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مصطلح في المعجم: نجم فائق الضخامة

ويُعرف أيضًا باسم نجم فائق العملقة

الوصف: النجوم فائقة الضخامة هي أكبر النجوم وأكثرها إضاءة. ويمكن أن تكون أكبر من الشمس بمئات المرات وأكثر إضاءة بآلاف المرات. تظهر هذه النجوم في المنطقة العليا من مخطط هيرتزبرونغ–راسل، حيث تتراوح القدر المطلق لها بين −3 و −8.

تغطي النجوم فائقة الضخامة نطاقاً واسعاً من درجات الحرارة، من حوالي 3400 كلفن إلى أكثر من 20,000 كلفن. قد تكون هذه النجوم إما نجوماً ذات كتلة كبيرة منذ ولادتها، أو نجوماً تمر بمرحلة متأخرة جداً من تطورها النجمي.

يمكن التعرف على النجوم فائقة الضخامة من خلال أطيافها الضوئية، حيث تتميز بخطوط طيفية خاصة تتأثر بشدة سطوعها وانخفاض جاذبيتها السطحية، وتكون هذه الخطوط أضيق مقارنة بخطوط النجوم الأصغر حجماً.

من الأمثلة الشهيرة على النجوم فائقة الضخامة: النجم منكب الجوزاء في كوكبة الجبار، ونجوم القيفاويات المتغيرة.

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ترجمة هذا المصطلح وتعريفه ما تزال بانتظار الموافقة

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".

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The nearby red supergiant Betelgeuse, seen as orange blob showing a non-symmetric shape with a bright spot to the upper left

The red supergiant Betelgeuse

الشرح: The image shows Betelgeuse, a red supergiant in the constellation Orion, observed by the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA consists of many antennae spread across a plain in Northern Chile. The observations from all of these receivers is synthesised together by a central computer to form an image. The wide distances between the antennae mean that is can resolve very fine details. Most stars we observe are just seen as points of light, but Betelgeuse is so large (with a radius about 1,400 times larger than the Sun) and is sufficiently nearby that it is one of the few stars to have been resolved to show it as an extended object. Betelgeuse is a massive star, more than 14 times the mass of the Sun and is relatively young for a star (less than 14 million years old). However, its high mass led to it having a very hot core which burned through its hydrogen fuel quickly. It has since evolved through many stages and now appears as a red supergiant, it's final stage before exploding as a supernova. When such an explosion will happen is not known for certain, but it could be in around 100,000 years. Such an explosion would be visible from Earth, even during the day.
المصدر: ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella رابط المصدر

License: CC-BY-4.0 المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات

الرسوم التوضيحية المرتبطة


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

Hertzsprung-Russell diagram

الشرح: 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.
المصدر: IAU OAE/Niall Deacon

License: CC-BY-4.0 المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات