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1)placing cosmological constraints on the expansion of the Universe through the determination of distances to galaxies

2)to measure many characteristics of our galaxy and our relationship to it

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What is a Cepheid Variable?

A Cepheid is a member of a particular class of variable stars. The relationship between a Cepheid variable's luminosity and pulsation period is quite precise, securing classical Cepheids as viable standard candles and the foundation of the Extragalactic Distance Scale. See related link for more information


Why are Cepheid variable so important for measuring long distances in the universe?

The perceived brightness of an object with known brightness can be used to gauge distances. Cepheid variables are known to have a brightness directly related to their period. Which means that if we know the period of the Cepheid variable, we know what its brightness is, and can use it to gauge the distance to the stellar group the Cepheid is part of.


Are any know stars 100000 light years away?

No. The Milky Way Galaxy is approximately 100,000 light years in diameter. The Solar System is about 26,000 light years from the center of the galaxy. Thus the furthest stars which are in the galaxy would be about 74,000 light years away but we can't actually see them because there is too much gas and dust and other stars in the way. The Milky Way does have four dwarf galaxies nearby. two of them are closer than 100,000 light years. The other two, the Magellanic Clouds are farther, 160,00 and 200,000 light years away, respectively. Individual stars can be seen in those galaxies and imortant studies of them have been made. In particular, study of the cepheid variable stars in those galaxies showed a simple mathematical relationship between their pariod of variability and their absolute magnitude, or brightness. Once the actual distance to a nearby cepheid was determined, this allowed us to calculate the distances to all known cepheid variables, including those in the Magellanic Clouds and other galaxies out to a few million light years distance.


Are some stars about as small as earth is?

Yes, there are some stars as small as earth. It depends, however, on where the stars are located and how long they have been burnt out.


Which sources of light have been found to be collections of billions of stars and not individual stars?

Galaxies, such as the Milky Way and Andromeda, are sources of light that have been found to be collections of billions of stars rather than individual stars. These galaxies contain vast numbers of stars, dust, and gas held together by gravity.

Related Questions

What is a Cepheid Variable?

A Cepheid is a member of a particular class of variable stars. The relationship between a Cepheid variable's luminosity and pulsation period is quite precise, securing classical Cepheids as viable standard candles and the foundation of the Extragalactic Distance Scale. See related link for more information


How far away is alpha lupi from earth?

Alpha Lupi is 550 ly from Earth. It is a giant hot blue star of type B1.5. It has also been classified as a Beta Cepheid Variable.


What should have been the only independent variable in paola's experiment?

The only independent variable in Paola's experiment should have been the factor that she intentionally manipulated or varied in order to observe its effect on the dependent variable. This allows her to determine any causal relationships between the independent variable and the outcomes.


Why are Cepheid variable so important for measuring long distances in the universe?

The perceived brightness of an object with known brightness can be used to gauge distances. Cepheid variables are known to have a brightness directly related to their period. Which means that if we know the period of the Cepheid variable, we know what its brightness is, and can use it to gauge the distance to the stellar group the Cepheid is part of.


How is star brightness mesured?

To find the distance to Cepheid variable stars and other pulsating stars, Astronomers find the period-luminosity relation (A relation between the pulsation period of a Cepheid variable and its absolute brightness).The period-luminosity relationship has been calibrated by many astronomers throughout the twentieth century. A calibration was published by Michael Feast and Robin Catchpole in 1997 using trigonometric parallaxes determined by the Hipparcos satellite. The relationship between a Population I Cepheid's period P, and its luminosity, measured as its mean absolute magnitude Mv was "Mv=-2.81log(P)-(1.43±0.1)" with P measured in days.The following relations can also be used to calculate the distance d and reddenings E(B − V) to classical Cepheids:"5log10d=V+(3.43)log10P-(2.58)(V-I)+7.50" "5log10d=V+(4.42)log10P-(3.43)(B-V)+7.15" "E(B-V)=-(0.27)log10P+(0.41)(V-J)-0.26" Where J is on the 2MASS photometric system, and B, I and V represent blue, near infrared, and visual, respectively.


What is sentence of always?

Passive voice: It has always been hard to determine distance to the stars. Present voice. As always, it is difficult to determine the distance to the stars. Future participle: According to Einstein, it will always be difficult to determine if relativity is correct. Object; What is a sentence of always?


Why are stars important to navigators and astrologers?

Stars have been used for centuries as a natural means of navigating the Earth. Stars are often used to determine the navigator's location. Astrologers use stars mostly for predictions in astrology.


Are any know stars 100000 light years away?

No. The Milky Way Galaxy is approximately 100,000 light years in diameter. The Solar System is about 26,000 light years from the center of the galaxy. Thus the furthest stars which are in the galaxy would be about 74,000 light years away but we can't actually see them because there is too much gas and dust and other stars in the way. The Milky Way does have four dwarf galaxies nearby. two of them are closer than 100,000 light years. The other two, the Magellanic Clouds are farther, 160,00 and 200,000 light years away, respectively. Individual stars can be seen in those galaxies and imortant studies of them have been made. In particular, study of the cepheid variable stars in those galaxies showed a simple mathematical relationship between their pariod of variability and their absolute magnitude, or brightness. Once the actual distance to a nearby cepheid was determined, this allowed us to calculate the distances to all known cepheid variables, including those in the Magellanic Clouds and other galaxies out to a few million light years distance.


What variable has pupil changed?

The variable that has been changed is the independent variable.


What is aforementioned variable?

A variable that has been mentioned previously.


How can called function determine number of arguments that have been passed to it in C language?

use the variable length argument - va_arg va_list ca_start and va_end macros


Which variable have been held constant?

Logic fault ---> no such thing as a constant variable (by axiom: def of variable) []