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Glossarbegriffe: Nebel

Description: Ein Nebel ist ein weit entferntes Himmelsobjekt, das wie eine Art Wolke aussieht. Normalerweise bestehen Nebel aus interstellarem Gas und Staub. Historisch gesehen umfasste der Begriff Nebel jedes ausgedehnte, "nebliges" Objekt: So wurden früher auch Galaxien - entfernte Sternensysteme ähnlich wie unsere eigene Milchstraße - als Nebel bezeichnet. Heute beschränkt sich der Begriff Nebel auf Gas- und Staubwolken, die Teil des interstellaren Mediums sind - das Gas und der Staub zwischen den Sternen innerhalb einer Galaxie. Es gibt verschiedene Arten von Nebeln: Molekülwolken sind vergleichsweise kalt und dunkel und bestehen überwiegend aus molekularem Wasserstoff; in solchen Wolken werden neue Sterne gebildet. Sehr große Molekülwolken (sogenannte Riesenmolekülwolken) können bis zu einigen Millionen Sonnenmassen an Wasserstoffgas enthalten. Eine andere Art von Nebel entsteht in der Umgebung von jungen Sternen: Junge Sterne stoßen häufig schmale Strahlen (Jets) aus ionisiertem Gas aus. Wenn diese Jets das umgebende Gas energetisch anregen, entsteht eine Art Nebel, der als Herbig-Haro-Objekt bezeichnet wird. Wenn sich massereiche Sterne gebildet haben, bringt ihre intensive Strahlung das umgebende Gas dazu, ein charakteristisches rötliches Licht auszustrahlen. Das Ergebnis sind Nebel aus heißem und ionisiertem Wasserstoffgas, die als HII-Regionen bezeichnet werden. Andere Arten von Nebeln sind mit dem Tod von Sternen verbunden: Sterne mit geringer Masse hinterlassen expandierende Gashüllen, die (etwas verwirrend) als planetarische Nebel bezeichnet werden. Wenn ein massereicher Stern als Supernova explodiert, bildet das ausgestoßene Gas eine Art von Nebel, der Supernova-Überrest genannt wird.

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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher
The translation of this term and its definition is still awaiting approval

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

Related Diagrams


Sagittarius is shaped like a teapot pouring tea south west. The ecliptic runs WSW to ENE at the top of the constellation

Sagittarius Constellation Map

Bildunterschriften: The constellation Sagittarius along with its bright stars and surrounding constellations. Sagittarius is surrounded by (going clockwise from the top) Aquila, Scutum, Serpens Cauda, Ophiuchus, Scorpius, Corona Australis, Telescopium, Microscopium and Capricornus. The brighter stars in Sagittarius form a distinctive teapot shape. Sagittarius lies on the ecliptic (shown here as a blue line), this is the path the Sun appears to take across the sky over the course of a year. The Sun is in Sagittarius from mid December to mid January. The other planets of the Solar System can often be found in Sagittarius. Sagittarius lies south of the celestial equator. The famous teapot asterism is visible for all but the most arctic regions of the world but the most southerly parts of the constellation are not visible in northern parts of Asia, Europe and North America. Sagittarius is most visible in the evenings in the northern hemisphere summer and southern hemisphere winter. The supermassive black hole Sagittarius A* which lies at the center of our Milky Way Galaxy is sits on the western (here right-hand) edge of Sagittarius. Due to it covering an area at the center of our Galaxy, Sagittarius is home to many star clusters including open clusters (marked here with yellow circles) and globular clusters (marked here with yellow circles with + signs superimposed on them). Three nebulae are also marked here with green squares. The y-axis of this diagram is in degrees of declination and with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the lines joining the stars appear on the sky.
Bildnachweis: Adapted by the IAU Office of Astronomy for Education from the original by IAU/Sky & Telescope

License: CC-BY-4.0 Creative Commons Namensnennung 4.0 International (CC BY 4.0) icons

Related Activities


Reading the Rainbow

Reading the Rainbow

astroEDU educational activity (links to astroEDU website)
Description: By understanding how rainbows work, you can discover about light and its properties, learning about stars, nebulae, galaxies, and our Universe.

License: CC-BY-4.0 Creative Commons Namensnennung 4.0 International (CC BY 4.0) icons

Age Ranges: 14-16 , 16-19 , 19+
Education Level: Informal , Middle School , Secondary , University
Areas of Learning: Interactive Lecture , Observation based , Social Research
Costs: Low Cost
Duration: 1 hour 30 mins
Group Size: Group
Skills: Analysing and interpreting data , Asking questions , Engaging in argument from evidence