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
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Selected lecture

Radiation astronomy objects

The image shows a chain of craters on Ganymede. Credit: Galileo Project, Brown University, JPL, NASA.

Def. a hemispherical pit a basinlike opening or mouth about which a cone is often built up any large roughly circular depression or hole is called a crater.

The image at right shows a chain of 13 craters (Enki Catena) on Ganymede measuring 161.3 km in length. "The Enki craters formed across the sharp boundary between areas of bright terrain and dark terrain, delimited by a thin trough running diagonally across the center of this image. The ejecta deposit surrounding the craters appears very bright on the bright terrain. Even though all the craters formed nearly simultaneously, it is difficult to discern any ejecta deposit on the dark terrain.

Selected theory

Stellar surface fusion

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."[1]

"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."[2]

"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."[3]

266Mt has been produced using the 209Bi(58Fe,n)266Mt reaction.[3]

"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) [1] compound nuclei (CNs) at bombarding energies at or near the Coulomb barrier that de-excite by the emission of one to two neutrons."[3]

"The laboratory-frame, center-of-target energy used was 291.5 MeV, corresponding to a CN excitation energy of 14.9 MeV."[3]

"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."[3]

"258Db [has been produced] via the 209Bi(50Ti,n) and 208Pb(51V,n) reactions [15], and 262Bh via the 209Bi(54Cr,n) and 208Pb(55Mn,n) reactions [13, 16]."[3]

"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) [19]."[3]

"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."[4]

References

  1. Vincent Tatischeff, J.-P. Thibaud, I. Ribas (January 2008). "Nucleosynthesis in stellar flares". eprint arXiv:0801.1777. http://arxiv.org/pdf/0801.1777. Retrieved 2012-11-09. 
  2. R. P. Lin and H. S. Hudson (September-October 1976). "Non-thermal processes in large solar flares". Solar Physics 50 (10): 153-78. doi:10.1007/BF00206199. http://adsabs.harvard.edu/full/1976SoPh...50..153L. Retrieved 2013-07-07. 
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 S. L. Nelson, K. E. Gregorich, I. Dragojević, J. Dvořák, P. A. Ellison, M. A. Garcia, J. M. Gates, L. Stavsetra, M. N. Ali, and H. Nitsche (February 25, 2009). "Comparison of complementary reactions in the production of Mt". Physical Review C 79 (2): e027605. doi:10.1103/PhysRevC.79.027605. http://prc.aps.org/abstract/PRC/v79/i2/e027605. Retrieved 2014-04-07. 
  4. A. Marinov, A. Pape, D. Kolb, L. Halicz, I. Segal, N. Tepliakov and R. Brandt (2011). "Enrichment of the Superheavy Element Roentgenium (Rg) in Natural Au". International Journal of Modern Physics E 20 (11): 2391-2401. doi:10.1142/S0218301311020393. http://www.phys.huji.ac.il/~marinov/publications/Rg_261_arXiv_77.pdf. Retrieved 2014-04-08. 
Selected topic

Backgrounds

This graph shows the power density spectrum of the extragalactic or cosmic gamma-ray background (CGB). Credit: pkisscs@konkoly.hu.

In the figure at right, CUVOB stands for the cosmic ultraviolet and optical background.

The diffuse extragalactic background light (EBL) is all the accumulated radiation in the Universe due to star formation processes, plus a contribution from active galactic nuclei (AGNs). This radiation covers the wavelength range between ~ 0.1-1000 microns (these are the ultraviolet, optical, and infrared regions of the electromagnetic spectrum). The EBL is part of the diffuse extragalactic background radiation (DEBRA), which by definition covers the overall electromagnetic spectrum. After the cosmic microwave background, the EBL produces the second-most energetic diffuse background, thus being essential for understanding the full energy balance of the universe.

Selected X-ray astronomy article
This X-ray image of Cygnus X-1 was taken by a balloon-borne telescope, the High Energy Replicated Optics (HERO) project. NASA image.

Cygnus X-1 (abbreviated Cyg X-1) is a well known galactic X-ray source in the constellation Cygnus. Cygnus X-1 was the first X-ray source widely accepted to be a black hole candidate and it remains among the most studied astronomical objects in its class. It is now estimated to have a mass about 8.7 times the mass of the Sun and has been shown to be too compact to be any known kind of normal star or other likely object besides a black hole.

Objects
Selected image

Classified as a peculiar star, Eta Carinae exhibits a superstar at its center as seen in this image from Chandra X-ray Observatory. The new X-ray observation shows three distinct structures: an outer, horseshoe-shaped ring about 2 light years in diameter, a hot inner core about 3 light-months in diameter, and a hot central source less than 1 light-month in diameter which may contain the superstar that drives the whole show. The outer ring provides evidence of another large explosion that occurred over 1,000 years ago. Credit: Chandra Science Center and NASA.

Selected lesson

First ultraviolet source in Sagittarius

These two photographs were made by combining data from NASA's Galaxy Evolution Explorer spacecraft and the Cerro Tololo Inter-American Observatory in Chile. Credit: NASA/JPL-Caltech/JHU.

The first ultraviolet source in Sagittarius is unknown.

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

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

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

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

This is a lesson in map reading, coordinate matching, and searching. It is also a project in the history of ultraviolet astronomy looking for the first astronomical ultraviolet source discovered in the constellation of Sagittarius.

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 ultraviolet sources, you'll run into concepts and experimental tests that are an actual search.

Selected quiz

Color astronomy quiz

Gases above Io's surface produced a ghostly glow that could be seen at visible wavelengths (red, green, and violet). Credit: NASA/JPL/University of Arizona.

Color astronomy is a lecture as part of the radiation astronomy department course development of principles of radiation astronomy.

You are free to take this quiz based on color astronomy at any time.

To improve your scores, read and study the lecture, the links contained within, and listed under See also, External links and 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.

This quiz may need up to an hour to take and is equivalent to an hourly.

Suggestion: Have the lecture available in a separate window.

Enjoy learning by doing!

Selected laboratory

Astronomical analysis laboratory

Circinus X-1 is imaged with the Chandra X-ray Observatory. Credit: X-ray: NASA/CXC/Univ. of Wisconsin-Madison/S.Heintz et al.

This laboratory is an activity for you to analyze an astronomical situation. While it is part of the astronomy course principles of radiation astronomy, it is also independent.

Astronomical analysis is the detailed examination of the elements or structure of some astronomical thing (an entity, source, or object), typically as a basis for discussion or interpretation.

Once an astronomical situation has been selected, it must be separated into its constituent elements, for example, the identification and measurement of the chemical constituents of a substance or specimen.

You may choose an astronomical situation to dissect.

I will provide one example of this process. 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

Angular momentum and energy

This diagram describes the relationship between force (F), torque (τ), momentum (p), and angular momentum (L) vectors in a rotating system. 'r' is the radius. Credit: Yawe.

Angular momentum and energy are concepts developed to try to understand everyday reality.

An angular momentum L of a particle about an origin is given by

where r is the radius vector of the particle relative to the origin, p is the linear momentum of the particle, and × denotes the cross product (r · p sin θ). Theta is the angle between r and p.

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

Enjoy learning by doing!

Selected X-ray astronomy pictures

Cassiopeia A: a false color image composited of data from three sources. Red is infrared data from the Spitzer Space Telescope, orange is visible data from the Hubble Space Telescope, and blue and green are data from the Chandra X-ray Observatory.

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