This simulation traces a star's complete life cycle, from a cold molecular cloud to its final remnant, while plotting its path across a live Hertzsprung-Russell diagram of luminosity against surface temperature. A set of evolutionary stages defined for each mass class supplies temperature, luminosity and radius values, and the model logarithmically interpolates between them as age advances, since these quantities span many orders of magnitude.
You set the birth mass with the Mass slider (0.5 to 20 solar masses), which alone selects the whole evolutionary path and final remnant. The Age slider scrubs from nebula to remnant, while Animate plays it through and the speed slider controls the pace. Reading such tracks is exactly how astronomers infer the ages and histories of star clusters and entire galaxies.
What does this simulation actually show?
It animates the full life of a single star and simultaneously plots its position on a Hertzsprung-Russell diagram. The left panel renders the star itself with particle effects for winds, jets and explosions, while the right panel shows its evolutionary track and current point in luminosity-temperature space.
Why does the star's birth mass matter so much?
Mass sets everything: how fast a star burns, how bright it shines and how it dies. Below about 2 solar masses a star ends as a white dwarf, between roughly 2 and 8 it leaves a neutron star, and above about 8 it can collapse into a black hole.
What do the Mass and Age sliders control?
Mass picks the birth mass from 0.5 to 20 solar masses and chooses the entire evolutionary path. Age is a 0 to 100 timeline that scrubs from the molecular cloud at the start to the final remnant at the end, letting you step through each stage by hand.
It is a plot of luminosity (vertical axis, in solar luminosities) against surface temperature (horizontal axis, in kelvin, with hot stars on the left). Stars cluster into the main sequence, giant and supergiant branches, and the white dwarf region, and the moving dot shows where your star sits at the current age.
The main-sequence lifetime follows roughly t = 10 Gyr divided by M to the power 2.5, where M is the mass in solar units. The simulation pairs this with the mass-luminosity relation, in which luminosity scales as about M to the power 3.5, so heavy stars are far brighter yet far shorter-lived.
For stars above 8 solar masses the simulation follows a high-mass track ending in a core-collapse supernova. The final remnant is shown as a neutron star for masses up to about 15 solar masses and as a black hole above that, reflecting roughly where the collapsing core exceeds the limit that neutron degeneracy pressure can support.
The colour is derived from the surface temperature using a blackbody approximation of the Planckian locus. Cool stages near 3000 kelvin appear red, a Sun-like 5800 kelvin looks yellow-white, and very hot phases above 25000 kelvin glow blue, matching how real stars are classified by spectral colour.
It is a faithful qualitative and order-of-magnitude model rather than a full numerical stellar-structure code. The stages, temperatures, luminosities, radii and lifetime scaling reflect real astrophysics, but transitions are smoothed by interpolation and timings are compressed so the whole life fits onto one slider.
Once core hydrogen is exhausted the star expands enormously, cools at the surface and brightens overall, sliding to the upper right of the diagram. Low-mass stars pass through red giant, helium flash and asymptotic giant branch phases; massive stars swell into red or blue supergiants and shed mass through powerful winds.
Stellar evolutionary tracks underpin much of astrophysics. By fitting the observed Hertzsprung-Russell diagram of a star cluster against these tracks, astronomers date the cluster, and the same physics explains the origin of elements, supernovae and the compact remnants that power pulsars and gravitational-wave events.
Watch a star's entire lifecycle from molecular cloud to final remnant. Low-mass stars become white dwarfs, medium stars explode as supernovae leaving neutron stars, and the most massive collapse into black holes.
Stars evolve along tracks on the Hertzsprung-Russell diagram. Main sequence lifetime ∝ M⁻²·⁵ — massive stars burn bright and die young.
Adjust initial stellar mass. Watch the star evolve through main sequence, red giant, and final stages. Follow its track on the live HR diagram.
A star like our Sun will live about 10 billion years. A star 10× the Sun's mass will live only 20 million years — but shine 10,000× brighter. The most massive stars known are over 200 solar masses.
This model traces the entire life cycle of a star, from a cold molecular cloud to its final remnant, while plotting its path across a live Hertzsprung-Russell diagram. The destiny of a star is decided almost entirely by one number — its birth mass — which sets whether it ends as a white dwarf, a neutron star, or a black hole. Astronomers use exactly this kind of evolutionary track to read the age and history of star clusters and entire galaxies.
t_MS ≈ 10 Gyr × M^(-2.5) — main-sequence lifetime t_MS in billions of years for stellar mass M in solar masses; the luminosity follows the mass-luminosity relation L ∝ M^3.5, so heavy stars are far brighter yet far shorter-lived.
A star like our Sun will shine for about 10 billion years, but a star ten times heavier burns out in only ~20 million years — while blazing roughly 10,000 times brighter.