Stellar evolution

Stellar evolution refers to the process by which stars change over time. This process involves various stages that a star goes through from its formation to its eventual death. The life cycle of a star is influenced by its initial mass, composition, and other factors. Here are the main stages of stellar evolution: 1. **Nebula**: Stars begin their lives in large clouds of gas and dust called nebulae.

ALESS 073.1 refers to a standard or guideline associated with the ALD (Atomic Layer Deposition) process. ALESS stands for "ALD Equipment Specification Standard," and it typically outlines requirements for the design and performance of ALD systems used in the semiconductor and materials science industries. The specific designation “073.1” suggests a particular version or section within the broader ALESS framework.

The Asymptotic Giant Branch (AGB) is a phase in the evolution of stars, particularly those with initial masses between approximately 0.6 and 8 times that of the Sun. This stage occurs after a star has completed the hydrogen and helium burning phases in its core and is characterized by significant changes in the star's structure and composition.

A black dwarf is a theoretical stellar remnant that forms when a white dwarf has cooled sufficiently that it no longer emits significant heat or light. This process involves the white dwarf radiating away its residual heat over billions of years until it reaches a state where it appears dark and is not detectable through electromagnetic radiation. The existence of black dwarfs is predicted by models of stellar evolution, but as of now, none have been observed.

A blue dwarf is a theoretical type of star that would occur at the end of the main sequence phase of red dwarfs in the far future. Red dwarfs are the smallest and coolest type of main-sequence stars. They burn their hydrogen at a low rate and can have lifespans that last for tens to hundreds of billions of years, far exceeding that of larger stars, which typically evolve into more massive stages like red giants.

"Blue loop" can refer to different concepts depending on the context, but it is not a widely recognized term with a singular definition. Here are a few interpretations based on different fields: 1. **Technology/Programming**: In programming, particularly in the context of loops, a "blue loop" might refer to a specific type or implementation of a loop within code. The term "blue" could be used informally to describe its function or the state of a debugging process.

The Boomerang Nebula, also known as MMS 13, is a protoplanetary nebula located in the constellation Centaurus, approximately 5,000 light-years away from Earth. It is notable for being one of the coldest known astronomical objects, with a temperature of about -272 degrees Celsius (-458 degrees Fahrenheit), which is just a degree above absolute zero. The nebula is shaped like an hourglass, which is characteristic of many planetary nebulae.

Carbon detonation isn't a widely recognized or standard term in scientific literature or practice, so it’s possible that it could refer to a few different concepts depending on the context in which it's used. Here are a few interpretations: 1. **Chemical Reaction**: If referring to carbon in a chemical context, it might relate to the combustion or explosive reactions involving carbon-based compounds. For instance, hydrocarbons (which contain carbon) can have explosive reactions under certain conditions, such as in gasoline or other fuels.

A circumstellar envelope is an outer region of gas and dust that surrounds a star or a stellar system. This envelope can arise from various processes, including stellar winds, mass loss from aging stars, and interactions with surrounding material. In many cases, particularly with evolved stars such as red giants or asymptotic giant branch (AGB) stars, these envelopes form as the star sheds its outer layers due to nuclear fusion processes ceasing or slowing down.

A common envelope jets supernova refers to a specific type of supernova explosion associated with binary star systems, particularly those involving a white dwarf and a companion star. In this scenario, the two stars orbit each other closely, and as they evolve, the outer layers of one star can transfer mass to the other via an unstable mass transfer, leading to a "common envelope" phase.

Dredge-up is a process occurring in stellar astrophysics, particularly in the context of red giant stars. It involves the mixing of materials from the interior of a star to its outer layers, specifically bringing nuclear fusion products from deeper layers, such as helium and heavier elements, to the surface. This process typically happens during specific phases of a star's evolution, notably during the red giant phase when a star expands and cools.

Electron degeneracy pressure is a quantum mechanical phenomenon that arises from the Pauli exclusion principle, which states that no two fermions (particles with half-integer spin, such as electrons) can occupy the same quantum state simultaneously. This principle plays a crucial role in the behavior of electrons in dense materials. In astrophysics, electron degeneracy pressure is especially significant in the context of white dwarfs, which are the remnants of stars that have exhausted their nuclear fuel and collapsed under gravity.

FU Orionis is a type of star that belongs to a category known as FUor stars, which are characterized by significant brightness increases over relatively short periods of time. FU Orionis itself is a young, pre-main-sequence star located in the constellation Orion. It was first observed to have a notable outburst in 1934, when it brightened dramatically by several magnitudes.

A galactic superwind is a large-scale outflow of gas and other materials from a galaxy, predominantly caused by various energetic processes related to star formation and supernova explosions. These outflows are typically observed in starburst galaxies, where intense star formation occurs, and play a crucial role in the galaxy's evolution and environment.

The Hayashi limit is a concept in astrophysics that refers to a boundary in the Hertzsprung-Russell diagram (a graph that plots stars according to their luminosity and temperature), specifically concerning the evolution of low-mass stars. It is named after the Japanese astronomer Chushiro Hayashi.

