Cosmic Rings: How M92 Preserved the Memory of Supernovae ✦
Original: "Evidence of Supernova Between Formation of Stellar Populations in a Globular Cluster"
With jeweler's precision, spectroscopy uncovered the difference in iron abundance between generations of stars in the globular cluster M92—a chemical signature of ancient supernovae.
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Globular cluster M92 is a forest 12 billion years old. Its stars, like trees, have preserved chemical rings: 3 million years after the first generation, supernovae exploded, fertilizing the second generation with iron. The same technique, applied to distant systems via the Webb telescope, will let us read the history of the early Universe.
🎯 M92 in the constellation Hercules is home to 330,000 stars, all over 12 billion years old. And every one of them holds a chemical memory of the cluster's first few million years—like tree rings recording ancient wildfires.
L = 4\pi R^2 \sigma T^4
The Stefan–Boltzmann law links a star's luminosity to its radius and temperature; it was used to precisely calculate surface gravity and eliminate systematic errors in determining element abundance.
\Delta[\mathrm{Fe/H}] = \log_{10}\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{\mathrm{2nd}} - \log_{10}\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{\mathrm{1st}} = 0.082\,\mathrm{dex}
The difference in iron abundance between the generations is expressed on a logarithmic scale; a value of 0.082 dex means the second generation has about 20% more iron than the first.
Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterAlbert Einsteinglobular cluster
supernova
nucleosynthesis
spectroscopy
metallicity
star formation
stellar evolution
photometry
neutron starLaws
Doppler effectmass–energy equivalenceMaxwell's equationsPlanck's lawPlanck–Einstein relationWien's displacement law