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Sample records for corotation resonance rossby

  1. On resonant Rossby-Haurwitz triads

    NASA Astrophysics Data System (ADS)

    Lynch, Peter

    2009-05-01

    The dynamics of non-divergent flow on a rotating sphere are described by the conservation of absolute vorticity. The analytical study of the non-linear barotropic vorticity equation is greatly facilitated by the expansion of the solution in spherical harmonics and truncation at low order. The normal modes are the well-known Rossby-Haurwitz (RH) waves, which represent the natural oscillations of the system. Triads of RH waves, which satisfy conditions for resonance, are of critical importance for the distribution of energy in the atmosphere. We show how non-linear interactions of resonant RH triads may result in dynamic instability of large-scale components. We also demonstrate a mathematical equivalence between the equations for an orographically forced triad and a simple mechanical system, the forced-damped swinging spring. This equivalence yields insight concerning the bounded response to a constant forcing in the absence of damping. An examination of triad interactions in atmospheric reanalysis data would be of great interest.

  2. A Rossby whistle: A resonant basin mode observed in the Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Hughes, Chris W.; Williams, Joanne; Hibbert, Angela; Boening, Carmen; Oram, James

    2016-07-01

    We show that an important source of coastal sea level variability around the Caribbean Sea is a resonant basin mode. The mode consists of a baroclinic Rossby wave which propagates westward across the basin and is rapidly returned to the east along the southern boundary as coastal shelf waves. Almost two wavelengths of the Rossby wave fit across the basin, and it has a period of 120 days. The porous boundary of the Caribbean Sea results in this mode exciting a mass exchange with the wider ocean, leading to a dominant mode of bottom pressure variability which is almost uniform over the Grenada, Venezuela, and Colombia basins and has a sharp spectral peak at 120 day period. As the Rossby waves have been shown to be excited by instability of the Caribbean Current, this resonant mode is dynamically equivalent to the operation of a whistle.

  3. Rossby wave resonance in the presence of a nonlinear critical layer

    NASA Astrophysics Data System (ADS)

    Ritchie, Harold

    1985-01-01

    The behavior of Rossby waves on a shear flow in the presence of a nonlinear critical layer is studied, with particular emphasis on the role played by the critical layer in a Rossby wave resonance mechanism. Previous steady analyses are extended to the resonant case and it is found that the forced wave dominates the solution, provided the flow configuration is not resonant for the higher harmonics induced by the critical layer. Numerical simulations for the forced initial value problem show that the solution evolves towards the analysed steady state when conditions are resonant for the forced wave, and demonstrate some of the complications that arise when they are resonant for higher harmonics. In relating the initial value and steady problems, it is argued that the time dependent solution does not require the large mean flow distortion that Haberman (1972) found to be necessary outside the critical layer in the steady case.

  4. F Ring Core Stability: Corotation Resonance Plus Antiresonance

    NASA Astrophysics Data System (ADS)

    Cuzzi, Jeffrey N.; Marouf, Essam; French, Richard; Jacobson, Robert

    2014-11-01

    The decades-or-longer stability of the narrow F Ring core in a sea of orbital chaos appears to be due to an unusual combination of traditional corotation resonance and a novel kind of “antiresonance”. At a series of specific locations in the F Ring region, apse precession between synodic encounters with Prometheus allows semimajor axis perturbations to promptly cancel before significant orbital period changes can occur (Cuzzi et al. 2014, Icarus 232, 157-175). This cancellation fails for particles that encounter Prometheus when it is near its apoapse, especially during periods of antialignment of its apse with that of the F Ring. At these times, the strength of the semimajor axis perturbation is large (tens of km) and highly nonsinusoidal in encounter longitude, making it impossible to cancel promptly on a subsequent encounter and leading to chaotic orbital diffusion. Only particles that consistently encounter Prometheus away from its apoapse can use antiresonance to maintain stable orbits, implying that the true mean motion nF of the stable core must be defined by a corotational resonance of the form nF = nP-κP/m, where (nP, κP) are Prometheus’ mean motion and epicycle frequency. To test this hypothesis we used the fact that Cassini RSS occultations only sporadically detect a “massive” F Ring core, composed of several-cm-and-larger particles. We regressed the inertial longitudes of 24 Cassini RSS (and VGR) detections and 43 nondetections to a common epoch, using a comb of candidate nP, and then folded them modulo the anticipated m-number of the corotational resonance (Prometheus m=110 outer CER), to see if clustering appears. We find the “true F Ring core” is actually arranged in a series of short longitudinal arcs separated by nearly empty longitudes, orbiting at a well determined semimajor axis of 140222.4km (from 2005-2012 at least). Small particles seen by imaging and stellar occultations spread quickly in azimuth and obscure this clumpy

  5. F Ring Core Stability: Corotation Resonance Plus Antiresonance

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.; Marouf, Essam; French, Richard; Jacobson, Robert

    2014-01-01

    The decades-or-longer stability of the narrow F Ring core in a sea of orbital chaos appears to be due to an unusual combination of traditional corotation resonance and a novel kind of "antiresonance". At a series of specific locations in the F Ring region, apse precession between synodic encounters with Prometheus allows semimajor axis perturbations to promptly cancel before significant orbital period changes can occur. This cancellation fails for particles that encounter Prometheus when it is near its apoapse, especially during periods of antialignment of its apse with that of the F Ring. At these times, the strength of the semimajor axis perturbation is large (tens of km) and highly nonsinusoidal in encounter longitude, making it impossible to cancel promptly on a subsequent encounter and leading to chaotic orbital diffusion. Only particles that consistently encounter Prometheus away from its apoapse can use antiresonance to maintain stable orbits, implying that the true mean motion nF of the stable core must be defined by a corotational resonance of the form nF = nP(-kappa)P/m, where (nP, kappaP) are Prometheus' mean motion and epicycle frequency. To test this hypothesis we used the fact that Cassini RSS occultations only sporadically detect a "massive" F Ring core, composed of several-cm-and-larger particles. We regressed the inertial longitudes of 24 Cassini RSS (and VGR) detections and 43 nondetections to a common epoch, using a comb of candidate nP, and then folded them modulo the anticipated m-number of the corotational resonance (Prometheus m = 110 outer CER), to see if clustering appears. We find the "true F Ring core" is actually arranged in a series of short longitudinal arcs separated by nearly empty longitudes, orbiting at a well determined semimajor axis of 140222.4 km (from 2005-2012 at least). Small particles seen by imaging and stellar occultations spread quickly in azimuth and obscure this clumpy structure. Small chaotic variations in the mean

  6. The Rossby whistle: A resonant basin mode in the Caribbean Sea.

    NASA Astrophysics Data System (ADS)

    Hughes, Christopher W.; Williams, Joanne; Hibbert, Angela; Boening, Carmen; Oram, James

    2016-04-01

    We present a a leaky, resonant Rossby basin mode in the Caribbean Sea, excited by instability of the Caribbean Current. The mode is seen at the surface as westward-propagating Rossby waves with period 120 days, but it is most distinctive in ocean bottom pressure where it is seen in both observations and in a wide variety of ocean models. This bottom pressure mode is a product of the leakiness of the basin, which allows for mass exchange with the surrounding ocean. The mode is found to dominate sea level variability on parts of the South American coast.

  7. The role of the corotation resonance in the secular evolution of disks of spiral galaxies

    NASA Astrophysics Data System (ADS)

    Lépine, J. R. D.; Scarano, S., Jr.; Barros, D. A.; Junqueira, T. C.; Dias, W. S.; Andrievsky, S.

    2014-10-01

    The corotation resonance plays an important role in the evolution of the disks of spiral galaxies, and in particular, of our Galaxy. Its effect on the chemical abundance gradients is even a tool to estimate the age of the present spiral arm structure, which we find to be long-lived, contrary to a recent common belief. The metallicity gradients usually decrease in the inner regions and become flat or rising at larger radii. In several galaxies, including the Milky Way, one observes not only a change in the slope of the abundance gradient, but also an abrupt step in metallicity at corotation. This step is because the corotation resonance separates the disk of a galaxy in two regions (inside corotation and outside corotation) which are isolated one from the other, so that the two sides evolve in an independent way. The barrier between the two regions is the result of the flow of gas in opposite directions on the two sides and by the ring-shaped void of gas observed at corotation. We investigated a sample of galaxies, which have a known corotation radius, and for which there are measurements of abundance gradients of Oxygen available in the literature. A very good correlation is found between corotation radii and the radii at which there is a break in the slope of the gradients. Besides this, an independent effect of corotation is a minimum of star formation associated with the minimum velocity at which the interstellar gas feeds the spiral arms (seen as potential wells and star-formation machines). Still another effect is the scattering of stars by the resonance, which causes their migration to different galactic radii.

