Types of stars, black holes and galaxies
Almost everything here is one answer to a single question: how heavy was the star when it formed? Mass decides how hot it burns, how long it lives, and what it leaves behind — a slowly cooling ember, a city-sized ball of neutrons, or a hole in spacetime. Thirty-four objects, from the cold cloud a star condenses out of to the largest structure in the universe, each modelled in real interactive 3D.
The black holes here are not illustrations. Light paths are integrated through curved spacetime one step at a time, so the shadow, the photon ring, the disk folded over the top and the Einstein rings in the background starfield all emerge from the physics rather than from a texture. The same marcher, with the metric or the horizon swapped out, draws the spinning hole, the merging pair and the wormhole.
Cold gas, dark clouds and the discs that form around new stars. Everything further down this page begins here, including the atoms you are made of.
Molecular Cloud
The coldest, darkest thing in the galaxy — and where every star comes from.
Emission Nebula
A molecular cloud with the lights switched on, being destroyed by its own children.
Protoplanetary Disk
A solar system caught in the act of assembling itself.
Balls of plasma held together by gravity and held up by fusion. Their whole story is set by one number at birth: mass.
Main-Sequence Star
A star in the long, stable middle of its life. The Sun is one.
Red Dwarf
The most common star in the galaxy, and the last one still burning.
Red Giant
A dying star, swollen to hundreds of times its old size.
Blue Supergiant
Burns a million times brighter than the Sun, and dies in a few million years.
Wolf-Rayet Star
A star so hot it is blowing its own atmosphere into space.
Brown Dwarf
Too heavy to be a planet, too light to ever be a star.
What is left when the fuel runs out — matter crushed until quantum mechanics is the only thing holding it up.
Planetary Nebula
A dying star's outer layers, lit from inside by the core it left behind.
White Dwarf
The Sun compressed to the size of Earth, cooling for eternity.
Black Dwarf
The end of a white dwarf. The universe is far too young for one to exist.
Neutron Star
A city-sized object with more mass than the Sun.
Pulsar
A lighthouse spinning up to 700 times a second.
Magnetar
The strongest magnets in the universe, by a factor of a trillion.
Quark Star
A star where even neutrons have been crushed into their parts.
Supernova Remnant
The wreckage of a dead star, still expanding at thousands of km/s.
Past a certain mass, no known force stops the collapse. What remains is pure geometry: a one-way surface in spacetime.
Stellar-Mass Black Hole
A star heavy enough that nothing could stop the fall.
Intermediate-Mass Black Hole
The class that was missing from the census for fifty years.
Supermassive Black Hole
One sits at the heart of nearly every galaxy, including ours.
Spinning Black Hole
Every real black hole is this one. Spin drags spacetime around with it.
Binary Black Hole
Two shadows, each lensing the other, spiralling toward a merger.
Quasar
A feeding black hole outshining every star in its galaxy combined.
Blazar
A quasar that happens to be pointing its jet straight at us.
Primordial Black Hole
Born in the first second of the universe, and possibly still here.
Solutions of general relativity that no star has to die to produce. Two of these have never been observed and one probably cannot exist — which is exactly why they are worth being able to look at.
Wormhole
Not a hole. A window — with a different universe on the other side.
White Hole
The same equations run backwards: nothing can get in, and it never stops pouring out.
Boson Star
Mass without matter, gravity without a surface, and no shadow at all.
Zoom out far enough and individual stars stop mattering. What is left is how they are arranged — in discs, in spheres, in clusters, and finally in the largest pattern there is.
Spiral Galaxy
Arms that survive because they are a traffic jam, not a structure.
Barred Spiral Galaxy
The Milky Way. A straight bar of stars feeding the centre.
Elliptical Galaxy
The largest galaxies there are, and nothing has been born in them for billions of years.
Irregular Galaxy
No disc, no bulge, no plan — and making stars faster than anything its size.
Globular Cluster
A million stars in a sphere, and older than the galaxy they orbit.
Cosmic Web
Every galaxy in the universe strung along filaments around enormous empty voids.
One number decides everything
Life cycle of a starA star does not choose its ending. The mass it happens to have when it finishes collapsing out of a gas cloud fixes how hot it burns, how long it lasts, and which of these five tracks it will follow to the end. Everything else — colour, size, luminosity, what it leaves behind — follows from that one number.
