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

Answer 1

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.

Answer 2

I'll answer half way to your Questions, Ancient people, they had chart stars using only inks and papers without any aids of Telescope or Hubble's and they actually see the same constellations of Stars as me, your RM 10.00 per day astronomer. If they see no changes and I've seen no changes, then How can you had seen changes?.

Next, yes there are dead stars and dying stars all over the Universe because like any creatures when it run out of fuel it'll dying and die , but if you want to know How a star begin?. then my answer would be the same as to any 7 years old boys, Stars came from dark places, some dark places are small and some dark places are very big.

And now, some inside to my books, I've read about your exploded stars and I think, I did examine some free pictures and I thank you for the free pictures, but I've found some errors on Einstein's Relativity Theory and I will not give it for free.

Also just for heads up, the answer are scarier and much worrying then most would want to admit.

Answer 3

These two methods are used to find the distance of stars. Parallax was used by Bessel in 1838 to discover the distance to the star 61 Cygni. Parallax is the tiny movement of a nearby star against the background stars, that happens as the Earth moves round the Sun.

The lack of parallax used to be taken as a sign that the Earth does not move; however there always was parallax but it was too small to be measured until 1838 when it was discovered by Bessel. Suddenly everyone realised how unimaginably far away the stars in fact are, but that was only a first step.

In 1912 Miss Henrietta Leavitt at the Harvard College Observatory made the next important discovery. All Cepehid variables (whose prototype star is Delta Cephei) have a steady and reliable brightness curve. Some local Cepheid variables had already had their parallax and distance measured, and Henrietta started observing more distant Cepheid variables in the Magellanic Clouds.

Henrietta knew that some Cepheid variables take longer to go through their cycle than others. But the ones in the Magellanic Clouds showed a definite trend that took her interest. She knew that all the stars in the Magellanic Clouds are about the same distance away from us, and she found that the brighter ones take longer to cycle. She reasoned that their apparent magnitude must be linked to their absolute magnitude (intrinsic brightness). She produced a graph that related the period of variability to the absolute magnitude - called the Period-Luminosity curve.

It didn't take long for people to realise that this was a great new yardstick for finding the distances to much more distant stars and galaxies. All you had to do was to find a few Cepheid variables in the Andromeda Nebula, and you would know how far away it is. That way it was discovered that it's over a million light-years to that nebula.

Later the Red Shift was discovered for measuring really distant objects, but the measurements are all based on this logical progression of measurements, each one standing on the previous one.

Answer 4

For any object, you need to compare the real brightness ("absolute magnitude") with the apparent brightness ("apparent magnitude"). Specifically in the case of Cepheids, the absolute magnitude can be deduced from its period.

Answer 5

Cepheid variables are important for measuring long distances in the universe because their brightness fluctuates in a predictable way based on their intrinsic luminosity. By measuring the period of these brightness fluctuations, astronomers can accurately determine the distance to Cepheid variables and, by extension, the distance to faraway galaxies and other celestial objects. This method, known as the cosmic distance ladder, is crucial for estimating the size and age of the universe.

Answer 6

These stars have been used to calculate the distance to most galaxies in which a cepheid is present.

Answer 7

Their luminosity can be inferred from their period.

Answer 8

the distance to most galaxies in which a cepheid is present.

Answer 9

A Cepheid is a type of star that varies in size and density. The link between a Cepheid variable's luminosity and pulsation period makes them valuable for measuring distances in astronomy.