Islands of Stability Stars
A chart of where stars spend their lives, from every well-measured star within 100 parsecs of the Sun.
Every star has a color, set mostly by its surface temperature, and a true brightness. Gaia has measured both, with the precision this chart needs, for 228,623 stars within 100 parsecs (about 326 light-years) of the Sun. Put on one chart, they do not spread out: most crowd into a single narrow band, the main sequence, and the rest gather in a few other places.
Why this chart is about islands. In a steady population, the number of stars in each part of the chart is proportional to how long stars stay there. Where the chart is crowded, stars linger. Where it is empty, they pass through quickly or never go. That is the chart-island sense exactly: regions whose occupants outlast their neighbors. And this chart holds both kinds of island the site distinguishes: one paid for continuously, and one that costs nothing.
The chart
Each star is placed by its color (across: blue on the left, red on the right) and its true brightness (up: brighter stars higher). Darker shading means more stars. The dashed band is the main sequence as fitted to these stars. The dashed line below it separates the white dwarfs. The ring marks where the Sun would sit.
Color: Gaia's BP minus RP. Brightness: absolute G magnitude, the brightness a star would have at 10 parsecs (smaller is brighter). Data: ESA Gaia DR3. The query and its filters are listed at the end of the page.
What the chart shows
Of the 228,623 stars, 198,056 (86.6 percent) lie within one magnitude of the main sequence's ridge. 4,150 (1.8 percent) are evolved stars, subgiants and giants, brighter than the band on its red side. 17,613 (7.7 percent) are white dwarfs, and the remaining 8,804 (3.9 percent) fall between these regions.
Stars spend most of their lives on the main sequence, which is why it holds most of them, and only a short time as giants, which is why the giants are few: a star like the Sun is a subgiant and giant for roughly a tenth as long as it burns hydrogen on the main sequence. The white dwarfs pile up because nothing ends them. They only cool and fade.
Two kinds of island on one chart
The main sequence is paid for. A star on the main sequence holds its size by burning hydrogen in its core: the energy streaming out holds the star up against its own gravity. The Sun turns about 4.3 million tonnes of its mass into energy every second to stay where it is. When the hydrogen in the core runs out, the balance fails and the star leaves the main sequence, swelling into a subgiant and then a giant. The Sun will spend about ten billion years on the main sequence, and it is a little under halfway through.
A white dwarf costs nothing. What is left when a star like the Sun has spent its fuel is a white dwarf: a core the size of the Earth, held up not by burning anything but by the resistance of its electrons to being squeezed. It has no fuel and needs none. It simply cools, over billions of years. The white dwarfs on this chart are an island of the kind the nuclear and orbits pages found: a stock, not a flow.
Cost line and fragility line
Cost line. For the main sequence, the fuel burned every second, about 4.3 million tonnes of mass turned into energy for the Sun, and far more for heavier stars, which burn faster and leave sooner. For white dwarfs, nothing.
Fragility line. For the main sequence, the fuel in the core: when it is spent, the star leaves, whatever else happens around it. For white dwarfs, a mass limit: above about 1.4 times the Sun's mass, electrons cannot hold a white dwarf up.
How the propositions meet the stars
| Proposition | On the stars | Status |
|---|---|---|
| P1 Sparsity | Not tested. Most stars sit in one narrow band, but the band covers the whole range of masses. The chart is crowded, not sparse. | not applied |
| P3 Exit statistics | Does not apply, and shows why. Proposition 3's condition is a stationary stream of disturbances. Stars leave the main sequence by using up their fuel, so a star's age does predict its remaining life there. Islands that run out of fuel end on schedule, not by chance. | condition not met |
| P4 Cost | Carries over, for the main sequence: its stability is bought by continuous burning, it ends when the burning stops, and the exit runs through the stabilizer, the core's fuel, rather than through outside shocks. White dwarfs, on the same chart, are the stock-held counterexample, like nuclei. An illustration in a domain where the causal structure transfers, not a test. | illustration |
| P2, P5, P6 | Not applied here. | not applied |
What this page is not
Nothing on this page tests a proposition: the physics of stars is settled, and the data were public before this page existed. The page measures the chart, shows where the site's words fit it, and names the one proposition whose structure it shares, P4, as an illustration.
Source and method
Data: ESA Gaia Archive, Gaia Data Release 3 (gaiadr3.gaia_source), retrieved 2026-09-29 through its query service, 228,623 rows, 13,317,543 bytes, SHA-256 c4d25979befe4906d98762bd13e259af01228e7bcceacbdc0f95f4cfd80c1af3. The query: SELECT source_id, phot_g_mean_mag, bp_rp, parallax FROM gaiadr3.gaia_source WHERE parallax > 10 AND parallax_over_error > 10 AND phot_g_mean_mag IS NOT NULL AND bp_rp IS NOT NULL AND phot_bp_mean_flux_over_error > 10 AND phot_rp_mean_flux_over_error > 10 AND ruwe < 1.4. This work has made use of data from the European Space Agency (ESA) mission Gaia, processed by the Gaia Data Processing and Analysis Consortium (DPAC). Gaia Collaboration, Vallenari et al., Astronomy and Astrophysics 674, A1 (2023).
Absolute magnitude is G + 5 log10(parallax in milliarcseconds) − 10. Within 100 parsecs dust dims stars too little to matter here and is ignored. Regions: white dwarfs lie below the line MG = 3.25 (BP−RP) + 9.625. The main sequence is the stars within 1 magnitude of a cubic fitted to the median brightness in color bins of 0.05 between 0.4 and 3.5. Evolved stars are brighter than that band by more than 1 magnitude and redder than 0.7. The Sun's place, color 0.82 and absolute magnitude 4.67, is from Casagrande and VandenBerg (Monthly Notices of the Royal Astronomical Society 479, 2018).