The pulsating stars swell and shrink, affecting their brightness and spectrum. Pulsations are generally split into: radial, where the entire star expands and shrinks as a whole; and non-radial, where one part of the star expand while another part shrinks. Some scientists consider non-radial pulsations to encompass everything, with radial pulsations as a special case, but considering them as mutually exclusive is convenient since they generally vary with one type or the other.
Depending on the type of pulsation and its location within the star, there is a natural or fundamental frequency which determines the period of the star. Stars may also pulsate in a harmonic or overtone which is a higher frequency, corresponding to a shorter period. Pulsating variable stars sometimes have a single well-defined period, but often they pulsate simultaneously with multiple frequencies and complex analysis is required to determine the separate interfering periods. In some cases, the pulsations do not have a defined frequency, causing a random variation, referred to as stochastic. The study of stellar interiors using their pulsations is asteroseismology.
VSS runs a number of projects related to pulsating variables, which are outlined below.
- Bright Southern Cepheids for DSLR & Similar Cameras
- Visual Measures of Bright Cepheids
- R & eta Carinae
- Dual-Maxima Miras
Older archived projects can be found here:
- No archived projects found