Theoretical astrophysics is the discipline that seeks to explain the phenomena observed by astronomers in physical terms with a theoretic approach. With this purpose, theoretical astrophysicists create and evaluate models and physical theories to reproduce and predict the observations. In most cases, trying to figure out the implications of physical models is not easy and takes a lot of time and effort. An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ... An astrophysicist is a person whose profession is astrophysics. ...

Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving you insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that you would not otherwise see. A polytrope is a solution to the Lane-Emden equation. ... The Pleiades star cluster A star is any massive gaseous body in outer space, just like the Sun. ... Computation can be defined as finding a solution to a problem from given inputs by means of an algorithm. ... Numerical analysis is the study of algorithms for the problems of continuous mathematics (as distinguished from discrete mathematics). ...

Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allows observers to look for data that can refute a model or help in choosing between several alternate or conflicting models. Spiral Galaxy ESO 269-57 Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature and chemical composition) of astronomical objects such as stars, galaxies, and the interstellar medium, as well as their interactions. ...

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Within the astronomical community, theorists are widely caricatured as being mechanically inept and unlucky for observational efforts. Having a theorist at an observatory is considered likely to jinx an observation run and cause machines to break inexplicably or to have the sky cloud over.

Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation; large-scale structure of matter in the Universe; origin of cosmic rays; general relativity and cosmology. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and serves as the basis for black hole (astro)physics and the study of gravitational waves. Stellar dynamics is the branch of astrophysics which describes in a statistical way the collective motions of stars subject to their mutual gravity. ... In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime, the millions or billions of years during which it emits light and heat. ... In astrophysics, the questions of galaxy formation and evolution are: How, from a homogeneous universe, did we obtain the very inhomogeneous one we live in? How did galaxies form? How do galaxies change over time? The formation of galaxies is still one of the most active research areas in astrophysics... The substance of which a physical object is composed. ... The deepest visible-light image of the cosmos. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ... Two-dimensional visualisation of space-time distortion. ... Wiktionary has a definition of: Cosmology For the jazz band, see: Cosmology (band) Cosmology, from the Greek: κοσμολογία (κόσμος world + λογια discourse) is the study of the universe in its totality and by extension mans place in it. ... An artists impression of a black hole with a closely orbiting companion star that exceeds its Roche limit. ... The willingness to question previously held truths and search for new answers resulted in a period of major scientific advancements, now known as the Scientific Revolution. ... In physics, gravitational radiation is energy that is transmitted through waves in the gravitational field of space-time, according to Albert Einsteins theory of general relativity: The Einstein field equations imply that any accelerated mass radiates energy this way, in the same way as the Maxwell equations that any...

Some widely-accepted theories/models in astrophysics include the Big Bang, Cosmic inflation, dark matter, and fundamental theories of physics. An astrophysical theory which has some supporters but widely seems to be at variance with observations is Plasma cosmology. An example of an astrophysical theory which not widely accepted but is considered viable enough to merit further work is Modified Newtonian Dynamics. According to the Big Bang theory, the universe originated in an extremely dense and hot state (bottom). ... Inflation is the idea—first proposed by Alan Guth (1981)—that the nascent universe passed through a phase of exponential expansion (the inflationary epoch) that was driven by a negative pressure vacuum energy density. ... In cosmology, dark matter consists of matter particles that cannot be detected by their emitted radiation but whose presence can be inferred from gravitational effects on visible matter such as stars and galaxies. ... The willingness to question previously held truths and search for new answers resulted in a period of major scientific advancements, now known as the Scientific Revolution. ... Plasma cosmology is a non-standard cosmological model which attempts to explain the large scale structure of the universe using electromagnetic interactions in astrophysical plasmas. ... The modified Newtonian dynamics (MOND) is a physical theory which attempts to explain the galaxy rotation problem by changing Newtons law of motion. ...

See also

• Astronomy
• Astrophysics