This image is a theory for the interior of the Sun. Credit: Pbroks13.
Theoretical astronomy at its simplest is the definition of terms to be applied to astronomical entities, sources, and objects.
Def. an "expanse of space that seems to be [overhead] like a dome" is called a sky.
Computer simulations are usually used to represent astronomical phenomena.
Part of the fun of theory is extending the known to what may be known to see if knowing is really occurring, or is it something else.
The laboratories of astronomy are limited to the observatories themselves. The phenomena observed are located in the heavens, far beyond the reach, let alone control, of the astronomical observer. “So how can one be sure that what one sees out there is subject to the same rules and disciplines of science that govern the local laboratory experiments of physics and chemistry?” “The most incomprehensible thing about the universe is that it is comprehensible.” - Albert Einstein.
At the bottom of this visible emission model is a visual intensity curve. Credit: Stanlekub.
At its simplest theoretical radiation astronomy is the definition of terms to be applied to astronomical radiation phenomena.
Def. a theory of the science of the biological, chemical, physical, and logical laws (or principles) with respect to any natural radiation source in the sky especially at night is called theoretical radiation astronomy.
Exploratory theory is the playtime activity that leads to discoveries which better our world. In the radiation physics laboratories here on Earth, the emission, reflection, transmission, absorption, and fluorescence of radiation is studied and laws relative to sources are proven.
A principle is a law or rule that has to be, or usually is to be followed, or can be desirably followed, or is an inevitable consequence of something, such as the laws observed in nature or the way that a system is constructed. The principles of such a system are understood by its users as the essential characteristics of the system, or reflecting system's designed purpose, and the effective operation or use of which would be impossible if any one of the principles was to be ignored.
Radiation astronomy consists of three fundamental parts:
derivation of logical laws with respect to incoming radiation,
natural radiation sources outside the Earth, and
the sky and associated realms with respect to radiation.
Def. a spontaneous emission of an α ray, β ray, or γ ray by the disintegration of an atomic nucleus is called radioactivity.
This is an image of the painting about Urknall. Credit: Hans Breinlinger.
Cosmogony is any scientific theory concerning the coming into existence, or origin, of the cosmos or universe, or about how what sentient beings perceive as "reality" came to be.
Usually, the philosophy of cause and effect needs a beginning, a first cause. Modal logic may only require a probability rather than a sequence of events. The concept of uncountable suggests an unknown somewhere between a finite number of likely rationales and an infinite number of possibilities.
From a sense of time as moving forward from yesterday to today and onward to tomorrow, there is again a suggestion of a prehistoric time before the first hominins.
The use of any system of thought or emotion to perceive reality suggests that some existences may precede others.
When more detail becomes available an existence may be transformed into something, an entity, a source, an object, a rocky object, or out of existence.
As a topic in astronomy, cosmogony deals with the origin of each astronomical entity.
RHESSI observes high-energy phenomena from a solar flare. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.
Stellar surface fusion occurs above a star's photosphere to a limited extent as found in studies of near coronal cloud activity.
Surface fusion is produced by reactions during or preceding a stellar flare and at much lower levels elsewhere above the photosphere of a star.
"Nuclear interactions of ions accelerated at the surface of flaring stars can produce fresh isotopes in stellar atmospheres."
"This energy [1032 to 1033 ergs] appears in the form of electromagnetic radiation over the entire spectrum from γ-rays to radio burst, in fast electrons and nuclei up to relativistic energies, in the creation of a hot coronal cloud, and in large-scale mass motions including the ejections of material from the Sun."
"The new reaction 208Pb(59Co,n)266Mt was studied using the Berkeley Gas-filled Separator [BGS] at the Lawrence Berkeley National Laboratory [LBNL] 88-Inch Cyclotron."
266Mt has been produced using the 209Bi(58Fe,n)266Mt reaction.
"Reactions with various medium-mass projectiles on nearly spherical, shell-stabilized 208Pb or 209Bi targets have been used in the investigations of transactinide (TAN) elements and their decay properties for many years. These so-called “cold fusion” reactions produce weakly excited (10-15 MeV)  compound nuclei (CNs) at bombarding energies at or near the Coulomb barrier that de-excite by the emission of one to two neutrons."
"The laboratory-frame, center-of-target energy used was 291.5 MeV, corresponding to a CN excitation energy of 14.9 MeV."
"At the start of the experiment the BGS magnet settings were chosen to guide products with a magnetic rigidity of 2.143 T·m to the center of the [focal plane detector] FPD. After the first event of 266Mt was detected in strip 45 (near one edge of the FPD), the magnetic field strength was decreased to 2.098 T·m in an effort to shift the distribution of products toward the center of the detector."
"258Db [has been produced] via the 209Bi(50Ti,n) and 208Pb(51V,n) reactions , and 262Bh via the 209Bi(54Cr,n) and 208Pb(55Mn,n) reactions [13, 16]."
"Hofmann et al. at Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany, and Morita et al., at the Institute of Physical and Chemical Research (RIKEN) in Saitama, Japan, have studied the 209Bi(64Ni,n)272Rg reaction [7, 17, 18]. The complementary 208Pb(65Cu,n)272Rg reaction was studied by Folden et al. at the Lawrence Berkeley National Laboratory (LBNL) ."
"Based on the observation of the long-lived isotopes of roentgenium, 261Rg and 265Rg (Z = 111, t1/2 ≥ 108 y) in natural Au, an experiment was performed to enrich Rg in 99.999% Au. 16 mg of Au were heated in vacuum for two weeks at a temperature of 1127°C (63°C above the melting point of Au). The content of 197Au and 261Rg in the residue was studied with high resolution inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). The residue of Au was 3 × 10−6 of its original quantity. The recovery of Rg was a few percent. The abundance of Rg compared to Au in the enriched solution was about 2 × 10−6, which is a three to four orders of magnitude enrichment."
W Ursae Majoris is an eclipsing binary, specifically a contact binary with a common envelope. The primary component has a radius of 1.08 solar. The secondary has a 0.78 solar radius. Credit: Aladin at SIMBAD.
This image shows the star Merope (23 Tauri) in the Pleiades. Credit: Henryk Kowalewski.
Star fission is the splitting of a star at a critical angular momentum, or period in its history, with the consequence of zero-age contact in the resultant binary star. This splitting may have its highest probability of occurring during early star formation.
Def. any small luminous dot appearing in the cloudless portion of the night sky, especially with a fixed location relative to other such dots or a luminous celestial body, made up of plasma (particularly hydrogen and helium) and having a spherical shape is called a star.
When any effort to acquire a system of laws or knowledge focusing on a stellar astr, aster, or astro, that is, any natural star in the sky especially at night, succeeds even in its smallest measurement, stellar astronomy is the name of the effort and the result.
This animation depicts the collision between our Milky Way galaxy and the Andromeda galaxy. Credit: Visualization Credit: NASA; ESA; and F. Summers, STScI; Simulation Credit: NASA; ESA; G. Besla, Columbia University; and R. van der Marel, STScI.
Most of the mathematics needed to understand the information acquired through astronomical radiation observation comes from physics. But, there are special needs for situations that intertwine mathematics with phenomena that may not yet have sufficient physics to explain the observations. Both uses constitute radiation mathematics, or astronomical radiation mathematics, or a portion of mathematical radiation astronomy.
Astronomical radiation mathematics is the laboratory mathematics such as simulations that are generated to try to understand the observations of radiation astronomy.
The mathematics needed to understand radiation astronomy starts with arithmetic and often needs various topics in calculus and differential equations to produce likely models.