DOCSLIB.ORG

Extra-Solar Planetary Systems

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Extra-Solar Planetary Systems From the Academy Extra-solar planetary systems Joan Najita*†, Willy Benz‡, and Artie Hatzes§ *National Optical Astronomy Observatories, 950 North Cherry Avenue, Tucson, AZ 85719; ‡Physikalisches Institut, Universita¨t Bern, Sidlerstrasse 5, Ch-3012, Bern, Switzerland; and §McDonald Observatory, University of Texas, Austin, TX 78712 he discovery of extra-solar planets has captured the imagi- Table 1. Properties of extra-solar planet candidates Tnation and interest of the public and scientific communities K, alike, and for the same reasons: we are all want to know the Parent star M sin i Period, days a,AU e m⅐sϪ1 answers to questions such as ‘‘Where do we come from?’’ and ‘‘Are we alone?’’ Throughout this century, popular culture has HD 187123 0.52 3.097 0.042 0. 72. presumed the existence of other worlds and extra-terrestrial ␶ Bootis 3.64 3.3126 0.042 0. 469. intelligence. As a result, the annals of popular culture are filled HD 75289 0.42 3.5097 0.046 0. 54. with thoughts on what extra-solar planets and their inhabitants 51 Peg 0.44 4.2308 0.051 0.01 56. are like. And now toward the end of the century, astronomers ␷ And b 0.71 4.617 0.059 0.034 73.0 have managed to confirm at least one aspect of this speculative HD 217107 1.28 7.11 0.07 0.14 140. search for understanding in finding convincing evidence of Gliese 86 3.6 15.83 0.11 0.042 379. planets beyond the solar system. ␳1 Cancri 0.85 14.656 0.12 0.03 75.8 The discovery of extra-solar planets has brought with it a HD 195019 3.43 18.3 0.14 0.05 268. number of surprises. To put things in context, the planet Jupiter Gliese 876 2.1 60.9 0.21 0.27 239. in our solar system has been a benchmark in planet searches ␳ CrB 1.1 39.6 0.23 0.05 67. because it is the most massive planet in our solar system and, HD 168443 5.04 57.9 0.277 0.54 330. from that relatively naive point of view, it is the object that we HD 114762 11.02 84.0 0.351 0.334 618. are most likely to detect in other systems. Even so, this is a 70 Vir 6.84 116.7 0.47 0.40 316.8 challenging task. All the known extra-solar planets have been ␷ And c 2.11 241.2 0.83 0.18 58.0 discovered through high-resolution stellar spectroscopy, which HD 210277 1.36 437 1.15 0.45 41.5 measures the line-of-sight reflex motion of the star in response 16 Cyg B 1.74 802.8 1.7 0.68 52.2 to the gravitational pull of the planet. In our solar system, Jupiter 47 Uma 2.42 1093 2.08 0.09 47.2 induces in the Sun a reflex motion of only about 12 m͞s, which ␷ And d 4.61 1266.6 2.50 0.41 72.9 is challenging to measure, given that the typical spectral reso- 14 Her 3.3 1650 2.5 0.326 73. ͞ lution employed is approximately several km s. Fully aware of M sin i, mass of the companion times the sine of the inclination of the this difficulty, planet-searching groups have worked hard to system; a, semimajor axis; AU, astronomical unit (ca. 150 million km or 93 achieve this velocity resolution by reducing the systematic effects million miles); e, eccentricity; K, reflex motion. in their experimental method. As one example, prior to detec- tion, the stellar light is passed through an iodine gas-filled absorption cell to imprint a velocity reference on the stellar relevant physical processes, but rather how these processes fit ACADEMY spectrum. together, i.e., our outlook on their relative importance and role FROM THE However, after honing search techniques in this way for years in the eventual outcome of the planet formation process. to detect ‘‘Jupiter’’ in other solar systems, a surprising result has The changing role of one of these processes, orbital migra- emerged: a much greater diversity of planetary systems than was tion, illustrates this point as well as the limitations inherent in expected! Searches have revealed planets with a wide range of trying to reconstruct the entire planet formation process from masses, including planets much more massive than Jupiter; observations of a single system (i.e., our solar system), and the planets with a wide range of orbital distances, including planets consequent importance of extra-solar planets for an improved much closer to their suns than Jupiter is to our sun; and planets understanding of the formation and evolutionary history of with a wide range of eccentricities, including some with much planetary systems, including our own. For example, the solar more eccentric orbits than those of the planets in our solar system is believed