Loading
Types of Variable Stars
There are several main types of variable stars - eclipsing, Cepheids, and semi-regular/irregular. Some of these have sub types, which are named after the first discovered star in the class.
Eclipsing binaries
These types of variables are actually binary systems, which orbits are aligned with the line-of-sight of the observer. Thus, when one of the stars gets in front of the other, we see eclipse and dip in the light curve. There are two main sub classes:
Here is how both systems and their light curves look like.
Eclipsing binaries
These types of variables are actually binary systems, which orbits are aligned with the line-of-sight of the observer. Thus, when one of the stars gets in front of the other, we see eclipse and dip in the light curve. There are two main sub classes:
- β Lyra. This type is a close binary. The two orbiting stars are so close to each other that one of them (or both stars) has shape no longer spherical, but more like a pear. This makes the dips in the light curve to be wider.
- β Persei (Algol). Both stars are fairly well separated and the light curve has sharper dips.
Here is how both systems and their light curves look like.
β Lyra
| 
Algol
|
Eclipsing variables have fixed periods and the shape of their light curves do not change.
Cepheids
The progenitor of this type is δ Cepheus. This class has one very important to astronomy property. For all cepheids there is a relation between their periods and luminosities. This was very important astronomical discovery, because by knowing the luminosity, the astronomers could calculate the distance to the Cepheid. Their light curves look more or less like this one:
Cepheids
The progenitor of this type is δ Cepheus. This class has one very important to astronomy property. For all cepheids there is a relation between their periods and luminosities. This was very important astronomical discovery, because by knowing the luminosity, the astronomers could calculate the distance to the Cepheid. Their light curves look more or less like this one:
Semi-regulars and irregulars
Semi-regular variable stars have light curve’s shapes that vary every cycle. These stars are typically giants that are not very stable. Very often such stars could have periods that change slightly.
Irregular, we can call such variables, that do not have constant period nor shape of their light curves. Some could stay at some magnitude for days, others for years, before a change in the brightness occurs.
Semi-regular variable stars have light curve’s shapes that vary every cycle. These stars are typically giants that are not very stable. Very often such stars could have periods that change slightly.
Irregular, we can call such variables, that do not have constant period nor shape of their light curves. Some could stay at some magnitude for days, others for years, before a change in the brightness occurs.