A helium flash is a crucial astrophysical event that occurs in the later stages of a star's life, particularly in low- to intermediate-mass stars (like those in the range of about 0.8 to 8 solar masses). This phenomenon happens when the core of a red giant, primarily composed of helium, becomes sufficiently hot and dense to ignite helium fusion after a period of hydrogen burning in the star's earlier life stages.

The Henyey track, also known as the Henyey-Greenstein phase function, is a mathematical function used in the field of radiative transfer, particularly in the context of light scattering in media such as atmospheric particles, biological tissues, or other scattering materials. The Henyey-Greenstein function describes how light is scattered by particles and is characterized by a single parameter \( g \), which represents the asymmetry of the scattering.

The Hertzsprung gap, also known as the Hertzsprung-Russell gap, refers to a region in the Hertzsprung-Russell diagram (HR diagram) that is largely empty of stars. The HR diagram plots stars according to their absolute brightness (or luminosity) and their surface temperature (or spectral class). In this diagram, most stars fall along a diagonal band known as the main sequence, where they spend the majority of their lifetimes fusing hydrogen into helium.

14 Ceti is a star located in the constellation Cetus, which is often referred to as the Whale. It is a G-type giant star, which means it has exited the main sequence phase of its life and has expanded and cooled after exhausting the hydrogen fuel in its core. The star is approximately 200 light-years away from Earth and has a brightness that is roughly 100 times that of our Sun.

31 Comae Berenices, also designated as 31 Com, is a binary star system located in the constellation Coma Berenices. It is not particularly bright, with an apparent magnitude of about 5.8, making it visible to the naked eye under good conditions. The system is approximately 80 light-years away from Earth.

AE Ursae Majoris is a binary star system located in the constellation Ursa Major. It consists of two stars that are close together in terms of their distance from Earth, making the system an interesting target for astronomical observation. The primary star is a focal point for researchers due to its classification as a variable star, specifically a type of AP star, which exhibits variations in luminosity.

HD 185269 is a star located in the constellation of Hercules. It is classified as a G-type main-sequence star (similar to the Sun) and is also known for being a candidate host for exoplanets. The star has been the subject of study in searches for planets, and various observations have been conducted to understand its composition and potential surrounding planetary system.

OU Andromedae is a binary star system located in the constellation of Andromeda. It is classified as a close binary system composed of two stars that are in orbit around each other. This system is particularly interesting because it includes a red giant star and a companion, which is typically a smaller and less luminous star. The properties of OU Andromedae have been studied extensively to understand its characteristics better, including its orbital parameters, brightness variations, and spectral types.

A hypernova is an exceptionally energetic explosion that occurs at the end of a massive star's life cycle. It is characterized by an enormous release of energy, significantly surpassing that of a typical supernova. Hypernovae are typically associated with the collapse of very massive stars—those with at least 30 times the mass of our Sun. When such a massive star exhausts its nuclear fuel, it can lead to the formation of a black hole or neutron star.

The term "instability strip" can refer to several different concepts depending on the context, but it is most commonly used in meteorology and atmospheric science. In this context, an instability strip is a region in a diagram that represents the stability properties of the atmosphere, particularly with regard to convection. In meteorology, the instability strip typically refers to a band on a thermodynamic diagram, such as a skew-T log-P diagram, where certain conditions indicate that the air is unstable.

The Kelvin–Helmholtz mechanism refers to a physical phenomenon that occurs when two different fluid layers of varying density and velocity are in contact with one another, leading to the formation of waves or instabilities at their interface. Named after the British physicist Lord Kelvin and the German physicist Hermann von Helmholtz, this mechanism is commonly observed in various contexts, including astronomy, meteorology, and oceanography.

The main sequence turnoff (MSTO) is an important concept in astrophysics, particularly in the study of stellar populations and the evolution of stars. It refers to the point on the Hertzsprung-Russell (H-R) diagram where a cluster of stars begins to evolve off the main sequence phase of their lifecycle.

The mass-luminosity relation is an important empirical relationship in astrophysics that describes how the luminosity (the amount of light energy radiated per unit time) of a star is related to its mass. This relationship is particularly applicable to main sequence stars, which are stars that are in the stable phase of hydrogen burning in their cores.

The metallicity distribution function (MDF) is a statistical description of the metallicity, which refers to the abundance of elements heavier than hydrogen and helium in a celestial object, such as stars or galaxies. Metallicity is often expressed in terms of the logarithmic ratio of the abundance of a given element to that of hydrogen, relative to the solar abundance, commonly denoted as [Fe/H] (for iron) or other similar indices.

Neutron star spin-up refers to the process by which a neutron star increases its rotational speed, or spin rate. Neutron stars are incredibly dense remnants of massive stars that have undergone supernova explosions. They typically have very strong magnetic fields and can rotate very rapidly, completing a rotation in fractions of a second.

