Shape models and spin states of Jupiter Trojans: Testing the streaming instability formation
Authors: Hanus Josef , Vokrouhlicky David , Nesvorny David , Durech Josef , Stephens Robert , Pejcha Ondrej , Benishek Vladimir , Oey Julian 
Published: September 2022

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&lt;div class=&quot;textLayer&quot;&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;The origin of Jupiter Trojans (JTs) remains an open problem.&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; The currently leading theory assumes that JTs were captured &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;to their orbits near the Lagrangian points during the early &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;reconfiguration of the giant planets (Morbidelli et al. 2005;&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; Nesvorn&amp;#253; et al. 2013). The natural source region for the majority &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;of JTs would then be the population of planetesimals born in &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;a massive trans-Neptunian disk. As a result, JTs should share &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;the physical properties of currently observed trans-Neptunian&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; objects (TNOs), as well as comets and irregular satellites of&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; giant planets.&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Other theories avoid involving the planetary &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;reconfiguration event and postulate that JTs formed at their&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; current location together with Jupiter (see reviews in Marzari&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; et al. 2002; Emery et al. 2015), or were born in the Jupiter&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; coorbital zone and accompanied its early inward migration &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;(Pirani et al. 2019). In this work, we adopt the capture model&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; for JTs as a baseline hypothesis, because several other pieces&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; of evidence support the view that giant planets underwent a &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;violent instability at some early moment of the Solar System&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; evolution (see, e.g., Nesvorn&amp;#253; 2018).&lt;/span&gt;&lt;/div&gt;
&lt;div class=&quot;textLayer&quot;&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;In our contribution, we compile photometric datasets for &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;about 900 JTs and apply the convex inversion technique in &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;order to derive their shapes and spin states. We obtained full&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; solutions for&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;71&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;JTs, and partial solutions (of a little less sta&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;tistical significance) for additional&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;15&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;JTs. This represents an &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;increase in the sample of known spin state and shape solu&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;tions for JTs by a factor of&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;&amp;#8764;&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;3. JTs librating about L&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;4&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;and L&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;5&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; points contribute roughly equally to our solutions. We found a factor of ~1.5 between the number of prograde and retrograde populations, or ~60% abundance of prograde rotators in the overall JT population.&lt;/span&gt;&lt;/div&gt;
&lt;div class=&quot;textLayer&quot;&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;We found evidence that the observed distribution of the ro&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;tation pole obliquities/latitudes of JTs qualitatively resembles &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;expectations from a numerical simulation of the streaming in&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;stability, the leading mechanism for the formation of planetes&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;imals in the trans-Neptunian disk. JTs pole distribution has a &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;slightly smaller north/south asymmetry, but this can be plau&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;sibly reconciled by the effects of a brief period of post-formation &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;collisional activity.&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Our numerical simulations of the post-&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;capture spin evolution indicate the JTs pole distribution is not&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; significantly affected by dynamical processes.&lt;/span&gt;&lt;/div&gt;
&lt;div class=&quot;textLayer&quot;&gt;&lt;strong&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Acknowledgments&lt;/span&gt;&lt;/strong&gt;&lt;br role=&quot;presentation&quot; /&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;The work of JH and JD has been supported by the Czech&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; Science Foundation through grant 20-08218S. The work &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;of DV has been supported by the Czech Science Founda&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;tion through grant 21-11058S. The work of OP has been&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; supported by INTER-EXCELLENCE grant LTAUSA18093&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; from the Ministry of Education, Youth, and Sports.&lt;/span&gt;&lt;/div&gt;
&lt;div class=&quot;textLayer&quot;&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;[1] Emery, J. P., Marzari, F., Morbidelli, A., French, L. M., &amp; Grav, &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;T. 2015, in Asteroids IV, ed. P. Michel, F. E. DeMeo, &amp; W. F.&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; Bottke, 203&amp;#8211;220&lt;/span&gt;&lt;br role=&quot;presentation&quot; /&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;[2] Marzari, F., Scholl, H., Murray, C., &amp; Lagerkvist, C. 2002, in &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Asteroids III, ed. W. F. Bottke, A. Cellino, P. Paolicchi, &amp; R. P. &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Binzel, 725&amp;#8211;738&lt;/span&gt;&lt;br role=&quot;presentation&quot; /&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;[3] Morbidelli, A., Levison, H. F., Tsiganis, K., &amp; Gomes, R. 2005,&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; Nature, 435, 462&lt;/span&gt;&lt;br role=&quot;presentation&quot; /&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;[4]&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Nesvorn&amp;#253;,&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;D.,&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Vokrouhlick&amp;#253;,&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;D.,&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;&amp;&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Morbidelli,&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;A.&lt;/span&gt; &lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;2013,&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; Astrophysical Journal, 768, 45&lt;/span&gt;&lt;br role=&quot;presentation&quot; /&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;[5] Nesvorn&amp;#253;, D. 2018, Annual Review of Astronomy and Astro&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;physics, 56, 137&lt;/span&gt;&lt;br role=&quot;presentation&quot; /&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;[6] Pirani, S., Johansen, A., &amp; Mustill, A. J. 2019, Astronomy and&lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt; Astrophysics, 631, A89&lt;/span&gt;&lt;br role=&quot;presentation&quot; /&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;[7] Morbidelli, A., Levison, H. F., Tsiganis, K., &amp; Gomes, R. 2005, &lt;/span&gt;&lt;span dir=&quot;ltr&quot; role=&quot;presentation&quot;&gt;Nature, 435, 462&lt;/span&gt;
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