The Effect of Close-In Giant Planets' Evolution on Tidal-Induced Migration of Exomoons
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The Subsurface Habitability of Small, Icy Exomoons J
A&A 636, A50 (2020) Astronomy https://doi.org/10.1051/0004-6361/201937035 & © ESO 2020 Astrophysics The subsurface habitability of small, icy exomoons J. N. K. Y. Tjoa1,?, M. Mueller1,2,3, and F. F. S. van der Tak1,2 1 Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands e-mail: [email protected] 2 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands 3 Leiden Observatory, Leiden University, Niels Bohrweg 2, 2300 RA Leiden, The Netherlands Received 1 November 2019 / Accepted 8 March 2020 ABSTRACT Context. Assuming our Solar System as typical, exomoons may outnumber exoplanets. If their habitability fraction is similar, they would thus constitute the largest portion of habitable real estate in the Universe. Icy moons in our Solar System, such as Europa and Enceladus, have already been shown to possess liquid water, a prerequisite for life on Earth. Aims. We intend to investigate under what thermal and orbital circumstances small, icy moons may sustain subsurface oceans and thus be “subsurface habitable”. We pay specific attention to tidal heating, which may keep a moon liquid far beyond the conservative habitable zone. Methods. We made use of a phenomenological approach to tidal heating. We computed the orbit averaged flux from both stellar and planetary (both thermal and reflected stellar) illumination. We then calculated subsurface temperatures depending on illumination and thermal conduction to the surface through the ice shell and an insulating layer of regolith. We adopted a conduction only model, ignoring volcanism and ice shell convection as an outlet for internal heat. -
Abstracts of the 50Th DDA Meeting (Boulder, CO)
Abstracts of the 50th DDA Meeting (Boulder, CO) American Astronomical Society June, 2019 100 — Dynamics on Asteroids break-up event around a Lagrange point. 100.01 — Simulations of a Synthetic Eurybates 100.02 — High-Fidelity Testing of Binary Asteroid Collisional Family Formation with Applications to 1999 KW4 Timothy Holt1; David Nesvorny2; Jonathan Horner1; Alex B. Davis1; Daniel Scheeres1 Rachel King1; Brad Carter1; Leigh Brookshaw1 1 Aerospace Engineering Sciences, University of Colorado Boulder 1 Centre for Astrophysics, University of Southern Queensland (Boulder, Colorado, United States) (Longmont, Colorado, United States) 2 Southwest Research Institute (Boulder, Connecticut, United The commonly accepted formation process for asym- States) metric binary asteroids is the spin up and eventual fission of rubble pile asteroids as proposed by Walsh, Of the six recognized collisional families in the Jo- Richardson and Michel (Walsh et al., Nature 2008) vian Trojan swarms, the Eurybates family is the and Scheeres (Scheeres, Icarus 2007). In this theory largest, with over 200 recognized members. Located a rubble pile asteroid is spun up by YORP until it around the Jovian L4 Lagrange point, librations of reaches a critical spin rate and experiences a mass the members make this family an interesting study shedding event forming a close, low-eccentricity in orbital dynamics. The Jovian Trojans are thought satellite. Further work by Jacobson and Scheeres to have been captured during an early period of in- used a planar, two-ellipsoid model to analyze the stability in the Solar system. The parent body of the evolutionary pathways of such a formation event family, 3548 Eurybates is one of the targets for the from the moment the bodies initially fission (Jacob- LUCY spacecraft, and our work will provide a dy- son and Scheeres, Icarus 2011). -
Resonant Moons of Neptune
