5/18/2023 0 Comments Reflection nebulaUnlike emission nebulae, whose reddish glow comes from ionized atoms of gas, reflection nebulae have a bluish cast as their interstellar dust grains reflect blue starlight. Iron and nickel are often aligned with the galactic magnetic field and cause the scattered light to be slightly polarized. Reflection nebula are very impressive to look at and are often the subject of astrophotography.Īmong the microscopic particles responsible for the scattering of the light within reflection nebulae are carbon compounds and compounds of other elements such as iron and nickel. Therefore, the frequency spectrum shown by reflection nebulae is similar to that of the illuminating stars. The energy from the nearby stars is not enough to ionize the gas of the nebula to create an emission nebula, but is enough to give sufficient scattering to make the dust visible. John S.A reflection nebula is a cloud of interstellar dust that reflects the light of a nearby star or stars. Calculations show that even graphite, which is black in bulk, reflects visible light well when dispersed into small particles. Grains reflect light almost as well as fresh snow, more because of their favourable size (which promotes scattering rather than absorption) than their chemical composition. Optical observations suggest that about 60–70 percent of the light is reflected rather than absorbed, while the corresponding fraction for Earth is only 35 percent and for the Moon a mere 5 percent. The extent and brightness of reflection nebulae show conclusively that dust grains are excellent reflectors in the broad range of wavelengths extending from the ultraviolet (as determined from observations from space) through the visible. The brightest reflection nebulae are illuminated by B-type stars that are very luminous but have temperatures lower than about 25,000 K, cooler than the O-type stars that would ionize the hydrogen in the gas and produce an H II region. ![]() The famous nebulosity in the Pleiades star cluster is of this type it was discovered in 1912 that the spectrum of this nebula mimics the absorption lines of the nearby stars, whereas bright nebulae that emit their own light show their own characteristic emission lines. Reflection nebula, interstellar cloud that would normally be a dark nebula (or molecular cloud) but whose dust reflects the light from a nearby bright star that is not hot enough to ionize the cloud’s hydrogen. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.This Time in History In these videos, find out what happened this month (or any month!) in history. ![]() #WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find. ![]() Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.
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