to have formed from the gravitational system (Table 1 and Fig. 1). These results were essentially collapse of a cloud of cold gas similar to those that we now unanticipated by theory; they reveal the diversity of possible observe in the Milky Way. Because of the finite angular outcomes of the planet-formation process, an important fact that momentum of the cloud, all of the collapsing material could was not apparent from the single example of our own solar not fall directly onto the star; some fraction of the gas formed system. instead a rotating circumstellar disk. The disk was a reservoir This diversity is believed to result from the intricate interplay of matter that might eventually accrete onto the star and also among the many physical processes that govern the formation was the raw material for formation of the planets. In such a and evolution of planetary systems, processes such as grain system, as the disk accretes onto the star, it can sweep inward sticking and planetesimal accumulation (e.g., see ref. 1), runaway any planets that have formed, resulting in inward orbital gas accretion (e.g., see ref. 2), gap formation (e.g., see ref. 3), migration of the planets. disk-driven eccentricity changes (e.g., see ref. 4), orbital migra- tion (e.g., see refs. 5 and 6), and dynamical scattering with other planets, companion stars, or passing stars (e.g., see refs. 7 and 8). This paper is a summary of a session presented at the fifth annual German-American What is interesting about our understanding of planet formation Frontiers of Science symposium, held June 10–13, 1999, at the Alexander von Humboldt following the discovery of extra-solar planets is that thus far, Foundation in Potsdam, Germany. what has changed is not so much our understanding of the †To whom correspondence should be addressed. E-mail: [email protected]. PNAS ͉ December 7, 1999 ͉ vol. 96 ͉ no. 25 ͉ 14197–14198 Downloaded by guest on October 1, 2021 Fig. 1. Extra-solar planetary candidates span a wide range in mass and orbital separation. MJ, mass of Jupiter. (Figure courtesy of Geoff Marcy.) So how has the role of orbital migration changed? A decade not as a way of destroying planets, but as a way of moving them ago, several well-known solar system theorists who were from their place of formation to where we see them today working on the formation of Jupiter used to say that their best (9, 10). model was one in which Jupiter formed about where it is now, The discovery of extra-solar planets and their diversity has and through orbital migration, migrated inward and was essentially highlighted old questions and reopened many of the incorporated into the Sun. So, Jupiter does not exist, or at least questions that we had plausible explanations for when we had it is not typical. At the same time, planet searches were already only the solar system to explain. In this sense, this discovery has underway but were not producing detections, a result that was reinspired astronomers to obtain more definitive answers to also attributed to inward orbital migration by at least one basic questions about the nature of planet formation, such well-known planet hunter. For it was imagined that planets questions as: Where do planets form? How do planets get to formed in those systems as they must have in our solar system, where we now find them? (That is, How do planetary systems but then migrated inward and were similarly absorbed. The evolve?) When and how frequently do planets form? In addition tentative conclusion then was, ‘‘Maybe we are alone!’’ Of to these questions, there remain basic questions regarding planet course, astronomers eventually went on to discover many formation processes, questions such as how do submillimeter- planets, but the point here is that with only one example of a sized grains accumulate into kilometer-sized rocks, the building planetary system, it is easier to regard the system as a fluke if blocks of planets? Future observations of extra-solar planetary it does not fit the theory. The situation is of course quite systems, those in the process of forming as well as those in different today, where we have numerous examples of Jupiter- mature systems similar to our own, when combined with the like planets spanning a wide range of radii. But even in this theoretical insight that they will inspire, will bring us closer to situation, orbital migration again plays a central role, this time answering these questions. 1. Weidenschilling, S. & Cuzzi, J. J. (1993) In Protostars and Planets III, eds.
