Matthew Steven Tiscareno
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Arxiv:1912.09192V2 [Astro-Ph.EP] 24 Feb 2020
Draft version February 25, 2020 Typeset using LATEX preprint style in AASTeX62 Photometric analyses of Saturn's small moons: Aegaeon, Methone and Pallene are dark; Helene and Calypso are bright. M. M. Hedman,1 P. Helfenstein,2 R. O. Chancia,1, 3 P. Thomas,2 E. Roussos,4 C. Paranicas,5 and A. J. Verbiscer6 1Department of Physics, University of Idaho, Moscow, ID 83844 2Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca NY 14853 3Center for Imaging Science, Rochester Institute of Technology, Rochester NY 14623 4Max Planck Institute for Solar System Research, G¨ottingen,Germany 37077 5APL, John Hopkins University, Laurel MD 20723 6Department of Astronomy, University of Virginia, Charlottesville, VA 22904 ABSTRACT We examine the surface brightnesses of Saturn's smaller satellites using a photometric model that explicitly accounts for their elongated shapes and thus facilitates compar- isons among different moons. Analyses of Cassini imaging data with this model reveals that the moons Aegaeon, Methone and Pallene are darker than one would expect given trends previously observed among the nearby mid-sized satellites. On the other hand, the trojan moons Calypso and Helene have substantially brighter surfaces than their co-orbital companions Tethys and Dione. These observations are inconsistent with the moons' surface brightnesses being entirely controlled by the local flux of E-ring par- ticles, and therefore strongly imply that other phenomena are affecting their surface properties. The darkness of Aegaeon, Methone and Pallene is correlated with the fluxes of high-energy protons, implying that high-energy radiation is responsible for darkening these small moons. Meanwhile, Prometheus and Pandora appear to be brightened by their interactions with nearby dusty F ring, implying that enhanced dust fluxes are most likely responsible for Calypso's and Helene's excess brightness. -
Water Masers in the Saturnian System
A&A 494, L1–L4 (2009) Astronomy DOI: 10.1051/0004-6361:200811186 & c ESO 2009 Astrophysics Letter to the Editor Water masers in the Saturnian system S. V. Pogrebenko1,L.I.Gurvits1, M. Elitzur2,C.B.Cosmovici3,I.M.Avruch1,4, S. Montebugnoli5 , E. Salerno5, S. Pluchino3,5, G. Maccaferri5, A. Mujunen6, J. Ritakari6, J. Wagner6,G.Molera6, and M. Uunila6 1 Joint Institute for VLBI in Europe, PO Box 2, 7990 AA Dwingeloo, The Netherlands e-mail: [pogrebenko;lgurvits]@jive.nl 2 Department of Physics and Astronomy, University of Kentucky, 600 Rose Street, Lexington, KY 40506-0055, USA e-mail: [email protected] 3 Istituto Nazionale di Astrofisica (INAF) – Istituto di Fisica dello Spazio Interplanetario (IFSI), via del Fosso del Cavaliere, 00133 Rome, Italy e-mail: [email protected] 4 Science & Technology BV, PO 608 2600 AP Delft, The Netherlands e-mail: [email protected] 5 Istituto Nazionale di Astrofisica (INAF) – Istituto di Radioastronomia (IRA) – Stazione Radioastronomica di Medicina, via Fiorentina 3508/B, 40059 Medicina (BO), Italy e-mail: [s.montebugnoli;e.salerno;g.maccaferri]@ira.inaf.it; [email protected] 6 Helsinki University of Technology TKK, Metsähovi Radio Observatory, 02540 Kylmälä, Finland e-mail: [amn;jr;jwagner;gofrito;minttu]@kurp.hut.fi Received 18 October 2008 / Accepted 4 December 2008 ABSTRACT Context. The presence of water has long been seen as a key condition for life in planetary environments. The Cassini spacecraft discovered water vapour in the Saturnian system by detecting absorption of UV emission from a background star. Investigating other possible manifestations of water is essential, one of which, provided physical conditions are suitable, is maser emission. -
Cassini Update
