Scientists Reveal Jupiter Grew in Different, Distinct Phases

Jupiter Grew in Different, Distinct Phases

This is Jupiter’s southern hemisphere photographed by NASA’s Juno spacecraft. ©NASA/JPL-Caltech/SwRI/MSSS/GeraldEichstaedt/Sean Doran

赤道直径约为143,000公里,Jupiteris the largest planet in the solar system and has 300 times the mass of the Earth. The formation mechanism of giant planets like Jupiter has been a hotly debated topic for several decades. Now, astrophysicists of the Swiss National Centre of Competence in Research (NCCR) PlanetS of the Universities of Bern and Zürich and ETH Zürich have joined forces to explain previous puzzles about how Jupiter was formed and new measurements. The research results were published in the magazine Nature Astronomy.

“我们可以展示木星在苏黎世大学的博尔尼亚文图卫星解释说,JuliaVenturini解释道。“特别有趣的是,带来质量和能量的身体并不是同类的身体,”行星的科学官员和本文的第一作者“。首先,行星胚胎迅速增加了小型,厘米大小的鹅卵石,并在最初的一百万年内快速建立了核心。在称为Planetesimals的较大,公里大小的岩石的速度较慢的速度下,这是一两百万年的主导地位。他们击中了越来越多的行星,能量很大,释放热量。“在第一阶段,鹅卵石带来了群众,”Yann Alibert解释道:“在第二阶段,行星也增加了一点质量,但更重要的是,他们带来了能量。”经过三百万年,木星已经成长为50个地球群众。然后,启动的第三种形成阶段由气体失控占据,导致今天的煤气巨头超过300个地球群众。

Jupiter Grew in Distinct Phases

第1阶段(最多1 MYR):木星(黑色)由鹅卵石增压(小圆圈)增长,并且行星增值可以忽略不计。大型原始行星(大圆圈)由不断增长的行星兴奋,遭受高碰撞速度(大箭头),导致破坏性碰撞(黄色),产生小型第二代手提料(中圆圈)。第2阶段(1-3 MYR):木星足够大,以防止鹅卵石增生。与小星座的吸积相关的能量足够大,以防止快速气体吸收(灰色箭头)。第3阶段(3 myr后):木星足够大量的燃气(氢,氦气)。附近的鹅卵石和小星期体可以重力捕获。最终,在太阳能星云中打开间隙(白色),停止进一步的气体增生。红色和蓝色表示小体(内外和木星的轨道内)的两个水库,这些水库分别被木星在第2阶段的增长分开,并在第3阶段重新连接。太阳显示在左侧。

Solar system divided into two parts

The new model for Jupiter’s birth matches the meteorite data that were presented at a conference in the US last year. At first, Julia Venturini and Yann Alibert were puzzled when they listened to the results. Measurements of the composition of meteorites showed that in the primordial times of the solar system the solar nebula was divided into two regions during two million years. It could therefore be concluded that Jupiter acted as a kind of a barrier when it grew from 20 to 50 Earth masses. During this period, the forming planet must have perturbed the dust disk, creating an over-density that trapped the pebbles outside of its orbit. Therefore, material from outward regions could not mix with material of the inner ones until the planet reached enough mass to perturb and scatter rocks inwards.

“How could it have taken two million years for Jupiter to grow from 20 to 50 Earth masses?” asked Julia Venturini. “That seemed much too long,” she explains: “That was the triggering question that motivated our study.” A discussion by email started among NCCR PlanetS researchers of the Universities of Bern and Zürich and ETH Zürich and the following week the experts in the fields of astrophysics, cosmochemistry and hydrodynamics arranged a meeting in Bern. “In a couple of hours we knew what we had to calculate for our study,” says Yann Alibert: “This was only possible within the framework of the NCCR, which links scientists from various fields.”

延迟增长的解释

通过计算,研究人员表明,年轻地球在15至50个地球群众的群众范围内花费的时间确实比以前的思想长得多。在该形成期间,与公里型岩石的碰撞提供足够的能量以加热年轻木星的气态气氛,并防止快速冷却,收缩和进一步的气体增生。“鹅卵石在第一阶段很重要,以便快速构建核心,但是由行星提供的热量对于延迟气体增值至关重要,以便与陨石数据给出的时间级,”天体物理学家总结。他们相信他们的结果提供了解决形成的长期存在的关键要素UranusNeptune和exoplanets in this mass regime.

出版物:Yann Alibert,等,“通过杂交卵石 - 行星血管成像,”木星的形成“Nature Astronomy (2018)

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