The Big Picture Flashcards
Spiral Galaxies
Spiral galaxies have a distinct disk-like structure with arms that spiral outward from a central bulge. The arms contain young stars, gas, and dust, while the bulge typically contains older stars.
Elliptical Galaxies:
Elliptical galaxies are smooth and featureless, lacking the spiral arms seen in spiral galaxies. They have a more rounded or elliptical shape and contain mostly older stars. Elliptical galaxies range from nearly spherical (E0) to highly elongated (E7) in shape.
irregular Galaxies
irregular galaxies lack a distinct shape and do not fit into the categories of spiral or elliptical galaxies. They often exhibit chaotic and irregular structures, containing young stars, gas, and dust. Irregular galaxies can be the result of interactions or mergers between galaxies.
Lenticular Galaxies:
Lenticular galaxies, also known as S0 galaxies, have features that are intermediate between spiral and elliptical galaxies. They possess a central bulge like ellipticals but lack the prominent spiral arms seen in spiral galaxies
Dwarf Galaxies:
Dwarf galaxies are small and relatively faint compared to their larger counterparts. They can come in various shapes, including dwarf elliptical, dwarf irregular, and dwarf spheroidal galaxies.
Active Galactic Nuclei / Quasars
Active Galactic Nuclei (AGN) and quasars are energetic phenomena that originate from the centers of galaxies and are powered by supermassive black holes
Active Galactic Nuclei (AGN):
GN refers to the central region of a galaxy where a supermassive black hole accretes matter from its surroundings. This process releases tremendous amounts of energy across the electromagnetic spectrum, making AGN some of the brightest objects in the universe.
Quasars:
Quasars, short for quasi-stellar radio sources, are a specific type of AGN. They are the most luminous and distant members of the AGN family. Quasars were first discovered as point-like, radio-emitting objects with no discernible stellar features.
Formation of Protogalactic Structures:
Galaxy evolution begins with the formation of protogalactic structures in the early universe. These structures arise from the gravitational collapse of density fluctuations in the primordial gas and dark matter.
Gas Accretion and Star Formation
as plays a crucial role in galaxy evolution. As galaxies form, they accrete gas from their surroundings, which fuels the process of star formation.
Morphological Transformations:
Galaxies can undergo morphological transformations, changing their shape and structure. Spiral galaxies can evolve into elliptical or lenticular galaxies through interactions and mergers with other galaxies.
Stellar Populations and Chemical Enrichment:
The composition and properties of stars within galaxies evolve over time. Stellar populations change as new generations of stars form, older stars age, and elements are synthesized through stellar nucleosynthesis.
Galactic Mergers and Interactions:
Interactions and mergers between galaxies are crucial drivers of galaxy evolution. When galaxies collide or come into close proximity, their gravitational interactions can induce tidal forces, trigger star formation, disturb gas and dust, and lead to the formation of new structures such as tidal tails, bars, and rings.
Feedback Mechanisms:
eedback processes, such as energy and mass injection from supernovae, active galactic nuclei (AGN), and stellar winds, regulate galaxy evolution. These processes can influence the gas content, star formation rates, and black hole growth within galaxies, shaping their evolutionary paths.
