23.3 Supernova Observations
3 min read•june 12, 2024
shook up our understanding of stellar explosions. This nearby blast let scientists watch a star die in real-time, confirming theories and challenging others. Its burst and chemical makeup provided key insights into how massive stars end their lives.
's blue supergiant surprised astronomers, who expected red giants to explode. This discovery led to updates in models. The 's and spectral changes over time helped refine our knowledge of these cosmic cataclysms.
Supernova 1987A
Features of SN 1987A
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- Brightness changes
- Rapidly increased in brightness over several months after initial observation
- Reached peak luminosity around May 1987, about 3 months post-observation
- Gradually declined in brightness over the following years (e.g., several magnitudes fainter by 1990)
- analysis provided crucial information about the supernova's evolution
- Neutrino emissions
- Detected by three separate neutrino observatories (, , )
- 24 neutrinos detected in total, arriving 2-3 hours before visible light from the supernova
- Neutrino burst lasted less than 13 seconds
- Confirmed the role of neutrinos in carrying away energy during process
- techniques have since been refined for future supernova observations
Confirmation of supernova theories
- Core collapse model
- Neutrino detections provided evidence for core collapse mechanism
- Supported theory that neutrinos carry away most energy released during collapse
- of heavy elements
- Spectroscopic observations revealed presence of heavy elements in supernova ejecta (e.g., oxygen, silicon, iron)
- Confirmed theory that supernovae are responsible for producing elements heavier than iron
- played a crucial role in identifying chemical composition of the ejecta
- Progenitor star identification
- Progenitor star, , identified as a blue supergiant
- Challenged prevailing theory that only red supergiants could produce
- Led to revision of models to include blue supergiants as possible progenitors
Stages before type II supernovae
- Main sequence
- Star fuses hydrogen into helium in its core
- Maintains between gravity and radiation pressure
- Red supergiant phase
- Hydrogen exhausted in core, fusion continues in shell surrounding core
- Core contracts and heats up, outer layers expand and cool (e.g., Betelgeuse, Antares)
- Core collapse
- Iron core reaches (1.4 solar masses)
- can no longer support core against gravity
- Core collapses in matter of seconds, reaching billions of degrees
- Neutrino burst and shock wave
- Protons and electrons combine to form neutrons, releasing burst of neutrinos
- Neutrinos carry away most gravitational energy released during collapse
- Infalling matter bounces off dense core, creating shock wave
- Supernova explosion
- Shock wave propagates outward, heating and ejecting outer layers of star
- Rapid occurs behind shock front, forming heavy elements
- expands into surrounding interstellar medium (e.g., , )
Supernova Types and Outcomes
- Type II supernovae (core-collapse)
- Result from massive stars (>8 solar masses)
- Can form neutron stars as remnants
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- Thermonuclear explosions of white dwarfs in binary systems
- Used as standard candles for cosmic distance measurements
- Stellar evolution plays a crucial role in determining the type and characteristics of supernovae
Key Terms to Review (33)
Baksan: Baksan is a neutrino observatory located in the Baksan Gorge of the Caucasus Mountains in Russia. It is one of the world's leading facilities for the detection and study of neutrinos, particularly those produced by supernovae.
Brahe: Tycho Brahe was a Danish astronomer known for his precise and comprehensive astronomical observations. His data greatly influenced the development of modern astronomy, particularly the laws of planetary motion.
Cassiopeia A: Cassiopeia A is the remnant of a supernova explosion that occurred approximately 300 years ago in the constellation Cassiopeia. It is one of the most studied and well-known supernova remnants in the Milky Way galaxy, providing valuable insights into the processes that occur during and after a star's violent death.
Chandrasekhar limit: The Chandrasekhar limit is the maximum mass (approximately 1.4 times the mass of the Sun) that a white dwarf star can have before it collapses under its own gravity. Beyond this limit, the white dwarf will undergo further gravitational collapse to form a neutron star or black hole.
Chandrasekhar Limit: The Chandrasekhar limit is the maximum mass above which a star can no longer support itself against gravitational collapse after exhausting its nuclear fuel. It is a critical threshold that determines the fate of a star's evolution and the type of stellar remnant it will leave behind.
Core Collapse: Core collapse refers to the final stage of a massive star's evolution, where the core of the star implodes under its own gravity, leading to a catastrophic explosion known as a supernova. This process is a critical component in the life cycle of stars and the formation of various celestial objects.
Crab Nebula: The Crab Nebula is a supernova remnant, the expanding debris field from the explosion of a massive star. It is located in the constellation of Taurus and is one of the most studied and well-known objects in the night sky, providing insights into the aftermath of a star's death and the formation of neutron stars.
Electron Degeneracy Pressure: Electron degeneracy pressure is a type of quantum mechanical pressure that arises in extremely dense stellar matter, such as in the cores of white dwarf stars or the interiors of neutron stars. It is a fundamental force that counteracts the gravitational forces that would otherwise cause the star to collapse under its own weight.
Hydrostatic equilibrium: Hydrostatic equilibrium is the balance between the inward gravitational force and the outward pressure within a star. This balance maintains the star's spherical shape and prevents it from collapsing or expanding uncontrollably.
Hydrostatic Equilibrium: Hydrostatic equilibrium is a state of balance where the gravitational force acting on a body is exactly balanced by the buoyant force, resulting in a stable, stationary state. This concept is fundamental to understanding the composition and structure of planets, the sources of energy in stars, and the evolution of stellar objects.