Load more

Recommended publications
  • Lurking in the Shadows: Wide-Separation Gas Giants As Tracers of Planet Formation
    Lurking in the Shadows: Wide-Separation Gas Giants as Tracers of Planet Formation Thesis by Marta Levesque Bryan In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2018 Defended May 1, 2018 ii © 2018 Marta Levesque Bryan ORCID: [0000-0002-6076-5967] All rights reserved iii ACKNOWLEDGEMENTS First and foremost I would like to thank Heather Knutson, who I had the great privilege of working with as my thesis advisor. Her encouragement, guidance, and perspective helped me navigate many a challenging problem, and my conversations with her were a consistent source of positivity and learning throughout my time at Caltech. I leave graduate school a better scientist and person for having her as a role model. Heather fostered a wonderfully positive and supportive environment for her students, giving us the space to explore and grow - I could not have asked for a better advisor or research experience. I would also like to thank Konstantin Batygin for enthusiastic and illuminating discussions that always left me more excited to explore the result at hand. Thank you as well to Dimitri Mawet for providing both expertise and contagious optimism for some of my latest direct imaging endeavors. Thank you to the rest of my thesis committee, namely Geoff Blake, Evan Kirby, and Chuck Steidel for their support, helpful conversations, and insightful questions. I am grateful to have had the opportunity to collaborate with Brendan Bowler. His talk at Caltech my second year of graduate school introduced me to an unexpected population of massive wide-separation planetary-mass companions, and lead to a long-running collaboration from which several of my thesis projects were born.
    [Show full text]
  • Naming the Extrasolar Planets
    Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named.
    [Show full text]
  • Arxiv:2105.11583V2 [Astro-Ph.EP] 2 Jul 2021 Keck-HIRES, APF-Levy, and Lick-Hamilton Spectrographs
    Draft version July 6, 2021 Typeset using LATEX twocolumn style in AASTeX63 The California Legacy Survey I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades Lee J. Rosenthal,1 Benjamin J. Fulton,1, 2 Lea A. Hirsch,3 Howard T. Isaacson,4 Andrew W. Howard,1 Cayla M. Dedrick,5, 6 Ilya A. Sherstyuk,1 Sarah C. Blunt,1, 7 Erik A. Petigura,8 Heather A. Knutson,9 Aida Behmard,9, 7 Ashley Chontos,10, 7 Justin R. Crepp,11 Ian J. M. Crossfield,12 Paul A. Dalba,13, 14 Debra A. Fischer,15 Gregory W. Henry,16 Stephen R. Kane,13 Molly Kosiarek,17, 7 Geoffrey W. Marcy,1, 7 Ryan A. Rubenzahl,1, 7 Lauren M. Weiss,10 and Jason T. Wright18, 19, 20 1Cahill Center for Astronomy & Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA 2IPAC-NASA Exoplanet Science Institute, Pasadena, CA 91125, USA 3Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA 4Department of Astronomy, University of California Berkeley, Berkeley, CA 94720, USA 5Cahill Center for Astronomy & Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA 6Department of Astronomy & Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA 7NSF Graduate Research Fellow 8Department of Physics & Astronomy, University of California Los Angeles, Los Angeles, CA 90095, USA 9Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA 10Institute for Astronomy, University of Hawai`i,
    [Show full text]
  • Arxiv:0809.1275V2
    How eccentric orbital solutions can hide planetary systems in 2:1 resonant orbits Guillem Anglada-Escud´e1, Mercedes L´opez-Morales1,2, John E. Chambers1 [email protected], [email protected], [email protected] ABSTRACT The Doppler technique measures the reflex radial motion of a star induced by the presence of companions and is the most successful method to detect ex- oplanets. If several planets are present, their signals will appear combined in the radial motion of the star, leading to potential misinterpretations of the data. Specifically, two planets in 2:1 resonant orbits can mimic the signal of a sin- gle planet in an eccentric orbit. We quantify the implications of this statistical degeneracy for a representative sample of the reported single exoplanets with available datasets, finding that 1) around 35% percent of the published eccentric one-planet solutions are statistically indistinguishible from planetary systems in 2:1 orbital resonance, 2) another 40% cannot be statistically distinguished from a circular orbital solution and 3) planets with masses comparable to Earth could be hidden in known orbital solutions of eccentric super-Earths and Neptune mass planets. Subject headings: Exoplanets – Orbital dynamics – Planet detection – Doppler method arXiv:0809.1275v2 [astro-ph] 25 Nov 2009 Introduction Most of the +300 exoplanets found to date have been discovered using the Doppler tech- nique, which measures the reflex motion of the host star induced by the planets (Mayor & Queloz 1995; Marcy & Butler 1996). The diverse characteristics of these exoplanets are somewhat surprising. Many of them are similar in mass to Jupiter, but orbit much closer to their 1Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Rd.
