An A-type main-sequence star is a type of star that falls within the spectral classification of A. These stars are characterized by their white to blue-white color and have surface temperatures ranging from about 7,500 to 10,000 Kelvin. They are more massive than the Sun and can be 1.5 to 2.5 times its mass. A-type stars are known for their strong hydrogen absorption lines in their spectra. A-type main-sequence stars typically have a lifespan of around 1 to 2 billion years before evolving into giant stars. Examples of A-type stars include Sirius A and Altair. These stars play a crucial role in the study of stellar evolution and the dynamics of galaxies.