Cassini Update Dr. Linda Spilker Cassini Project Scientist Outer Planets Assessment Group 22 February 2017 Sols%ce Mission Inclina%on Profile equator Saturn wrt Inclination 22 February 2017 LJS-3 Year 3 Key Flybys Since Aug. 2016 OPAG T124 – Titan flyby (1584 km) • November 13, 2016 • LAST Radio Science flyby • One of only two (cf. T106) ideal bistatic observations capturing Titan’s Northern Seas • First and only bistatic observation of Punga Mare • Western Kraken Mare not explored by RSS before T125 – Titan flyby (3158 km) • November 29, 2016 • LAST Optical Remote Sensing targeted flyby • VIMS high-resolution map of the North Pole looking for variations at and around the seas and lakes. • CIRS last opportunity for vertical profile determination of gases (e.g. water, aerosols) • UVIS limb viewing opportunity at the highest spatial resolution available outside of occultations 22 February 2017 4 Interior of Hexagon Turning “Less Blue” • Bluish to golden haze results from increased production of photochemical hazes as north pole approaches summer solstice. • Hexagon acts as a barrier that prevents haze particles outside hexagon from migrating inward. • 5 Refracting Atmosphere Saturn's• 22unlit February rings appear 2017 to bend as they pass behind the planet’s darkened limb due• 6 to refraction by Saturn's upper atmosphere. (Resolution 5 km/pixel) Dione Harbors A Subsurface Ocean Researchers at the Royal Observatory of Belgium reanalyzed Cassini RSS gravity data• 7 of Dione and predict a crust 100 km thick with a global ocean 10’s of km deep. Titan’s Summer Clouds Pose a Mystery Why would clouds on Titan be visible in VIMS images, but not in ISS images? ISS ISS VIMS High, thin cirrus clouds that are optically thicker than Titan’s atmospheric haze at longer VIMS wavelengths,• 22 February but optically 2017 thinner than the haze at shorter ISS wavelengths, could be• 8 detected by VIMS while simultaneously lost in the haze to ISS. -
SETI Is Part of Astrobiology
SETI is Part of Astrobiology Jason T. Wright Department of Astronomy & Physics Center for Exoplanets and Habitable Worlds Penn State University Phone: (814) 863-8470 [email protected] I. SETI is Part of Astrobiology “Traditional SETI is not part of astrobiology” declares the NASA Astrobiology Strategy 2015 document (p. 150). This is incorrect.1 Astrobiology is the study of life in the universe, in particular its “origin, evolution, distribution, and future in the universe.” [emphasis mine] Searches for biosignatures are searches for the results of interactions between life and its environment, and could be sensitive to even primitive life on other worlds. As such, these searches focus on the origin and evolution of life, using past life on Earth as a guide. But some of the most obvious ways in which Earth is inhabited today are its technosignatures such as radio transmissions, alterations of its atmosphere by industrial pollutants, and probes throughout the Solar System. It seems clear that the future of life on Earth includes the development of ever more obvious technosignatures. Indeed, the NASA Astrobiology Strategy 2015 document acknowledges “the possibility” that such technosignatures exist, but erroneously declares them to be “not part of contemporary SETI,” and mentions them only to declare that we should “be aware of the possibility” and to “be sure to include [technosignatures] as a possible kind of interpretation we should consider as we begin to get data on the exoplanets.” In other words, while speculation on the nature of biosignatures and the design of multi-billion dollar missions to find those signatures is consistent with NASA’s vision for astrobiology, speculation on the nature of technosignatures and the design of observations to find them is not. -
ASU Colloquium
New Frontiers in Artifact SETI: Waste Heat, Alien Megastructures, and "Tabby's Star" Jason T Wright Penn State University SESE Colloquium Arizona State University October 4, 2017 Contact (Warner Bros.) What is SETI? • “The Search for Extraterrestrial Intelligence” • A field of study, like cosmology or planetary science • SETI Institute: • Research center in Mountain View, California • Astrobiology, astronomy, planetary science, radio SETI • Runs the Allen Telescope Array • Berkeley SETI Research Center: • Hosted by the UC Berkeley Astronomy Department • Mostly radio astronomy and exoplanet detection • Runs SETI@Home • Runs the $90M Breakthrough Listen Project Communication SETI The birth of Radio SETI 1960 — Cocconi & Morrison suggest interstellar communication via radio waves Allen Telescope Array Operated by the SETI Institute Green Bank Telescope Operated by the National Radio Astronomy Observatory Artifact SETI Dyson (1960) Energy-hungry civilizations might use a significant fraction of available starlight to power themselves Energy is never “used up”, it is just converted to a lower temperature If a civilization collects or generates energy, that energy must emerge at higher entropy (e.g. mid-infrared radiation) This approach is general: practically any energy use by a civilization should give a star (or galaxy) a MIR excess IRAS All-Sky map (1983) The discovery of infrared cirrus complicated Dyson sphere searches. Credit: NASA GSFC, LAMBDA Carrigan reported on the Fermilab Dyson Sphere search with IRAS: Lots of interesting red sources: -
A Deeper Look at the Colors of the Saturnian Irregular Satellites Arxiv
A deeper look at the colors of the Saturnian irregular satellites Tommy Grav Harvard-Smithsonian Center for Astrophysics, MS51, 60 Garden St., Cambridge, MA02138 and Instiute for Astronomy, University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI86822 [email protected] James Bauer Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Dr., MS183-501, Pasadena, CA91109 [email protected] September 13, 2018 arXiv:astro-ph/0611590v2 8 Mar 2007 Manuscript: 36 pages, with 11 figures and 5 tables. 1 Proposed running head: Colors of Saturnian irregular satellites Corresponding author: Tommy Grav MS51, 60 Garden St. Cambridge, MA02138 USA Phone: (617) 384-7689 Fax: (617) 495-7093 Email: [email protected] 2 Abstract We have performed broadband color photometry of the twelve brightest irregular satellites of Saturn with the goal of understanding their surface composition, as well as their physical relationship. We find that the satellites have a wide variety of different surface colors, from the negative spectral slopes of the two retrograde satellites S IX Phoebe (S0 = −2:5 ± 0:4) and S XXV Mundilfari (S0 = −5:0 ± 1:9) to the fairly red slope of S XXII Ijiraq (S0 = 19:5 ± 0:9). We further find that there exist a correlation between dynamical families and spectral slope, with the prograde clusters, the Gallic and Inuit, showing tight clustering in colors among most of their members. The retrograde objects are dynamically and physically more dispersed, but some internal structure is apparent. Keywords: Irregular satellites; Photometry, Satellites, Surfaces; Saturn, Satellites. 3 1 Introduction The satellites of Saturn can be divided into two distinct groups, the regular and irregular, based on their orbital characteristics. -
7 Planetary Rings Matthew S
7 Planetary Rings Matthew S. Tiscareno Center for Radiophysics and Space Research, Cornell University, Ithaca, NY, USA 1Introduction..................................................... 311 1.1 Orbital Elements ..................................................... 312 1.2 Roche Limits, Roche Lobes, and Roche Critical Densities .................... 313 1.3 Optical Depth ....................................................... 316 2 Rings by Planetary System .......................................... 317 2.1 The Rings of Jupiter ................................................... 317 2.2 The Rings of Saturn ................................................... 319 2.3 The Rings of Uranus .................................................. 320 2.4 The Rings of Neptune ................................................. 323 2.5 Unconfirmed Ring Systems ............................................. 324 2.5.1 Mars ............................................................... 324 2.5.2 Pluto ............................................................... 325 2.5.3 Rhea and Other Moons ................................................ 325 2.5.4 Exoplanets ........................................................... 327 3RingsbyType.................................................... 328 3.1 Dense Broad Disks ................................................... 328 3.1.1 Spiral Waves ......................................................... 329 3.1.2 Gap Edges and Moonlet Wakes .......................................... 333 3.1.3 Radial Structure ..................................................... -
