distortion.



Lazarus Star:Lazarusstar1.png

A Lazarus Star is a supernova remnant which, instead of being forced inward into neutron-star mode, survives as a normal star.
After expansion into red giant phase, Lazarus stars collapse and undergo supernova for a second time. (comment: Photo may represent other phenomena... or even just be a star located directly in line behind ejected proto-mater.)


Nova:Nova1.jpg

Start with two stars. Usually, one is much smaller and dimmer than the other.
These two stars are in a binary pair and are spinning around each-other.
As they spin, some of the mass leaves the larger of the two stars and accretes on the smaller of the two.
This continues until there is sufficient mass on the smaller to ignite nuclear fusion, at which point the smaller star gets extremely bright in a very large nuclear reaction.
This brightening is known as a Nova, because people in ancient years on Sol III believed that they were seeing a new star in the heavens.
After a number of days, the nuclear reaction has consumed the fuel available and the cycle begins again.
Usually, the recipient of the falling matter is either a white dwarf or a small, dim-lighted star; however, this can also happen with a normal-sized star, similar to Sol.


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Acknowledgements - Images:


White Dwarf: "http://cronodon.com/SpaceTech/WhiteDwarf.html" cronodon.com
Red Dwarf:"http://wolflodge.org/bluestar/bluestar.htm" wolflodge.org
Brown Dwarf:"http://scienceforkids.kidipede.com/physics/space/browndwarf.htm" 1998-2012.Kidipede.com
Black Dwarf:"http://www.williamsclass.com/EighthScienceWork/StellarEvolution.htm"2003.williamsclass.com
Sun:"http://curious.astro.cornell.edu/sun.php"2011.astro.cornell.edu
Red Giant:"http://cse.ssl.berkeley.edu/bmendez/ay10/2000/cycle/redgiant.html"2000.<berkeley.edu
Blue Straggler: "http://www.orionsarm.com/eg-article/4f7ae10c85741"2012.orionsarm.com
Red Super Giant:"http://www.passmyexams.co.uk/GCSE/physics/death-of-very-high-mass-stars-black-holes.html"2012.passmyexams.co.uk
Supernova: "http://www.hans-peter.org/NiceDay/index.php hans-peter.org
Neutron Star: "http://www.orionsarm.com/eg-article/46d4bf6c4e652"2001. orionsarm.com
Black Hole: "http://didyouknowarchive.com/?p=1755"2012. didyouknowarchive.com
Lazarus Star: "http://annesastronomynews.com/photo-gallery-ii/nebulae-clouds/supernova-remnant-1e-0102-2-7219-e0102-is-an-oxygen-rich-supernova-with-a-hotter-outer-ring-surrounding-a-cooler-denser-inner-ring-190000-ly-away-in-tucana-in-the-small-megallanic-cloud/"2012-2013.annesastronomynews.com
Nova: "http://science.psu.edu/news-and-events/2005-news/Burrows8-2005.htm"2005.science.psu.edu