Asteroids DOI: 10.17794/Rgn.2016.1.5
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Hydrostatic Shapes
7 Hydrostatic shapes It is primarily the interplay between gravity and contact forces that shapes the macroscopic world around us. The seas, the air, planets and stars all owe their shape to gravity, and even our own bodies bear witness to the strength of gravity at the surface of our massive planet. What physics principles determine the shape of the surface of the sea? The sea is obviously horizontal at short distances, but bends below the horizon at larger distances following the planet’s curvature. The Earth as a whole is spherical and so is the sea, but that is only the first approximation. The Moon’s gravity tugs at the water in the seas and raises tides, and even the massive Earth itself is flattened by the centrifugal forces of its own rotation. Disregarding surface tension, the simple answer is that in hydrostatic equi- librium with gravity, an interface between two fluids of different densities, for example the sea and the atmosphere, must coincide with a surface of constant ¡A potential, an equipotential surface. Otherwise, if an interface crosses an equipo- ¡ A ¡ A tential surface, there will arise a tangential component of gravity which can only ¡ ©¼AAA be balanced by shear contact forces that a fluid at rest is unable to supply. An ¡ AAA ¡ g AUA iceberg rising out of the sea does not obey this principle because it is solid, not ¡ ? A fluid. But if you try to build a little local “waterberg”, it quickly subsides back into the sea again, conforming to an equipotential surface. Hydrostatic balance in a gravitational field also implies that surfaces of con- A triangular “waterberg” in the sea. -
08 August 2013C.Indd
Published monthly since 1985 by The Binocular and Telescope Shop 84 Wentworth Park Road, Glebe NSW 2037 and 519 Burke Road, Camberwell Vic 3124 available at the shop and at all good Astronomy clubs, centres and free by email or by post for $20 per year. www.bintel.com.au August 2013 * Volume 338 MOON HIT BY SMALL ROCK NARRABRI BRIGHT FLASH SEEN HERE Since 2005 NASA astronomers have The impact crater in Mare UImbri- been monitoring the Moon for signs um could be twenty metres wide. of explosions caused by meteoroids The Lunar Reconissance Orbiter hitting the lunar surface. Lunar will probably be tasked with pho- REVEALED meteor showers have turned out to tographing the area when an op- be more common than anyone ex- portunity presents itself. pected, with hundreds of detectable impacts occurring every year. Since the monitoring program On March 17 the biggest explosion began in 2005, NASA’s lunar im- in the eight years of the program. pact team has detected more than was recorded. An object about the three hundred strikes, mostly much A few people got very excited size of a small boulder hit the lunar fainter than the March 17th event. recently when they saw some surface in Mare Imbrium, exploded More than half of all lunar mete- telescope equipment being ad- in a flash nearly ten times as bright ors come from known meteoroid vertised at very low prices on as anything seen before. streams such as the Perseids and a website (http://www.sale-tel- Anyone looking at the Moon at the Leonids. -
Astronomy 201 Review 2 Answers What Is Hydrostatic Equilibrium? How Does Hydrostatic Equilibrium Maintain the Su
Astronomy 201 Review 2 Answers What is hydrostatic equilibrium? How does hydrostatic equilibrium maintain the Sun©s stable size? Hydrostatic equilibrium, also known as gravitational equilibrium, describes a balance between gravity and pressure. Gravity works to contract while pressure works to expand. Hydrostatic equilibrium is the state where the force of gravity pulling inward is balanced by pressure pushing outward. In the core of the Sun, hydrogen is being fused into helium via nuclear fusion. This creates a large amount of energy flowing from the core which effectively creates an outward-pushing pressure. Gravity, on the other hand, is working to contract the Sun towards its center. The outward pressure of hot gas is balanced by the inward force of gravity, and not just in the core, but at every point within the Sun. What is the Sun composed of? Explain how the Sun formed from a cloud of gas. Why wasn©t the contracting cloud of gas in hydrostatic equilibrium until fusion began? The Sun is primarily composed of hydrogen (70%) and helium (28%) with the remaining mass in the form of heavier elements (2%). The Sun was formed from a collapsing cloud of interstellar gas. Gravity contracted the cloud of gas and in doing so the interior temperature of the cloud increased because the contraction converted gravitational potential energy into thermal energy (contraction leads to heating). The cloud of gas was not in hydrostatic equilibrium because although the contraction produced heat, it did not produce enough heat (pressure) to counter the gravitational collapse and the cloud continued to collapse. -
The Minor Planet Bulletin