EPSC Abstracts Vol. 13, EPSC-DPS2019-901-1, 2019 EPSC-DPS Joint Meeting 2019 c Author(s) 2019. CC Attribution 4.0 license. Resonant moons of Neptune Marina Brozović (1), Mark R. Showalter (2), Robert A. Jacobson (1), Robert S. French (2), Jack L. Lissauer (3), Imke de Pater (4) (1) Jet Propulsion Laboratory, California Institute of Technology, California, USA, (2) SETI Institute, California, USA, (3) NASA Ames Research Center, California, USA, (4) University of California Berkeley, California, USA Abstract We used integrated orbits to fit astrometric data of the 2. Methods regular moons of Neptune. We found a 73:69 inclination resonance between Naiad and Thalassa, the 2.1 Observations two innermost moons. Their resonant argument librates around 180° with an average amplitude of The astrometric data cover the period from 1981-2016, ~66° and a period of ~1.9 years. This is the first fourth- with the most significant amount of data originating order resonance discovered between the moons of the from the Voyager 2 spacecraft and HST. Voyager 2 outer planets. The resonance enabled an estimate of imaged all regular satellites except Hippocamp the GMs for Naiad and Thalassa, GMN= between 1989 June 7 and 1989 August 24. The follow- 3 -2 3 0.0080±0.0043 km s and GMT=0.0236±0.0064 km up observations originated from several Earth-based s-2. More high-precision astrometry of Naiad and telescopes, but the majority were still obtained by HST. Thalassa will help better constrain their masses. The [4] published the latest set of the HST astrometry GMs of Despina, Galatea, and Larissa are more including the discovery and follow up observations of difficult to measure because they are not in any direct Hippocamp. -
The Excited Spin State of Dimorphos Resulting from the DART Impact
Highlights The Excited Spin State of Dimorphos Resulting from the DART Impact Harrison F. Agrusa,Ioannis Gkolias,Kleomenis Tsiganis,Derek C. Richardson,Alex J. Meyer,Daniel J. Scheeres,Matija Ćuk,Seth A. Jacobson,Patrick Michel,Özgür Karatekin,Andrew F. Cheng,Masatoshi Hirabayashi,Yun Zhang,Eugene G. Fahnestock,Alex B. Davis • High-fidelity numerical codes are essential for modeling the long-term spin evolution • DART may excite Dimorphos’ spin, leading to attitude instability and chaotic tumbling • Dimorphos is especially prone to unstable rotation about its long axis • A chaotic spin state will affect the system’s BYORP and tidal evolution • ESA’s Hera mission may be able to place constraints on the system’s tidal parameters arXiv:2107.07996v2 [astro-ph.EP] 29 Jul 2021 The Excited Spin State of Dimorphos Resulting from the DART Impact a < b b a Harrison F. Agrusa , , Ioannis Gkolias , Kleomenis Tsiganis , Derek C. Richardson , Alex c c d e f J. Meyer , Daniel J. Scheeres , Matija Ćuk , Seth A. Jacobson , Patrick Michel , g h i f Özgür Karatekin , Andrew F. Cheng , Masatoshi Hirabayashi , Yun Zhang , Eugene j j G. Fahnestock and Alex B. Davis aDepartment of Astronomy, University of Maryland, College Park, MD, USA bDepartment of Physics, Aristotle University of Thessaloniki, GR 54124 Thessaloniki, Greece cSmead Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO, USA dCarl Sagan Center, SETI Institute, Mountain View, CA, USA eDepartment of Earth and Environmental Sciences, Michigan State University, -
Master Astronomer Program
MASTER ASTRONOMER PROGRAM 2019 Program Handbook by Zach Schierl and Leesa Ricci Cedar Breaks National Monument National Park Service i Table of Contents Section 1: About the Master Astronomer Program Section 2: Astronomy & the Night Sky 2.1 Light 2.2 Celestial Motions 2.3 History of Astronomy 2.4 Telescopes & Observatories 2.5 The Cosmic Cast of Characters 2.6 Our Solar System 2.7 Stars 2.8 Constellations 2.9 Extrasolar Planets Section 3: Protecting the Night Sky 3.1 Introduction to Light Pollution 3.2 Why Protect the Night Sky? 3.3 Measuring and Monitoring Light at Night 3.4 Dark-Sky Friendly Lighting Section 4: Sharing the Night Sky 4.1 Using a Telescope 4.2 Communicating Astronomy & the Importance of Dark Skies to the Public Appendices: A. Glossary of Terms B. General Astronomy Resources C. Acknowledgements D. Endnotes & Works Cited 1 SECTION 1: ABOUT THE MASTER ASTRONOMER PROGRAM 3 Section 1: About the Master Astronomer Program WELCOME TO THE MASTER ASTRONOMER PROGRAM All of us at Cedar Breaks National Monument are glad that you are excited to learn more about astronomy, the night sky, and dark sky stewardship. In addition to learning about these topics, we also hope to empower you to share your newfound knowledge with your friends, family, and neighbors, so that all residents of Southern Utah can enjoy our beautiful dark night skies. The Master Astronomer Program is an interactive, hands-on, 40-hour workshop developed by Cedar Breaks National Monument that weaves together themes of astronomy, telescopes, dark sky stewardship, and science communication. -
