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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.
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What is it called when a star suddenly increases in brightness?
A nova is a star that suddenly increases in brightness.
List three factors that control the apparent brightness of a star as seen from earth?
Three factors that affect a star's brightness are the star's distance from earth, its age and its luminosity. The farther the star is from earth, the less bright it appears. As a star increases in age, its brightness also increases. Its brightness also depends on its luminosity, which is the amount of energy the star emits per second.
Which factor does not affect the apparent brightness of a star?
How old a star is.
Which star has the greatest brightness?
Sirius.
A star brightness is called?
Apparent magnitude.
What does the absolute brightness of the star depend on?
the brightness of a star
What is the measure of the star's brightness?
The measure of a star's brightness is its magnitude. A star's brightness as it appears from Earth is called its Apparent Magnitude.Star's brightness is measured by there magnitude.
What measures the brightness of the star?
photographs use to measure the brightness of a star
A star's brightness is the brightness seen by humans on Earth. A star's brightness is its actual brightness and does not depend on where the star is viewed from.?
The brightness as seen from Earth is called the "apparent magnitude".The real brightness (defined as the apparent brightness, as seen from a standard distance) is called the "absolute magnitude".
What is difference between apparent brightness and absolute brightness?
Absolute Brightness: How bright a star appears at a certain distance. Apparent Brightness: The brightness of a star as seen from Earth.
What is the purpose of a star's brightness?
There is no purpose of a star's brightness. They just exist and shine.
What is an apparent brightness?
An apparent brightness is the brightness of a star as measured by an observer.
What the measure of a stars brightness called?
The measure of a star's brightness is its magnitude. A star's brightness as it appears from Earth is called its Apparent Magnitude.Star's brightness is measured by there magnitude.
What is it called when a star suddenly increases in brightness?
A nova is a star that suddenly increases in brightness.
What is star's magnitude?
The magnitude is the brightness of the star.
What does the magnitude of a star measure?
The brightness of a star.
A star's brightness as if it were a standard distance is called?
Absolute Brightness .
