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How is the brightness of a Cepheid star calculated by knowing the period?
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How do you calculate the distance of nebulae?
There are many ways to calculate distance at huge scales. One popular way is using a Cepheid within the nebula. A Cepheid is a very luminous variable star (a star that changes brightness). The changing of brightness tells us a lot about the distance by measuring the period (time) and the luminosity. See the related link for more methods.
Why are pulsating variable stars useful for finding distances to globular clusters?
It really depends on the type of star, but for certain star types, there is a relationship between the period and the absolute brightness, so if the period is observed, the absolute brightness can be deduced. Yes. It seems like this question is about the Cepheid variables.
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.
How do you measure the distance to a cepheid?
Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.
What fundamental principle did Shapely use to calibrate the period-luminosity relationship for Cepheid variable stars?
Objects with large proper motion tend to be closer than objects with small proper motion. /\
How do you calculate the distance of nebulae?
There are many ways to calculate distance at huge scales. One popular way is using a Cepheid within the nebula. A Cepheid is a very luminous variable star (a star that changes brightness). The changing of brightness tells us a lot about the distance by measuring the period (time) and the luminosity. See the related link for more methods.
Why are pulsating variable stars useful for finding distances to globular clusters?
It really depends on the type of star, but for certain star types, there is a relationship between the period and the absolute brightness, so if the period is observed, the absolute brightness can be deduced. Yes. It seems like this question is about the Cepheid variables.
How do lighthouses of the sky measure distance of star groups?
"Lighthouses of the sky" are the Cepheid Variables. These are stars that periodically change in brightness, somewhat the way a rotating beam from a lighthouse would as it fell on an observer. The brightness of a Cepheid is proportional to the period of its variance. So if we know the period (how long it takes the beam to come around), we know how bright the star should be. Comparing that to the observed brightness tells us how far away it is (if it's one-quarter as bright as it would be at a standard distance - 32.6 light years - then it's twice as distant (65.2 light years).)
Why was Henrietta Swan Leavitt's study of these stars important in the area of astronomy?
Henrietta Leavitt studied Cepheid variables, a certain type of variable star with brightness that varies in a very regular cycle. By studying Cepheid variables in the Magellanic clouds, she discovered a simple relationship between the brightness of a Cepheid variable star and the length of time the cycle takes to repeat itself. To do this she used the fact that all such variables in the clouds are at the same distance from us, approximately. This allowed her to calculate the absolute magnitude of the star just by measuring the time period of the variation in brightness. The importance of this technique is that Cepheid variables can be found in more distant galaxies, and this provides a yardstick for finding out how far away they are. All you have to do is find a Cepheid variable in a galaxy and measure its variation period, then you know its absolute magnitude. You already know its apparent magnitude so it becomes possible to calculate how far away it is. This is one of the methods that astronomers used in the early 20th century to reveal the unexpectedly huge distances of other galaxies in the universe. Let's hear it for Miss Henrietta Leavitt!
What does Cepheid mean?
A Cepheid is a member of a class of pulsating variable stars. The relationship between a Cepheid variable's luminosity and pulsation period is quite precise, securing Cepheids as viable standard candles and the foundation of the Extragalactic Distance Scale.
What is the pulsation period of a Cepheid star?
The time it takes for a Cepheid star to go from it's brightest, to it's dimmest, and back to it's brightest again. =] Hope that helped.
What was the scientist Henrietta leavitt famous for?
She discovered the period luminosity relationship of cepheid variables
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 did Edwin Hubble measure the distance to the Andromeda Galaxy?
He applied the period-luminosity relation to Cepheid variables.
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.
Who stated the universe is expanding?
The Doppler effect is well known, and Fizeau observed the red-shift of the light from distant stars. So the effect was called Doppler-Fizeau. There are a class of astronomic objects called the Cepheid Variables in which it is observed that the rate of variation in the brightness of the star related to its absolute brightness, and therefore its mass. Thus these stars can be used as a measure of distance, as the period of their variability does not change with distance, but their apparent brightness and their red-shift does. Hubble made a number of observations of Cepheids in the Andromeda galaxy. The article on Cepheid Variables in wikipedia.org is well worth reading, as it illustrates scientific discovery and enquiry. He went on to reason that the Cepheids could be used as a standard measure of astronomical distance. And this formed the basis of the Expanding Universe. These observations are one of the foundations of cosmology.