  8. Complete classification of discrete resonant Rossby/drift wave triads on periodic domains

    NASA Astrophysics Data System (ADS)

    Bustamante, Miguel D.; Hayat, Umar

    2013-09-01

    We consider the set of Diophantine equations that arise in the context of the partial differential equation called "barotropic vorticity equation" on periodic domains, when nonlinear wave interactions are studied to leading order in the amplitudes. The solutions to this set of Diophantine equations are of interest in atmosphere (Rossby waves) and Tokamak plasmas (drift waves), because they provide the values of the spectral wavevectors that interact resonantly via three-wave interactions. These wavenumbers come in "triads", i.e., groups of three wavevectors. We provide the full solution to the Diophantine equations in the physically sensible limit when the Rossby deformation radius is infinite. The method is completely new, and relies on mapping the unknown variables via rational transformations, first to rational points on elliptic curves and surfaces, and from there to rational points on quadratic forms of "Minkowski" type (such as the familiar space-time in special relativity). Classical methods invented centuries ago by Fermat, Euler, Lagrange, Minkowski, are used to classify all solutions to our original Diophantine equations, thus providing a computational method to generate numerically all the resonant triads in the system. Computationally speaking, our method has a clear advantage over brute-force numerical search: on a 10,0002 grid, the brute-force search would take 15 years using optimised C codes on a cluster, whereas our method takes about 40 min using a laptop. Moreover, the method is extended to generate so-called quasi-resonant triads, which are defined by relaxing the resonant condition on the frequencies, allowing for a small mismatch. Quasi-resonant triads' distribution in wavevector space is robust with respect to physical perturbations, unlike resonant triads' distribution. Therefore, the extended method is really valuable in practical terms. We show that the set of quasi-resonant triads form an intricate network of connected triads, forming

  9. Percolation transition in the kinematics of nonlinear resonance broadening in Charney-Hasegawa-Mima model of Rossby wave turbulence

    NASA Astrophysics Data System (ADS)

    Harris, Jamie; Connaughton, Colm; Bustamante, Miguel D.

    2013-08-01

    We study the kinematics of nonlinear resonance broadening of interacting Rossby waves as modelled by the Charney-Hasegawa-Mima equation on a biperiodic domain. We focus on the set of wave modes which can interact quasi-resonantly at a particular level of resonance broadening and aim to characterize how the structure of this set changes as the level of resonance broadening is varied. The commonly held view that resonance broadening can be thought of as a thickening of the resonant manifold is misleading. We show that in fact the set of modes corresponding to a single quasi-resonant triad has a non-trivial structure and that its area in fact diverges for a finite degree of broadening. We also study the connectivity of the network of modes which is generated when quasi-resonant triads share common modes. This network has been argued to form the backbone for energy transfer in Rossby wave turbulence. We show that this network undergoes a percolation transition when the level of resonance broadening exceeds a critical value. Below this critical value, the largest connected component of the quasi-resonant network contains a negligible fraction of the total number of modes in the system whereas above this critical value a finite fraction of the total number of modes in the system are contained in the largest connected component. We argue that this percolation transition should correspond to the transition to turbulence in the system.

  10. Coupling between corotation and Lindblad resonances in the presence of secular precession rates

    NASA Astrophysics Data System (ADS)

    El Moutamid, Maryame; Sicardy, Bruno; Renner, Stéfan

    2014-03-01

    We investigate the dynamics of two satellites with masses and orbiting a massive central planet in a common plane, near a first order mean motion resonance ( m integer). We consider only the resonant terms of first order in eccentricity in the disturbing potential of the satellites, plus the secular terms causing the orbital apsidal precessions. We obtain a two-degrees-of-freedom system, associated with the two critical resonant angles and , where and are the mean longitude and longitude of periapsis of , respectively, and where the primed quantities apply to . We consider the special case where (restricted problem). The symmetry between the two angles and is then broken, leading to two different kinds of resonances, classically referred to as corotation eccentric resonance (CER) and Lindblad eccentric Resonance (LER), respectively. We write the four reduced equations of motion near the CER and LER, that form what we call the CoraLin model. This model depends upon only two dimensionless parameters that control the dynamics of the system: the distance between the CER and LER, and a forcing parameter that includes both the mass and the orbital eccentricity of the disturbing satellite. Three regimes are found: for the system is integrable, for of order unity, it exhibits prominent chaotic regions, while for large compared to 2, the behavior of the system is regular and can be qualitatively described using simple adiabatic invariant arguments. We apply this model to three recently discovered small Saturnian satellites dynamically linked to Mimas through first order mean motion resonances: Aegaeon, Methone and Anthe. Poincaré surfaces of section reveal the dynamical structure of each orbit, and their proximity to chaotic regions. This work may be useful to explore various scenarii of resonant capture for those satellites.

  11. Rossby rip currents

    NASA Astrophysics Data System (ADS)

    Marshall, David P.; Vogel, Bendix; Zhai, Xiaoming

    2013-08-01

    Oceanic Rossby waves and eddies flux energy and fluid westward, the latter through the Stokes drift or bolus transport. While the wave energy is largely dissipated at the western boundary, mass conservation requires that the fluid be returned offshore through Rossby rip currents. The form and magnitude of these rip currents are investigated through linear Rossby wave theory, a nonlinear numerical model, and analysis of sea surface height satellite observations. The net eastward volume transport by Rossby rip currents over the global ocean is estimated to be of order 10 Sv (1 Sv ≡106 m3 s-1). In an eddying ocean, both the westward Stokes drift and eastward rip currents can assume the form of banded quasi-zonal jets.

  12. Global observations of ocean Rossby waves

    SciTech Connect

    Chelton, D.B.; Schlax, M.G.

    1996-04-12

    Rossby waves play a critical role in the transient adjustment of ocean circulation to changes in large-scale atmospheric forcing. The TOPEX/POSEIDON satellite altimeter has detected Rossby waves throughout much of the world ocean from sea level signals with {approx_lt} 10-centimeters amplitude and {approx_lt} 500-kilometer wavelength. Outside of the tropics Rossby waves are abruptly amplified by major topographic features. Analysis of 3 years of data reveals discrepancies between observed and theoretical Rossby wave phase speeds that indicate that the standard theory for free, linear Rossby waves in an incomplete description of the observed waves. 32 refs., 5 figs.

  13. Large-scale drift and Rossby wave turbulence

    NASA Astrophysics Data System (ADS)

    Harper, K. L.; Nazarenko, S. V.

    2016-08-01

    We study drift/Rossby wave turbulence described by the large-scale limit of the Charney–Hasegawa–Mima equation. We define the zonal and meridional regions as Z:= \\{{k} :| {k}y| \\gt \\sqrt{3}{k}x\\} and M:= \\{{k} :| {k}y| \\lt \\sqrt{3}{k}x\\} respectively, where {k}=({k}x,{k}y) is in a plane perpendicular to the magnetic field such that k x is along the isopycnals and k y is along the plasma density gradient. We prove that the only types of resonant triads allowed are M≤ftrightarrow M+Z and Z≤ftrightarrow Z+Z. Therefore, if the spectrum of weak large-scale drift/Rossby turbulence is initially in Z it will remain in Z indefinitely. We present a generalised Fjørtoft’s argument to find transfer directions for the quadratic invariants in the two-dimensional {k}-space. Using direct numerical simulations, we test and confirm our theoretical predictions for weak large-scale drift/Rossby turbulence, and establish qualitative differences with cases when turbulence is strong. We demonstrate that the qualitative features of the large-scale limit survive when the typical turbulent scale is only moderately greater than the Larmor/Rossby radius.

  14. Rossby waves and cascade phenomena

    NASA Astrophysics Data System (ADS)

    Reshetnyak, M. Yu.

    2012-09-01

    Nonlinear triad interactions in the Navier-Stokes equation describing quasi-geostrophic thermal convection in a spherical layer are considered. The analysis provides an insight into the nature of kinetic energy transfer across the spectrum and allows us to assess the degree of nonlocality in the energy transfer. The distinguishing feature of the spherical problem is the emergence of the Rossby waves, which cause nonlocal redistribution of energy in the system. The results of this study are compared with their counterparts for the plane model.

