Excitation of Jovian Seismic Waves by the Shoemaker-Levy 9 Cometary Impact
Excitation of Jovian Seismic Waves by the Shoemaker-Levy 9 Cometary Impact
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舒梅克-利维 9 号彗星撞击激发木星地震波
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
F. Dahlen
中科院分区：
文献类型：
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作者：
P. Lognonné;B. Mosser;F. Dahlen
苏梅克-列维9号彗星与木星碰撞所释放的动能预计在1020焦耳至1023焦耳之间，这一能量将激发地震波，地震波将在木星内部传播。这些地震波是通过将l度至1400和频率ν至10 mHz的简正波求和来计算的。激发振幅得到使用的爆炸引起的彗星爆炸的冲击波模型。考虑到可能的检测波与红外相机，我们研究的热签名的全球模式和瞬态波激发的影响。我们表明，只有在强撞击时，表面波和简正模的激发才会产生直接可观察到的信号。能量大于2.8 × 1021 J的撞击将产生频率为10 mHz的P波，其对极处的峰-峰温度波动大于0.01 K。频率小于3 mHz的表面波在大于9 × 1022 J的撞击下会在任何地方产生超过0.01 K的波动。由于相机单个像素上的信噪比太低，因此无法直接检测到较低能量的撞击。叠加方法可能能够探测到在Δ = 90°时能量低至7.25 × 1020 J的撞击所产生的P波，以及低至1.4 × 1021 J的撞击所产生的表面波。在剩余的观测时间内进行低频监测可能会提供有关木星内部结构的独特信息，包括核心和由于可能的氢等离子体相变而造成的不连续性。
The kinetic energy released by the collision of the comet Shoemaker-Levy 9 with Jupiter is expected to be between 1020 J and 1023 J. This energy will excite seismic waves, which will propagate within Jupiter. These seismic waves are computed by summing normal modes of degree l up to 1400 and frequency ν up to 10 mHz. The excitation amplitudes are obtained using a model of the blast wave induced by the explosion of the comet. Keeping in mind the possible detection of the waves with an IR camera, we examine the thermal signature of the global modes and transient waves excited by the impact. We show that the excitation of surface waves and normal modes will produce a directly observable signal for strong impacts only. An impact with an energy greater than 2.8 × 1021 J will produce a 10-mHz frequency P wave with associated peak-to-peak temperature fluctuations greater than 0.01 K at the antipode. Surface waves with frequencies less than 3 mHz will give rise to fluctuations everywhere in excess of 0.01 K for impacts greater than 9 × 1022 J. Lower energy impacts will not be directly detectable, the signal-to-noise ratio on a single pixel of the camera being too low. Stacking methods might enable the detection of P waves generated by impacts with energies as low as 7.25 × 1020 J at Δ = 90° and of surface waves generated by impacts as low as 1.4 × 1021 J. High-frequency monitoring of the temperature in the jovian troposphere daring at least 2 hr after each impact, and low-frequency monitoring during the remaining observation time may provide unique information on the inner structure of Jupiter, including the core and the discontinuity due to the possible plasma phase transition of hydrogen.