What is eruptive variable star?
Eruptive variables, stars who experience eruptions on their surfaces like flares or mass ejections. Cataclysmic or explosive variables, stars that undergo a cataclysmic change in their properties like novae and supernovae.
What are the types of variable stars?
There are two basic types of variable stars: intrinsic variables, whose luminosity actually changes, and extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth. A star could be an intrinsic variable because it periodically swells and shrinks.
How do you observe a variable star?
To make the observation, compare the brightness of the variable to two or more of the comparison stars on the chart – one fainter and one brighter. Two methods are in common use, the Fractional and the Pogson Step method, the former being more suited to beginners.
What is intrinsic variable?
Intrinsic variables are those in which the change in brightness is due to some change within the star itself such as in pulsating stars like the Cepheids. Extrinsic variables are those in which the light output changes due to some process external to the star itself.
What characteristic of a star determines the way it finally dies?
All stars eventually run out of their hydrogen gas fuel and die. The way a star dies depends on how much matter it contains—its mass. As the hydrogen runs out, a star with a similar mass to our sun will expand and become a red giant.
What do Cepheid variables tell us?
A Cepheid variable (/ˈsɛfiːɪd, ˈsiːfiːɪd/) is a type of star that pulsates radially, varying in both diameter and temperature and producing changes in brightness with a well-defined stable period and amplitude. This discovery allows one to know the true luminosity of a Cepheid by simply observing its pulsation period.
Why do variable stars pulsate in brightness?
Pulsating variable stars are intrinsic variables as their variation in brightness is due to a physical change within the star. In the case of pulsating variables this is due to the periodic expansion and contraction of the surface layers of the stars.
What are examples of intrinsic properties?
Examples of intrinsic properties include:
- Hardness.
- Ductility.
- Malleability.
- Density (of a liquid or solid)
- Specific gravity.
- Specific volume.
- Melting point.
- Boiling point.
What are intrinsic and extrinsic variables?
Properties that are proportional to the size of the sample are extrinsic properties. Extrinsic variables have definite values regardless of whether or not a sample is in a state of equilibrium. Properties that are not proportional to the sample size are called intrinsic properties.
How can a Cepheid variable indicate distance?
Through observations of Cepheid variables, astronomers have determined the distances to other galaxies. They compare the Cepheid variable’s apparent brightness with its intrinsic brightness. The difference between observed and actual brightness yields the distance.