csillagok

Stars, or csillagok in Hungarian, are luminous spheres of plasma that generate light and heat through nuclear fusion in their cores. They form from collapsing regions of interstellar gas and dust and vary widely in mass, temperature, brightness, and age. As the primary light sources in most galaxies, they shape the thermal and chemical evolution of their environments.

Most stars fuse hydrogen into helium while on the main sequence, a stage whose duration depends on mass. Low‑mass stars burn comparatively slowly and can shine for trillions of years, whereas the most massive stars exhaust their fuel in a few million years and end in explosive events. Stellar masses range roughly from 0.08 to well over 100 solar masses, affecting radius, temperature, and luminosity.

Stars are classified by spectral type and luminosity class. The spectral sequence O, B, A, F, G, K, M runs from hottest to coolest, with colors ranging from blue to red. Luminosity class I to V indicates giants, subgiants, main‑sequence (dwarfs), and other stages. The study of these properties is organized on the Hertzsprung‑Russell diagram, which correlates luminosity with surface temperature.

Lifecycle and endpoints vary by mass. Sun‑like stars become red giants, shed outer layers, and leave behind white dwarfs. More massive stars may explode as supernovae, leaving neutron stars or black holes. Stars form in giant molecular clouds, and their birth and death drive the evolution of galaxies and the chemical enrichment of the universe. Planets commonly form in the surrounding disks around young stars.

Distances to stars are measured by parallax and reported in parsecs or light‑years. Brightness is described by apparent magnitude, while intrinsic brightness is absolute magnitude or luminosity. The Sun is a G‑type main‑sequence star and serves as a reference point for many measurements.