  15. COROT telescope development

    NASA Astrophysics Data System (ADS)

    Viard, Thierry; Bodin, Pierre; Magnan, Alain

    2004-06-01

    COROTEL is the telescope of the future COROT satellite which aims at measuring stellar flux variations very accurately. To perform this mission, COROTEL has to be very well protected against straylight (from Sun and Earth) and must be very stable with time. Thanks to its high experience in this field, Alcatel Space has proposed an original optical concept associated with a high performance baffle. From 2001, the LAM (Laboratoire d'Astrophysique de Marseille, CNRS) has placed the telescope development contract to Alcatel Space and is presently almost finished. Based on relevant material and efficient thermal control design, COROTEL should meet its ambitious performance and bring to scientific community for the first time precious data coming from stars and their possible companions.

  16. The COROT Archive at LAEFF

    NASA Astrophysics Data System (ADS)

    Velasco, Almudena; Gutiérrez, Raúl; Solano, Enrique; García-Torres, Miguel; López, Mauro; Sarro, Luis Manuel

    We describe here the main capabilities of the COROT archive. The archive (http://sdc.laeff.inta.es/corotfa/jsp/searchform.jsp), managed at LAEFF in the framework of the Spanish Virtual Observatory (http://svo.laeff.inta.es), has been developed following the standards and requirements defined by IVOA (http://www.ivoa.net). The COROT archive at LAEFF will be publicly available by the end of 2008.

  17. Rossby Wave Instability in Astrophysical Disks

    NASA Astrophysics Data System (ADS)

    Lovelace, Richard; Li, Hui

    2014-10-01

    A brief review is given of the Rossby wave instability in astrophysical disks. In non-self-gravitating discs, around for example a newly forming stars, the instability can be triggered by an axisymmetric bump at some radius r0 in the disk surface mass-density. It gives rise to exponentially growing non-axisymmetric perturbation (proportional to Exp[im ϕ], m = 1,2,...) in the vicinity of r0 consisting of anticyclonic vortices. These vortices are regions of high pressure and consequently act to trap dust particles which in turn can facilitate planetesimal growth in protoplanetary disks. The Rossby vortices in the disks around stars and black holes may cause the observed quasi-periodic modulations of the disk's thermal emission. Stirling Colgate's long standing interest in all types of vortices - particularly tornados - had an important part in stimulating the research on the Rossby wave instability.

  18. Rossby rogons in atmosphere and in the solar photosphere

    NASA Astrophysics Data System (ADS)

    Misra, A. P.; Shukla, P. K.

    2012-12-01

    The generation of Rossby rogue waves (Rossby rogons), as well as the excitation of bright and dark Rossby envelpe solitons are demonstrated on the basis of the modulational instability (MI) of a coherent Rossby wave packet. The evolution of an amplitude-modulated Rossby wave packet is governed by a one-dimensional (1D) nonlinear Schrödinger equation (NLSE). The latter is used to study the amplitude modulation of Rossby wave packets for fluids in Earth's atmosphere and in the solar photosphere. It is found that an ampitude-modulated Rossby wave packet becomes stable (unstable) against quasi-stationary, long-wavelength (in comparision with the Rossby wavelength) perturbations, when the carrier Rossby wave number satisfies k2 < 1/2 or \\sqrt {2}+1 (k2 > 3 or 1/2). It is also shown that a Rossby rogon or a bright Rossby envelope soliton may be excited in the shallow-water approximation for the Rossby waves in solar photosphere. However, the excitation of small- or large-scale perturbations may be possible for magnetized plasmas in the ionosphereic E-layer.

  19. NONLINEAR DYNAMICS OF MAGNETOHYDRODYNAMIC ROSSBY WAVES AND THE CYCLIC NATURE OF SOLAR MAGNETIC ACTIVITY

    SciTech Connect

    Raphaldini, Breno; Raupp, Carlos F. M. E-mail: carlos.raupp@iag.usp.br

    2015-01-20

    The solar dynamo is known to be associated with several periodicities, with the nearly 11/22 yr cycle being the most pronounced one. Even though these quasiperiodic variations of solar activity have been attributed to the underlying dynamo action in the Sun's interior, a fundamental theoretical description of these cycles is still elusive. Here, we present a new possible direction in understanding the Sun's cycles based on resonant nonlinear interactions among magnetohydrodynamic (MHD) Rossby waves. The WKB theory for dispersive waves is applied to magnetohydrodynamic shallow-water equations describing the dynamics of the solar tachocline, and the reduced dynamics of a resonant triad composed of MHD Rossby waves embedded in constant toroidal magnetic field is analyzed. In the conservative case, the wave amplitudes evolve periodically in time, with periods on the order of the dominant solar activity timescale (∼11 yr). In addition, the presence of linear forcings representative of either convection or instabilities of meridionally varying background states appears to be crucial in balancing dissipation and thus sustaining the periodic oscillations of wave amplitudes associated with resonant triad interactions. Examination of the linear theory of MHD Rossby waves embedded in a latitudinally varying mean flow demonstrates that MHD Rossby waves propagate toward the equator in a waveguide from –35° to 35° in latitude, showing a remarkable resemblance to the structure of the butterfly diagram of the solar activity. Therefore, we argue that resonant nonlinear magnetohydrodynamic Rossby wave interactions might significantly contribute to the observed cycles of magnetic solar activity.

  20. The Hilsch Tube, Rossby Vortices, and a Carnot Engine: Angular Momentum Transport in Astrophysics

    NASA Astrophysics Data System (ADS)

    Beckley, Howard F.; Klein, B.; Milburn, M.; Schindel, P.; Westpfahl, D. J.; Teare, S.; Li, H.; Colgate, S. A.

    2008-05-01

    We are attempting to demonstrate that the common laboratory vortex or Hilsch tube is a paradigm for the angular momentum transport by Rossby vortices in Keplerian accretion disks, either in super massive black hole formation or in star formation. Near supersonic rotating flow is induced in a cylinder by gas pressure injected through a tangential nozzle in a typical Ranque vortex or Hilsch tube. The gas exits through both an on-axis hole and a peripheral radially-aligned hole. The surprising result, demonstrated in hundreds of class rooms, is that one of the exit gas streams is hot and the other is cold. Depressing is that the typical explanation is given in terms of a "Maxwell daemon” that separates hot molecules from cold molecules, just as is the basis of any perpetual motion machine that violates the second law of thermodynamics. Instead we believe that the rotational flow is unstable to the formation of Rossby vortices that co-rotate with the azimuthal flow and act like semi-ridged turbine vanes. These quasi-vanes act like a Carnot turbine engine to the flow that escapes on axis and is therefore cooled by doing work. With the resulting free-energy, the vortices accelerate the peripheral flow which in turn becomes hot by friction with the cylinder wall. As a first step we expect to demonstrate that a free-running turbine, where metal vanes form the Carnot engine, will demonstrate the temperature effect. Such a suggestive result may lead to funding of time-dependent Schlerian photography of a vortex tube that can demonstrate the formation and pressure distribution of the Rossby vortices and coherent transport of angular momentum. This work is supported by a cooperative agreement between the New Mexico Institute of Mining and Technology, the University of California, Los Alamos National Laboratory, and the U.S. Dept. of Energy.

  1. Solar Rossby Wave 'Hills' Identified As Supergranules

    NASA Technical Reports Server (NTRS)

    Williams, P. E.; Hathaway, David H.; Cuntz, M.

    2007-01-01

    We explore the nature of 'hills' observed on the solar surface which had previously been attributed to Rossby waves. We investigate the sol ar hills phenomenon by analyzing the output from a synthetic model ba sed solely on the observed solar photospheric convection spectrum. We show that the characteristics of these hills can be explained by the corrugation of the surface produced by the radial flows of the conve ction. The hills in our simulations are dominated by supergranules, a well-known component of solar convection. Rossby waves have been predicted to exist within the Sun and may play an important role in the d ynamics of the solar interior, including the Sun's differential rotat ion and magnetic dynamo. Our study suggests, however, that the hills observed at the solar limb do not confirm the existence of solar Ross by waves.

  2. Do eddies ride on Rossby waves?

    NASA Astrophysics Data System (ADS)

    Polito, Paulo S.; Sato, Olga T.

