1. Bayer Designation: This system uses Greek letters (α, β, γ, etc.) followed by the constellation name (e.g., α Cephei, β Lyrae). However, it's mainly used for bright stars, not all variable stars.
2. Flamsteed Designation: This system uses numbers followed by the constellation name (e.g., 31 Cephei, 51 Pegasi). It's also mostly for bright stars and not specifically designed for variable stars.
3. Variable Star Designations:
* General Variable Star: This is the most common system. It uses a capital letter (R, S, T, etc.) followed by the constellation name (e.g., R Leonis, S Sagittarii). This system starts anew for each constellation.
* Nova Designations: Novae are given a designation based on the year of their discovery and a letter (e.g., Nova Cygni 1975).
* Supernova Designations: Supernovae are designated by the year of discovery, followed by a letter and the constellation (e.g., SN 1987A).
4. Other Designations:
* Catalog Numbers: Some variable stars are also identified by their catalog numbers, such as the General Catalogue of Variable Stars (GCVS). These numbers can be very long and are not widely used for general reference.
* Designation by discoverer: Some variable stars are identified by the name of their discoverer, followed by the year of discovery (e.g., "Zwicky's Star" or "Nova T Pyxidis 1966").
5. Modern Variable Star Naming Conventions:
* VSX (Variable Star Index): This system is a modern, comprehensive database of variable stars. It uses a unique, six-character identifier for each star (e.g., VSX J200000+000000).
* Other Online Databases: Other databases, such as the AAVSO (American Association of Variable Star Observers), also use their own specific naming conventions.
It's important to note that many variable stars have multiple designations depending on their discovery and historical context.