IMB: IMB, or Interstellar Magnetic Field, refers to the magnetic field that permeates the space between stars within a galaxy. This field is a crucial component in understanding the dynamics and evolution of the interstellar medium, as it influences the movement and behavior of charged particles and plasma within the galaxy.
Kamiokande II: Kamiokande II was a large underground water Cherenkov detector located in the Kamioka mine in Japan, designed to detect neutrinos and study various astrophysical phenomena, including supernovae. It was an important instrument in the field of neutrino astronomy and played a crucial role in the observation and study of supernova events.
Light curve: A light curve is a graph that plots the brightness of an astronomical object over time. It is crucial for studying the variability and periodicity of stars and other celestial bodies.
Light Curve: A light curve is a graph that shows the variation in brightness or luminosity of an astronomical object over time. It is a fundamental tool used in the study of various celestial phenomena, including the search and discovery of exoplanets and the observation of supernovae.
Neutrino: Neutrinos are nearly massless, chargeless subatomic particles that interact very weakly with matter. They are produced in large quantities during nuclear reactions, such as those occurring in the Sun and during supernova explosions.
Neutrino Detection: Neutrino detection is the process of identifying and measuring the properties of elusive subatomic particles called neutrinos. Neutrinos are produced in nuclear reactions, such as those occurring in the Sun or in supernova explosions, and can provide valuable information about these cosmic events.
Neutron Star: A neutron star is an extremely dense, collapsed stellar remnant that forms when a massive star runs out of fuel and undergoes a supernova explosion, leaving behind a core so dense that the electrons are forced to combine with protons, creating a star composed almost entirely of neutrons. These incredibly dense objects have immense gravitational fields and are some of the most extreme objects in the universe.
Nucleosynthesis: Nucleosynthesis is the process by which new atomic nuclei are created from existing protons and neutrons. This occurs primarily in the cores of stars through nuclear fusion reactions.
Nucleosynthesis: Nucleosynthesis is the process by which new atomic nuclei are created from pre-existing nucleons, primarily protons and neutrons. This process is responsible for the formation of all the chemical elements in the universe, from the lightest elements like hydrogen and helium to the heavier elements like carbon, oxygen, and iron.
Progenitor: A progenitor is the original ancestor or source from which something is derived. In the context of supernova observations, a progenitor refers to the star that ultimately explodes and becomes a supernova, providing insights into the life cycle and death of massive stars.
Sanduleak -69° 202: Sanduleak -69° 202 is a star located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. It is known for its connection to the supernova SN 1987A, one of the most significant astronomical events of the 20th century.
SN 1054: SN 1054 is a supernova that was first observed in the year 1054 AD by astronomers in several different cultures. Its remnants form the Crab Nebula, which is one of the most studied astronomical objects today.
SN 1987A: SN 1987A is the name given to a supernova that was observed in 1987, making it one of the closest and best-studied supernovae in modern times. It is a significant astronomical event that has provided valuable insights into the evolution of binary star systems and the observation of supernovae.
Spectroscopy: Spectroscopy is the study of the interaction between matter and electromagnetic radiation, which provides valuable information about the composition, temperature, and motion of celestial objects. This technique is widely used in astronomy to analyze the properties of stars, galaxies, and other cosmic phenomena.
Stellar evolution: Stellar evolution is the process by which a star changes over the course of time. It encompasses the formation, life cycle, and eventual fate of stars.
Stellar Evolution: Stellar evolution is the process by which a star changes over the course of its lifetime, from birth to death. This term encompasses the various stages and transformations a star undergoes, driven by the complex interplay of gravitational, thermal, and nuclear forces within the star. Understanding stellar evolution is crucial in astronomy, as it provides insights into the life cycle of stars and their impact on the broader cosmic landscape.
Supernova: A supernova is a powerful and luminous explosion marking the death of a massive star. It can outshine entire galaxies for short periods and significantly impact its surrounding space.
Supernova 1987A: Supernova 1987A is a stellar explosion observed in 1987 within the Large Magellanic Cloud, a neighboring galaxy to the Milky Way. It was the closest supernova observed in nearly 400 years and has provided valuable insights into the death of massive stars.
Supernova Remnant: A supernova remnant is the structure that remains after a massive star has reached the end of its life and exploded in a supernova event. These remnants are the result of the violent death of a star and provide valuable insights into the evolution of massive stars and the observations of supernovae.
Tycho’s Supernova: Tycho's Supernova is a Type Ia supernova that was observed in 1572 by the astronomer Tycho Brahe. It is one of the most famous and well-studied supernovae in history, providing critical insights into stellar evolution and binary star systems.
Type Ia supernovae: A Type Ia supernova is a powerful and luminous stellar explosion resulting from the thermonuclear disruption of a white dwarf in a binary system. It occurs when the white dwarf accretes matter from its companion star, reaching the Chandrasekhar limit and igniting carbon fusion uncontrollably.
Type Ia Supernovae: Type Ia supernovae are a specific class of supernovae that occur when a white dwarf star in a binary system accretes enough material from its companion to exceed the Chandrasekhar limit, causing the white dwarf to undergo a thermonuclear explosion. These events are remarkably consistent in their intrinsic brightness, making them valuable standard candles for measuring extragalactic distances and studying the expansion of the universe.
Type II Supernovae: Type II supernovae are a class of supernovae that occur when a massive star (8-20 times the mass of the Sun) runs out of fuel and collapses under its own gravity, resulting in a catastrophic explosion. These events are characterized by the presence of hydrogen in their spectra, indicating that the progenitor star had retained its outer hydrogen envelope prior to the explosion.