THE MINOR PLANET BULLETIN OF THE MINOR PLANETS SECTION OF THE BULLETIN ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS VOLUME 36, NUMBER 3, A.D. 2009 JULY-SEPTEMBER 77. PHOTOMETRIC MEASUREMENTS OF 343 OSTARA Our data can be obtained from http://www.uwec.edu/physics/ AND OTHER ASTEROIDS AT HOBBS OBSERVATORY asteroid/. Lyle Ford, George Stecher, Kayla Lorenzen, and Cole Cook Acknowledgements Department of Physics and Astronomy University of Wisconsin-Eau Claire We thank the Theodore Dunham Fund for Astrophysics, the Eau Claire, WI 54702-4004 National Science Foundation (award number 0519006), the [email protected] University of Wisconsin-Eau Claire Office of Research and Sponsored Programs, and the University of Wisconsin-Eau Claire (Received: 2009 Feb 11) Blugold Fellow and McNair programs for financial support. References We observed 343 Ostara on 2008 October 4 and obtained R and V standard magnitudes. The period was Binzel, R.P. (1987). “A Photoelectric Survey of 130 Asteroids”, found to be significantly greater than the previously Icarus 72, 135-208. reported value of 6.42 hours. Measurements of 2660 Wasserman and (17010) 1999 CQ72 made on 2008 Stecher, G.J., Ford, L.A., and Elbert, J.D. (1999). “Equipping a March 25 are also reported. 0.6 Meter Alt-Azimuth Telescope for Photometry”, IAPPP Comm, 76, 68-74. We made R band and V band photometric measurements of 343 Warner, B.D. (2006). A Practical Guide to Lightcurve Photometry Ostara on 2008 October 4 using the 0.6 m “Air Force” Telescope and Analysis. Springer, New York, NY. located at Hobbs Observatory (MPC code 750) near Fall Creek, Wisconsin. -
1922MNRAS..82..149G Jan. 1922. Long-Period Inequalities In
Jan. 1922. Long-Period Inequalities in Movements of Asteroids. 149 In the case = an integer ~ is a multiple of and the solutions X2 X2 a1 1922MNRAS..82..149G with period nearly equal to — may also be regarded as periodic solution» Ai with period nearly equal to —-. A . But we have not been able (in the case when ^ is an integer) to A2 prove the existence of periodic solutions with period ^ which are not A2 • • • 2 TT at the same time periodic with period nearly equal to — . Ax Note.—The above work was completed in 1920 November, before the appearance of Moulton’s Periodic Orbits. The details of the exist- ence proofs are different from those of Buck, and it is hoped that they may be of interest. In Buck’s paper, which apparently was completed in 1912 or earlier, the equations of motion are transformed and the jacobians take a relatively simple form. In this paper only two of the families of periodic orbits treated by Buck are discussed. A full account of the other families, and also of the actual development in series of the periodic solutions, is given in Back’s paper. On Long-Period Inequalities in the Movements of Asteroids ivhose Mean Motions are nearly half that of Mars. By Wt M. H. Greaves, B. A., Isaac Newton Student in the University of Cambridge. (Communicated by Professor H. F. Baker.) In the ordinary theory of the movements of the planets as developed by Laplace and Le Verrier, the equations of motion are integrated by a method of successive approximation with regard to the masses. -
Year XIX, Supplement Ethnographic Study And/Or a Theoretical Survey of a Their Position in the Article Should Be Clearly Indicated
III. TITLES OF ARTICLES DRU[TVO ANTROPOLOGOV SLOVENIJE The journal of the Slovene Anthropological Society Titles (in English and Slovene) must be short, informa- SLOVENE ANTHROPOLOGICAL SOCIETY Anthropological Notebooks welcomes the submis- tive, and understandable. The title should be followed sion of papers from the field of anthropology and by the name of the author(s), their position, institutional related disciplines. Submissions are considered for affiliation, and if possible, by e-mail address. publication on the understanding that the paper is not currently under consideration for publication IV. ABSTRACT AND KEYWORDS elsewhere. It is the responsibility of the author to The abstract must give concise information about the obtain permission for using any previously published objective, the method used, the results obtained, and material. Please submit your manuscript as an e-mail the conclusions. Authors are asked to enclose in English attachment on [email protected] and enclose your contact information: name, position, and Slovene an abstract of 100 – 200 words followed institutional affiliation, address, phone number, and by three to five keywords. They must reflect the field of e-mail address. research covered in the article. English abstract should be placed at the beginning of an article and the Slovene one after the references at the end. V. NOTES A N T H R O P O L O G I C A L INSTRUCTIONS Notes should also be double-spaced and used sparingly. They must be numbered consecutively throughout the text and assembled at the end of the article just before references. VI. QUOTATIONS Short quotations (less than 30 words) should be placed in single quotation marks with double marks for quotations within quotations. -
Perspective in Search of Planets and Life Around Other Stars
