X Ray Telescope

8 Key excerpts on "X Ray Telescope"

• 

  eBook - PDF

  Solar Planetary Systems

  Stardust to Terrestrial and Extraterrestrial Planetary Sciences

  • Asit B. Bhattacharya, Jeffrey M. Lichtman(Authors)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  443 20 Space Telescopes—An In-Depth View 20.1 Introduction The space telescopes are categorized by the task that they were designed for. In most cases, these tasks are for the research of gamma rays, X-rays, ultraviolet light, visible light, infra-red, microwave emission, and radio waves. Space telescopes which collect particles, such as cosmic ray nuclei, electrons, and instruments used to detect gravitational waves, are also among the categories listed. Two values are given for the dimensions of the initial orbit. For telescopes in Earth orbit, the minimum and maximum altitude are given in kilometers. For telescopes in solar orbit, the minimum distance (periapsis) and the maximum distance (apoapsis) between the telescope and the center of mass of the Sun are given in astronomical units (AU). 20.2 Gamma Ray Space Telescopes Gamma ray telescopes (Table 20.1) are used to collect and measure individual, high-energy gamma rays from different astrophysical sources. These are absorbed by the atmosphere, requiring that observations are made by high-altitude balloons or space missions. Gamma rays are generated by supernovae, pulsars, neutron stars, and black holes. Gamma ray bursts, with sufficiently high energies, have also been detected but have yet to be identified [1]. 20.3 X-Ray Telescopes The purpose of X-ray telescopes (Table 20.2) are to measure high-energy photons termed as X-rays. X-rays cannot travel long distances through the atmosphere. They can only be seen in the upper altitudes of our atmosphere or in space. There are a variety of astrophysical objects that emit X-rays, from galaxy clusters, through black holes, supernova remnants, stars, and binary stars having white dwarf and neutron stars. Some solar system bodies emit X-rays through the process of reflection. A combination of many unresolved X-ray sources is assumed to produce the observed X-ray background.

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  Solar Planetary Systems

  Stardust to Terrestrial and Extraterrestrial Planetary Sciences

  • Asit B. Bhattacharya, Jeffrey M. Lichtman(Authors)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  20 Space Telescopes—An In-Depth View 20.1 Introduction The space telescopes are categorized by the task that they were designed for. In most cases, these tasks are for the research of gamma rays, X-rays, ultraviolet light, visible light, infrared, microwave emission, and radio waves. Space telescopes which collect particles, such as cosmic ray nuclei, electrons, and instruments used to detect gravitational waves, are also among the categories listed. Two values are given for the dimensions of the initial orbit. For telescopes in Earth orbit, the minimum and maximum altitude are given in kilometers. For telescopes in solar orbit, the minimum distance (periapsis) and the maximum distance (apoapsis) between the telescope and the center of mass of the Sun are given in astronomical units (AU). 20.2 Gamma Ray Space Telescopes Gamma ray telescopes (Table 20.1) are used to collect and measure individual, high-energy gamma rays from different astrophysical sources. These are absorbed by the atmosphere, requiring that observations are made by high-altitude balloons or space missions. Gamma rays are generated by supernovae, pulsars, neutron stars, and black holes. Gamma ray bursts, with sufficiently high energies, have also been detected but have yet to be identified [ 1 ]. 20.3 X-Ray Telescopes The purpose of X-ray telescopes (Table 20.2) are to measure high-energy photons termed as X-rays. X-rays cannot travel long distances through the atmosphere. They can only be seen in the upper altitudes of our atmosphere or in space. There are a variety of astrophysical objects that emit X-rays, from galaxy clusters, through black holes, supernova remnants, stars, and binary stars having white dwarf and neutron stars. Some solar system bodies emit X-rays through the process of reflection

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Observational Astronomy

  Techniques and Instrumentation

  • Edmund C. Sutton(Author)
  • 2011(Publication Date)
  • Cambridge University Press

    (Publisher)

  11 Ultraviolet, x-ray, and gamma ray astronomy 11.1 Telescopes and imaging As photon energies increase beyond those of visible and near-ultraviolet light, conventional telescope designs fail. We will look at some variations on conven- tional optical designs which are effective for x-ray telescopes and then at other approaches to imaging for gamma ray observations. Earth’s atmosphere is opaque to radiation beyond the near-ultraviolet, so observations at these energies require space missions. 11.1.1 X-ray telescopes From our earlier discussion of the complex index of refraction, we can see that for soft x-rays, generally ω  ω 0i , and n 2 − 1 n 2 + 2 ≈ − 1 3 ω 2 p ω 2 . (11.1) When, in addition, ω  ω p , n 2 ≈ 1 − . (11.2) The index of refraction is real and slightly less than 1. Materials become transparent – all materials. How then can one hope to build a focussing system, i.e. a telescope? Since materials are transparent, one might first consider making lenses, but the fact that the index of refraction is near unity leads to impractically long focal lengths. Instead, it is better to use mirrors. Snell’s law for refraction is n sin θ = n  sin θ  . (11.3) If n = 1 and n  < 1, then for some angles θ there is no allowed value of θ  , since sin θ  would need to be greater than 1. Thus there can be no refracted ray; 190 11.1 Telescopes and imaging 191 Figure 11.1 Examples of total internal reflection. On the left, visible light is totally internally reflected inside a piece of glass. On the right, an x-ray at grazing incidence is totally “internally” reflected by a metallic surface. Figure 11.2 Cross section of a Wolter type-I telescope with nested optics such as in ROSAT and Chandra. Paraboloidal shells are shown as solid extensions of dashed lines (red in electronic version). Hyperboloidal shells are extensions of dotted (blue) lines.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Astronomy