    2015-08-01

    Both vortices and baroclinic Rossby waves show up as westward-propagating features in the sea surface height anomaly (SSHA) records when displayed in the form of zonal-temporal or Hovmöller diagrams. A chain of filters was used to separate the SSHA into orthogonal components. Each of the filtered components was then reassembled as a set of maps. In the maps of individual components, we clearly see westward propagating Rossby waves. Our most striking findings are: (i) limited within their critical latitudes, the wave extrema coincide with a significant number of vortices; (ii) eddy-wave coincidence occurs at a preferred latitude that depends on the wave period; (iii) among the vortices that, at some point of their existence coincide with a wave, a relatively large percentage of them remained their whole lifetime with the wave, and (iv) a mechanism is proposed to explain why eddies tend to remain over the wave extrema (crests and troughs). Our answer to the title question is: yes, they often do.

  3. Counterpropagating Rossby waves in confined plane wakes

    PubMed Central

    Biancofiore, L.; Gallaire, F.

    2012-01-01

    In the present work, we revisit the temporal and the spatio-temporal stability of confined plane wakes under the perspective of the counterpropagating Rossby waves (CRWs). Within the context of broken line velocity profiles, each vorticity discontinuity can be associated to a counterpropagating Rossby wave. In the case of a wake modeled by a broken line profile, the interaction of two CRWs is shown to originate in a shear instability. Following this description, we first recover the stability results obtained by Juniper [J. Fluid Mech. 590, 163–185 (2007)]10.1017/S0022112007007975 and Biancofiore and Gallaire [Phys. Fluids 23, 034103 (2011)]10.1063/1.3554764 by means of the classical normal mode analysis. In this manner, we propose an explanation of the stabilizing influence of the confinement on the temporal stability properties. The CRW description further allows us to propose a new interpretation of the counterintuitive spatio-temporal destabilization in wake flows at moderate confinement noticed by Juniper [J. Fluid Mech. 565, 171–195 (2006)]10.1017/S0022112006001558: it is well predicted by the mean group velocity of the uncoupled CRWs. PMID:22865998

  4. Counterpropagating Rossby waves in confined plane wakes

    NASA Astrophysics Data System (ADS)

    Biancofiore, L.; Gallaire, F.

    2012-07-01

    In the present work, we revisit the temporal and the spatio-temporal stability of confined plane wakes under the perspective of the counterpropagating Rossby waves (CRWs). Within the context of broken line velocity profiles, each vorticity discontinuity can be associated to a counterpropagating Rossby wave. In the case of a wake modeled by a broken line profile, the interaction of two CRWs is shown to originate in a shear instability. Following this description, we first recover the stability results obtained by Juniper [J. Fluid Mech. 590, 163-185 (2007)], 10.1017/S0022112007007975 and Biancofiore and Gallaire [Phys. Fluids 23, 034103 (2011)], 10.1063/1.3554764 by means of the classical normal mode analysis. In this manner, we propose an explanation of the stabilizing influence of the confinement on the temporal stability properties. The CRW description further allows us to propose a new interpretation of the counterintuitive spatio-temporal destabilization in wake flows at moderate confinement noticed by Juniper [J. Fluid Mech. 565, 171-195 (2006)], 10.1017/S0022112006001558: it is well predicted by the mean group velocity of the uncoupled CRWs.

  5. Counterpropagating Rossby waves in confined plane wakes.

    PubMed

    Biancofiore, L; Gallaire, F

    2012-07-01

    In the present work, we revisit the temporal and the spatio-temporal stability of confined plane wakes under the perspective of the counterpropagating Rossby waves (CRWs). Within the context of broken line velocity profiles, each vorticity discontinuity can be associated to a counterpropagating Rossby wave. In the case of a wake modeled by a broken line profile, the interaction of two CRWs is shown to originate in a shear instability. Following this description, we first recover the stability results obtained by Juniper [J. Fluid Mech. 590, 163-185 (2007)]10.1017/S0022112007007975 and Biancofiore and Gallaire [Phys. Fluids 23, 034103 (2011)]10.1063/1.3554764 by means of the classical normal mode analysis. In this manner, we propose an explanation of the stabilizing influence of the confinement on the temporal stability properties. The CRW description further allows us to propose a new interpretation of the counterintuitive spatio-temporal destabilization in wake flows at moderate confinement noticed by Juniper [J. Fluid Mech. 565, 171-195 (2006)]10.1017/S0022112006001558: it is well predicted by the mean group velocity of the uncoupled CRWs. PMID:22865998

  6. Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

    SciTech Connect

    Sugimoto, Norihiko

    2015-12-15

    Inertia-gravity wave radiation from the merging of two co-rotating vortices is investigated numerically in a rotating shallow water system in order to focus on cyclone–anticyclone asymmetry at different values of the Rossby number (Ro). A numerical study is conducted on a model using a spectral method in an unbounded domain to estimate the gravity wave flux with high accuracy. Continuous gravity wave radiation is observed in three stages of vortical flows: co-rotating of the vortices, merging of the vortices, and unsteady motion of the merged vortex. A cyclone–anticyclone asymmetry appears at all stages at smaller Ro (≤20). Gravity waves from anticyclones are always larger than those from cyclones and have a local maximum at smaller Ro (∼2) compared with that for an idealized case of a co-rotating vortex pair with a constant rotation rate. The source originating in the Coriolis acceleration has a key role in cyclone–anticyclone asymmetry in gravity waves. An additional important factor is that at later stages, the merged axisymmetric anticyclone rotates faster than the elliptical cyclone due to the effect of the Rossby deformation radius, since a rotation rate higher than the inertial cutoff frequency is required to radiate gravity waves.

  7. Inertia-gravity wave radiation from the merging of two co-rotating vortices in the f-plane shallow water system

    NASA Astrophysics Data System (ADS)

    Sugimoto, Norihiko

    2015-12-01

    Inertia-gravity wave radiation from the merging of two co-rotating vortices is investigated numerically in a rotating shallow water system in order to focus on cyclone-anticyclone asymmetry at different values of the Rossby number (Ro). A numerical study is conducted on a model using a spectral method in an unbounded domain to estimate the gravity wave flux with high accuracy. Continuous gravity wave radiation is observed in three stages of vortical flows: co-rotating of the vortices, merging of the vortices, and unsteady motion of the merged vortex. A cyclone-anticyclone asymmetry appears at all stages at smaller Ro (≤20). Gravity waves from anticyclones are always larger than those from cyclones and have a local maximum at smaller Ro (˜2) compared with that for an idealized case of a co-rotating vortex pair with a constant rotation rate. The source originating in the Coriolis acceleration has a key role in cyclone-anticyclone asymmetry in gravity waves. An additional important factor is that at later stages, the merged axisymmetric anticyclone rotates faster than the elliptical cyclone due to the effect of the Rossby deformation radius, since a rotation rate higher than the inertial cutoff frequency is required to radiate gravity waves.

  8. The seasonal cycle of boreal Rossby wave breaking processes

    NASA Astrophysics Data System (ADS)

    Peters, D. H.; Schneidereit, A.; Gabriel, A.

    2010-12-01

    In a changing climate coupling processes between the atmospheric layers play an important role. For example, the changing zonally asymmetric ozone distribution of the stratosphere has an influence on the strength and position of stratospheric jet streams as well as on the upper tropospheric large-scale flow characteristics and teleconnection patterns. The radiative influence of zonally asymmetric ozone forcing on model dynamics was investigated by ensemble runs of the GCM ECHAM5. Induced by the zonally asymmetric forcing we identified a strong polar vortex shift which was connected to changes of regions of Rossby wave breaking and storm track activity. In the extratropics, Rossby waves play an important role in determining the jet streams of the polar front, especially in the upper troposphere and lower stratosphere region. It is known that events of poleward breaking Rossby waves are often observed over the North Atlantic-European or Eastern Pacific region in wintertime. In this study we investigate the seasonal influence of the observed background flow in the upper troposphere on poleward Rossby wave breaking events and the link to severe weather in a changing climate. The seasonal cycle of events of poleward breaking Rossby waves for the 1980s and 1990s has been revealed with ECMWF Reanalysis data (ERA-40). We found that the different, diffluent and confluent, large-scale flow structure determine the occurrence rate of Rossby wave breaking events. These events are differentiated into four breaking types: cyclonically (poleward or equatorward) and anticyclonically (poleward or equatorward). Especially we focused on the seasonal behavior of these four breaking types. We found a strong seasonal dependence with major poleward breaking events in winter and minor in summer time. Further, with SGCM experiments we could show that the seasonal changing zonally varying large-scale flow explains mainly the seasonal variation of poleward Rossby wave breaking events

  9. The stability of Rossby waves in a stratified shear fluid

    NASA Astrophysics Data System (ADS)

    Tan, Benkui

    1990-11-01

    An investigation is undertaken of the stability of linear Rossby waves in a stratified shear fluid by means of a qualitative theory employing ordinary differential equations. It is noted that, while the basic current has no detectable shear, the Rossby waves are always stable. If the basic current possesses only horizontal shear, the unstable criterion for waves takes one form, but it takes entirely another in the case where the basic current possesses only vertical shear.