The Habitability of Icy Exomoons
University of Groningen Master thesis Astronomy The habitability of icy exomoons Supervisor: Author: Prof. Floris F.S. Van Der Tak Jesper N.K.Y. Tjoa Dr. Michael \Migo" Muller¨ June 27, 2019 Abstract We present surface illumination maps, tidal heating models and melting depth models for several icy Solar System moons and use these to discuss the potential subsurface habitability of exomoons. Small icy moons like Saturn's Enceladus may maintain oceans under their ice shells, heated by en- dogenic processes. Under the right circumstances, these environments might sustain extraterrestrial life. We investigate the influence of multiple orbital and physical characteristics of moons on the subsurface habitability of these bodies and model how the ice melting depth changes. Assuming a conduction only model, we derive an analytic expression for the melting depth dependent on seven- teen physical and orbital parameters of a hypothetical moon. We find that small to mid-sized icy satellites (Enceladus up to Uranus' Titania) locked in an orbital resonance and in relatively close orbits to their host planet are best suited to sustaining a subsurface habitable environment, and may do so largely irrespective of their host's distance from the parent star: endogenic heating is the primary key to habitable success, either by tidal heating or radiogenic processes. We also find that the circumplanetary habitable edge as formulated by Heller and Barnes (2013) might be better described as a manifold criterion, since the melting depth depends on seventeen (more or less) free parameters. We conclude that habitable exomoons, given the right physical characteristics, may be found at any orbit beyond the planetary habitable zone, rendering the habitable zone for moons (in principle) arbitrarily large. -
The Planets in Our Comets Are Just Big Chunks of Dirty Ice That Come from the Solar System Orbit
Our Solar System The Sun Comets The Sun is a star around which all of the planets in our Comets are just big chunks of dirty ice that come from the Solar System orbit. It is a hot ball of gas that has been outer reaches of our Solar System. Comets have amazing burning for 5 billion years. In its centre, temperatures can tails that can be hundreds of millions of kilometres long! reach an astronomical 15 million degrees! Life on Earth is Solar winds travelling through space hit the comet and totally dependant on the Sun but it is so powerful that even cause bits of it to vaporise and form a ‘tail’. from Earth, its light and heat can seriously harm us. Did you know? Some scientists think that comets could Did you know? The Sun is so big you could fit Earth into it have brought life to Earth! Not only do they contain loads over a million times! of water (as ice) but some comets also contain amino acids, the building blocks of DNA! Mercury Mercury is the nearest planet to the Sun but it is not the So you want to be an Asteroids hottest! During the day, as the Sun shines on it, it roasts and temperatures often reach 350 degrees Celsius but at night, Asteroids are just odd shaped bits of rock! all the heat from the day escapes back out into space and it Some asteroids can be very small (only 1km freezes. In fact, temperatures can drop to minus 170 degrees! across) and others are the size of Britain! Some So why does the heat escape? Mercury has a very thin look like potatoes, others look like peanuts and atmospheric layer. -
Space Physics Project the Moons of the Planets
