Weighing a Red Giant's Mass Loss express
A red giant is like a balloon slowly letting out gas. The star swells, its outer layers weaken, and stellar wind carries mass into space. But exactly how much does a star lose? This is a crucial question: the answer determines what kind of remnant it will leave behind — a white dwarf, a neutron star, or a black hole.
Astronomers have found a way to measure mass loss without watching a star for centuries. In a star's interior, carbon and nitrogen are mixed during burning, and their surface ratio depends on the mass with which the star was born. Mass loss does not change this ratio: it's like a fingerprint. By comparing the masses of stars with the same 'fingerprint' but at different life stages, scientists calculated the net mass loss.
This means old models of stellar evolution need calibration. The authors propose a new tuning of the formula, depending on mass and metallicity. Also, the sample contained 207 stars (3.33%) that deviate from the overall trend — possibly survivors of mass transfer from a companion star. Such cases are important for studying the history of our Galaxy.
The discovery reminds us: a balloon that looks the same can lose gas differently depending on what it's made of and how tight it is. Red giants are no exception, and now we have a way to measure their 'leak' more accurately.
Red giants can lose up to half their mass, but the exact amount depends on the star's composition and initial mass, and now this can be measured without waiting for the end of its life.
In Stanislaw Lem's novel 'Solaris', the ocean-planet behaves like a living organism, changing its mass and shape — almost like a red giant shedding material into space.