  10. ROSSBY WAVE INSTABILITY IN LOCALLY ISOTHERMAL AND POLYTROPIC DISKS: THREE-DIMENSIONAL LINEAR CALCULATIONS

    SciTech Connect

    Lin, Min-Kai

    2012-07-20

    Numerical calculations of the linear Rossby wave instability (RWI) in global three-dimensional (3D) disks are presented. The linearized fluid equations are solved for vertically stratified, radially structured disks with either a locally isothermal or polytropic equation of state, by decomposing the vertical dependence of the perturbed hydrodynamic quantities into Hermite and Gegenbauer polynomials, respectively. It is confirmed that the RWI operates in 3D. For perturbations with vertical dependence assumed above, there is little difference in growth rates between 3D and two-dimensional (2D) calculations. Comparison between 2D and 3D solutions of this type suggests the RWI is predominantly a 2D instability and that 3D effects, such as vertical motion, can be interpreted as a perturbative consequence of the dominant 2D flow. The vertical flow around corotation, where vortex formation is expected, is examined. In locally isothermal disks, the expected vortex center remains in approximate vertical hydrostatic equilibrium. For polytropic disks, the vortex center has positive vertical velocity, whose magnitude increases with decreasing polytropic index n.

  11. Large Rossby number flows in Cozumel Channel

    NASA Astrophysics Data System (ADS)

    Ochoa, J.; Candela, J.; Sheinbaum, J.; Badan, A.

    2003-04-01

    The Caribbean Current flows to the west impinging the Yucatan coast south of Cozumel Island, then, most of its flow turns north, surrounds the island and continues towards the Yucatan Straits. About 4 Sv in the mean pass between the Yucatan coast and the Cozumel Island; through the Cozumel Channel, where subinertial currents exhibit large ageostrophic fluctuations [Chavez et. al. (2003)]. This channel is about 18 km wide, 50 km long, 400 m deep, and 70 km southwest of the Yucatan Straits. The curvature and latitude of the Caribbean Current on its approach to the Yucatan coast vary significantly. Observations with two upward-looking ADCPs, 8.6 km from each other, closely aligned with the mean current at the channel's axis and entrance, allow robust estimations of the current speed (U), direction and curvature (|R|-1). A signed Rossby number (Uf-1R-1), where f is the Coriolis parameter, is readily available as a function of time. The positive/negative curvature is defined by the cyclonic/anticyclonic turn. The currents observations along with pressure measurements at both sides of the channel produce evidence that favor the bend of the current as the cause of the ageostrophic fluctuations. Another possible cause for the ageostrophic fluctuations is the passage of eddies within the channel. We test the gradient wind balance between the currents and pressure observations. A very low frequency component on the seasonal time scale and high frequency fluctuations (superinercial) do not adjust to this balance, only the intermediate frequency variations show a clear equilibrium of centripetal (i.e. due to curvature) plus Coriolis accelerations against the pressure gradient perpendicular to the velocity. The conjecture is that the ageostrophic fluctuations occur when the bend and approach of the Caribbean Current is just south of Cozumel Island, thus influencing all its entrance. When the current impinges the coast further south, the flow, with a longer path to transit

  12. The Roles of Tidal Evolution and Evaporative Mass Loss in the Origin of CoRoT-7 b

    NASA Technical Reports Server (NTRS)

    Jackson, Brian; Miller, Neil; Barnes, Rory; Raymond, Sean N.; Fortney, Jonathan J.; Greenberg, Richard

    2010-01-01

    CoRoT-7 b is the first confirmed rocky exoplanet, but, with an orbital semimajor axis of 0.0172 au, its origins may be unlike any rocky planet in our Solar System. In this study, we consider the roles of tidal evolution and evaporative mass loss in CoRoT-7 b's history, which together have modified the planet's mass and orbit. If CoRoT-7 b has always been a rocky body, evaporation may have driven off almost half its original mass, but the mass loss may depend sensitively on the extent of tidal decay of its orbit. As tides caused CoRoT-7 b's orbit to decay, they brought the planet closer to its host star, thereby enhancing the mass loss rate. Such a large mass loss also suggests the possibility that CoRoT-7 b began as a gas giant planet and had its original atmosphere completely evaporated. In this case, we find that CoRoT-7 b's original mass probably did not exceed 200 Earth masses (about two-third of a Jupiter mass). Tides raised on the host star by the planet may have significantly reduced the orbital semimajor axis, perhaps causing the planet to migrate through mean-motion resonances with the other planet in the system, CoRoT-7 c. The coupling between tidal evolution and mass loss may be important not only for CoRoT-7 b but also for other close-in exoplanets, and future studies of mass loss and orbital evolution may provide insight into the origin and fate of close-in planets, both rocky and gaseous.

  13. Free and forced Rossby normal modes in a rectangular gulf of arbitrary orientation

    NASA Astrophysics Data System (ADS)

    Graef, Federico

    2016-09-01

    A free Rossby normal mode in a rectangular gulf of arbitrary orientation is constructed by considering the reflection of a Rossby mode in a channel at the head of the gulf. Therefore, it is the superposition of four Rossby waves in an otherwise unbounded ocean with the same frequency and wavenumbers perpendicular to the gulf axis whose difference is equal to 2mπ/W, where m is a positive integer and W the gulf's width. The lower (or higher) modes with small m (or large m) are oscillatory (evanescent) in the coordinate along the gulf; these are elucidated geometrically. However for oceanographically realistic parameter values, most of the modes are evanescent. When the gulf is forced at the mouth with a single Fourier component, the response is in general an infinite sum of modes that are needed to match the value of the streamfunction at the gulf's entrance. The dominant mode of the response is the resonant one, which corresponds to forcing with a frequency ω and wavenumber normal to the gulf axis η appropriate to a gulf mode: η =- β sin α/(2ω) ± Mπ/W, where α is the angle between the gulf's axis and the eastern direction (+ve clockwise) and M the resonant's mode number. For zonal gulfs ω drops out of the resonance condition. For the special cases η = 0 in which the free surface goes up and down at the mouth with no flow through it, or a flow with a sinusoidal profile, resonant modes can get excited for very specific frequencies (only for non-zonal gulfs in the η = 0 case). The resonant mode is around the annual frequency for a wide range of gulf orientations α ∈ [40°, 130°] or α ∈ [220°, 310°] and gulf widths between 150 and 200 km; these include the Gulf of California and the Adriatic Sea. If η is imaginary, i.e. a flow with an exponential profile, there is no resonance. In general less modes get excited if the gulf is zonally oriented.

  14. The Hadley and Rossby regimes in a spherical atmosphere

    NASA Technical Reports Server (NTRS)

    Feldstein, S. B.; Clark, J. H. E.

    1985-01-01

    The properties of the steady Hadley and Rossby regimes for a thermally forced rotating fluid on a sphere are studied. The two layer modified geostrophic model is employed which allows for thermal advection by the divergent wind and time dependent static stability. Heating processes are parameterized using the Newtonian approximation and Rayleigh friction is accounted for. The equations are transformed to spectral form using spherical harmonics and then truncated retaining a simple axisymmetric state and initial, one wave. A time independent Hadley circulation is obtained which is neutral to axisymmetric disturbances but unstable to wave like perturbations for intermediate values of the meridional temperature gradient, indicating the existence of both an upper and lower symmetric Hadley regime. An analytical solution for the steady Rossby circulation is determined for values of the meridional temperature gradient where the Hadley regime is unstable. Linear perturbation theory is used to show that within the steady Rossby regime two or more waves cannot exist simultaneously.

