DOCSLIB.ORG

2 the Origin and Evolution of Saturn, with Exoplanet Perspective

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
2 the Origin and Evolution of Saturn, with Exoplanet Perspective 2 The Origin and Evolution of Saturn, with Exoplanet Perspective Sushil K. Atreya, Aurélien Crida, Tristan Guillot, Jonathan I. Lunine, Nikku Madhusudhan, and Olivier Mousis faceted approach that combines diverse sets of Copyright Notice observations on volatile composition and abundances, relevant properties of the moons and rings, comparison "The Chapter, 'The Origin and Evolution of Saturn, with the other gas giant planet, Jupiter, analogies to with Exoplanet Perspective', is to be published by the extrasolar giant planets, as well as pertinent Cambridge University Press as part of a multi- theoretical models. volume work edited by Kevin Baines, Michael Flasar, Norbert Krupp, and Thomas Stallard, entitled 2.1 Introduction “Saturn in the 21st Century” (‘the Volume’) Saturn, though about one-third the mass of Jupiter, is © in the Chapter, Sushil K. Atreya, Aurélien Crida, the largest planetary system in the solar system, Tristan Guillot, Jonathan I. Lunine, Nikku considering the vast reach of its rings and dozens of Madhusudhan, and Olivier Mousis © in the Volume, known moons. Thus, Saturn is key to understanding Cambridge University Press the origin and evolution of the solar system itself. Models, observations, comparison with Jupiter, the NB: The copy of the Chapter, as displayed on this other gas giant planet, and analogies with extrasolar website, is a draft, pre-publication copy only. The giant planets have begun to give a sense of how final, published version of the Chapter will be Saturn, in particular, and the giant planets in general, available to purchase through Cambridge University originated and evolved. Press and other standard distribution channels as part of the wider, edited Volume, once published. Two distinct mechanisms of giant planet formation This draft copy is made available for personal use have been proposed in the literature: (1) disk only and must not be sold or re-distributed." instability (or “grey” instability) and (2) nucleated instability (or core accretion). The latter goes back to Abstract papers by Hayashi (1981) and his colleagues (e.g. Mizuno, 1980), and requires the accretion of a solid Saturn formed beyond the snow line in the primordial body (rock/metal, ice, and possibly, refractory solar nebula that made it possible for it to accrete a organics) up to a critical mass threshold at which rapid large mass. Disk instability and core accretion models accretion of gas becomes inevitable—typically 10 have been proposed for Saturn’s formation, but core times the mass of the Earth (see Armitage, 2010, for a accretion is favored on the basis of its volatile discussion). The former had its origin in the 1970’s abundances, internal structure, hydrodynamic models, (see Cameron, 1979) for hot, massive disks, but it was chemical characteristics of protoplanetary disk, etc. determined later (Boss, 2000; Mayer et al., 2002) that The observed frequency, properties and models of the instabilities required to break up a portion of a exoplanets provide additional supporting evidence for gaseous disk into clumps are a feature of cold, massive core accretion. The heavy elements with mass greater disks. We focus on each of these contrasting models in than 4He make up the core of Saturn, but are presently turn, and then discuss the observational indicators in poorly constrained, except for carbon. The C/H ratio is our own and extrasolar planetary systems that might super-solar, and twice that in Jupiter. The enrichment distinguish between the two models. of carbon and other heavy elements in Saturn and Jupiter requires special delivery mechanisms for The disk instability model is based on numerical volatiles to these planets. In this chapter we will simulations showing that massive, relatively cold review our current understanding of the origin and disks will spontaneously fragment due to a evolution of Saturn and its atmosphere, using a multi- gravitational instability, leading to multiple discrete, self-gravitating masses. In computer simulations of enrichment of heavy elements as well. The model’s the process these features seem somewhat ill-defined, Achilles heel is the time required to build the heavy and it is not possible to track the subsequent element core to the point where rapid gas accretion condensation of these features in the same