SIMBAD references

As standard candles, RR Lyrae stars are taken as distance markers and age indicators, which is helpful to estimate the distance and age of globular clusters as well as galactic and extragalactic (Local Group) locations. At the same time, as tracers, they reveal the structure, chemical and dynamic evolution of the galaxy, as well as the substructure of the halo. However, the number of RR stars is very small compared with other types of stars in nature. With the development and operation of large-scale sky survey projects, they have made a qualitative leap in number. Compared with other types of stars, RR Lyrae stars are still not enough in number. Therefore, separating RR Lyrae stars from stars belongs to an imbalanced learning problem. It may be solved by popular imbalanced learning methods.