Proc. Natl. Acad. Sci. USA Vol. 96, pp. 5353–5355, May 1999 Perspective In search of planets and life around other stars Jonathan I. Lunine* Reparto di Planetologia, Consiglio Nazionale delle Ricerche, Istituto di Astrofisica Spaziale, Rome I-00133, Italy The discovery of over a dozen low-mass companions to nearby stars has intensified scientific and public interest in a longer term search for habitable planets like our own. However, the nature of the detected companions, and in particular whether they resemble Jupiter in properties and origin, remains undetermined. The first detection of a planet orbiting around another star like Table 1. Jovian-mass planets around main-sequence stars our Sun came in 1995, after decades of null results and false Star’s Semi-major Period, alarms. As of this writing, 18 objects have been found with masses Star mass axis, AU days Eccentricity* Mass† potentially less than 12 times that of Jupiter, but none less than 40% of Jupiter’s mass, around main-sequence stars (1) (see Table HD187123 1.00 0.042 3.097 0.03 0.57 1). In addition, several planetary-mass bodies have been detected HD75289 1.05 0.046 3.5097 0.00 0.42 orbiting pulsars. Although these are interesting as well, the exotic Tau Boo 1.20 0.047 3.3126 0.00 3.66 environments around neutron stars make it unlikely that their 51 Peg 0.98 0.051 4.2308 0.01 0.44 companions are abodes for life. It is the success in finding planets Ups And 1.10 0.054 4.62 0.15 0.61 around Sun-like stars that provides a technological stepping stone HD217107 0.96 0.072 7.11 0.14 1.28 ‡ to one of the great aspirations of humanity: to find a world like 55 Cnc 0.90 0.110 14.656 0.04 1.5–3 the Earth orbiting around a distant star. -
Deleoneulalia.Pdf
Publication Year 2016 Acceptance in OA@INAF 2020-05-13T12:53:09Z Title Visible spectroscopy of the Polana-Eulalia family complex: Spectral homogeneity Authors de León, J.; Pinilla-Alonso, N.; Delbo, M.; Campins, H.; Cabrera-Lavers, A.; et al. DOI 10.1016/j.icarus.2015.11.014 Handle http://hdl.handle.net/20.500.12386/24794 Journal ICARUS Number 266 Visible Spectroscopy of the Polana-Eulalia Family Complex: Spectral Homogeneity J. de Le´ona,b, N. Pinilla-Alonsoc, M. Delb´od, H. Campinse, A. Cabrera-Laversf,a, P. Tangad, A. Cellinog, P. Bendjoyad, J. Licandroa,b, V. Lorenzih, D. Moratea,b, K. Walshi, F. DeMeoj, Z. Landsmane aInstituto de Astrof´ısica de Canarias, C/V´ıaL´actea s/n, 38205, La Laguna, Spain bDepartment of Astrophysics, University of La Laguna, 38205, Tenerife, Spain cDepartment of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996, USA dLaboratoire Lagrange, Observatoire de la Co^te d'Azur, Nice, France eof Central Florida, Physics Department, PO Box 162385, Orlando, FL 32816.2385, USA fGTC Project, 38205 La Laguna, Tenerife, Spain gINAF, Osservatorio Astrofisico di Torino, Pino Torinese, Italy hFundacin Galileo Galilei - INAF, La Palma, Spain iSouthwest Research Institute, Boulder, CO, USA jMIT, Cambridge, MA, USA Abstract Insert abstract text here Keywords: Asteroids, composition, Spectroscopy, Asteroids, dynamics 1. Introduction The main asteroid belt, located between the orbits of Mars and Jupiter, is considered the principal source of near-Earth asteroids (Bottke et al., 2002). In particular the region bounded by two major resonances, the ν6 secular resonance near 2.15 AU that marks the inner border of the main belt, and the 3:1 mean motion resonance with Jupiter at 2.5 AU. -
Color Study of Asteroid Families Within the MOVIS Catalog David Morate1,2, Javier Licandro1,2, Marcel Popescu1,2,3, and Julia De León1,2
A&A 617, A72 (2018) Astronomy https://doi.org/10.1051/0004-6361/201832780 & © ESO 2018 Astrophysics Color study of asteroid families within the MOVIS catalog David Morate1,2, Javier Licandro1,2, Marcel Popescu1,2,3, and Julia de León1,2 1 Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain e-mail: [email protected] 2 Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain 3 Astronomical Institute of the Romanian Academy, 5 Cu¸titulde Argint, 040557 Bucharest, Romania Received 6 February 2018 / Accepted 13 March 2018 ABSTRACT The aim of this work is to study the compositional diversity of asteroid families based on their near-infrared colors, using the data within the MOVIS catalog. As of 2017, this catalog presents data for 53 436 asteroids observed in at least two near-infrared filters (Y, J, H, or Ks). Among these asteroids, we find information for 6299 belonging to collisional families with both Y J and J Ks colors defined. The work presented here complements the data from SDSS and NEOWISE, and allows a detailed description− of− the overall composition of asteroid families. We derived a near-infrared parameter, the ML∗, that allows us to distinguish between four generic compositions: two different primitive groups (P1 and P2), a rocky population, and basaltic asteroids. We conducted statistical tests comparing the families in the MOVIS catalog with the theoretical distributions derived from our ML∗ in order to classify them according to the above-mentioned groups. We also studied the background populations in order to check how similar they are to their associated families. -
What Lies Immediately Outside of the Heliosphere in the Very Local Interstellar Medium (VLISM): What Will ISP Detect?