occurs—millions of years or more. The onset of rapid hydrodynamical simulation that tracks the onset of the gaseous accretion, by which point further growth may instability itself. Nonetheless, basic disk physics be rapid, depends not only on the core accretion rate dictates that such fragmentation will occur for a but also, through the critical core mass (roughly 10 ME, sufficiently massive or cold disk (Armitage, 2010), where ME is an Earth mass) needed to trigger rapid gas and that the timescale for the fragmentation once the accretion, the envelope opacity and hence metallicity. instability does occur is extremely short—hundreds to Furthermore, the core accretion rate itself is a sensitive thousands of years. function of what one assumes about the planetesimal size distribution and surface density in the disk. Once formed, the fragments (assuming they continue to contract to form giant planets) are usually A plausible timescale for the formation of Saturn sufficiently numerous that the aggregate planetary must be consistent with the lifetime of gas in disks, system is dynamically unstable. The planets will but may also be constrained by the 3-5 million year gravitationally interact, scattering some out of the estimate of the formation duration of Iapetus from its system and leaving the others in a variety of possible geophysical shape and thermal history (Castillo- orbits. The evidence from microlensing of a Rogez et al., 2009). Earliest models had lengthy substantial population of free-floating Jupiter-mass formation times (e.g. 8 Myr; Pollack et al., 1996) but objects (Sumi et al., 2011) − not associated with a more recent models can make Saturn in a few million parent star − constitutes one argument in favor of the years by appropriate selection of nebular parameters importance of this formation mechanism. such as grain distribution and opacity (Dodson- Robinson et al., 2008). On the other hand, it is not evident how giant planets formed by the disk instability mechanism acquire The overall history of the solar system and presence significant amounts of heavy elements over and of a substantial terrestrial planet system inward of above their parent star’s abundances. It has been Jupiter and Saturn suggests that the extreme argued that subsequent accretion of planetesimals dynamical scattering suffered after disk instability would generate the increased metallicity, but the protoplanets are formed did not happen in our solar disruption of the disk associated with the system. Furthermore, if the 3-5 million year estimate gravitational instability might have removed the raw of the interval between the formation of the first material for large amounts of planetesimals—the solids and the formation of Iapetus (Castillo-Rogez et materials going into numerous giant planets that are al., 2009) is correct, the disk instability − if it then kicked out of the system. A subsequent phase of occurred − would have produced Saturn much too disk building or direct accretion of planetesimals soon after (or even before), the first solids in the solar from the surrounding molecular cloud may have to be system condensed out. There is sufficient evidence invoked. And this begs the question of core formation that the first solids, millimeter size chondrules and − giant planets formed in this way may have super- calcium aluminum inclusions (CAI’s) in chondrites, solar metallicities but lack a heavy element core date back to 4.5682 Gyr (Amelin et al., 2010), which unless (as seems unlikely) very large (Earth-sized) provides clear evidence that submicron size planets are consumed by these objects. interstellar grains were sticking and accumulating to form solids at the very beginning of the solar system. The core accretion model, in contrast, begins by building a heavy element core through planetesimal Measurement by the Juno mission of the water and embryo accretion in the gaseous disk (embryo is abundance below the meteorology layer in Jupiter, tied usually reserved for lunar-sized bodies and upward). At to the abundances of other major elements measured some point, the gravitational attraction of the large core by the Galileo probe, will also provide an indication of leads to an enhanced accretion of gas, so much so that how much planetesimal material was accreted (Helled gas accretion quickly dominates in a runaway process and Lunine, 2014), and to some extent, the nature of and the object gains largely nebular-composition gas the carrier species (e.g., Mousis, 2012). Although