Variable Stars

A variable star is a star whose brightness
as seen from Earth fluctuates.

Variable Stars

• Variable stars are stars that do not burn steadily like the sun, but flare up and down
• Pulsation variable are stars that expand and contract – they include stars known as Cepheid variable and RR Lyare variable.

Perioic Variable Stars

Cepheid
  -  variable are big, bright stars that pulsate with energy, flaring up regulatory every one to 50 days.
-  variable are so predictable in brightness they make good distance markers.

RR Lyrae
-  variable are yellow supergaint stars near the end of their life that flicker as their fuel runs down.

Mira
-  Mira-type variable are similar to Mira in Cetus, the whale, and vary regularly over months or years.

RV Tauri
-  variables are very unpredictable, flaring up and down over changing period of time.
-   eclipsing variable are really eclipsing binaries (see binary stars). they seem to flare up and down, but in fact are simply one star getting in the way of other.

Algol
-  the Demon Star is Algol in Perseus. It seems to burn fiercely for 59 hours, become dim, then flare up again after 10 hours later. It is really an eclipsing binary.

Chi
-  the vanishing star is Chi in Cygnus – it can be seen with the naked eye for a few months each year, but them become so dim it cannot be seen, even with large armature telescope.

 

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