An OH/IR star is a type of late-stage star that is characterized by strong emissions of hydroxyl (OH) and infrared (IR) radiation. These stars are typically red giants or supergiants that are experiencing significant mass loss due to stellar winds. The OH emissions are produced by the molecules formed in the outer layers of the star, while the infrared emissions are typically associated with dust grains that have formed in the expanded outer atmosphere.

An open cluster remnant typically refers to the remnants of an open star cluster, which is a group of stars that were formed from the same giant molecular cloud and are loosely bound by mutual gravitational attraction. Open clusters are generally younger than globular clusters, containing younger stars that tend to have a wider range of temperatures and spectral types.

Photo-erosion refers to the process by which materials, such as soil, rock, or other surfaces, are gradually worn away or eroded due to exposure to light, particularly ultraviolet (UV) radiation from the sun. This phenomenon can occur in various geological and environmental contexts, often influencing the stability and structure of landscapes.

A planetary nebula is an astronomical phenomenon that occurs during the late stages of a star's evolution, particularly for stars of intermediate mass (generally 1 to 8 times the mass of the Sun). It is the result of a star exhausting the nuclear fuel in its core, leading to changes in its structure and composition.

A protoplanetary nebula is an astronomical object that represents a stage in the evolution of a star, specifically a low- to intermediate-mass star, as it transitions from the asymptotic giant branch (AGB) phase to the planetary nebula phase.

Red clump stars are a specific type of red giant star in the later stages of stellar evolution. These stars are typically in the horizontal branch phase, which follows the giant phase of a star's life cycle. Red clump stars represent a phase where stars have exhausted the hydrogen in their cores and are now fusing helium into carbon and oxygen. They are somewhat hotter and brighter than ordinary red giants, and their spectra show strong absorption lines indicative of helium fusion.

SN 1972E is a type Ia supernova that was discovered in 1972 in the galaxy NGC 5253, which is located in the constellation Centaurus. Type Ia supernovae are significant in astrophysics because they occur in binary systems where a white dwarf accretes matter from a companion star, eventually reaching a critical mass that leads to a thermonuclear explosion.

Sakurai's Object, also known as Sakurai's Supernova Remnant, is a notable astronomical object located in the constellation Centaurus. It is the remnant of a supernova explosion, which occurred approximately 10,000 years ago. The object is particularly interesting because it exhibits characteristics of both a supernova remnant and a planetary nebula.

The Standard Solar Model (SSM) is a theoretical framework used by astrophysicists to describe the structure and evolution of the Sun. This model aims to explain the Sun's properties, such as its temperature, luminosity, and internal structure, based on physical principles and fundamental laws of physics. Key components of the Standard Solar Model include: 1. **Hydrostatic Equilibrium**: The balance between gravitational forces pulling inward and the pressure from nuclear reactions pushing outward.

The term "Stellar Birthline" generally refers to a conceptual line on the Hertzsprung-Russell diagram, which is a scatter plot that shows the relationship between the stars' luminosity and their effective temperature (or color). The Stellar Birthline specifically denotes the region where new stars are expected to be found shortly after their formation. In more detail, when stars form from clouds of gas and dust through the process of gravitational collapse, they pass through various stages of development.

A stellar isochrone is a curve representing the positions of stars of different masses that are at the same age but in different stages of their evolution on a Hertzsprung-Russell diagram (H-R diagram). The H-R diagram plots a star's luminosity (or absolute magnitude) against its temperature (or spectral type), allowing astronomers to analyze stellar populations and their evolutionary stages.

Stellification is a term that can refer to different concepts depending on the context, but it is primarily associated with two main areas: 1. **Astronomy/Physics**: In the context of astrophysics, stellification describes the process through which certain celestial bodies are formed or evolve into star-like objects. This can involve the gravitational collapse of gas clouds to form stars or other processes that lead to star-like characteristics.

A Super-AGB star is a type of massive star that represents an extended evolutionary phase beyond the asymptotic giant branch (AGB) stage. These stars typically have initial masses in the range of about 9 to 11 solar masses, placing them between the more common AGB stars and the more massive types of stars, such as supernova progenitors.

A superluminous supernova (SLSN) is an exceptionally bright type of supernova that can emit up to 100 times more light than a typical supernova. These astronomical events are characterized by their extraordinary luminosity, which can persist for an extended period, often lasting for months to years.

As of my last update in October 2023, "Superwind" could refer to a few different things, depending on the context. Without specific context, here are a couple of possibilities: 1. **Superwind (Wind Energy)**: It might refer to advanced technologies or projects in wind energy generation or wind turbine design that focus on maximizing efficiency and energy output.

A Thorne–Żytkow object (TZO) is a hypothetical type of astronomical object that is a unique combination of a neutron star and a red giant star. This concept arises from theoretical studies in astrophysics and is named after physicists Kip Thorne and Edward Żytkow, who proposed the idea in the 1970s.