Design of Low-Altitude Martian Orbits Using Frequency Analysis A
Design of Low-Altitude Martian Orbits using Frequency Analysis A. Noullez, K. Tsiganis To cite this version: A. Noullez, K. Tsiganis. Design of Low-Altitude Martian Orbits using Frequency Analysis. Advances in Space Research, Elsevier, 2021, 67, pp.477-495. 10.1016/j.asr.2020.10.032. hal-03007909 HAL Id: hal-03007909 https://hal.archives-ouvertes.fr/hal-03007909 Submitted on 16 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Design of Low-Altitude Martian Orbits using Frequency Analysis A. Noulleza,∗, K. Tsiganisb aUniversit´eC^oted'Azur, Observatoire de la C^oted'Azur, CNRS, Laboratoire Lagrange, bd. de l'Observatoire, C.S. 34229, 06304 Nice Cedex 4, France bSection of Astrophysics Astronomy & Mechanics, Department of Physics, Aristotle University of Thessaloniki, GR 541 24 Thessaloniki, Greece Abstract Nearly-circular Frozen Orbits (FOs) around axisymmetric bodies | or, quasi-circular Periodic Orbits (POs) around non-axisymmetric bodies | are of primary concern in the design of low-altitude survey missions. Here, we study very low-altitude orbits (down to 50 km) in a high-degree and order model of the Martian gravity field. We apply Prony's Frequency Analysis (FA) to characterize the time variation of their orbital elements by computing accurate quasi-periodic decompositions of the eccentricity and inclination vectors. -
The Orbits of Saturn's Small Satellites Derived From
The Astronomical Journal, 132:692–710, 2006 August A # 2006. The American Astronomical Society. All rights reserved. Printed in U.S.A. THE ORBITS OF SATURN’S SMALL SATELLITES DERIVED FROM COMBINED HISTORIC AND CASSINI IMAGING OBSERVATIONS J. N. Spitale CICLOPS, Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301; [email protected] R. A. Jacobson Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 C. C. Porco CICLOPS, Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 and W. M. Owen, Jr. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 Received 2006 February 28; accepted 2006 April 12 ABSTRACT We report on the orbits of the small, inner Saturnian satellites, either recovered or newly discovered in recent Cassini imaging observations. The orbits presented here reflect improvements over our previously published values in that the time base of Cassini observations has been extended, and numerical orbital integrations have been performed in those cases in which simple precessing elliptical, inclined orbit solutions were found to be inadequate. Using combined Cassini and Voyager observations, we obtain an eccentricity for Pan 7 times smaller than previously reported because of the predominance of higher quality Cassini data in the fit. The orbit of the small satellite (S/2005 S1 [Daphnis]) discovered by Cassini in the Keeler gap in the outer A ring appears to be circular and coplanar; no external perturbations are appar- ent. Refined orbits of Atlas, Prometheus, Pandora, Janus, and Epimetheus are based on Cassini , Voyager, Hubble Space Telescope, and Earth-based data and a numerical integration perturbed by all the massive satellites and each other. -
Chapter 14. Saturn and Its Attendants
14. Saturn and Its Attendants 1 Chapter 14. Saturn and Its Attendants Figure 14.3. A Voyager portrait. Note. In this section we survey physical properties of Saturn. Note. Some general facts about Saturn include: Orbital Period 29.5 years Rotation Period 10 hours 40 minutes Tilt of Axis 26◦ Mass 95 times Earth’s mass Surface Gravity 1.13 of Earth’s Albedo 34% Satellites 17 known Galileo was the first to see Saturn’s rings. Huygens explained them as rings and discovered the moon Titan. Cassini observed gaps in the rings and discovered four satellites. Saturn also has differential rotation, and a composition similar to that of Jupiter. 