Stars Are Not Made from a Single Mold: The Gaia Discovery ⚡ экспресс
Direct measurements of the Initial Mass Function (IMF) require resolving stellar populations down to low-mass stars, which has long limited the test of its universality even within our own Galaxy. New Gaia data on open clusters and a method that separates IMF properties from subsequent dynamical evolution have for the first time allowed us to reliably investigate IMF variations. It has been found that the IMF is not universal: it varies from cluster to cluster, reflecting the evolution of average conditions in molecular clouds over cosmic history. The observed pattern agrees with a simple astrophysical model where the IMF depends on the environment, and the Milky Way exhibits typical behavior of galaxies in the recent past. Thus, observational data confirm long-standing theoretical and numerical predictions.
For a long time, the Universe was seen as a strict baker: it was thought that in every corner, stars were mixed from the same recipe — for each giant star, there were roughly the same number of dwarfs, no matter where they were born. This ratio was called the initial mass function, but checking it was tricky: to count all the buns in a faraway bakery, you need to see even the tiniest ones.
The Gaia satellite, armed with ultra-precise brightness measurements, peered into hundreds of open clusters — batches of star-formed ‘bakes’. It turned out that different galactic regions follow their own recipes: where gas and dust were denser and hydrogen was hotter, giants emerged several times more often. The Universe is more like a network of bakeries with distinct traditions than a single assembly line.
This simple fact changes a lot. For instance, estimates of the number of habitable planets and the distribution of dark matter in galaxies were based on the old assumptions. Now it’s clear: even the basic ingredients of the cosmos are mixed without a template, and astronomers have to rewrite their cookbooks.
🎯 The Sun is a middleweight, but the vast majority of stars in the Milky Way are dim red dwarfs, which live hundreds of times longer and shine hundreds of times fainter.