it is until its mass is large enough to create a gap in the disk possible to enrich the envelopes of the giant planets and slow accretion. Such a model produces, by even in the disk instability model by adding definition, a heavy element core, and through co- planetesimals much later, the presence of both a accretion of gas and planetesimals an envelope substantial (10 ME) core and envelope enrichment of heavy elements would strongly militate in favor of the 2.2 Observational constraints core accretion model. Saturn’s core mass may be measured by Cassini, but an inventory of the envelope The models of Saturn’s formation and evolution are enrichment of heavy elements and measurement of the constrained
Load more

Recommended publications
  • Lecture 23: Jupiter Solar System Jupiter's Orbit
    Lecture 23: Jupiter Solar System Jupiter’s Orbit •The semi-major axis of Jupiter’s orbit is a = 5.2 AU Jupiter Sun a •Kepler’s third law relates the semi-major axis to the orbital period 1 Jupiter’s Orbit •Kepler’s third law relates the semi-major axis a to the orbital period P 2 3 ⎛ P ⎞ = ⎛ a ⎞ ⎜ ⎟ ⎜ ⎟ ⎝ years⎠ ⎝ AU ⎠ •Solving for the period P yields 3/ 2 ⎛ P ⎞ = ⎛ a ⎞ ⎜ ⎟ ⎜ ⎟ ⎝ years ⎠ ⎝ AU ⎠ •Since a = 5.2 AU for Jupiter, we obtain P = 11.9 Earth years •Jupiter’s orbit has eccentricity e = 0.048 Jupiter’s Orbit •The distance from the Sun varies by about 10% during an orbit Dperihelion = 4.95 AU Daphelion = 5.45 AU •Like Mars, Jupiter is easiest to observe during favorable opposition •At this time, the Earth-Jupiter distance is only about 3.95 AU Earth Jupiter Jupiter Sun (perihelion) (aphelion) •Jupiter appears full during favorable opposition Bulk Properties of Jupiter •Jupiter is the largest planet in the solar system •We have for the radius and mass of Jupiter Rjupiter = 71,400 km = 11.2 Rearth 30 Mjupiter = 1.9 x 10 g = 318 Mearth •The volume of Jupiter is therefore given by 4 V = π R 3 jupiter 3 jupiter 30 3 •Hence Vjupiter = 1.5 x 10 cm 2 Bulk Properties of Jupiter •The average density of Jupiter is therefore M × 30 ρ = jupiter = 1.9 10 g jupiter × 30 3 Vjupiter 1.5 10 cm •We obtain ρ = −3 jupiter 1.24 g cm •This is much less than the average density of the Earth •Hence there is little if any iron and no dense core inside Jupiter Bulk Properties of Jupiter •The average density of the Earth is equal to −3 ρ⊕ = 6 g cm •The density
    [Show full text]
  • Elliptical Instability in Terrestrial Planets and Moons
    A&A 539, A78 (2012) Astronomy DOI: 10.1051/0004-6361/201117741 & c ESO 2012 Astrophysics Elliptical instability in terrestrial planets and moons D. Cebron1,M.LeBars1, C. Moutou2,andP.LeGal1 1 Institut de Recherche sur les Phénomènes Hors Equilibre, UMR 6594, CNRS and Aix-Marseille Université, 49 rue F. Joliot-Curie, BP 146, 13384 Marseille Cedex 13, France e-mail: [email protected] 2 Observatoire Astronomique de Marseille-Provence, Laboratoire d’Astrophysique de Marseille, 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13, France Received 21 July 2011 / Accepted 16 January 2012 ABSTRACT Context. The presence of celestial companions means that any planet may be subject to three kinds of harmonic mechanical forcing: tides, precession/nutation, and libration. These forcings can generate flows in internal fluid layers, such as fluid cores and subsurface oceans, whose dynamics then significantly differ from solid body rotation. In particular, tides in non-synchronized bodies and libration in synchronized ones are known to be capable of exciting the so-called elliptical instability, i.e. a generic instability corresponding to the destabilization of two-dimensional flows with elliptical streamlines, leading to three-dimensional turbulence. Aims. We aim here at confirming the relevance of such an elliptical instability in terrestrial bodies by determining its growth rate, as well as its consequences on energy dissipation, on magnetic field induction, and on heat flux fluctuations on planetary scales. Methods. Previous studies and theoretical results for the elliptical instability are re-evaluated and extended to cope with an astro- physical context. In particular, generic analytical expressions of the elliptical instability growth rate are obtained using a local WKB approach, simultaneously considering for the first time (i) a local temperature gradient due to an imposed temperature contrast across the considered layer or to the presence of a volumic heat source and (ii) an imposed magnetic field along the rotation axis, coming from an external source.
