there are seven main types of stars.In order of decreasing temperature O,B,A,F,G,K and M.
O and B stars are uncommon but very bright;
M stars are commonn but dim.
Hertzsprung:
The Hertsprung russell(H-R)diagarm is a graph plots stars color(spectral type or surface temperature)vs. its limonisity(instrinsic brightness or absolute magnitude).
- Most stars including to the sun, are "main sequence stars"fueled by Nuclear fusion converting hydrogen into helium.For these stare the hotter are the brigther.
- As stars to begin to die, they become giant and supergiants(above the main sequence).These stars are depleted their hydrogen supply and are very old.These stars will eventually explode and the become white drwafs,neutron stars or black holes.
- Smaller stars become eventually faint whits dwarfs that are belowthe masin sequence,These hot, shrinking stars have depleted their nuclear fuels and will eventually cold,dark and black dwarfs.
DWARF STARS
Dward stars are relatively small stars,up to 20 times larger than our sun and up wo 20,000 times brightness.Our sun is a Dwarf star
Yellow Dwarf
Yellow Dwarf is small,main sequence, The sun is yellow Dwarf.
Red Dwarf
Is small,cool,very faint main sequence star whose surface temperature in under about 4,000K.Red dwarfs are the most common type of star.Proxima centuari is a red dwarf.
Red giant
Is a relatively old star whose diameter is about 100 times bigger than it was originally,and had become cooler(the surface temperature is under 6,500K).They are frequently orange in color.Betelgeuse is a red giant.It is about 20 times as massive as the sun about 14,000 times brighter than the sun,and about 600 light-years from earth.
Blue giant
Is a huge,very hot,blue star.it is a post-main sequence star thet burns helium.
Supergiant
Is the largest known star;some are almost as large as our entire solar system.Betelgeuse and Rigel are supergiant.These stars are rare.When supergiants die they supernova and become a black hole.
White dwarf
is a small very dence,very hot that is mad of carbon.These faint stars are what remains after a red giant star loses our outer layers.Their nuclear cores are depleted.They are about size of the earth(but tremendously havier) They will eventually lose their weight and become a cold,dark black dwarf.Our sun will someday turn into a white dwarf and then a black dwarf.the companion of sirius is a white star.
Brown star
Is a "star" whose mass is too small to have nuclear fusion at its core(the temperature and pressure as its core are insufficient for fusion) A brown dwarf is not very luminous.It is usually regarded as having a mass between 1028kg and 84 x 1028.
Neutron star
A neutron star is a very small, super-dense star which is composed mostly of tightly-packed neutrons. It has a thin atmosphere of hydrogen. It has a diameter of about 5-10 miles (5-16 km) and a density of roughly 10 15 gm/cm3.
PULSAR
A pulsar is a rapidly spinning neutron star that emits energy in pulses.
DOUBLE STAR
A double star is two stars that appear close to one another in the sky. Some are true binaries (two stars that revolve around one another); others just appear together from the Earth because they are both in the same line-of-sight.
BINARY STAR
A binary star is a system of two stars that rotate around a common center of mass (the barycenter). About half of all stars are in a group of at least two stars.
ECLIPSING BINARY
An eclipsing binary is two close stars that appear to be a single star varying in brightness. The variation in brightness is due to the stars periodically obscuring or enhancing one another. This binary star system is tilted (with respect ot us) so that its orbital plane is viewed from its edge.
X-RAY BINARY STAR
X-ray binary stars are a special type of binary star in which one of the stars is a collapsed object such as a white dwarf, neutron star, or black hole. As matter is stripped from the normal star, it falls into the collapsed star, producing X-rays.
CEPHEID VARIABLE STARS
Cepheid variables are stars that regularly pulsate in size and change in brightness. As the star increases in size, its brightness decreases; then, the reverse occurs. Cepheid Variables may not be permanently variable; the fluctuations may just be an unstable phase the star is going through. Polaris and Delta Cephei are examples of Cepheids.
Is small,cool,very faint main sequence star whose surface temperature in under about 4,000K.Red dwarfs are the most common type of star.Proxima centuari is a red dwarf.
Red giant
Is a relatively old star whose diameter is about 100 times bigger than it was originally,and had become cooler(the surface temperature is under 6,500K).They are frequently orange in color.Betelgeuse is a red giant.It is about 20 times as massive as the sun about 14,000 times brighter than the sun,and about 600 light-years from earth.
Blue giant
Is a huge,very hot,blue star.it is a post-main sequence star thet burns helium.
Supergiant
Is the largest known star;some are almost as large as our entire solar system.Betelgeuse and Rigel are supergiant.These stars are rare.When supergiants die they supernova and become a black hole.
White dwarf
is a small very dence,very hot that is mad of carbon.These faint stars are what remains after a red giant star loses our outer layers.Their nuclear cores are depleted.They are about size of the earth(but tremendously havier) They will eventually lose their weight and become a cold,dark black dwarf.Our sun will someday turn into a white dwarf and then a black dwarf.the companion of sirius is a white star.
Brown star
Is a "star" whose mass is too small to have nuclear fusion at its core(the temperature and pressure as its core are insufficient for fusion) A brown dwarf is not very luminous.It is usually regarded as having a mass between 1028kg and 84 x 1028.
Neutron star
A neutron star is a very small, super-dense star which is composed mostly of tightly-packed neutrons. It has a thin atmosphere of hydrogen. It has a diameter of about 5-10 miles (5-16 km) and a density of roughly 10 15 gm/cm3.
PULSAR
A pulsar is a rapidly spinning neutron star that emits energy in pulses.
DOUBLE STAR
A double star is two stars that appear close to one another in the sky. Some are true binaries (two stars that revolve around one another); others just appear together from the Earth because they are both in the same line-of-sight.
BINARY STAR
A binary star is a system of two stars that rotate around a common center of mass (the barycenter). About half of all stars are in a group of at least two stars.
ECLIPSING BINARY
An eclipsing binary is two close stars that appear to be a single star varying in brightness. The variation in brightness is due to the stars periodically obscuring or enhancing one another. This binary star system is tilted (with respect ot us) so that its orbital plane is viewed from its edge.
X-RAY BINARY STAR
X-ray binary stars are a special type of binary star in which one of the stars is a collapsed object such as a white dwarf, neutron star, or black hole. As matter is stripped from the normal star, it falls into the collapsed star, producing X-rays.
CEPHEID VARIABLE STARS
Cepheid variables are stars that regularly pulsate in size and change in brightness. As the star increases in size, its brightness decreases; then, the reverse occurs. Cepheid Variables may not be permanently variable; the fluctuations may just be an unstable phase the star is going through. Polaris and Delta Cephei are examples of Cepheids.
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