Portal:Radiation astronomy

Radiation astronomy
This image is a composite of several types of radiation astronomy: radio, infrared, visual, ultraviolet, soft and hard X-ray. Credit: NASA.

Radiation astronomy is astronomy applied to the various extraterrestrial sources of radiation, especially at night. It is also conducted above the Earth's atmosphere and at locations away from the Earth, by satellites and space probes, as a part of explorational (or exploratory) radiation astronomy.

Seeing the Sun and feeling the warmth of its rays is probably a student's first encounter with an astronomical radiation source. This will happen from a very early age, but a first understanding of the concepts of radiation may occur at a secondary educational level.

Radiation is all around us on top of the Earth's crust, regolith, and soil, where we live. The study of radiation, including radiation astronomy, usually intensifies at the university undergraduate level.

And, generally, radiation becomes hazardous, when a student embarks on graduate study.

Cautionary speculation may be introduced unexpectedly to stimulate the imagination and open a small crack in a few doors that may appear closed at present. As such, this learning resource incorporates some state-of-the-art results from the scholarly literature.

The laboratories of radiation astronomy are limited to the radiation observatories themselves and the computers and other instruments (sometimes off site) used to analyze the results.

Selected radiation astronomy
The Moon is seen by the Compton Gamma Ray Observatory, in gamma rays of greater than 20 MeV. Credit: D. J. Thompson, D. L. Bertsch (NASA/GSFC), D. J. Morris (UNH), R. Mukherjee (NASA/GSFC/USRA).

Gamma-ray astronomy is radiation astronomy applied to the various extraterrestrial gamma-ray sources, especially at night. It is usually conducted above the Earth's atmosphere and at locations away from the Earth as a part of explorational (or exploratory) gamma-ray astronomy.

An introduction to gamma rays may occur at the secondary education level. The study of this type of radiation usually intensifies at the university undergraduate level. The more hazardous aspects of gamma radiation become known when a student embarks on graduate study.

As with general radiation astronomy some cautionary speculation may be introduced unexpectedly to stimulate the imagination and open a small crack in a few doors that may appear closed at present. This advances the learning portion of the resource to being a lecture and part article so some state-of -the-art results from the scholarly literature can be included.

The laboratories of gamma-ray astronomy are limited to the observatories themselves and the computers and other instruments (sometimes off site) used to analyze the results.

"Gamma radiation astronomy" is a term that dates back to 1965: PETERSON, LE. "Experiments in X-ray and gamma-ray astronomy(X-ray and gamma radiation astronomy- OSO MEASUREMENTS)." 1965. 15 P (1965).

Selected lecture

Radiation astronomy sources

Volcanic bombs are thrown into the sky and travel some distance before returning to the ground. This bomb is in the Craters of the Moon National Monument and Preserve, Idaho, USA. Credit: National Park Service.

In source astronomy, the question is "Where did it come from?"

Source astronomy has its origins in the actions of intelligent life on Earth when they noticed things or entities falling from above and became aware of the sky. Sometimes what they noticed is an acorn or walnut being dropped on them or thrown at them by a squirrel in a tree. Other events coupled with keen intellect allowed these life forms to deduce that some entities falling from the sky are coming down from locations higher than the tops of local trees.

Def. a source or apparent source detected or “created at or near the time of the [ event or] events”[1] is called a primary source.

Direct observation and tracking of the origination and trajectories of falling entities such as volcanic bombs presented early intelligent life with vital albeit sometimes dangerous opportunities to compose the science that led to source astronomy.

References

  1. primary source. San Francisco, California: Wikimedia Foundation, Inc. February 16, 2012. Retrieved 2012-07-14.
Selected theory

Stellar fissions

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.

Selected topic

Bands

This is Saturn imaged with the Stockholm Infrared Camera (SIRCA) in the H2O band. Credit: M. Gålfalk, G. Olofsson and H.-G. Florén, Nordic Optical Telescope.

At the right is Saturn imaged by the Stockholm Infrared Camera (SIRCA) in the H2O infrared band to show the presence of water vapor. The image is cut off near the top due to the presence of Saturn's rings.

The Sun's emission in the lowest UV bands, the UVA, UVB, and UVC bands, are of interest, as these are the UV bands commonly encountered from artificial sources on Earth. The shorter bands of UVC, as well as even more energetic radiation as produced by the Sun, generate the ozone in the ozone layer when single oxygen atoms produced by UV photolysis of dioxygen react with more dioxygen. The ozone layer is especially important in blocking UVB and part of UVC, since the shortest wavelengths of UVC (and those even shorter) are blocked by ordinary air.

Selected X-ray astronomy article
This is an artist's impression of an X-ray Binary. Credit: ESA, NASA, and Felix Mirabel (French Atomic Energy Commission and Institute for Astronomy and Space Physics/Conicet of Argentina).

An X-ray binary is a class of binary star that is luminous in X-rays.

The X-rays are produced by matter falling from one component, called the donor (usually a relatively normal star) to the other component, called the accretor, which is compact: a white dwarf, neutron star, or black hole. The infalling matter releases gravitational potential energy, up to several tenths of its rest mass, as X-rays. (Hydrogen fusion releases only about 0.7 percent of rest mass.)

Objects
Selected image
Jupiter xray ill.jpg

Jupiter shows intense X-ray emission associated with auroras in its polar regions (Chandra X-ray Observatory X-ray image on the left). The accompanying schematic illustrates how Jupiter's unusually frequent and spectacular auroral activity is produced. Observation period: 17 h, 24-26 February 2003. Credit: X-ray: NASA/CXC/MSFC/R. Elsner et al.; Illustration: CXC/M. Weiss.

Selected lesson

First positron source in Phoenix

Positron astronomy results have been obtained using the INTEGRAL spectrometer SPI shown. Credit: Medialab, ESA.