    [Show full text]
  • Arxiv:1904.05358V1 [Astro-Ph.EP] 10 Apr 2019
    Draft version April 12, 2019 Typeset using LATEX default style in AASTeX62 The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10{100 AU Eric L. Nielsen,1 Robert J. De Rosa,1 Bruce Macintosh,1 Jason J. Wang,2, 3, ∗ Jean-Baptiste Ruffio,1 Eugene Chiang,3 Mark S. Marley,4 Didier Saumon,5 Dmitry Savransky,6 S. Mark Ammons,7 Vanessa P. Bailey,8 Travis Barman,9 Celia´ Blain,10 Joanna Bulger,11 Jeffrey Chilcote,1, 12 Tara Cotten,13 Ian Czekala,3, 1, y Rene Doyon,14 Gaspard Duchene^ ,3, 15 Thomas M. Esposito,3 Daniel Fabrycky,16 Michael P. Fitzgerald,17 Katherine B. Follette,18 Jonathan J. Fortney,19 Benjamin L. Gerard,20, 10 Stephen J. Goodsell,21 James R. Graham,3 Alexandra Z. Greenbaum,22 Pascale Hibon,23 Sasha Hinkley,24 Lea A. Hirsch,1 Justin Hom,25 Li-Wei Hung,26 Rebekah Ilene Dawson,27 Patrick Ingraham,28 Paul Kalas,3, 29 Quinn Konopacky,30 James E. Larkin,17 Eve J. Lee,31 Jonathan W. Lin,3 Jer´ ome^ Maire,30 Franck Marchis,29 Christian Marois,10, 20 Stanimir Metchev,32, 33 Maxwell A. Millar-Blanchaer,8, 34 Katie M. Morzinski,35 Rebecca Oppenheimer,36 David Palmer,7 Jennifer Patience,25 Marshall Perrin,37 Lisa Poyneer,7 Laurent Pueyo,37 Roman R. Rafikov,38 Abhijith Rajan,37 Julien Rameau,14 Fredrik T. Rantakyro¨,39 Bin Ren,40 Adam C. Schneider,25 Anand Sivaramakrishnan,37 Inseok Song,13 Remi Soummer,37 Melisa Tallis,1 Sandrine Thomas,28 Kimberly Ward-Duong,25 and Schuyler Wolff41 1Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA 2Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA 3Department of Astronomy, University of California, Berkeley, CA 94720, USA 4NASA Ames Research Center, Mountain View, CA 94035, USA 5Los Alamos National Laboratory, P.O.
    [Show full text]
  • Correlations Between the Stellar, Planetary, and Debris Components of Exoplanet Systems Observed by Herschel⋆
    A&A 565, A15 (2014) Astronomy DOI: 10.1051/0004-6361/201323058 & c ESO 2014 Astrophysics Correlations between the stellar, planetary, and debris components of exoplanet systems observed by Herschel J. P. Marshall1,2, A. Moro-Martín3,4, C. Eiroa1, G. Kennedy5,A.Mora6, B. Sibthorpe7, J.-F. Lestrade8, J. Maldonado1,9, J. Sanz-Forcada10,M.C.Wyatt5,B.Matthews11,12,J.Horner2,13,14, B. Montesinos10,G.Bryden15, C. del Burgo16,J.S.Greaves17,R.J.Ivison18,19, G. Meeus1, G. Olofsson20, G. L. Pilbratt21, and G. J. White22,23 (Affiliations can be found after the references) Received 15 November 2013 / Accepted 6 March 2014 ABSTRACT Context. Stars form surrounded by gas- and dust-rich protoplanetary discs. Generally, these discs dissipate over a few (3–10) Myr, leaving a faint tenuous debris disc composed of second-generation dust produced by the attrition of larger bodies formed in the protoplanetary disc. Giant planets detected in radial velocity and transit surveys of main-sequence stars also form within the protoplanetary disc, whilst super-Earths now detectable may form once the gas has dissipated. Our own solar system, with its eight planets and two debris belts, is a prime example of an end state of this process. Aims. The Herschel DEBRIS, DUNES, and GT programmes observed 37 exoplanet host stars within 25 pc at 70, 100, and 160 μm with the sensitiv- ity to detect far-infrared excess emission at flux density levels only an order of magnitude greater than that of the solar system’s Edgeworth-Kuiper belt. Here we present an analysis of that sample, using it to more accurately determine the (possible) level of dust emission from these exoplanet host stars and thereafter determine the links between the various components of these exoplanetary systems through statistical analysis.