  15. Midlatitude Rossby wave forcing of equatorial Kelvin waves

    NASA Astrophysics Data System (ADS)

    Biello, J. A.; Kiladis, G. N.; Back, A.

    2015-12-01

    Observations strongly suggest that convectively coupled Kelvin waves can be generated by extratropical wave activity. This mechanism is particularly efficient over Australia, where wave activity appears immediately after the extratropical Rossby waves propagate into the region during the Austral winter. This interaction occurs where the zonal wind is strongly sheared both in the meridional and vertical directions. In order to understand this phenomenon the authors study the linear primitive equations in the presence of barotropic and baroclinic shear and the dispersion characteristics of the sheared Matsuno modes are calculated. Depending on the shear strength, the waves are stable or unstable and can be categorized into three groups. First there are the classical Matsuno modes modified by shear. Second there are extratropical "free" Rossby waves. Third, there are Rossby waves meridionally confined to the shear layer - these latter modes can be unstable, or stable and part of the continuous spectrum. In examples where the zonal winds are barotropically and baroclinically stable, we show that a continuous spectrum of Rossby waves exists. If the zonal winds are strong enough, the Rossby waves in the continuous spectrum have an equatorial signature exactly like the Matsuno Kelvin wave - despite the fact that, in these examples, the Matsuno Kelvin wave also exists on its own and that all modes are stable. For stronger shears, these continuous spectrum modes become unstable. Although the appear similar to Sakai's Rossby/Kelvin instability, their existence arises from a completely different phenomenon. The Sakai instability requires the frequency of a stable equatorial Rossby mode to coincide with the stable Kelvin wave frequency in order for the two modes to create a stable/unstable pair. Our results show that unstable Rossby waves need only have their frequencies Doppler shifted to that of the Kelvin wave frequency by the underlying shear in order that they acquire a

  16. Rossby wave Green's functions in an azimuthal wind

    NASA Astrophysics Data System (ADS)

    Webb, G. M.; Duba, C. T.; Hu, Q.

    2016-05-01

    Green's functions for Rossby waves in an azimuthal wind are obtained, in which the stream-function $\\psi$ depends on $r$, $\\phi$ and $t$, where $r$ is cylindrical radius and $\\phi$ is the azimuthal angle in the $\\beta$-plane relative to the easterly direction, in which the $x$-axis points east and the $y$-axis points north. The Rossby wave Green's function with no wind is obtained using Fourier transform methods, and is related to the previously known Green's function obtained for this case, which has a different but equivalent form to the Green's function obtained in the present paper. We emphasize the role of the wave eikonal solution, which plays an important role in the form of the solution. The corresponding Green's function for a rotating wind with azimuthal wind velocity ${\\bf u}=\\Omega r{\\bf e}_\\phi$ ($\\Omega=$const.) is also obtained by Fourier methods, in which the advective rotation operator in position space is transformed to a rotation operator in ${\\bf k}$ transform space. The finite Rossby deformation radius is included in the analysis. The physical characteristics of the Green's functions are delineated and applications are discussed. In the limit as $\\Omega\\to 0$, the rotating wind Green's function reduces to the Rossby wave Green function with no wind.

  17. Rossby solitary vortices, on giant planets and in the laboratory.

    PubMed

    Nezlin, Mikhail V.

    1994-06-01

    This is a review of laboratory experiments with a layer of shallow water having a free surface and rotating together with a vessel of parabolic form. Such a (rather original) setup has allowed one to create Rossby solitary vortex for the first time. The latter is an anticyclonic Rossby vortex not subjected to dispersive spread owing to its compensation by the nonlinearity of KdV type. By its structural, collisional, and other properties, including clear-cut cyclonic-anticyclonic asymmetry, it may be considered as a physical prototype of the large-scale long-lived anticyclonic Rossby vortices like the Great Red Spot of Jupiter or the Great Dark Spot of Neptune (this remarkable vortex was discovered by the spacecraft Voyager-2 during its farewell to the Solar System) and other vortices dominating in the atmospheres of giant planets and created by the unstable zonal flows. It has been shown that the vortex under study is a long-lived entity provided it satisfies "antitwisting condition," i.e., it has rather large amplitude (at which it rotates more quickly than it propagates and thereby carries the trapped fluid). In this case, it is not subjected to the "twisting" deformation and may be ascribed by the generalized Charney-Obukhov equation for Rossby vortices on shallow water with a free surface. The results of creating the vortex under consideration by the different methods have been compared with the results obtained by other authors in the experiments on shear-flow generation of Rossby vortices. PMID:12780099

  18. Corotation of an intermittent solar wind source

    NASA Technical Reports Server (NTRS)

    Croft, T. A.

    1972-01-01

    The measured electron content of the solar wind in mid-1970 exhibited a region of relatively high electron density that reappeared at intervals of about 27.8 days. It is shown that the repeating event cannot be reconciled with the concept of a long-enduring steady flow, even though the recurrence period is close to the rotation period of the sun. This evidence of transients is inferred from the short duration of each appearance of the interval of higher density; each should last for roughly one corotation interval if it is caused by a steady stream. The radio path was approximately 0.8 AU long, and the corotation interval exceeded 3 days. Other aspects of the content data patterns support the view that such transient events are common in the solar wind. The mid-1970 repeating event is an unusually good example of the intermittent character of flow regions in the solar wind that fluctuate on a time scale of days but endure as identifiable regions for many months. A sputtering corotating source of thin solar plasma streams could explain this series of events; it could also be explained in terms of a stream that is steady in density and speed but undulating north-south so that it passes into and out of the 0.8 AU radio path in a matter of a day or less.

  19. Linear corotation torques in non-barotropic disks

    SciTech Connect

    Tsang, David

    2014-02-20

    A fully analytic expression for the linear corotation torque to first order in eccentricity for planets in non-barotropic protoplanetary disks is derived, taking into account the effect of disk entropy gradients. This torque formula is applicable to both the co-orbital, corotation torques and the non-co-orbital, corotation torques—for planets in orbits with non-zero eccentricity—in disks where the thermal diffusivity and viscosity are sufficient to maintain the linearity of these interactions. While the co-orbital, corotation torque is important for migration of planets in Type I migration, the non-co-orbital, corotation torque plays an important role in the eccentricity evolution of giant planets that have opened gaps in the disk. The presence of an entropy gradient in the disk can significantly modify the corotation torque in both these cases.

  20. The instability of finite amplitude Rossby waves on the infinite beta-plane

    NASA Astrophysics Data System (ADS)

    Anderson, Jeffrey L.

    The normal mode instability problem for a stationary Rossby wave of finite amplitude and arbitrary orientation is examined on the infinite beta-plane using a Floquet technique. A survey of the instability problem as a function of the basic state wave amplitude and wave orientation is presented. In the large amplitude case, two modes of instability are found, while in the small amplitude case, a family of resonant interactions can completely describe the Floquet results. For intermediate values of amplitude, a combination of the large and small amplitude limits can explain the instabilities. For the range of greatest geophysical interest, two physically distinct unstable modes of approximately equal growth rate are available for certain values of the basic state wave orientation. Relevance to geophysical flows and the instability problem on the sphere are discussed briefly.

  1. Theoretical evolution of Rossby number for solar analog stars

    NASA Astrophysics Data System (ADS)

    Castro, Matthieu; Duarte, Tharcísyo; do Nascimento, José Dias

    2014-08-01

    Magnetic fields of late-type stars are presumably generated by a dynamo mechanism at the interface layer between the radiative interior and the outer convective zone. The Rossby number, which is related to the dynamo process, shows an observational correlation with activity. It represents the ratio between the rotation period of the star and the local convective turnover time. The former is well determined from observations but the latter is estimated by an empirical iterated function depending on the color index (B-V) and the mixing-length parameter. We computed the theoretical Rossby number of stellar models with the TGEC code, and analyze its evolution with time during the main sequence. We estimated a function for the local convective turnover time corresponding to a mixing-length parameter inferred from a solar model, and compare our results to the estimated Rossby number of 33 solar analogs and twins, observed with the spectropolarimeters ESPaDOnS@CFHT and Narval@LBT.

