* The mass of a star is the most important factor in determining its other physical properties.

* Stars with more mass are generally hotter, more luminous, and have a shorter lifespan than stars with less mass.

Radius

* The radius of a star is the distance from its center to its surface.

* Stars with more mass are generally larger in radius than stars with less mass.

Luminosity

* The luminosity of a star is the total amount of energy it emits in all directions per second.

* Stars with more mass are generally more luminous than stars with less mass.

Temperature

* The temperature of a star is the average kinetic energy of the atoms in its atmosphere.

* Stars with more mass are generally hotter than stars with less mass.

Color

* The color of a star is determined by its temperature.

* Hotter stars are blue or white, while cooler stars are red or orange.

Spectral Type

* The spectral type of a star is a classification based on its absorption spectrum.

* Stars are classified into seven spectral types: O, B, A, F, G, K, and M.

* O-type stars are the hottest, while M-type stars are the coolest.

Variability

* Some stars vary in brightness over time.

* Variable stars are classified into several different types, including pulsating variables, eclipsing variables, and flare stars.

Magnetic Field

* Stars have magnetic fields that are generated by the movement of charged particles in their interiors.

* The magnetic field of a star can affect its surface activity, including the formation of sunspots and flares.