    [Show full text]
  • Arxiv:2012.11628V3 [Astro-Ph.EP] 26 Jan 2021
    manuscript submitted to JGR: Planets The Fundamental Connections Between the Solar System and Exoplanetary Science Stephen R. Kane1, Giada N. Arney2, Paul K. Byrne3, Paul A. Dalba1∗, Steven J. Desch4, Jonti Horner5, Noam R. Izenberg6, Kathleen E. Mandt6, Victoria S. Meadows7, Lynnae C. Quick8 1Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA 2Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 3Planetary Research Group, Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695, USA 4School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA 5Centre for Astrophysics, University of Southern Queensland, Toowoomba, QLD 4350, Australia 6Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA 7Department of Astronomy, University of Washington, Seattle, WA 98195, USA 8Planetary Geology, Geophysics and Geochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA Key Points: • Exoplanetary science is rapidly expanding towards characterization of atmospheres and interiors. • Planetary science has similarly undergone rapid expansion of understanding plan- etary processes and evolution. • Effective studies of exoplanets require models and in-situ data derived from plan- etary science observations and exploration. arXiv:2012.11628v4 [astro-ph.EP] 8 Aug 2021 ∗NSF Astronomy and Astrophysics Postdoctoral Fellow Corresponding author: Stephen R. Kane, [email protected] {1{ manuscript submitted to JGR: Planets Abstract Over the past several decades, thousands of planets have been discovered outside of our Solar System. These planets exhibit enormous diversity, and their large numbers provide a statistical opportunity to place our Solar System within the broader context of planetary structure, atmospheres, architectures, formation, and evolution.
    [Show full text]
  • Thermal Structure and Composition of Jupiter's Great Red Spot from High-Resolution Thermal Imaging
    Thermal Structure and Composition of Jupiter’s Great Red Spot from High-Resolution Thermal Imaging Leigh N. Fletchera,b, G. S. Ortona, O. Mousisc,d, P. Yanamandra-Fishera, P. D. Parrishe,a, P. G. J. Irwinb, B. M. Fishera, L. Vanzif, T. Fujiyoshig, T. Fuseg, A.A. Simon-Millerh, E. Edkinsi, T.L. Haywardj, J. De Buizerk aJet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA bAtmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK cInstitut UTINAM, CNRS-UMR 6213, Observatoire de Besan¸con, Universit´ede Franche-Comt´e, Besan¸con, France dLunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA eSchool of GeoScience, University of Edinburgh, Crew Building, King’s Buildings, Edinburgh, EH9 3JN, UK fPontificia Universidad Catolica de Chile, Department of Electrical Engineering, Av. Vicuna Makenna 4860, Santiago, Chile. gSubaru Telescope, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 650 North A’ohoku Place, Hilo, Hawaii 96720, USA hNASA/Goddard Spaceflight Center, Greenbelt, Maryland, 20771, USA iUniversity of California, Santa Barbara, Santa Barbara, CA 93106, USA jGemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena, Chile. kSOFIA - USRA, NASA Ames Research Center, Moffet Field, CA 94035, USA. Abstract Thermal-IR imaging from space-borne and ground-based observatories was used to investigate the temperature, composition and aerosol structure of Jupiter’s Great Red Spot (GRS) and its temporal variability between 1995-2008. An elliptical warm core, extending over 8◦ of longitude and 3◦ of latitude, was observed within the cold anticyclonic vortex at 21◦S.
    [Show full text]
  • The Composition of Planetary Atmospheres 1
    The Composition of Planetary Atmospheres 1 All of the planets in our solar system, and some of its smaller bodies too, have an outer layer of gas we call the atmosphere. The atmosphere usually sits atop a denser, rocky crust or planetary core. Atmospheres can extend thousands of kilometers into space. The table below gives the name of the kind of gas found in each object’s atmosphere, and the total mass of the atmosphere in kilograms. The table also gives the percentage of the atmosphere composed of the gas. Object Mass Carbon Nitrogen Oxygen Argon Methane Sodium Hydrogen Helium Other (kilograms) Dioxide Sun 3.0x1030 71% 26% 3% Mercury 1000 42% 22% 22% 6% 8% Venus 4.8x1020 96% 4% Earth 1.4x1021 78% 21% 1% <1% Moon 100,000 70% 1% 29% Mars 2.5x1016 95% 2.7% 1.6% 0.7% Jupiter 1.9x1027 89.8% 10.2% Saturn 5.4x1026 96.3% 3.2% 0.5% Titan 9.1x1018 97% 2% 1% Uranus 8.6x1025 2.3% 82.5% 15.2% Neptune 1.0x1026 1.0% 80% 19% Pluto 1.3x1014 8% 90% 2% Problem 1 – Draw a pie graph (circle graph) that shows the atmosphere constituents for Mars and Earth. Problem 2 – Draw a pie graph that shows the percentage of Nitrogen for Venus, Earth, Mars, Titan and Pluto. Problem 3 – Which planet has the atmosphere with the greatest percentage of Oxygen? Problem 4 – Which planet has the atmosphere with the greatest number of kilograms of oxygen? Problem 5 – Compare and contrast the objects with the greatest percentage of hydrogen, and the least percentage of hydrogen.
