Video Experimental Relacionado
Updated: Jul 12, 2026
06:28
Visualization of Low-Level Gamma Radiation Sources Using a Low-Cost, High-Sensitivity, Omnidirectional Compton Camera
Published on: January 30, 2020
Líneas de rayos gamma del proceso s de corta duración en las supernovas de tipo II
Science (New York, N.Y.)
|April 1, 1988
Resumen
La reacción (22) Ne ((alfa,n) ((23) Mg en estrellas masivas crea elementos del proceso s como el hierro-59 y el cobalto-60. Los rayos gamma de estos elementos deberían ser detectables en la mayoría de las supernovas de tipo II.
Área de la Ciencia:
- La astrofísica nuclear es una astrofísica nuclear.
- Evolución estelar de la evolución estelar.
- La nucleosíntesis de las supernovas.
Sus antecedentes:
- La quema de helio en las estrellas masivas es crucial para la producción de elementos.
- El proceso s (captura lenta de neutrones) es una vía clave de la nucleosíntesis.
- La comprensión de las condiciones de presupernova informa las observaciones de supernovas.
Objetivo del estudio:
- Para calcular las abundancias nucleares en las capas de helio de las estrellas presupernovas.
- Para investigar la producción de isótopos específicos a través de reacciones de captura de neutrones.
- Para predecir la detectabilidad de las emisiones de rayos gamma de los restos de supernovas.
Principales métodos:
- Modelado de abundancias nucleares en el interior estelar.
- Simulación de la producción de neutrones a través de la reacción (22) Ne ((alfa, n) ((23) Mg.
- Evaluación de la supervivencia de isótopos sintetizados a través de ondas de choque de supernovas.
Principales resultados:
- Para las estrellas de más de 20 masas solares, la reacción (22) Ne ((alfa, n) ((23) Mg produce suficientes neutrones para el proceso s-nucleosíntesis.
- Se sintetizan el hierro-59 (semivida de 45 días) y el cobalto-60 (semivida de 5,3 años).
- Se predice que estos isótopos sobrevivirán a las explosiones de supernovas.
Conclusiones:
- Los rayos gamma de la desintegración del hierro-59 y el cobalto-60 deberían ser detectables en la mayoría de las supernovas galácticas de tipo II.
- Es poco probable que estas líneas específicas de rayos gamma sean observables desde la supernova 1987A debido a su distancia y baja metalicidad.
Videos de Conceptos Relacionados
03:23Types of Radioactivity
The most common types of radioactivity are α decay, β decay, γ decay, neutron emission, and electron capture.
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
02:39Emission Spectra
When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
03:18Radioactivity and Nuclear Equations
Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for hydrogen, neutrons. The number of protons in the nucleus is called the atomic number (Z) of the element, and the sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are isotopes of the same element.
A nuclide of an element has a specific number of protons and...
A nuclide of an element has a specific number of protons and...
03:18Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
03:20Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
01:28Atomic Nuclei: Types of Nuclear Relaxation
Nuclear relaxation restores the equilibrium population imbalance and can occur via spin–lattice or spin–spin mechanisms, which are first-order exponential decay processes.
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...