37 Nebulae-Mid

Nebulae FOCUS Question What is the relationship between nebulae and stars?

星云和恒星之间的关系是什么?

What Is a Nebula? The universe is made of billions of galaxies—groups of thousands to trillions of stars held together by the force of gravity. Dust and gas are scattered in the space between the stars. A nebula forms when some of the dust and gas clumps together into a cloud-like formation. Emission nebulae form around stars. The stars heat up the gas and dust so much that the nebulae give off their own light. A stellar remnant nebula is a special type of emission nebula Stellar remnant nebulae. form when a dying star blows off layers of gas. The gas is so hot that it emits its own light. This type of nebula is also called a planetary nebula because it is shaped like a planet. Word Wise The plural form of nebula is nebulae (NEB-yoo-lee).

什么是星云?宇宙是由数十亿个星系组成的——由数千到数万亿颗恒星组成的星系群在引力的作用下聚集在一起。 尘埃和气体散布在恒星之间的空间。 当一些尘埃和气体聚集在一起形成云状结构时，星云就形成了。 发射星云在恒星周围形成。 恒星将气体和尘埃加热得如此之高，以至于星云发出了自己的光。 恒星残余星云是一种特殊类型的发射星云。 当垂死的恒星吹出气体层时形成。 这种气体非常热，因此会发出自己的光。 这种类型的星云也被称为行星状星云，因为它的形状像一个行星。 星云的复数形式是星云(NEB-yoo-lee)。

Reflection nebulae are cooler than emission nebulae and do not give off their own light. Instead, they reflect the light from nearby stars. Unlike other types of nebulae, absorption nebulae do not look much like clouds. They neither emit nor reflect light. Instead, they absorb light. They appear as black regions in space. Nebulae are mostly made of the gases hydrogen and helium. About 90 percent of a nebula is hydrogen, and 9 percent is helium. There are smaller amounts of other elements such as oxygen, carbon, and nitrogen. In fact, nebulae have the same mix of elements as stars. Astronomers now know that nebulae are made of materials that came from ancient stars.

反射星云比发射星云温度低，并且不自己发光。 相反，它们会反射附近恒星的光。 与其他类型的星云不同，吸收星云看起来不太像云。 它们既不发光也不反射光。 相反，它们吸收光。 它们在空间中呈现为黑色区域。 星云主要由氢和氦两种气体构成。 星云的90%是氢，9%是氦。 还有少量的其他元素，如氧、碳和氮。 事实上，星云的元素组成和恒星是一样的。 天文学家现在知道，星云是由来自古代恒星的物质构成的。

If you look into a clear, dark sky, you might be able to see some nebulae without a telescope. The Orion Nebula, for example, is visible in the constellation Orion. Most nebulae are hard to distinguish from stars, however. To learn much about them, we need telescopes. Some telescopes allow us to observe the visible light energy coming from nebulae. We can learn what nebulae are made of by observing their visible light, but nebulae also give off other types of energy that we cannot see. These forms of light energy include infrared, ultraviolet, X-rays, and gamma rays. Studying different types of light that nebulae emit and reflect helps us understand them. The Hubble Space Telescope (HST), which has been orbiting Earth since 1990, has recorded infrared, visible light, and ultraviolet pictures from space. With the HST, we learned that dust and gas of the Orion Nebula is heated by thousands of stars.

如果你观察晴朗、黑暗的天空，你可能不用望远镜就能看到一些星云。 例如，猎户座星云在猎户座中可见。 然而，大多数星云很难与恒星区分开来。 为了更多地了解它们，我们需要望远镜。 有些望远镜使我们能够观测到来自星云的可见光能量。 我们可以通过观察星云的可见光来了解星云是由什么组成的，但星云也会释放出我们看不到的其他类型的能量。 这些形式的光能包括红外线、紫外线、x射线和伽马射线。 研究星云发射和反射的不同类型的光有助于我们理解它们。 哈勃太空望远镜(HST)自1990年以来一直围绕地球运行，记录了来自太空的红外、可见光和紫外线照片。 通过HST，我们了解到猎户座星云的尘埃和气体是由数千颗恒星加热的。

This image of the Eskimo Nebula was made using the Chandra X-Ray Observatory, a space telescope. The pink parts of this image are "false color." The light is not actually pink; it represents the light from X-rays. All of the other colors are the actual colors that we can see with our eyes. The Spitzer Space Telescope observes infrared light. The colors in the image below represent different wavelengths of infrared light. The dark parts of the image are not giving off any infrared light. They are dense, cold, dark regions of sooty dust.

这张爱斯基摩星云的图片是用钱德拉x射线天文台的太空望远镜拍摄的。 图片中的粉红色部分是“假色”。 灯光实际上并不是粉红色的;它代表x射线的光。 所有其他的颜色都是我们肉眼能看到的颜色。 斯皮策太空望远镜观测红外光。 下图中的颜色代表不同波长的红外光。 图像中较暗的部分没有发出任何红外光。 它们是稠密、寒冷、黑暗的煤烟粉尘地区。

Star Nurseries When astronomers first began studying nebulae, all they could see were fuzzy regions in space. Today, using powerful telescopes, scientists can see nebulae more clearly. They have discovered that many nebulae are star nurseries—places where new stars are forming. Because gravity pulls matter together, over time the gas and dust of a nebula begin to collapse. Clumps of material come together. The gravitational pull increases, and clumps of particles move faster. As the particles move faster and faster, they become hotter. and hotter When the clumps get big enough and have enough energy, they become hot, glowing stars. Word Wise The word nebula comes from the Latin word for mist or clouds. The word nebulous comes from the same root. Something that is nebulous is very unclear or vague.

当天文学家最初开始研究星云时，他们所能看到的只是空间中的模糊区域。 今天，通过使用功能强大的望远镜，科学家们可以更清楚地看到星云。 他们已经发现许多星云是恒星的摇篮——新恒星形成的地方。 由于重力将物质拉在一起，随着时间的推移，星云中的气体和尘埃开始坍塌。 物质团块聚集在一起。 引力增加，粒子团移动得更快。 随着粒子运动越来越快，它们变得越来越热。 当团块变得足够大并有足够的能量时，它们就会变成炽热的发光恒星。 星云这个词来自拉丁语，意思是雾或云。 “朦胧的”这个词来自同一个词根。 模糊不清的东西是指非常不清楚或模糊的东西。