    [Show full text]
  • Internal Constitution of Mars
    Journalof GeophysicalResearch VOLUME 77 FEBRUARY 10., 1972 NUMBER 15 Internal Constitution of Mars Do• L. ANDERSON SeismologicalLaboratory, California Institute o/ Technology Pasadena, California 91109 Models for the internal structure of Mars that are consistentwith its mass, radius, and moment of inertia have been constructed.Mars cannot be homogeneousbut must have a core, the size of which dependson its density and, therefore, on its composition.A meteorite model for Mars implies an Fe-S-Ni core (12% by massof the planet) and an Fe- or FeO-rich mantle with a zero-pressuredensity of approximately 3.54 g/cm•. Mars has an iron content of 25 wt %, which is significantly less than the iron content of the earth, Mercury, or Venus but is close to the total iron content of ordinary and carbonaceouschondrites. A satisfactory model for Mars can be obtained by exposing ordinary chondrites to relatively modest temperatures. Core formation will start when temperaturesexceed the cutecftc temperature in the system Fe-FeS (•990øC) but will not go to completionunless temperatures exceed the liquidus through- out most of the planet. No high-temperature reduction stage is required. The size and density of the core and the density of the mantle indicate that approximately63% of the potential core-forming material (Fe-S-Ni) has entered the core. Therefore, Mars, in contrast to the earth, is an incompletely differentiated planet, and its core is substantially richer in sulfur than the earth's core. The thermal energy associated with core formation in Mars is negligible. The absenceof a magnetic field can be explained by lack of lunar precessional torques and by the small size and high resistivity of the Martian core.
    [Show full text]
  • Appendix: Spectroscopy of Variable Stars
    Appendix: Spectroscopy of Variable Stars As amateur astronomers gain ever-increasing access to professional tools, the science of spectroscopy of variable stars is now within reach of the experienced variable star observer. In this section we shall examine the basic tools used to perform spectroscopy and how to use the data collected in ways that augment our understanding of variable stars. Naturally, this section cannot cover every aspect of this vast subject, and we will concentrate just on the basics of this field so that the observer can come to grips with it. It will be noticed by experienced observers that variable stars often alter their spectral characteristics as they vary in light output. Cepheid variable stars can change from G types to F types during their periods of oscillation, and young variables can change from A to B types or vice versa. Spec­ troscopy enables observers to monitor these changes if their instrumentation is sensitive enough. However, this is not an easy field of study. It requires patience and dedication and access to resources that most amateurs do not possess. Nevertheless, it is an emerging field, and should the reader wish to get involved with this type of observation know that there are some excellent guides to variable star spectroscopy via the BAA and the AAVSO. Some of the workshops run by Robin Leadbeater of the BAA Variable Star section and others such as Christian Buil are a very good introduction to the field. © Springer Nature Switzerland AG 2018 M. Griffiths, Observer’s Guide to Variable Stars, The Patrick Moore 291 Practical Astronomy Series, https://doi.org/10.1007/978-3-030-00904-5 292 Appendix: Spectroscopy of Variable Stars Spectra, Spectroscopes and Image Acquisition What are spectra, and how are they observed? The spectra we see from stars is the result of the complete output in visible light of the star (in simple terms).
    [Show full text]
  • Wolf-Rayet Stars and O-Star Runaways with HIPPARCOS II. Photometry?