The first positron source in Phoenix is unknown.

The field of positron astronomy is the result of observations and theories about positron sources detected in the sky above.

The first astronomical positron source discovered may have been the Sun.

But, positrons from the Sun are intermingled with other radiation so that the Sun may appear as other than a primary source for positrons.

The early use of sounding rockets and balloons to carry positron detectors high enough may have detected positrons from the Sun as early as the 1940s.

This is a lesson in map reading, coordinate matching, and researching. It is also a research project in the history of positron astronomy looking for the first astronomical positron source discovered in the constellation of Phoenix.

Nearly all the background you need to participate and learn by doing you've probably already been introduced to at a secondary level and perhaps even a primary education level.

Some of the material and information is at the college or university level, and as you progress in finding positron sources, you'll run into concepts and experimental tests that are actual research.

Selected quiz

Beta particle astronomy quiz

Beta particles are produced by X-rays passing through air. Credit: Unknown.

Beta-particles astronomy is a lecture from the radiation astronomy department that is included in the course on the principles of radiation astronomy.

You are free to take this quiz based on beta-particles astronomy at any time.

To improve your score, read and study the lecture, the links contained within, listed under See also, External links, and in the {{radiation astronomy resources}} and {{principles of radiation astronomy}} templates. This should give you adequate background to get 100 %.

As a "learning by doing" resource, this quiz helps you to assess your knowledge and understanding of the information, and it is a quiz you may take over and over as a learning resource to improve your knowledge, understanding, test-taking skills, and your score.

Suggestion: Have the lecture available in a separate window.

To master the information and use only your memory while taking the quiz, try rewriting the information from more familiar points of view, or be creative with association.

Enjoy learning by doing!

Selected laboratory

Cratering astronomy laboratory

The crater in Santa Ana Volcano is photographed from a United States Air Force C-130 Hercules flying above El Salvador. Credit: José Fernández, U.S Air Force.

This laboratory is an activity for you to create or analyze a cratering. While it is part of the astronomy course principles of radiation astronomy, it is also independent.

Some suggested types of cratering to consider include a lightning strike, a bullet shot into some material, a water droplet hitting the surface of a beaker of water, a subterranean explosion, a sand vortex, or a meteorite impact.

More importantly, there is your cratering idea. And, yes, you can crater a peanut butter and jelly sandwich if you wish to.

Okay, this is an astronomy cratering laboratory, but you may create what a crater is. Another example is a volcanic crater.

I will provide an example of a cratering experiment. The rest is up to you.

Please put any questions you may have, and your laboratory results, you'd like evaluated, on the laboratory's discussion page.

Enjoy learning by doing!

Selected problems

Energy phantoms

This is an optical image in the visual range of Theta Ursae Majoris. It is listed in SIMBAD as an F7V spectral type star with a parallax of 74.19 mas. Credit: Aladin at SIMBAD.

Students start from specific situations of motion, determine how to calculate energy and convert units, then evaluate types of energy.

Def. a quantity that denotes the ability to do work and is measured in a unit dimensioned in mass × distance²/time² (ML²/T²) or the equivalent is called energy.

Def. a physical quantity that denotes ability to push, pull, twist or accelerate a body which is measured in a unit dimensioned in mass × distance/time² (ML/T²): SI: newton (N); CGS: dyne (dyn) is called force.

In astronomy we estimate distances and times when and where possible to obtain forces and energy.

The key values to determine in both force and energy are (L/T²) and (L²/T²). Force (F) x distance (L) = energy (E), L/T² x L = L²/T². Force and energy are related to distance and time using proportionality constants.

Every point mass attracts every single other point mass by a force pointing along the line intersecting both points. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between them:[1]
,

where:

  • F is the force between the masses,
  • G is the gravitational constant,
  • m1 is the first mass,
  • m2 is the second mass, and
  • r is the distance between the centers of the masses.
The diagram shows two masses attracting one another. Credit: Dna-Dennis.

In the International System of Units (SI) units, F is measured in newtons (N), m1 and m2 in kilograms (kg), r in meters (m), and the constant G is approximately equal to 6.674×1011
 N m2 kg−2
.[2]

Observationally, we may not know the origin of the force.

Coulomb's law states that the electrostatic force experienced by a charge, at position , in the vicinity of another charge, at position , in vacuum is equal to:

where is the electric constant and is the distance between the two charges.

Coulomb's constant is

where the constant is called the permittivity of free space in SI units of C2 m−2 N−1.

For reality, is the relative (dimensionless) permittivity of the substance in which the charges may exist.

The energy for this system is

where is the displacement.

References

  1. - Proposition 75, Theorem 35: p.956 - I.Bernard Cohen and Anne Whitman, translators: Isaac Newton, The Principia: Mathematical Principles of Natural Philosophy. Preceded by A Guide to Newton's Principia, by I. Bernard Cohen. University of California Press 1999 ISBN 0-520-08816-6 ISBN 0-520-08817-4
  2. CODATA2006.
Selected X-ray astronomy pictures
Hydra A gas cloud.jpg
Composite radio + x-ray.jpg

On the left is a Chandra X-ray image that reveals a large cloud of hot gas that extends throughout the Hydra A galaxy cluster. Image is 2.7 arcmin across. RA 09h 18m 06s Dec -12° 05' 45" in Hydra. Observation date: October 30, 1999. Instrument: ACIS. Credit:NASA/CXC/SAO. On the right is an image that has the radio image of Greg Taylor, NRAO, overlain on the X-ray image from Chandra. The radio source Hydra A originates in a galaxy near the center of the cluster. Optical observations show a few hundred galaxies in the cluster. Credit:NASA/CXC/SAO; Radio: NRAO.

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