Space Physics Project The Moons of the Planets Ria Becker October 27, 2008 Contents 1 Contents 1 Introduction 2 2 Definitions 2 3 The Earth's Moon 3 4 The Moons of Mars 3 4.1 Phobos . 3 4.2 Deimos . 4 5 The Moons of Jupiter 4 5.1 Io........................................... 5 5.2 Europa . 5 5.3 Ganymede . 6 5.4 Callisto . 6 6 The Moons of Saturn 7 6.1 Titan . 7 6.2 Enceladus . 8 6.3 Mimas . 8 6.4 Hyperion . 9 6.5 Epimetheus and Janus . 9 7 The Moons of Uranus 9 8 The Moons of Neptun 10 8.1 Triton . 10 1 Introduction 2 1 Introduction The aim of this project is to give an overview over the different moons of the planets in our solar system. The longest and best known is naturally the Earth's moon. In 1610 discovered Galileo Galilei four moons of Jupiter: Io, Europa, Ganymede and Callisto. Those where the first celestial objects confirmed to orbit an body other than the Earth. Until today there are more than 165 confirmed moons in the solar system discovered and the number of moons belonging to a planet differs greatly. The Earth has one large one, Mars has two small ones, Jupiter and Saturn have about 60, Uranus has 27 and Neptun 13. In contrary to that Mer- cury and Venus possess no natural satellites. Due to this large number of moons in the solar system, this report covers only the most interesting ones. Figure 1: Selected moons of the solar system [1]. -
The Irregular Satellites of Saturn
Denk T., Mottola S., Tosi F., Bottke W. F., and Hamilton D. P. (2018) The irregular satellites of Saturn. In Enceladus and the Icy Moons of Saturn (P. M. Schenk et al., eds.), pp. 409–434. Univ. of Arizona, Tucson, DOI: 10.2458/azu_uapress_9780816537075-ch020. The Irregular Satellites of Saturn Tilmann Denk Freie Universität Berlin Stefano Mottola Deutsches Zentrum für Luft- und Raumfahrt Federico Tosi Istituto di Astrofsica e Planetologia Spaziali William F. Bottke Southwest Research Institute Douglas P. Hamilton University of Maryland, College Park With 38 known members, the outer or irregular moons constitute the largest group of sat- ellites in the saturnian system. All but exceptionally big Phoebe were discovered between the years 2000 and 2007. Observations from the ground and from near-Earth space constrained the orbits and revealed their approximate sizes (~4 to ~40 km), low visible albedos (likely below ~0.1), and large variety of colors (slightly bluish to medium-reddish). These fndings suggest the existence of satellite dynamical families, indicative of collisional evolution and common progenitors. Observations with the Cassini spacecraft allowed lightcurves to be obtained that helped determine rotational periods, coarse shape models, pole-axis orientations, possible global color variations over their surfaces, and other basic properties of the irregulars. Among the 25 measured moons, the fastest period is 5.45 h. This is much slower than the disruption rotation barrier of asteroids, indicating that the outer moons may have rather low densities, possibly as low as comets. Likely non-random correlations were found between the ranges to Saturn, orbit directions, object sizes, and rotation periods. -
Mjd,Amjd,Hossz,Fi, H, Rlst,Ro, Rmsi0, Rmsir, Droms0,Drmsrk
THE ODDITY OF THE SATURNIAN SYSTEM Erzsébet Illés-Almár Konkoly Observatory, Budapest, Hungary, e-mail: [email protected] Keywords: Saturnian satellite system, Iapetus, Hyperion, origin of ice-rings, Nice model ABSTRACT On the basis of Cassini images and of some diagrams a few provocative questions are raised in connection with the Saturnian System as a whole, namely the origin and evolution of the Saturnian ice-ring system, as well as that of Hyperion and Iapetus. (The recognitions of the author are italicized.) THE SATURNIAN SATELLITE SYSTEM Fig. 1. diagram demonstrates the oddity of the Saturnian system as a whole, as compared to that of Jupiter.Was it possible that the original regular satellite system of Saturn might have been broken into fragments? a b c Fig. 1 Distances of the regular satellites from the Fig. 2 The densities (a), the eccentricities (b) four giant planets are plotted in units of their own and the inclinations (c) of the larger planetary radius. The resonant positions between satellites of the Solar System are plotted in the satellites are marked by arcs. order of increasing inclinations respectively. Jupiter and Saturn have giant moons, Jupiter four (Galilean moons), Saturn one (Titan). If around Saturn, in the distance of Titan, there was so many material in the circum-saturnian ring that a moon (Titan) as big as Ganymede could have originated, it is difficult to understand why 1 Saturn does not also has more giant moons nearer than Titan. Or Saturn also had more giant moons in its original regular satellite system, only something has happened with them? Is it possible, for example, that when migrating Jupiter and Saturn reached the 1:2 resonance (Nice model, Tsiganis et. -
