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مصطلح في المعجم: المجرة العدسية

الوصف: تُستخدم كلمة "عدسية" لوصف الأجسام التي لها شكل العدسة. وتتميّز المجرات العدسية (S0 أو SB0) بخصائص رصدية تجمع بين المجرات الحلزونية والمجرات الإهليلجية. فهي تبدو وكأن لها قرصاً وانتفاخاً مركزياً يشبهان ما يوجد في المجرات الحلزونية، ولكنها لا تمتلك أذرعاً حلزونية واضحة. كما أنها تحتوي في الغالب على نجوم قديمة جداً، مثل تلك التي تهيمن على المجرات الإهليلجية.

لا يزال العلماء يدرسون آلية تشكّل المجرات العدسية، لكن هناك بعض الأدلة التي تشير إلى أنها قد تتكوّن نتيجة التفاعل بين المجرات.

مصطلحات ذات صلة:



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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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وسائط ذات صلة


The bright core of this galaxy is surrounded by a much fainter disk. This faint disk has thin dark rings.

The Lenticular Galaxy NGC 2787

الشرح: The lenticular galaxy NGC 2787. This galaxy is a disk galaxy but lacks the large, dominant spiral arm structure seen in the disks of spiral galaxies. Its core is very bright compared to the core of a spiral galaxy. Thin rings of dust can be seen in the galaxy's disk.
المصدر: NASA/ESA and The Hubble Heritage Team رابط المصدر

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

الرسوم التوضيحية المرتبطة


The stars in Sextans take the shape of a hook with the concave part pointing south

Sextans Constellation Map

الشرح: The constellation Sextans with its brighter stars and surrounding constellations. Sextans is surrounded by (going clockwise from the top): Leo, Hydra and Crater. Sextans is a small constellation with relatively few bright stars. Sextans spans the celestial equator and thus parts of the constellation are visible at some point in the year across the Earth. The whole constellation is visible in all but the most arctic and most antarctic regions. Sextans is best viewed in the evening in the northern hemisphere spring and southern hemisphere autumn. The lenticular galaxy NGC 3115 lies in Sextans. It is marked here with a red ellipse. The y-axis of this diagram is in degrees of declination 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. The blue line at the top of the diagram marks the ecliptic. Neither the constellation boundaries, nor the lines joining the stars, nor the ecliptic, appear on the sky.
المصدر: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope

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