The brightest star of the constellation, located on the line connecting the stars Castor - Pollux of Gemini. Its remarkable orange color can certainly be noticed with the naked eye, and it belongs to the spectral class K3. This star has a magnitude of 2 and is located in an area relatively poor in stars. That is why its translated name from Arabic means "Lonely Star". However, Tycho de Brahe called it Cor Hydraul - "Heart of the Hydra". It is located at a distance of 177 light years and is 780 times more luminous than the Sun.