行星狀星雲 Abell 7
Planetary Nebula Abell 7
來源：Vikas Chander｜發表日期：2025-03-07
非常暗的行星狀星雲 Abell 7 距地球約 1800 光年。它位於地球天空中獵戶座的正南方，朝向天兔座。它被銀河系恆星環繞，靠近遙遠背景星系的視線，在這幅深遠的望遠鏡影像中，它大致呈簡單的球形，直徑約為 8 光年。不過，宇宙雲中有美麗而複雜的結構，由於使用了長曝光和窄帶濾光片，捕捉到了氫原子、硫原子和氧原子的發射，這些結構得到了加強。否則，Abell 7 就會非常暗淡，無法用肉眼欣賞。行星狀星雲代表了恆星演化過程中一個非常短暫的最後階段，我們的太陽將在 50 億年後經歷這一階段，因為星雲的中心，曾經像太陽一樣的恆星將脫落其外層。據估計，Abell 7 本身已有 2 萬年的歷史。但是它的中心恆星，也就是這裡看到的一顆正在褪色的白矮星，已經有大約 100 億年的歷史了。
原文：Very faint planetary nebula Abell 7 is about 1,800 light-years distant. It lies just south of Orion in planet Earth's skies toward the constellation Lepus, The Hare. Surrounded by Milky Way stars and near the line-of-sight to distant background galaxies its generally simple spherical shape, about 8 light-years in diameter, is revealed in this deep telescopic image. Within the cosmic cloud are beautiful and complex structures though, enhanced by the use of long exposures and narrowband filters that capture emission from hydrogen, sulfur, and oxygen atoms. Otherwise Abell 7 would be much too faint to be appreciated by eye. A planetary nebula represents a very brief final phase in stellar evolution that our own Sun will experience 5 billion years hence, as the nebula's central, once sun-like star shrugs off its outer layers. Abell 7 itself is estimated to be 20,000 years old. But its central star, seen here as a fading white dwarf, is some 10 billion years old.
※ 本文由萌芽機器人自動轉貼自每日一天文圖（Astronomy Picture of the Day，APOD），原文為英文，正體中文是透過 DeepL 翻譯及 OpenCC 進行自動處理，內容僅供參考，若有任何錯誤之處還請見諒！
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