  2. Dynamics of vortex Rossby waves in tropical cyclones

    NASA Astrophysics Data System (ADS)

    Nikitina, Lidia

    This thesis describes an analytical study of vortex Rossby waves in tropical cyclones. Observational analyses of hurricanes in the tropical atmosphere indicate the existence of spiral rainbands which propagate outwards from the eye and affect the structure and intensity of the hurricane. These disturbances may be described as vortex Rossby waves. The aim of this research is to study the propagation of vortex Rossby waves in tropical cyclones and wave-mean-flow interactions near the critical radius where the mean flow angular velocity matches the phase speed of the waves. Depending on the wave magnitude, the problem can be linear or nonlinear. Analytical techniques including Laplace transforms, multiple scaling and asymptotic expansions are used to obtain approximate solutions of the governing linear and nonlinear equations. In this study we carry out asymptotic analyses to examine the evolution of the interactions near the critical radius in some two-dimensional configurations on an f-plane and a beta-plane. The results are used to explain some features of the tropical cyclone's development, namely, the change of angular wind in the critical layer, the secondary eyewall formation and the eyewall dynamics.

  3. Anisotropy and corotation of galactic cosmic rays.

    PubMed

    Amenomori, M; Ayabe, S; Bi, X J; Chen, D; Cui, S W; Danzengluobu; Ding, L K; Ding, X H; Feng, C F; Feng, Zhaoyang; Feng, Z Y; Gao, X Y; Geng, Q X; Guo, H W; He, H H; He, M; Hibino, K; Hotta, N; Hu, Haibing; Hu, H B; Huang, J; Huang, Q; Jia, H Y; Kajino, F; Kasahara, K; Katayose, Y; Kato, C; Kawata, K; Labaciren; Le, G M; Li, A F; Li, J Y; Lou, Y-Q; Lu, H; Lu, S L; Meng, X R; Mizutani, K; Mu, J; Munakata, K; Nagai, A; Nanjo, H; Nishizawa, M; Ohnishi, M; Ohta, I; Onuma, H; Ouchi, T; Ozawa, S; Ren, J R; Saito, T; Saito, T Y; Sakata, M; Sako, T K; Sasaki, T; Shibata, M; Shiomi, A; Shirai, T; Sugimoto, H; Takita, M; Tan, Y H; Tateyama, N; Torii, S; Tsuchiya, H; Udo, S; Wang, B; Wang, H; Wang, X; Wang, Y G; Wu, H R; Xue, L; Yamamoto, Y; Yan, C T; Yang, X C; Yasue, S; Ye, Z H; Yu, G C; Yuan, A F; Yuda, T; Zhang, H M; Zhang, J L; Zhang, N J; Zhang, X Y; Zhang, Y; Zhang, Yi; Zhaxisangzhu; Zhou, X X

    2006-10-20

    The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments. PMID:17053141

  4. From CoRoT 102899501 to the Sun. A time evolution model of chromospheric activity on the main sequence

    NASA Astrophysics Data System (ADS)

    Gondoin, P.; Gandolfi, D.; Fridlund, M.; Frasca, A.; Guenther, E. W.; Hatzes, A.; Deeg, H. J.; Parviainen, H.; Eigmüller, P.; Deleuil, M.

    2012-12-01

    Aims: The present study reports measurements of the rotation period of a young solar analogue, estimates of its surface coverage by photospheric starspots and of its chromospheric activity level, and derivations of its evolutionary status. Detailed observations of many young solar-type stars, such as the one reported in the present paper, provide insight into rotation and magnetic properties that may have prevailed on the Sun in its early evolution. Methods: Using a model based on the rotational modulation of the visibility of active regions, we analysed the high-accuracy CoRoT lightcurve of the active star CoRoT 102899501. Spectroscopic follow-up observations were used to derive its fundamental parameters. We compared the chromospheric activity level of Corot 102899501 with the R'HK index distribution vs age established on a large sample of solar-type dwarfs in open clusters. We also compared the chromospheric activity level of this young star with a model of chromospheric activity evolution established by combining relationships between the R'HK index and the Rossby number with a recent model of stellar rotation evolution on the main sequence. Results: We measure the spot coverage of the stellar surface as a function of time and find evidence for a tentative increase from 5 - 14% at the beginning of the observing run to 13-29% 35 days later. A high level of magnetic activity on Corot 102899501 is corroborated by a strong emission in the Balmer and Ca ii H and K lines (R'HK ~ -4). The starspots used as tracers of the star rotation constrain the rotation period to 1.625 ± 0.002 days and do not show evidence for differential rotation. The effective temperature (Teff = 5180 ± 80 K), surface gravity (log g = 4.35 ± 0.1), and metallicity ([M/H] = 0.05 ± 0.07 dex) indicate that the object is located near the evolutionary track of a 1.09 ± 0.12 M⊙ pre-main sequence star at an age of 23 ± 10 Myr. This value is consistent with the "gyro-age" of about 8-25 Myr

  5. Classification of CoRoT Exoplanet Light Curves

    NASA Astrophysics Data System (ADS)

    Sarro, L. M.; Debosscher, J.; Aerts, C.

    2006-11-01

    We describe the methodology developed for the classification of the exoplanet light curves to be assembled by the CoRoT space mission. A supervised classification method will be used to deliver the N3 data products to the CoRoT Additional Programme community. Unsupervised classification will also be performed, but at a later stage of the mission. In the current paper, we provide the class definitions and attributes under consideration for the fast supervised classification. These definitions and attributes will be improved after each long run of CoRoT.

  6. Tilted Rossby-wave critical layers in stratified atmospheres

    NASA Astrophysics Data System (ADS)

    Parham, Frederick Melvin, Jr.

    The quasigeostrophic potential vorticity equations linearized about a zonal mean flow, which describe Rossby waves, become singular at the critical level where the mean flow equals the wave's phase velocity. The Wentzel-Kramer-Brillouin solution describes a superposition of two eigenmodes, each of which has meridional structure corresponding to that of Dickenson's (1968) two-dimensional solutions. Rossby waves in a continuously stratified atmosphere are studied whose basic state zonal winds vary over large meridional scales. Again, WKB is used. The linearized potential vorticity equation is separable to lowest order. The WKB analysis applies to the outer solution. The inner solution, which provides a condition on the jump in the derivative of the outer solution across the critical line, depends on whether the critical line is desingularized by damping or by weak nonlinearity. Using the results on the matching across the critical line, the vertical structure eigenfunctions and eigenvalues are calculated for low critical layer heights with the basic state as given in the Charney model. Asymptotic values of the eigenvalues are also calculated as the critical height approaches zero or infinity. Finally, the eigenfunctions and eigenvalues are used to calculate the structure of waves on a basic state with a region of easterly winds surrounded by westerlies. The assumption of constant N makes it possible to compute the wave-forced change in the mean flow by means of modified Bessel functions.

  7. Assuring the Legacy of the CoRoT Planets

    NASA Astrophysics Data System (ADS)

    Deeg, H. J.; Klagyivik, P.; Alonso, R.; Hoyer, S.

    2015-09-01

    For the long-lasting impact of CoRoT's planet findings, precise knowledge of the times of their transits is of vital importance for any future observing campaigns. Here we give the motivation and first results of a systematic revisit of the transits of most CoRoT planets to refine their ephemeris. As secondary objectives, more precise planet characterisations, from period or transit shape variations on/and from use of a well-defined passband may be obtained.

  8. Distribution of refractory and volatile elements in CoRoT exoplanet host stars

    NASA Astrophysics Data System (ADS)

    Chavero, C.; de La Reza, R.; Domingos, R. C.; Drake, N. A.; Pereira, C. B.; Winter, O. C.

    2010-07-01

    The relative distribution of abundances of refractory, intermediate, and volatile elements in stars with planets can be an important tool for investigating the internal migration of a giant planet. This migration can lead to the accretion of planetesimals and the selective enrichment of the star with these elements. We report on a spectroscopic determination of the atmospheric parameters and chemical abundances of the parent stars in transiting planets CoRoT-2b and CoRoT-4b. Adding data for CoRoT-3 and CoRoT-5 from the literature, we find a flat distribution of the relative abundances as a function of their condensation temperatures. For CoRoT-2, the relatively high lithium abundance and intensity of its Li i resonance line permit us to propose an age of 120 Myr, making this star one of the youngest stars with planets to date. We introduce a new methodology to investigate a relation between the abundances of these stars and the internal migration of their planets. By simulating the internal migration of a planet in a disk formed only by planetesimals, we are able, for the first time, to separate the stellar fractions of refractory, intermediate, and volatile rich planetesimals accreting onto the central star. Intermediate and volatile element fractions enriching the star are similar and much larger than those of pure refractory ones. This result is opposite to what has been considered in the literature for the accreting self-enrichment processes of stars with planets. We also show that these results are highly dependent on the model adopted for the disk distribution regions in terms of refractory, intermediate, and also volatile elements and other parameters considered. We note however, that this self-enrichment mechanism is only efficient during the first 20-30 Myr or later in the lifetime of the disk when the surface convection layers of the central star for the first time attain its minimum size configuration. Based on observations made with the 2.2 m telescope

  9. Weak nonlinear coupling of Rossby-Haurwitz waves

    NASA Astrophysics Data System (ADS)

    Becker, G.