    [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]
  • Exoplanet.Eu Catalog Page 1 # Name Mass Star Name
    exoplanet.eu_catalog # name mass star_name star_distance star_mass OGLE-2016-BLG-1469L b 13.6 OGLE-2016-BLG-1469L 4500.0 0.048 11 Com b 19.4 11 Com 110.6 2.7 11 Oph b 21 11 Oph 145.0 0.0162 11 UMi b 10.5 11 UMi 119.5 1.8 14 And b 5.33 14 And 76.4 2.2 14 Her b 4.64 14 Her 18.1 0.9 16 Cyg B b 1.68 16 Cyg B 21.4 1.01 18 Del b 10.3 18 Del 73.1 2.3 1RXS 1609 b 14 1RXS1609 145.0 0.73 1SWASP J1407 b 20 1SWASP J1407 133.0 0.9 24 Sex b 1.99 24 Sex 74.8 1.54 24 Sex c 0.86 24 Sex 74.8 1.54 2M 0103-55 (AB) b 13 2M 0103-55 (AB) 47.2 0.4 2M 0122-24 b 20 2M 0122-24 36.0 0.4 2M 0219-39 b 13.9 2M 0219-39 39.4 0.11 2M 0441+23 b 7.5 2M 0441+23 140.0 0.02 2M 0746+20 b 30 2M 0746+20 12.2 0.12 2M 1207-39 24 2M 1207-39 52.4 0.025 2M 1207-39 b 4 2M 1207-39 52.4 0.025 2M 1938+46 b 1.9 2M 1938+46 0.6 2M 2140+16 b 20 2M 2140+16 25.0 0.08 2M 2206-20 b 30 2M 2206-20 26.7 0.13 2M 2236+4751 b 12.5 2M 2236+4751 63.0 0.6 2M J2126-81 b 13.3 TYC 9486-927-1 24.8 0.4 2MASS J11193254 AB 3.7 2MASS J11193254 AB 2MASS J1450-7841 A 40 2MASS J1450-7841 A 75.0 0.04 2MASS J1450-7841 B 40 2MASS J1450-7841 B 75.0 0.04 2MASS J2250+2325 b 30 2MASS J2250+2325 41.5 30 Ari B b 9.88 30 Ari B 39.4 1.22 38 Vir b 4.51 38 Vir 1.18 4 Uma b 7.1 4 Uma 78.5 1.234 42 Dra b 3.88 42 Dra 97.3 0.98 47 Uma b 2.53 47 Uma 14.0 1.03 47 Uma c 0.54 47 Uma 14.0 1.03 47 Uma d 1.64 47 Uma 14.0 1.03 51 Eri b 9.1 51 Eri 29.4 1.75 51 Peg b 0.47 51 Peg 14.7 1.11 55 Cnc b 0.84 55 Cnc 12.3 0.905 55 Cnc c 0.1784 55 Cnc 12.3 0.905 55 Cnc d 3.86 55 Cnc 12.3 0.905 55 Cnc e 0.02547 55 Cnc 12.3 0.905 55 Cnc f 0.1479 55
    [Show full text]
  • Simulating (Sub)Millimeter Observations of Exoplanet Atmospheres in Search of Water
    University of Groningen Kapteyn Astronomical Institute Simulating (Sub)Millimeter Observations of Exoplanet Atmospheres in Search of Water September 5, 2018 Author: N.O. Oberg Supervisor: Prof. Dr. F.F.S. van der Tak Abstract Context: Spectroscopic characterization of exoplanetary atmospheres is a field still in its in- fancy. The detection of molecular spectral features in the atmosphere of several hot-Jupiters and hot-Neptunes has led to the preliminary identification of atmospheric H2O. The Atacama Large Millimiter/Submillimeter Array is particularly well suited in the search for extraterrestrial water, considering its wavelength coverage, sensitivity, resolving power and spectral resolution. Aims: Our aim is to determine the detectability of various spectroscopic signatures of H2O in the (sub)millimeter by a range of current and future observatories and the suitability of (sub)millimeter astronomy for the detection and characterization of exoplanets. Methods: We have created an atmospheric modeling framework based on the HAPI radiative transfer code. We have generated planetary spectra in the (sub)millimeter regime, covering a wide variety of possible exoplanet properties and atmospheric compositions. We have set limits on the detectability of these spectral features and of the planets themselves with emphasis on ALMA. We estimate the capabilities required to study exoplanet atmospheres directly in the (sub)millimeter by using a custom sensitivity calculator. Results: Even trace abundances of atmospheric water vapor can cause high-contrast spectral ab- sorption features in (sub)millimeter transmission spectra of exoplanets, however stellar (sub) millime- ter brightness is insufficient for transit spectroscopy with modern instruments. Excess stellar (sub) millimeter emission due to activity is unlikely to significantly enhance the detectability of planets in transit except in select pre-main-sequence stars.
