Roman Gerasimov

In the dense swarm of old stars known as the globular cluster M15, astronomers have spotted not just stars but layers of time. Some stars were born earlier, others later, and their chemical composition reveals their origin with the precision of an archaeologist reading the strata of an ancient settlement.

Brown dwarfs are objects that sit between planets and stars: they are more massive than planets but not heavy enough to sustain stable fusion in their cores.

Globular clusters are dense stellar archives, where the youth of the Galaxy is recorded. But reading this chronicle was hindered by imprecise chronometers: age estimates diverged by a billion years.

Imagine a forest planted in a single day. At first glance, all trees look alike, but their cross sections tell different stories: some grew on clean soil, others on the ashes of ancient fires.

Two stars, AF Lep A and ε Indi A, have become the focus of close attention. Using the GHOST spectrograph on the Gemini telescope, astronomers split their light into colors and, from absorption lines, determined how much carbon, oxygen, sulfur, and thirteen other elements are in the stars' atmospheres.