EPSC Abstracts Vol. 14, EPSC2020-68, 2020 https://doi.org/10.5194/epsc2020-68 Europlanet Science Congress 2020 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. What lies immediately outside of the heliosphere in the very local interstellar medium (VLISM): What will ISP detect? Jeffrey Linsky1 and Seth Redfield2 1University of Colorado, JILA, Boulder CO, United States of America ([email protected]) 2Wesleyan University, Astronomy Department, Middletown CT, United States of America ([email protected]) The Interstellar Probe (ISP) will provide the first direct measurements of interstellar gas and dust when it travels far beyond the heliopause where the solar wind no longer influences the ambient medium. We summarize in this presentation what we have been learning about the VLISM from 20 years of remote observations with the high-resolution spectrographs on the Hubble Space Telescope. Radial velocity measurements of interstellar absorption lines seen in the lines of sight to nearby stars allow us to measure the kinematics of gas flows in the VLISM. We find that the heliosphere is passing through a cluster of warm partially ionized interstellar clouds. The heliosphere is now at the edge of the Local Interstellar Cloud (LIC) and heading in the direction of the slighly cooler G cloud. Two other warm clouds (Blue and Aql) are very close to the heliosphere. We find that there is a large region of the sky with very low neutral hydrogen column density, which we call the hydrogen hole. In the direction of the hydrogen hole is the brightest photoionizing source, the star Epsilon Canis Majoris (CMa). -
Geologic Mapping of Vesta
Planetary and Space Science 103 (2014) 2–23 Contents lists available at ScienceDirect Planetary and Space Science journal homepage: www.elsevier.com/locate/pss Geologic mapping of Vesta R.A. Yingst a,n, S.C. Mest a, D.C. Berman a, W.B. Garry a, D.A. Williams b, D. Buczkowski c, R. Jaumann d, C.M. Pieters e, M.C. De Sanctis f, A. Frigeri f, L. Le Corre g, F. Preusker d, C.A. Raymond h, V. Reddy g, C.T. Russell i, T. Roatsch d, P.M. Schenk j a Planetary Science Institute, 1700 E. Ft. Lowell, Suite 106, Tucson, AZ 85719, United States b Arizona State University, AZ, United States c JHU-APL, MD, United States d DLR, Institute of Planetary Research, Berlin, Germany e Brown University, RI, United States f National Institute of Astrophysics, Italy g Max Planck Institute for Solar System Research, Germany h NASA JPL, California Institute of Technology, CA, United States i UCLA, CA, United States j LPI, TX, United States article info abstract Article history: We report on a preliminary global geologic map of Vesta, based on data from the Dawn spacecraft’s High- Received 14 February 2013 Altitude Mapping Orbit (HAMO) and informed by Low-Altitude Mapping Orbit (LAMO) data. This map is Received in revised form part of an iterative mapping effort; the geologic map has been refined with each improvement in 25 November 2013 resolution. Vesta has a heavily-cratered surface, with large craters evident in numerous locations. The Accepted 21 December 2013 south pole is dominated by an impact structure identified before Dawn’s arrival. -
Asteroid Regolith Weathering: a Large-Scale Observational Investigation
University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2019 Asteroid Regolith Weathering: A Large-Scale Observational Investigation Eric Michael MacLennan University of Tennessee, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Recommended Citation MacLennan, Eric Michael, "Asteroid Regolith Weathering: A Large-Scale Observational Investigation. " PhD diss., University of Tennessee, 2019. https://trace.tennessee.edu/utk_graddiss/5467 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Eric Michael MacLennan entitled "Asteroid Regolith Weathering: A Large-Scale Observational Investigation." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Geology. Joshua P. Emery, Major Professor We have read this dissertation and recommend its acceptance: Jeffrey E. Moersch, Harry Y. McSween Jr., Liem T. Tran Accepted for the Council: Dixie L. Thompson Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Asteroid Regolith Weathering: A Large-Scale Observational Investigation A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Eric Michael MacLennan May 2019 © by Eric Michael MacLennan, 2019 All Rights Reserved.