  • Andrew Fraknoi, David Morrison, Sidney C. Wolff(Authors)
  • 2016(Publication Date)
  • Openstax

    (Publisher)

  Such observations first became possible in 1946, with V2 rockets captured from Germany after World War II. The US Naval Research Laboratory put instruments on these rockets for a series of pioneering flights, used initially to detect ultraviolet radiation from the Sun. Since then, many other rockets have been launched to make X-ray and ultraviolet observations of the Sun, and later of other celestial objects. Beginning in the 1960s, a steady stream of high-energy observatories has been launched into orbit to reveal and explore the universe at short wavelengths. Among recent X-ray telescopes is the Chandra X-ray Observatory, which was launched in 1999 (Figure 6.26). It is producing X-ray images with unprecedented resolution and sensitivity. Designing instruments that can collect and focus energetic radiation like X-rays and gamma rays 220 Chapter 6 Astronomical Instruments This OpenStax book is available for free at http://cnx.org/content/col11992/1.13 is an enormous technological challenge. The 2002 Nobel Prize in physics was awarded to Riccardo Giacconi, a pioneer in the field of building and launching sophisticated X-ray instruments. In 2008, NASA launched the Fermi Gamma-ray Space Telescope, designed to measure cosmic gamma rays at energies greater than any previous telescope, and thus able to collect radiation from some of the most energetic events in the universe. Figure 6.26 Chandra X-Ray Satellite. Chandra, the world’s most powerful X-ray telescope, was developed by NASA and launched in July 1999. (credit: modification of work by NASA) One major challenge is to design “mirrors” to reflect such penetrating radiation as X-rays and gamma rays, which normally pass straight through matter.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Pulsar Astronomy

  • Andrew Lyne, Francis Graham-Smith(Authors)
  • 2012(Publication Date)
  • Cambridge University Press

    (Publisher)

  Several energetic young pul- sars which radiate high-energy pulses can be detected with smaller telescopes. These, and notably the Crab and Vela Pulsars (Chapter 9), are usefully studied using high time resolu- tion and polarimetry. Apart from these direct observations of neutron stars, there are valuable optical observations of the companions to many binary pulsars, either white dwarfs or main- sequence stars (Chapter 11), and of nebulae associated with pulsar winds and bowshocks (Chapter 14). The new generation of very large optical telescopes (Chapter 22) will bring many more neutron stars into our observable range. 3.3 X-ray observations Two decades of the X-ray spectrum, from about 0.1 keV to 10 keV (or in terms of wavelength, from 12 nm to 0.12 nm), are accessible to imaging X-ray telescopes orbiting 3.4 Gamma-ray space-based telescopes 29 Incoming X-rays To focal plane To focal plane Nested cylindrical reflectors Paraboloids Hyperboloids Fig. 3.1. The Wolter X-ray telescope. The grazing incidence reflecting elements are sections of paraboloids followed by sections of hyperboloids. above the atmosphere. In this energy region it is possible to focus X-rays by reflection at glancing incidence on highly polished metal surfaces. The basic geometric arrangement is shown in Figure 3.1. The cylindrical mirror has two successive reflecting components which are sections of a paraboloid and a hyperboloid; this brings rays to a focus at a distance from these components of several times their diameter, while the use of the two profiles gives a larger field of view than a simple paraboloid. A set of mirrors may be nested inside one another to increase the effective area of the telescope. The first imaging X-ray telescope was HEAO-2 (Einstein), launched in 1978. At the time of writing (2011), X-ray astronomy relies mainly on two orbiting imaging telescopes, both launched in 1999.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Stars and Galaxies