    [Show full text]
  • The Search for Exomoons and the Characterization of Exoplanet Atmospheres
    Corso di Laurea Specialistica in Astronomia e Astrofisica The search for exomoons and the characterization of exoplanet atmospheres Relatore interno : dott. Alessandro Melchiorri Relatore esterno : dott.ssa Giovanna Tinetti Candidato: Giammarco Campanella Anno Accademico 2008/2009 The search for exomoons and the characterization of exoplanet atmospheres Giammarco Campanella Dipartimento di Fisica Università degli studi di Roma “La Sapienza” Associate at Department of Physics & Astronomy University College London A thesis submitted for the MSc Degree in Astronomy and Astrophysics September 4th, 2009 Università degli Studi di Roma ―La Sapienza‖ Abstract THE SEARCH FOR EXOMOONS AND THE CHARACTERIZATION OF EXOPLANET ATMOSPHERES by Giammarco Campanella Since planets were first discovered outside our own Solar System in 1992 (around a pulsar) and in 1995 (around a main sequence star), extrasolar planet studies have become one of the most dynamic research fields in astronomy. Our knowledge of extrasolar planets has grown exponentially, from our understanding of their formation and evolution to the development of different methods to detect them. Now that more than 370 exoplanets have been discovered, focus has moved from finding planets to characterise these alien worlds. As well as detecting the atmospheres of these exoplanets, part of the characterisation process undoubtedly involves the search for extrasolar moons. The structure of the thesis is as follows. In Chapter 1 an historical background is provided and some general aspects about ongoing situation in the research field of extrasolar planets are shown. In Chapter 2, various detection techniques such as radial velocity, microlensing, astrometry, circumstellar disks, pulsar timing and magnetospheric emission are described. A special emphasis is given to the transit photometry technique and to the two already operational transit space missions, CoRoT and Kepler.
    [Show full text]
  • Symplectic Integration of Equations of Motion and Variational Equations for Extrasolar Systems of N - Planets
    A U T D P MS C P Symplectic Integration of Equations of Motion and Variational Equations for Extrasolar Systems of N - Planets Author Supervisor Dimitra S Prof. George V October, 2017 ii iii Abstract The aim of this present thesis was the symplectic integration of the equations of motion and the variational equations for a N - body system. In order to implement the integration we use a symplectic 6th order integrator presented by Yoshida. For the integration of variational equations we apply the Tangent Map (TM) method. The algorithm is applied on three Extrasolar systems : GJ 876, HR 8799 and TRAPPIST-1. The Fast Lyapunov Indicator (FLI) of the system is calculated for all systems and it is used as a tool to detect chaotic orbits. We also apply the Angu- lar Momentum Deficit criterion to decide whether this systems are AMD - stable or not. Περίληψη Σκοπός αυτής της διατριβής είναι η συμπλεκτική ολοκλήρωση των εξισώσεων της κίνησης και των εξισώσεων των μεταβολών σε ένα σύστημα Ν - σωμάτων. Για να επιτύχουμε την αριθμητική ολοκλήρωση υλοποιούμε τον αλγόριθμο του συμπλε- κτικού ολοκληρωτή 6ης τάξης του Yoshida. Για την ολοκλήρωση των εξισώσεων των μεταβολών εφαρμόσαμε τη μέθοδο Tangent Map (TM). Ο αλγόριθμος που δη- μιουργήσαμε τον εφαρμόσαμε σε τρία εξωπλανητικά συστήματα τα GJ 876, HR 8799 και TRAPPIST-1. Ο Γρήγορος Δείκτης Lyapunov (Fast Lyapunov Indicator, FLI) του συστήματος, υπολογίζεται με σκοπός την ταξινόμηση των τροχιών στο σύστημα σε τακτικές και χαοτικές. Εφαρμόζουμε επίσης το κριτήριο σταθερότη- τας κατά την ποσότητα Angular Momentum Deficit (AMD) ή Έλλειμμα Στρο- φορμής για την κατηγοριοποίηση των συστημάτων ως ευσταθή ή ασταθή κατά την ποσότητα αυτή.