14. Saturn and Its Attendants 2 Note. Saturn is similar to Jupiter, with belts and zones, but the contrast on Saturn is less extreme. Rising and descending gas combines with rapid rotation to form strips circling the planet, as on Jupiter. The interior is similar to Jupiter, with a very thick layer of clouds, a layer of liquid hydrogen and helium, a layer of liquid metallic hydrogen, and a rock-and-ice solid core. Saturn puts out 1.8 times as much energy as it takes in, the excess is from continued differentiation (the heavy stuff sinks and releases energy). Saturn has a magnetic field slightly stronger than Earth’s and its magnetosphere fluctuates in size with solar activity. Figure 14.7. The internal structure of Saturn. Note. There is evidence for as many as 22 satellites. Of primary concern are (in no particular order): Titan. It is only one of two satellites that has an atmosphere. -
Dr. Seth Shostak
Written Text for Congressional Testimony Advances in the Search for Life Seth Shostak, Senior Astronomer, SETI Institute 189 Bernardo Ave., #200, Mountain View, CA 94043, [email protected] It is no longer considered foolish to argue that biology could exist on some of the trillion other planets in our galaxy. Its discovery would produce a lasting change in our perceptions, demonstrating that life is not confined to our world. We would know that biology is not some sort of miracle, but a commonplace – an ubiquitous, cosmic infection. The discovery of intelligence elsewhere would be of even greater import, as we have always considered humans to be special, even the pinnacle of Creation. To learn that there are others out there – others whose cognitive abilities exceed our own – would be a discovery that would recalibrate how our species views itself. It would also have consequences that can be only vaguely gauged, in much the way that the discovery of the New World led to societal changes that were largely unpredictable at the time of its happening. However, the search for extraterrestrial intelligence, known by the acronym SETI, has been pursued for more than a half century with no unambiguous, positive result. We haven’t found conclusive proof of any intelligent (or even unintelligent) life beyond the confines of Earth. Claims that our planet is being visited by alien beings, while popular with the citizenry, are not considered credible by most scientists. However, recent developments in both astronomy and technology are accelerating the speed of SETI searches, and it is hardly fantastic to suggest that we could find evidence of cosmic company within a few decades. -
Search for Rings and Satellites Around the Exoplanet Corot-9B Using Spitzer Photometry A
Search for rings and satellites around the exoplanet CoRoT-9b using Spitzer photometry A. Lecavelier Etangs, G. Hebrard, S. Blandin, J. Cassier, H. J. Deeg, A. S. Bonomo, F. Bouchy, J. -m. Desert, D. Ehrenreich, M. Deleuil, et al. To cite this version: A. Lecavelier Etangs, G. Hebrard, S. Blandin, J. Cassier, H. J. Deeg, et al.. Search for rings and satellites around the exoplanet CoRoT-9b using Spitzer photometry. Astronomy and Astrophysics - A&A, EDP Sciences, 2017, 603, pp.A115. 10.1051/0004-6361/201730554. hal-01678524 HAL Id: hal-01678524 https://hal.archives-ouvertes.fr/hal-01678524 Submitted on 16 Jan 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. A&A 603, A115 (2017) Astronomy DOI: 10.1051/0004-6361/201730554 & c ESO 2017 Astrophysics Search for rings and satellites around the exoplanet CoRoT-9b using Spitzer photometry A. Lecavelier des Etangs1, G. Hébrard1; 2, S. Blandin1, J. Cassier1, H. J. Deeg3; 4, A. S. Bonomo5, F. Bouchy6, J.-M. Désert7, D. Ehrenreich6, M. Deleuil8, R. F. Díaz9; 10, C. Moutou11, and A. Vidal-Madjar1 1 Institut d’astrophysique de Paris, CNRS, UMR 7095 & Sorbonne Universités, UPMC Paris 6, 98bis Bd Arago, 75014 Paris, France e-mail: [email protected] 2 Observatoire de Haute-Provence, CNRS/OAMP, 04870 Saint-Michel-l’Observatoire, France 3 Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain 4 Universidad de La Laguna, Dept.