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Glossarbegriffe: Leuchtkraftklasse

Description: Die Helligkeit eines Sterns hängt von seiner Temperatur und seiner Größe ab. Heißere Sterne sind heller, ebenso wie größere Sterne. Die Spektralklasse klassifiziert Sterne nach dem Aussehen ihrer Spektrallinien, was in etwa Veränderungen in der Temperatur entspricht. Die Leuchtkraftklasse hingegen ordnet Sterne danach, wie hell sie im Vergleich zu anderen Sternen ihres Spektraltyps sind. Das heißt: Zwei Sterne desselben Spektraltyps können unterschiedlich hell sein. Die Leuchtkraftklasse wird mit römischen Ziffern angegeben: Sterne auf der Hauptreihe, die Wasserstoff verbrennen, werden als Zwerge (V) eingestuft. Die Sonne hat beispielsweise die Klasse G2 V. Darüber liegen (in der Reihenfolge zunehmender Größe und Helligkeit) die Unterriesen (IV), die Riesen (III), die hellen Riesen (II) und die Überriesen (Ib für die weniger leuchtstarken und Ia für die leuchtstärksten). Bei all diesen Typen handelt es sich um alternde Sterne jenseits der Hauptreihe, die in ihrem Kern keinen Wasserstoff mehr verbrennen. Metallarme Unterzwerge (VI) sind wasserstoffverbrennende Sterne mit einem geringen Metallgehalt, die unterhalb der Hauptreihe liegen. Bei Weißen Zwergen (VII) handelt es sich um die ausgebrannten Überreste von Sternen, die noch weiter unterhalb der Hauptreihe liegen.

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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


A line of stars goes from cool faint stars to hot bright stars. Some stars lie above or below this line

Hertzsprung-Russell diagram

Bildunterschriften: This diagram shows the temperature and luminosity of different stars. The size of each point represents the star’s radius and its colour is the colour the human eye would see. The stars range in colour from a washed-out blue to a washed-out reddish-orange. No star has a pure colour like red, green or blue as stars’ spectra include light from lots of different colours. However the reddest stars are commonly referred to as red and the bluest stars as blue. The sample of stars used to make this diagram was chosen to show a wide range of stars of different types so the relative number of each type of star is not representative of how commonly each type is found. From the top left to bottom right there is a long line of stars burning hydrogen in their cores. This is called the main sequence. On this line, one sees the stars Mintaka, Achenar, Sirius A, the Sun and Proxima Centauri. The objects around Proxima Centauri at the lower right end of the main sequence are known as red dwarfs. To the lower right of the red dwarfs are Teide 1 and Kelu-1 A. These two objects are brown dwarfs, objects too low in mass to have cores hot enough to fuse hydrogen for a sustained period of time. As they do not burn hydrogen, brown dwarfs are not considered main sequence stars. The name brown dwarf is unrelated to their colour. Above the main sequence, we find subgiants, giants and supergiants. These are stars that have finished burning hydrogen in their core and have evolved into larger objects. A star’s brightness depends on its temperature and size so giant stars are brighter than stars with a smaller radius but the same temperature. In time these objects will move towards the end of their lives and undergo either a planetary nebula phase or become supernovae. Stars which end their lives with a planetary nebula phase become a type of stellar remnant called a white dwarf. Such objects are much smaller than stars of the same temperature and thus are fainter and are found significantly below the main sequence. Stars which end their lives as supernovae become either black holes or neutron stars. These are not shown on this plot.
Bildnachweis: IAU OAE/Niall Deacon

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