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Hi everyone,
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<div class="">Just a reminder that we will be hosting Dr. Chi Yan tomorrow for our planetary seminar. There are still a few slots remaining on her schedule. If you’d like to meet with Dr. Yan, you can sign up <a href="https://docs.google.com/spreadsheets/d/1TxdbkMat4Zp7lO6-JF1GH48wioLi0RBx4eX9VVM3lMc/edit#gid=0" class="">here</a>.</div>
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<div class="">Looking forward to seeing you there!</div>
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<div class="">-John<br class="">
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<div class="">On Nov 9, 2023, at 17:05, John B. Biersteker <<a href="mailto:jo22395@mit.edu" class="">jo22395@mit.edu</a>> wrote:</div>
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Hello planeteers,
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<div class="">We are very happy to announce that we will have <a href="https://chiyan.me/" class="">Dr. Chi Yan</a> from the Earth & Planets Laboratory at the Carnegie Institute joining us next week to talk about the planetary dynamos of Saturn and Mars. Please
join us on Tuesday, November 14 @ 12:30 in 54-517 or on Zoom. As usual, lunch will be provided and we encourage arriving early to get food.</div>
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<div class="">Chi will be visiting our department all day Tuesday and is available for meetings. If you’d like to sign up for an individual meeting, you can do so
<a href="https://docs.google.com/spreadsheets/d/1TxdbkMat4Zp7lO6-JF1GH48wioLi0RBx4eX9VVM3lMc/edit?usp=sharing" class="">
here</a>.</div>
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<div class="">Additional talk and Zoom information are below. We hope to see you there!</div>
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<div class="">-John</div>
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<div class=""><i class="">Planetary Dynamos: Case Studies for Saturn and Mars</i></div>
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<div class="">Over the decades, space missions have revealed many planet/moons have or once had their own magnetic fields. These fields are generated deep within the planets’ interiors by a self-sustained dynamo process that involves complex motions of electrically
conducting fluids in the presence of existing magnetic fields. Numerical simulations have shown that dynamo action is sensitive to variations of interior structures and boundary conditions (e.g., thermal perturbations) and would affect the resulting magnetic
field we oversee beyond the surface. Diagnosis of the effect of specific properties and conditions are therefore useful for comparison to the observational data of planetary magnetic fields, providing information on their interior structures. Here I present
two case studies:</div>
<div class=""> (1) the curious Saturnian dynamo </div>
<div class=""> For Saturn, the magnetic data from Cassini Grand Finale demonstrates that Saturn’s magnetic field is purely axisymmetric. This is problematic because Cowling’s theorem states that such a field cannot be maintained by dynamo action. Here
I investigate that if the presence of a helium rainout layer at the top of Saturn’s dynamo region can resolve this dilemma by preferentially attenuating the non-axisymmetric magnetic field so that the field appears axisymmetric outside the planet. Using the
characteristics of Saturn’s magnetic field, we are able to constrain properties of the deep interior of Saturn. </div>
<div class="">(2)<span class="Apple-tab-span" style="white-space:pre"> </span>the ancient Martian dynamo</div>
<div class="">Magnetic field observations from the MGS, MAVEN, and InSight missions reveal that a dynamo was active in Mars’ early history. The ancient martian dynamo is curious both spatially, i.e., the hemispheric dichotomy of the crustal magnetic fields,
and temporally, i.e., the timeline of the martian dynamo history. Additionally, recent seismic measurements from the InSight mission revealed that Mars’ core has a relatively low density, implying the absence of a solid inner core throughout Mars’ history.
Here I investigate the effects of thermal perturbations at the core mantle boundary on the morphology of the resulting field and compare those to dynamo models obtaining a small Earth-sized inner core.</div>
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<div class="">Zoom: <a href="https://mit.zoom.us/j/92448700577" class="">https://mit.zoom.us/j/92448700577</a></div>
<div class="">PW: 54100</div>
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