  • Michael Seeds(Author)
  • 2018(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  Modern astronomy has come to depend on observations that cover the entire electromagnetic spectrum. More orbiting space telescopes are planned that will be even more versatile and sensitive than the ones operating now. 6-5 Astronomical Instruments and Techniques Just looking through a telescope doesn’t tell you much. A star looks like a point of light. A planet looks like a little disk. A galaxy looks like a hazy patch. To use a research telescope to learn about the Universe, you need to carefully analyze the light the telescope gathers. Special instruments attached to the tele-scope make that possible. X-rays focused on detector Incoming X-rays Nested metal mirrors ▲ Figure 6-18 X-rays that hit a mirror at grazing angles are reflected like a pebble skipping across a pond. Thus, X-ray telescope mirrors like the ones in Chandra are shaped like barrels rather than dishes. NASA/SAO/CXC Adding liquid nitrogen to the camera on a telescope is a familiar task for astronomers. ▲ Figure 6-19 Astronomical cameras with CCD and other types of array detectors must be cooled to low temperatures to operate properly, and that is especially true for infrared cameras. Kris Koenig/Coast Learning Systems Copyright 2019 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 119 Chapter 6 Light and Telescopes (shortwavelength) light passing through a prism bends the most, and red (long-wavelength) light bends least. Thus, the white light entering the prism is spread into a spectrum exiting the prism ( Figure 6-22 ).

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  An Introduction to Modern Astrophysics

  • Bradley W. Carroll, Dale A. Ostlie(Authors)
  • 2017(Publication Date)
  • Cambridge University Press

    (Publisher)

  The distance between the atoms corresponds to the separation between slits in an optical diffraction grating. In 1970 UHURU (also known as the Small Astronomy Satellite–1, SAS 1) made the first comprehensive survey of the X-ray sky. In the late 1970s the three High Energy Astrophysical Observatories , including the Einstein Observatory , discovered thousands of X-ray and gamma-ray sources. Between 1990 and 1999, the X-ray observatory ROSAT (the Roentgen Satellite ), a German–American–British satellite consisting of two detectors and an imaging telescope operating in the range of 0.51 nm to 12.4 nm, investigated the hot coronas of stars, supernova remnants, and quasars. Japan’s Advanced Satellite for Cosmology and Astrophysics , which began its mission in 1993, also made valuable X-ray observations of the heavens before attitude control was lost as a result of a geomagnetic storm July 14, 2000. Launched in 1999 and named for the Nobel Prize–winning astrophysicist Subrahmanyan Chandrasekhar (1910–1995), the Chandra X-ray Observatory [Fig. 6.27(a)] operates in the energy range from 0.2 keV to 10 keV (6.2 nm to 0.1 nm, respectively) with an angular resolution of approximately 0 . 5 . Because X-rays cannot be focused in the same way that longer wavelengths can, grazing incidence mirrors are used to achieve the outstanding resolving power of Chandra. The European Space Agency operates another X-ray telescope also launched in 1999, the X-ray Multi-Mirror Newton Observatory (XMM-Newton). Complementing Chandra’s sensitivity range, XMM-Newton operates between 0.01 nm and 1.2 nm. The Compton Gamma Ray Observatory [CGRO; Fig. 6.27(b)] observed the heavens at wavelengths shorter than those measured by the X-ray telescopes. Placed into orbit by the Space Shuttle Atlantis in 1991, the observatory was deorbited into the Pacific Ocean in June 2000.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  The Cosmos

  Astronomy in the New Millennium

  • Jay M. Pasachoff, Alex Filippenko(Authors)
  • 2019(Publication Date)
  • Cambridge University Press

    (Publisher)

  And x-rays and gamma rays do not pass through Earth’s atmosphere, so they can be observed only from satellites in space. NASA’s series of three High-Energy Astronomy Observatories (HEAOs) was tremendously successful in the late 1970s. One of them even made detailed x-ray observations of individual objects with resolution approaching that of ground-based telescopes working with ordinary light. NASA’s current and best x-ray telescope is called the Chandra X-ray Observatory, named after a scientist (S. Chandrasekhar; see Chapter 13) who made important studies of white dwarfs and black holes. It was launched in 1999. It makes its high-resolution Jay M. Pasachoff and Kamen Kozarev, Williams College-Hopkins Observatory ■ Figure 3–25 Spikes of hot chromospheric gas from the Transition Region and Coronal Explorer (TRACE) spacecraft imaged in the ultraviolet as part of one of the authors’ (J.M.P.) research. 58 3 Light and Telescopes: Extending Our Senses images with a set of nested mirrors made on cylinders (■ Fig. 3–28). Ordinary mirrors could not be used because x-rays would pass right through them. However, x-rays bounce off mirrors at low angles, just as stones can be skipped across a lake at low angles (■ Fig. 3–29). Chandra joins Hubble as one of NASA’s series called the “Great Observatories.” The European Space Agency’s XMM-Newton mis- sion has more telescope area and so is more sensitive to faint sources than Chandra, but it doesn’t have Chandra’s high angular resolution. (An earlier European x-ray satellite, Roentgensatellite, or ROSAT for short – named after Wilhelm Roentgen, a German who was the dis- coverer of x-rays over 100 years ago – was long defunct and reentered the atmosphere in 2011, crashing into the Indian Ocean as expected and not injuring anyone, but nonetheless causing a bit of worldwide panic over the possibility of being hit.) The Japanese Suzaku x-ray satellite took x-ray images during 2005–2015.

  Sign up to read

  Learn more about book