To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

4,5
Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.
.
Leo
Newton
Brights
Milds

Reflection nebula

From Wikipedia, the free encyclopedia

The Witch Head reflection nebula (IC2118), about 900 light years from earth, is associated with the bright star Rigel in the constellation Orion. The nebula glows primarily by light reflected from Rigel, located just outside the top right corner of the image. Fine dust in the nebula reflects the light. The blue color is caused not only by Rigel's blue color but because the dust grains reflect blue light more efficiently than red.
The Witch Head reflection nebula (IC2118), about 900 light years from earth, is associated with the bright star Rigel in the constellation Orion. The nebula glows primarily by light reflected from Rigel, located just outside the top right corner of the image. Fine dust in the nebula reflects the light. The blue color is caused not only by Rigel's blue color but because the dust grains reflect blue light more efficiently than red.

In astronomy, reflection nebulae are clouds of interstellar dust which might reflect the light of a nearby star or stars. The energy from the nearby stars is insufficient to ionize the gas of the nebula to create an emission nebula, but is enough to give sufficient scattering to make the dust visible. Thus, the frequency spectrum shown by reflection nebulae is similar to that of the illuminating stars. Among the microscopic particles responsible for the scattering are carbon compounds (e. g. diamond dust) and compounds of other elements such as iron and nickel. The latter two are often aligned with the galactic magnetic field and cause the scattered light to be slightly polarized.[1]

YouTube Encyclopedic

  • 1/3
    Views:
    4 333
    3 541
    4 755
  • ✪ What is a Reflection Nebula?
  • ✪ Classroom Aid - Reflection, Emission and Dark Nebula
  • ✪ Types of Nebulae

Transcription

Contents

Discovery

Reflection nebula IC 2631.[2]
Reflection nebula IC 2631.[2]
Reflection Nebula vdB1
Reflection Nebula vdB1

Analyzing the spectrum of the nebula associated with the star Merope in the Pleiades, Vesto Slipher concluded in 1912 that the source of its light is most likely the star itself, and that the nebula reflects light from the star (and that of the star Alcyone).[3] Calculations by Ejnar Hertzsprung in 1913 lend credence to that hypothesis.[4] Edwin Hubble further distinguished between the emission and reflection nebulae in 1922.[5]

Reflection nebulae are usually blue because the scattering is more efficient for blue light than red (this is the same scattering process that gives us blue skies and red sunsets).

Reflection nebulae and emission nebulae are often seen together and are sometimes both referred to as diffuse nebulae.

Some 500 reflection nebulae are known. A blue reflection nebula can also be seen in the same area of the sky as the Trifid Nebula. The giant star Antares, which is very red (spectral class M1), is surrounded by a large, red reflection nebula.

Reflection nebulae may also be the site of star formation.

Luminosity law

Cosmic dust clouds in Messier 78.[6]
Cosmic dust clouds in Messier 78.[6]

In 1922, Edwin Hubble published the result of his investigations on bright nebulae. One part of this work is the Hubble luminosity law for reflection nebulae, which makes a relationship between the angular size (R) of the nebula and the apparent magnitude (m) of the associated star:

5 log(R) = -m + k

where k is a constant that depends on the sensitivity of the measurement.

See also

References

  1. ^ Kaler, 1997.
  2. ^ "A Star's Moment in the Spotlight". Retrieved 10 February 2016.
  3. ^ Slipher, Vesto M. (1922). "On the spectrum of the nebula in the Pleiades". Lowell Observatory Bulletin. 2: 26–27. Bibcode:1912LowOB...2...26S.
  4. ^ Hertzsprung, E. (1913). "Über die Helligkeit der Plejadennebel" (PDF). Astronomische Nachrichten. 195 (23): 449–452. Bibcode:1913AN....195..449H. doi:10.1002/asna.19131952302.
  5. ^ Hubble, E. P. (1922). "The source of luminosity in galactic nebulae". Astrophysical Journal. 56: 400. Bibcode:1922ApJ....56..400H. doi:10.1086/142713.
  6. ^ "Sifting through Dust near Orion's Belt". ESO Press Release. Retrieved 2 May 2012.

Bibliography

  • James B. Kaler (1997). Cosmic Clouds -- Birth, Death, and Recycling in the Galaxy, Scientific American Library, Freeman, New York, 1997.
This page was last edited on 5 November 2019, at 14:30
Basis of this page is in Wikipedia. Text is available under the CC BY-SA 3.0 Unported License. Non-text media are available under their specified licenses. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc. WIKI 2 is an independent company and has no affiliation with Wikimedia Foundation.