Evaluation of the star HD 222925 by the College of Michigan astronomer Ian Roederer revealed 65 parts. It includes 42 heavy parts, together with these detected within the fast neutron seize course of.
The fast neutron seize course of or r-process begins with the presence of lighter parts akin to iron. Then immediately, inside only a second, neutrons are added to the nuclei of the lighter elements- creating heavier parts.
Plenty of free neutrons and a really excessive vitality set of circumstances are required to permit and add them to the nuclei of atoms. This course of can happen solely in restricted environments. There could also be solely two environments: the merging of neutron stars and the explosive dying of large stars.
College of Michigan astronomer Ian Roederer mentioned, “That’s an vital step ahead: recognizing the place the r-process can happen. Nevertheless it’s a a lot larger step to say, ‘What did that occasion do? What was produced there? That’s the place our examine is available in.”
“To one of the best of my information, that’s a file for any object past our photo voltaic system. And what makes this star so distinctive is that it has a really excessive relative proportion of the weather listed alongside the underside two-thirds of the periodic desk. We even detected gold. The fast neutron seize course of made these parts. We’re attempting to check: the physics in understanding how, the place and when these parts have been made.”
In accordance with scientists, the weather present in star HD 222925 have been produced in both large supernovae or a merger of neutron stars very early within the universe. The fabric was ejected and thrown again into area, later reformed into the star.
Roederer mentioned, “This star can then be used to proxy what a type of occasions would have produced. Any mannequin developed sooner or later that demonstrates how the r-process or nature produces parts on the underside two-thirds of the periodic desk will need to have the identical signature as HD 222925.”
For this examine, scientists used observations made with the NASA/ESA Hubble Area Telescope and one of many Magellan telescopes—a consortium of which U-M is a accomplice—at Las Campanas Observatory in Chile.
Hubble Area Telescope allowed astronomers to gather mild within the ultraviolet a part of the sunshine spectrum. One other telescope collected mild from HD 222925 within the optical a part of the sunshine spectrum.
These spectra encode the “chemical fingerprint” of parts inside stars. Studying these spectra permits astronomers to establish the weather contained within the star and the way a lot of a component the star accommodates.
Anna Frebel, a co-author of the examine, mentioned, “We now know the detailed element-by-element output of some r-process occasion that occurred early within the universe. Any mannequin that tries to grasp what’s happening with the r-process has to have the ability to reproduce that.”
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