A star whose spectrum shows strong hydrogen Balmer lines accompanied by many faint to moderately strong metallic lines. In contrast to B and O stars, the lines of He I and He II are absent. Their surf
ace temperature ranges from 7,500 to 10,000 K. The main metallic lines seen in A-type stars are those of Fe I and Fe II, Cr I and II, Ti I and II, and account for about two-thirds of all lines. Some famous examples of A star are Sirius, Deneb, Altair, and Vega. Also known as A-type star.
A star whose spectrum shows strong hydrogen Balmer lines accompanied by many faint to moderately strong metallic lines. In contrast to B and O stars, the lines of He I and He II are absent. Their surf
ace temperature ranges from 7,500 to 10,000 K. The main metallic lines seen in A-type stars are those of Fe I and Fe II, Cr I and II, Ti I and II, and account for about two-thirds of all lines. Some famous examples of A star are Sirius, Deneb, Altair, and Vega. Also known as A-type star.
A small rocky object orbiting the Sun. There are millions of asteroids moving in orbits in the main asteroid belt, between Mars and Jupiter and in the Kuiper belt. The largest and the first discovered
, Ceres, about 1,000 km in size, is now classified as dwarf planet (2006 IAU General Assembly). The largest asteroid in the solar system (Ceres apart), is Pallas, with a size of 582 x 556 x 500 km. On the other hand, the smallest asteroid ever studied is the 2 meters space rock 2015 TC25, which was observed when it made a close flyby of Earth in October 2015.