    UvA-DARE (Digital Academic Repository) Wolf-Rayet stars and O-stars runaways with HIPPARCOS. II. Photometry Marchenko, S.V.; Moffat, A.F.J.; van der Hucht, K.A.; Seggewiss, W.; Schrijver, H.; Stenholm, B.; Lundstrom, I.; Setia Gunawan, D.Y.A.; Sutantyo, W.; van den Heuvel, E.P.J.; Cuyper, J.- P.; Gomez, A.E. Publication date 1998 Published in Astronomy & Astrophysics Link to publication Citation for published version (APA): Marchenko, S. V., Moffat, A. F. J., van der Hucht, K. A., Seggewiss, W., Schrijver, H., Stenholm, B., Lundstrom, I., Setia Gunawan, D. Y. A., Sutantyo, W., van den Heuvel, E. P. J., Cuyper, J-P., & Gomez, A. E. (1998). Wolf-Rayet stars and O-stars runaways with HIPPARCOS. II. Photometry. Astronomy & Astrophysics, 331, 1022-1036. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:30 Sep 2021 Astron.
    [Show full text]
  • Dynamics of Jupiter's Atmosphere
    6 Dynamics of Jupiter's Atmosphere Andrew P. Ingersoll California Institute of Technology Timothy E. Dowling University of Louisville P eter J. Gierasch Cornell University GlennS. Orton J et P ropulsion Laboratory, California Institute of Technology Peter L. Read Oxford. University Agustin Sanchez-Lavega Universidad del P ais Vasco, Spain Adam P. Showman University of A rizona Amy A. Simon-Miller NASA Goddard. Space Flight Center Ashwin R . V asavada J et Propulsion Laboratory, California Institute of Technology 6.1 INTRODUCTION occurs on both planets. On Earth, electrical charge separa­ tion is associated with falling ice and rain. On Jupiter, t he Giant planet atmospheres provided many of the surprises separation mechanism is still to be determined. and remarkable discoveries of planetary exploration during The winds of Jupiter are only 1/ 3 as strong as t hose t he past few decades. Studying Jupiter's atmosphere and of aturn and Neptune, and yet the other giant planets comparing it with Earth's gives us critical insight and a have less sunlight and less internal heat than Jupiter. Earth broad understanding of how atmospheres work that could probably has the weakest winds of any planet, although its not be obtained by studying Earth alone. absorbed solar power per unit area is largest. All the gi­ ant planets are banded. Even Uranus, whose rotation axis Jupiter has half a dozen eastward jet streams in each is tipped 98° relative to its orbit axis. exhibits banded hemisphere. On average, Earth has only one in each hemi­ cloud patterns and east- west (zonal) jets.
    [Show full text]
  • Worlds Apart - Finding Exoplanets
    Worlds Apart - Finding Exoplanets Illustrated Video Credit: NASA, JPL-Caltech, T. Pyle; Acknowledgement: djxatlanta Dr. Billy Teets Vanderbilt University Dyer Observatory Osher Lifelong Learning Institute Thursday, November 5, 2020 Outline • A bit of info and history about planet formation theory. • A discussion of the main exoplanet detection techniques including some of the missions and telescopes that are searching the skies. • A few examples of “notable” results. Evolution of our Thinking of the Solar System • First “accepted models” were geocentric – Ptolemy • Copernicus – heliocentric solar system • By 1800s, heliocentric model widely accepted in scientific community • 1755 – Immanuel Kant hypothesizes clouds of gas and dust • 1796 – Kant and P.-S. LaPlace both put forward the Solar Nebula Disk Theory • Today – if Solar System formed from an interstellar cloud, maybe other clouds formed planets elsewhere in the universe. Retrograde Motion - Mars Image Credits: Tunc Tezel Retrograde Motion as Explained by Ptolemy To explain retrograde, the concept of the epicycle was introduced. A planet would move on the epicycle (the smaller circle) as the epicycle went around the Earth on the deferent (the larger circle). The planet would appear to shift back and forth among the background stars. Evolution of our Thinking of the Solar System • First “accepted models” were geocentric – Ptolemy • Copernicus – heliocentric solar system • By 1800s, heliocentric model widely accepted in scientific community • 1755 – Immanuel Kant hypothesizes clouds of gas and dust • 1796 – Kant and P.-S. LaPlace both put forward the Solar Nebula Disk Theory • Today – if Solar System formed from an interstellar cloud, maybe other clouds formed planets elsewhere in the universe.
    [Show full text]