Solar telescope

Source: Wikipedia, the free encyclopedia.
The Swedish 1-m Solar Telescope at Roque de los Muchachos Observatory, La Palma in the Canary Islands.

A solar telescope is a special purpose telescope used to observe the Sun. Solar telescopes usually detect light with wavelengths in, or not far outside, the visible spectrum. Obsolete names for Sun telescopes include heliograph and photoheliograph.

Professional solar telescopes

Solar telescopes need optics large enough to achieve the best possible diffraction limit but less so for the associated light-collecting power of other astronomical telescopes. However, recently newer narrower filters and higher framerates have also driven solar telescopes towards photon-starved operations.[1] Both the Daniel K. Inouye Solar Telescope as well as the proposed European Solar Telescope (EST) have larger apertures not only to increase the resolution, but also to increase the light-collecting power.

Because solar telescopes operate during the day, seeing is generally worse than for night-time telescopes, because the ground around the telescope is heated, which causes turbulence and degrades the resolution. To alleviate this, solar telescopes are usually built on towers and the structures are painted white. The Dutch Open Telescope is built on an open framework to allow the wind to pass through the complete structure and provide cooling around the telescope's main mirror.

Another solar telescope-specific problem is the heat generated by the tightly-focused sunlight. For this reason, a heat stop is an integral part of the design of solar telescopes. For the Daniel K. Inouye Solar Telescope, the heat load is 2.5 MW/m2, with peak powers of 11.4 kW.[2] The goal of such a heat stop is not only to survive this heat load, but also to remain cool enough not to induce any additional turbulence inside the telescope's dome.

Professional solar observatories may have main optical elements with very long focal lengths (although not always, Dutch Open Telescope) and light paths operating in a vacuum or helium to eliminate air motion due to convection inside the telescope. However, this is not possible for apertures over 1 meter, at which the pressure difference at the entrance window of the vacuum tube becomes too large. Therefore, the Daniel K. Inouye Solar Telescope and the EST have active cooling of the dome to minimize the temperature difference between the air inside and outside the telescope.

Due to the sun's narrow path across the sky, some solar telescopes are fixed in position (and are sometimes buried underground), with the only moving part being a

McMath-Pierce Solar Telescope
.

Selected solar telescopes

See also: List of solar telescopes

Other types of observation

Most solar observatories observe optically at visible, UV, and near infrared wavelengths, but other solar phenomena can be observed — albeit not from the Earth's surface due to the absorption of the atmosphere:

  • Solar X-ray astronomy, observations of the Sun in x-rays
  • Multi-spectral solar telescope array (MSSTA), a rocket launched payload of UV telescopes in the 1990s
  • Leoncito Astronomical Complex operated a submillimeter wavelength solar telescope.
  • The
    Air Force Weather Agency
    .
  • axions
    in the early 2000s

Amateur solar telescopes

hydrogen-alpha filter
system.
Diagram of a Herschel Wedge and other solar viewing methods.

In the field of

hydrogen-alpha filter systems and even home built spectrohelioscopes. In contrast to professional telescopes, amateur solar telescopes are usually much smaller.[citation needed
]

With a conventional telescope, an extremely dark filter at the opening of the primary tube is used to reduce the light of the sun to tolerable levels. Since the full available spectrum is observed, this is known as "white-light" viewing, and the opening filter is called a "white-light filter". The problem is that even reduced, the full spectrum of white light tends to obscure many of the specific features associated with solar activity, such as prominences and details of the

Fabry-Perot etalon.[4]

See also

References

  1. Bibcode:2001ASPC..248..639S
    .
  2. ^ Dalrymple (1 April 2003). "Heat Stop Concepts" (PDF). ATST Technical Notes. {{cite journal}}: Cite journal requires |journal= (help)
  3. ISBN 978-1-85233-160-3
    .
  4. ^ Morison, Ian (2016-12-25). H-alpha Solar Telescopes - An In-depth Discussion and Survey. Professor Morison's Astronomy Digest, 25 December 2016. Retrieved on 2020-04-17 from http://www.ianmorison.com/h-alpha-solar-telescopes-an-in-depth-discussion-and-survey/.

External links

Look up solar telescope in Wiktionary, the free dictionary.
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