    [Show full text]
  • An Empirically Derived Three-Dimensional Laplace Resonance in the Gliese 876 Planetary System
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Caltech Authors MNRAS 455, 2484–2499 (2016) doi:10.1093/mnras/stv2367 An empirically derived three-dimensional Laplace resonance in the Gliese 876 planetary system Benjamin E. Nelson,1,2‹ Paul M. Robertson,1,2 Matthew J. Payne,3 Seth M. Pritchard,4 Katherine M. Deck,5 Eric B. Ford,1,2 Jason T. Wright1,2 and Howard T. Isaacson6 1Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802, USA 2Department of Astronomy & Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802, USA 3Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 4Department of Physics & Astronomy, University of Texas San Antonio, UTSA Circle, San Antonio, TX 78249, USA 5Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91101, USA 6Department of Astronomy, University of California, Berkeley, CA 94720, USA Downloaded from Accepted 2015 October 8. Received 2015 October 5; in original form 2015 April 24 ABSTRACT http://mnras.oxfordjournals.org/ We report constraints on the three-dimensional orbital architecture for all four planets known to orbit the nearby M dwarf Gliese 876 based solely on Doppler measurements and demand- ing long-term orbital stability. Our data set incorporates publicly available radial velocities taken with the ELODIE and CORALIE spectrographs, High Accuracy Radial velocity Planet Searcher (HARPS), and Keck HIgh Resolution Echelle Spectrometer (HIRES) as well as pre- viously unpublished HIRES velocities. We first quantitatively assess the validity of the planets thought to orbit GJ 876 by computing the Bayes factors for a variety of different coplanar models using an importance sampling algorithm.
    [Show full text]
  • On the Stability of the Gliese 876 System of Planets and the Importance of the Inner Planet
    On the Stability of the Gliese 876 System of Planets and the Importance of the Inner Planet By: Ricky Leon Murphy Major Project – HET617 – Computational Astrophysics S2 – 2005 | Supervisor: Professor James Murray Background Image Credits: HIRES Echelleogram: http://exoplanets.org/gl876_web/gl876_tech.html Above: Gliese 876d Artist Rendition: http://exoplanets.org/gl876_web/gl876_graphics.html Abstract: Above: Above: Above: Using the SWIFT simulator code, a 5,000 Changing the mass of the inner body has In addition to mass, the eccentricity of the inner year simulation of the current Gliese 876 resulted in the middle planet to take on a body also severely affects system stability. A third planet with a mass of 0.023 MJ was found orbiting the star Gliese 876. system was performed (Monte Carlo more distant orbit. The eccentricity of this Here the mass of the inner body is the same simulations - to determine the best Cartesian body was very high, so the mass of the inner The initial two body system was found to have a perfect orbital resonance as the stable system (0.023M J ) with a change of 2/1. This paper will demonstrate the orbital stability to maintain this coordinates). The result is a system that is body was not available to ensure system in the orbital eccentricity from 0 to 0.1. None of stable. These parameters will be used for the stability. The mass of the inner body was the planets are able to hold their orbits. ratio is highly dependant on the presence of the small, inner planet. In remaining simulations of Gliese 876.
    [Show full text]
  • Planets and Exoplanets
    NASE Publications Planets and exoplanets Planets and exoplanets Rosa M. Ros, Hans Deeg International Astronomical Union, Technical University of Catalonia (Spain), Instituto de Astrofísica de Canarias and University of La Laguna (Spain) Summary This workshop provides a series of activities to compare the many observed properties (such as size, distances, orbital speeds and escape velocities) of the planets in our Solar System. Each section provides context to various planetary data tables by providing demonstrations or calculations to contrast the properties of the planets, giving the students a concrete sense for what the data mean. At present, several methods are used to find exoplanets, more or less indirectly. It has been possible to detect nearly 4000 planets, and about 500 systems with multiple planets. Objetives - Understand what the numerical values in the Solar Sytem summary data table mean. - Understand the main characteristics of extrasolar planetary systems by comparing their properties to the orbital system of Jupiter and its Galilean satellites. The Solar System By creating scale models of the Solar System, the students will compare the different planetary parameters. To perform these activities, we will use the data in Table 1. Planets Diameter (km) Distance to Sun (km) Sun 1 392 000 Mercury 4 878 57.9 106 Venus 12 180 108.3 106 Earth 12 756 149.7 106 Marte 6 760 228.1 106 Jupiter 142 800 778.7 106 Saturn 120 000 1 430.1 106 Uranus 50 000 2 876.5 106 Neptune 49 000 4 506.6 106 Table 1: Data of the Solar System bodies In all cases, the main goal of the model is to make the data understandable.
    [Show full text]