| Object | Mass | Radius | Temperature | Lifespan |
|---|---|---|---|---|
| Molecular Cloud | 10^3 - 10^7 M(sun) | 15 - 600 light years | 10 - 20 K | ~10 - 30 Myr |
| Emission Nebula | 10^2 - 10^5 M(sun) | 1 - 100 light years | ~10,000 K | ~1 - 5 Myr |
| Protoplanetary Disk | 0.001 - 0.1 M(sun) | 10 - 1,000 AU | 20 - 1,500 K | ~1 - 10 Myr |
| Main-Sequence Star | 0.08 - 150 M(sun) | 0.1 - 15 R(sun) | 2,400 - 50,000 K | 10 Myr - 10 Tyr |
| Red Dwarf | 0.08 - 0.45 M(sun) | 0.1 - 0.6 R(sun) | 2,300 - 3,900 K | up to 10 trillion yr |
| Red Giant | 0.3 - 8 M(sun) | 10 - 1,000 R(sun) | 3,000 - 5,000 K | ~1 billion yr in phase |
| Blue Supergiant | 10 - 100 M(sun) | 20 - 200 R(sun) | 10,000 - 50,000 K | 3 - 30 million yr |
| Wolf-Rayet Star | 10 - 25 M(sun) now | 1 - 25 R(sun) | 30,000 - 210,000 K | a few 100,000 yr |
| Brown Dwarf | 13 - 80 M(Jupiter) | ~1 R(Jupiter) | 250 - 2,500 K | cools forever |
| Planetary Nebula | 0.1 - 1 M(sun) shell | 0.1 - 3 light-years | Core 30,000 - 200,000 K | ~20,000 yr |
| White Dwarf | 0.17 - 1.4 M(sun) | ~1 R(Earth) | 4,000 - 150,000 K | cools for 10^15 yr |
| Black Dwarf | 0.17 - 1.4 M(sun) | ~1 R(Earth) | Background cold | Effectively forever |
| Neutron Star | 1.1 - 2.3 M(sun) | ~11 km | ~600,000 K surface | cools for billions of yr |
| Pulsar | ~1.4 M(sun) | ~11 km | Beamed radio to gamma | spins down over Myr |
| Magnetar | ~1.4 M(sun) | ~11 km | Field 10^14 - 10^15 gauss | active ~10,000 yr |
| Quark Star | 1.5 - 2.5 M(sun) | ~8 - 11 km | 10^6 - 10^11 K | Indefinite |
| Supernova Remnant | 1 - 20 M(sun) ejected | grows to 100+ ly | 10^6 - 10^7 K shock | ~100,000 yr |
| Stellar-Mass Black Hole | 3 - 150 M(sun) | 9 - 450 km horizon | Disk 10^7 K | 10^67 yr to evaporate |
| Spinning Black Hole | Any | Horizon shrinks with spin | Disc to 10^7 K | Spin decays over Gyr |
| Binary Black Hole | 2 x (5 - 100) M(sun) | Separation shrinks to zero | Disc to 10^6 K | Myr to Gyr, then seconds |
| Intermediate-Mass Black Hole | 100 - 100,000 M(sun) | 300 km - 300,000 km | Disk 10^6 K | gigayears |
| Supermassive Black Hole | 10^5 - 10^10 M(sun) | up to 1,300 AU horizon | Disk 10^5 - 10^6 K | 10^100 yr to evaporate |
| Quasar | 10^8 - 10^10 M(sun) | disk ~ light-days | Disk up to 10^5 K | ~10 - 100 Myr active |
| Blazar | 10^8 - 10^10 M(sun) | Jet up to Mpc | Gamma-ray dominated | Flares in hours |
| Primordial Black Hole | 10^-8 - 10^5 M(sun) | atom to kilometres | Hawking glow | set by mass |
| Wormhole | Negative (exotic) | Throat radius, free parameter | None | Unstable without exotic matter |
| White Hole | Any | Same as a black hole | Surface emission, unbounded | Violently unstable |
| Boson Star | Set by particle mass | Compact, no surface | None | Stable if below critical mass |
| Globular Cluster | 10^4 - 10^6 M(sun) | 30 - 300 light years | Stars 3,000 - 8,000 K | > 12 Gyr |
| Irregular Galaxy | 10^8 - 10^10 M(sun) | 3,000 - 30,000 ly | Stars 3,000 - 40,000 K | > 10 Gyr |
| Spiral Galaxy | 10^10 - 10^12 M(sun) | 15,000 - 150,000 ly | Stars 3,000 - 40,000 K | > 10 Gyr |
| Barred Spiral Galaxy | 10^10 - 10^12 M(sun) | 15,000 - 150,000 ly | Stars 3,000 - 40,000 K | > 10 Gyr |
| Elliptical Galaxy | 10^8 - 10^13 M(sun) | 3,000 - 700,000 ly | Stars 3,000 - 6,000 K | > 10 Gyr |
| Cosmic Web | ~10^53 kg observable | Filaments 10^8 ly | Voids near 0 K | Age of the universe |
What are the different types of stars?
Stars are classified by temperature into the spectral sequence O, B, A, F, G, K and M, and by size into dwarfs, giants and supergiants. In practice the useful families are red dwarfs, Sun-like main-sequence stars, red giants, blue supergiants and the substellar brown dwarfs that never quite ignite.
What are the different types of black holes?
Four classes are recognised by mass: stellar-mass black holes of 3 to 150 solar masses formed from collapsing stars; intermediate-mass black holes of 100 to 100,000 solar masses; supermassive black holes of 100,000 to tens of billions at galactic centres; and hypothetical primordial black holes formed in the first second after the Big Bang.
What is the difference between a neutron star and a black hole?
Both are collapsed stellar cores, but a neutron star still has a surface — neutron degeneracy pressure and the strong force hold it up at around 22 km across. Above roughly 2.3 solar masses nothing can resist gravity, the collapse continues past the event horizon, and a black hole forms instead.
What happens to a star when it dies?
It depends on mass. Stars up to about 8 solar masses swell into red giants, shed their outer layers and leave a white dwarf. Heavier stars explode as supernovae and leave a neutron star, or a black hole if the collapsing core exceeds about 2.3 solar masses.
Are these 3D models physically accurate?
They are built from the physics rather than from artwork. The black-hole scenes integrate light paths through Schwarzschild spacetime, so the shadow, photon ring, lensed accretion disk, Doppler beaming and Einstein rings are computed, not drawn. The stars use temperature-driven colour, limb darkening and convective granulation. Sizes are framed for legibility, not to scale.