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Scientists have recently observed a large planet at an early stage of formation. The planet is already nine times the mass of Jupiter.

科学家最近观察到一颗处于早期形成阶段的大行星。这颗行星的质量已经是木星的9倍。

The researchers used the Subaru Telescope in Hawaii and the Hubble Space Telescope to find and study the planet. It is a gas giant orbiting an unusually far away young star. Gas giants are planets, like our solar system's Jupiter and Saturn¹. They are made up of hydrogen and helium. Those gases surround a smaller solid core, the innermost part of a planet.

研究人员使用夏威夷的昴星望远镜以及哈勃太空望远镜发现并研究这颗行星。它是一颗气态巨星，围绕着异常遥远的一颗年轻恒星运行。气态巨星是行星，就像我们太阳系的木星和土星一样。它们是由氢和氦组成。这些气体围绕着一个较小的固体核心，即行星的内核部分运行。

"We think it is still very early on in its 'birthing' process," said astrophysicist Thayne Currie of the Subaru Telescope and the NASA-Ames Research Center. He is the lead writer of the study that appeared recently in the publication Nature Astronomy. "Evidence suggests that this is the earliest stage of formation ever observed for a gas giant," he added.

昴星望远镜以及美国宇航局艾姆斯研究中心的天体物理学家塞恩·柯里表示：“我们认为它仍处于‘诞生’过程的早期阶段。”他是最近发表在《自然·天文学》杂志上的这项研究的主要作者。他还表示：“有证据表明，这是有史以来观察到的气态巨行星形成的最早阶段。”

The planet surrounds a star called AB Aurigae, about 9.5 trillion kilometers from Earth. An image of the star appeared in the 2021 film "Don't Look Up."

这颗行星围绕着一颗名为御夫座AB的恒星，它距离地球约9.5万亿公里。这颗恒星的图片出现在2021年电影《不要抬头》当中。

About 5,000 planets beyond our solar system, or exoplanets, have been identified. This one, called AB Aur b, is among the largest.

我们已经确定了太阳系外的大约5000颗行星或系外行星。这颗名为御夫座AB b的行星是其中最大的。

Planets in the process of formation - called protoplanets - have been observed around only one other star.

人类仅在另一颗恒星周围观测到过处于形成过程中的原行星。

Almost all known exoplanets have orbits around their stars within the distance that separates our sun and its most faraway planet, Neptune². But this planet orbits three times as far as Neptune from the sun and 93 times Earth's distance from the sun.

几乎所有已知的系外行星都围绕着它们的恒星运行，其距离相当于我们的太阳与其最遥远的行星海王星之间的距离。但是这颗行星的轨道距离是海王星到太阳距离的3倍，是地球到太阳距离的93倍。

Its formation appears to be following a different process than the way planets usually form.

它的形成似乎遵循了一种与行星常规形成方式不同的过程。

Olivier Guyon is an astronomer³ with the Subaru Telescope and the University of Arizona. He is a co-writer of the planet study. Guyon said the usual thinking is that most planets form by the slow growth of solids onto a rocky core. He noted⁴ that gas giants go through this process before the solid core is large enough to start layering gases.

奥利弗·盖恩是昴星望远镜和亚利桑那大学的天文学家。他是这项行星研究的合著者。盖恩表示，通常认为大多数行星是由固体缓慢生长到岩石核心上形成的。他指出，气体巨星在固体核心大到足以开始分层气体之前就经历了这个过程。

In this situation, protoplanets in the area surrounding a young star slowly grow out of dust- to large rock-sized solid objects. If this core reaches several times Earth's mass, they begin gathering⁵ gas from the surrounding dust and gas.

在这种情况下，一颗年轻恒星周围区域的原行星缓慢地从尘埃演变成岩石大小的固态物体。如果这个核心达到地球质量的数倍，它们就会开始从周围的尘埃和气体中收集气体。

"This process cannot form giant planets at large orbital distance, so this discovery challenges our understanding of planet formation," Guyon said.

盖恩表示，“这个过程无法在大轨道距离上形成巨行星，因此这一发现挑战了我们对行星形成的理解。”

The researchers believe AB Aur b is forming in a situation in which the area around the star cools. Gravity then causes it to break up into one or more huge masses that form into planets.

研究人员认为御夫座AB b是在恒星周围区域冷却的情况下形成的。然后重力使它分裂成为一个或多个形成行星的巨大碎块。

The star AB Aurigae is about 2.4 times bigger than our sun and almost 60 times brighter. It is about 2 million years old -- very young compared to our 4.5-billion-year-old sun.

御夫座AB恒星的大小是我们太阳的2.4倍，亮度是近60倍。它大约有200万年的历史，这跟我们45亿年前形成的太阳相比非常年轻。

"New astronomical⁶ observations continuously challenge our current theories, ultimately improving our understanding of the universe," Guyon said.

盖恩表示：“新的天文观测不断挑战我们目前的理论，最终提高了我们对宇宙的理解。”

He added, "Planet formation is very complex and messy, with many surprises still ahead."

他还表示：“行星的形成非常复杂和混乱，未来还会有更多惊喜。”