The Future of Planetary Defense Begins with DART
The Future of Planetary Defense Begins with DART The Future of Planetary Defense Begins with DART Elena Y. Adams, R. Terik Daly, Angela M. Stickle, Andrew S. Rivkin, Andrew F. Cheng, Justin A. Atchison, Evan J. Smith, and Daniel J. O’Shaughnessy ABSTRACT Doomsday scenarios of near-Earth objects (asteroids and comets) hitting Earth are fodder for action movies and science fiction books, but the potential for such an event cannot be dismissed as mere fiction. In 2022, the Johns Hopkins University Applied Physics Laboratory (APL) will dem- onstrate an important step in planetary defense, mitigating the threat of a direct hit by develop- ing the ability to prevent an impact to Earth. DART (Double Asteroid Redirection Test) is a NASA mission managed by APL with support from several NASA centers. DART launches in 2021 and will be the first demonstration of the kinetic impactor technique to change the motion of an asteroid in space. As the first kinetic impactor far from Earth, DART will prove the ability to deflect cata- strophic threats and lead to innovations in impactor/redirect technologies. This article explains DART’s novelty and extrapolates how it might shape the future of planetary defense. HAZARDS Extraterrestrial matter falls onto Earth benignly SBAG points out,1 fortunately most collisions with Earth every day as dust or meteorites. On longer timescales, involve harmless dust and the occasional meteorite— large objects impact Earth and pose risks to humans. objects that are too small to threaten the planet. Larger The Small Bodies Assessment Group (SBAG),1 which objects do not impact Earth frequently: it is estimated NASA established in 2008 to bring together experts on that asteroids larger than 30 m in diameter collide with small bodies throughout the Solar System, offers a few Earth only about once every few centuries, and those examples: In 2013, a bolide estimated to be only 20 m larger than 300 m in diameter impact the planet only in diameter exploded in the atmosphere over Chely- once per 100,000 years on average. -
Moon-Moon Scattering and the Origin of Irregular and Runaway Moons
Moon-moon Scattering and the Origin of Irregular and Runaway Moons By Maham Siddiqi Supervised by Dr. Hagai Perets Abstract Observations of the Solar system show that planetary satellites exist in various configurations; some have circular, co-planar orbits, and these are termed regular satellites. Other irregular satellites, have typically eccentric, inclined, and even retrograde orbits. Regular satellites are formed through core-accretion; similar to planet formation scenarios, but the origin of irregular satellites is still debated. Various formation scenarios have been suggested, involving capture of external unbound objects, either following a disruption of a binary minor planet, interaction of a single planetesimal with the planetary atmosphere of the planet, or through chaotic capture of planetesimals during rapid growth of the planetary embryos. However, it is difficult to reconcile the number of irregular moons with these hypotheses. Here we present a different hypothesis for the origin of irregular moons, through the in-situ formation of regular moons, which then scatter each other into irregular inclined and eccentric configurations. Such interaction could possibly lead to ejection from the system, producing “runaway moons”. We find instability regions where moons similar to the two biggest moons of Jupiter, Saturn and Uranus, could have become dynamically unstable due to mutual interactions. We show that moon-moon scattering in these regions could lead to ejection of moons from the system, and explore the eccentricity and inclination excitations of the moons' orbits as a function of distance from the host planet. Section 1: Introduction There are two kinds of moons that are found in the Solar system.