Size
The disks of most stars are too small to be directly observed with today's terrestrial telescopes. Interferometers are used to create images. Another method of measuring angular magnitude is the so-called eclipse, in which the angular magnitude can be calculated based on accurate measurements of changes in the brightness of a star during an eclipse by the moon or another body.
The range of star sizes is huge. It ranges from 20-45 km for neutron stars to 100 times the diameter of the Sun for supernaturants (for example, Betelgeuse in the constellation Orion, which is 650 times the diameter of the Sun, about 900,000 km). The radii of stars can be 3,000 times larger than the radius of the Sun. In general, the density of a star decreases with increasing diameter.
Age
Most stars are between 1 and 10 billion years old. The oldest star discovered is HE 1523-0901, which is estimated to be 13.2 billion years old.
The heavier the star, the shorter its lifetime, because there is more pressure in the cores of heavy stars, which causes hydrogen to burn faster. The heaviest stars live on average only a few million years, while the lightest burn their fuel slowly and live from tens to hundreds of billions of years.
Variability
No star shines continuously from the moment of its birth to its demise. However, those stars that change their brightness rapidly (from hours to decades) or by a significant amount are called variables. The reason for the variability varies from star to star. This is either due to the fact that they are obscured by a darker object (eclipsing stars), or due to the physical cause of the star itself, for example, pulsating stars change their diameter in a certain range and over a certain period of time. Eruptive variable stars suddenly increase in brightness due to eruptions and explosions of matter. This group includes, for example, protostars or Wolf-Rayet stars.. Cataclysmic (explosive) variable stars undergo drastic changes in their properties. This group includes novae and supernovae. Expanding stars suddenly change their diameter due to huge explosions (supernovae increase their brightness up to 100 million times during explosions). However, most of the changes in clarity are not so dramatic, and many changes are invisible to the naked eye. Stars are more susceptible to physical changes in brightness at the beginning (T-type stars) and at the end (Cepheid, Mirid, supernovae...) of their evolution. On the other hand, some stars change their brightness slightly due to extreme spots on their surface. Maximize your winnings with 1xbet promo code today and enter when registering to get a 130% welcome bonus up to €130 on your first deposit. Enjoy enhanced odds on sports betting, thrilling casino games, and exciting slots. Just create an account, apply the promo code, make your deposit, and watch your balance grow! This amazing offer won't last forever - claim your bonus today and start playing with extra funds! Terms and conditions apply.