    1986-11-01

    The Rossby-Haurwitz waves as solutions of the linearized free barotropic vorticity equation in a spherical coordinate system are in good agreement with the observed ultralong planetary waves of the troposphere. Within an antisymmetric basic flow, as in the middle atmosphere, the solutions become unstable because of mathematical singularities, called 'critical latitudes'. Therefore the nonlinear advection terms have to be considered in such a case. Analytical solutions of a corresponding spectral truncated model demonstrate the weak interaction between the mean flow and the ultralong waves of zonal wavenumbers one to three. The time structures of the planetary waves change from periodic oscillations via vacillations to turbulent character with increasing initial amplitudes. Finally the spectral model is extended by the waves of wavenumber four. The numerical solutions for the periods of the planetary waves within tropospheric and stratospheric basic flow configurations agree with observations.

  10. Discovery Of A Rossby Wave In Jupiter's South Equatorial Region

    NASA Astrophysics Data System (ADS)

    Simon-Miller, Amy A.; Choi, D. S.; Rogers, J. H.; Gierasch, P. J.

    2012-10-01

    A detailed study of the chevron-shaped dark spots on the strong southern equatorial wind jet near 7.5 deg S planetographic latitude shows variations in velocity with longitude and time. The chevrons move with velocities near the maximum wind jet velocity of 140 m/s, as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7 deg N latitude. Their repetitive nature is consistent with an inertia-gravity wave (n = 75-100) with phase speed up to 25 m/s, relative to the local flow, but the identity of this wave mode is not well constrained. However, high spatial resolution movies from Cassini images show that the chevrons oscillate in latitude with a 7-day period. This oscillating motion has a wavelength of 20 deg and a speed of 100 m/s, following a pattern similar to that seen in the Rossby wave plumes of the North Equatorial Zone, and possibly reinforced by it, though they are not perfectly in phase. The transient anticyclonic South Equatorial Disturbance (SED) may be a similar wave feature, but moves at slower velocity. All data show chevron latitude variability, but it is unclear if this Rossby wave is present during other epochs, without time series movies that fully delineate it. In the presence of multiple wave modes, the difference in dominant cloud appearance between 7 deg N and 7.5 deg S may be due to the presence of the Great Red Spot, either through changes in stratification and stability or by acting as a wave boundary.

  11. Discovery Of A Rossby Wave In Jupiter's South Equatorial Region

    NASA Technical Reports Server (NTRS)

    Simon-Miller, Amy A.; Choi, D. S.; Rogers, J. H.; Gierasch, P. J.

    2012-01-01

    A detailed study of the chevron-shaped dark spots on the strong southern equatorial wind jet near 7.5 deg S planetographic latitude shows variations in velocity with longitude and time. The chevrons move with velocities near the maximum wind jet velocity of approx.140 m/s, as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7 deg N latitude. Their repetitive nature is consistent with an inertia-gravity wave (n = 75-100) with phase speed up to 25 m/s, relative to the local flow, but the identity of this wave mode is not well constrained. However, high spatial resolution movies from Cassini images show that the chevrons oscillate in latitude with a approx.7-day period. This oscillating motion has a wavelength of approx.20 deg and a speed of approx.100 m/s, following a pattern similar to that seen in the Rossby wave plumes of the North Equatorial Zone, and possibly reinforced by it, though they are not perfectly in phase. The transient anticyclonic South Equatorial Disturbance (SED) may be a similar wave feature, but moves at slower velocity. All data show chevron latitude variability, but it is unclear if this Rossby wave is present during other epochs, without time series movies that fully delineate it. In the presence of multiple wave modes, the difference in dominant cloud appearance between 7 deg N and 7.5 deg S may be due to the presence of the Great Red Spot, either through changes in stratification and stability or by acting as a wave boundary.

  12. Stellar cycles from photometric data: CoRoT stars

    NASA Astrophysics Data System (ADS)

    Ferreira Lopes, C. E.; Leão, I. C.; de Freitas, D. B.; Canto Martins, B. L.; Catelan, M.; De Medeiros, J. R.

    2015-11-01

    Context. Until a few years ago, the amplitude variation in the photometric data had been explored to a limited extent mainly because of time resolution and photometric sensitivity limitations. This investigation is now possible thanks to the Kepler and CoRoT databases which provide a unique set of data for studying the nature of stellar variability cycles. Aims: The present study characterizes the amplitude variation in a sample of main-sequence stars with light curves collected using CoRoT exofield CCDs. Methods: We analyze potential stellar activity cycles by studying the variability amplitude over small boxes. The cycle periods and amplitudes were computed based on the Lomb-Scargle periodogram, harmonic fits, and visual inspection. As a first application of our approach, we considered the photometric data for 16 CoRoT FGK main sequence stars, revisited during the IRa01, LRa01 and LRa06 CoRoT runs. Results: The 16 CoRoT stars appear to follow the empirical relations between activity cycle periods (Pcyc) and the rotation period (Prot) found by previous works. In addition to the so-called A (active) and I (inactive) sequences previously identified, there is a possible third sequence, here named S (short-cycles) sequence. However, recovery fractions estimated from simulations suggest that only a half of our sample has confident cycle measurements. Therefore, more study is needed to verify our results, and Kepler data will clearly be useful for such a study. Overall, our procedure provides a key tool for exploring the CoRoT and Kepler databases to identify and characterize stellar cycle variability. The CoRoT space mission was developed and is operated by the French space agency CNES, with the participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.

  13. Oceanic Rossby Waves Acting As a ``Hay Rake'' for Ecosystem Floating By-Products

    NASA Astrophysics Data System (ADS)

    Dandonneau, Yves; Vega, Andres; Loisel, Hubert; du Penhoat, Yves; Menkes, Christophe

    2003-11-01

    Recent satellite observations of Rossby waves and chlorophyll anomalies propagating in subtropical gyres have suggested that wave-induced upwelling could stimulate photosynthesis. Instead, we show that chlorophyll maxima are located in abnormally warm water, in Rossby wave-induced convergences. This excludes inputs of nutrients from deeper water. We argue that the sea color anomalies are not caused by chlorophyll but by floating particles evolved from the ecosystem and accumulated by Rossby waves, acting as ``marine hay rakes,'' in convergence zones. Such processes may be determinant for the distribution of living organisms in oligotrophic areas.

  14. CoRoT data reduction by example

    NASA Astrophysics Data System (ADS)

    Weingrill, J.

    2015-02-01

    Data reduction techniques published so far for the CoRoT N2 data product were targeted primarily on the detection of extrasolar planets. Since the whole dataset has been released, specific algorithms are required to process the lightcurves from CoRoT correctly. Though only unflagged datapoints must be chosen for scientific processing, some flags might be reconsidered. The reduction of data along with improving the signal-to-noise ratio can be achieved by applying a one dimensional drizzle algorithm. Gaps can be filled by linear interpolated data without harming the frequency spectrum. Magnitudes derived from the CoRoT color channels might be used to derive additional information about the targets. Depending on the needs, various filters in the frequency domain remove either the red noise background or high frequency noise. The autocorrelation function or the least squares periodogram are appropriate methods to identify periodic signals. The methods described here are not strictly limited to CoRoT data but may also be applied on Kepler data or the upcoming PLATO mission. The CoRoT space mission, launched on 2006 December 27, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain.

  15. Equatorward shift of annual Rossby waves in the Equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Ma, Xiao; Sun, Che

    2016-01-01

    Annual Rossby wave is a key component of the ENSO phenomenon in the equatorial Pacific Ocean. Due to the paucity and seasonal bias in historical hydrographic data, previous studies on equatorial Rossby waves only gave qualitative description. The accumulation of Argo measurements in recent years has greatly alleviated the data problem. In this study, seasonal variation of the equatorial Pacific Ocean is examined with annual harmonic analysis of Argo gridded data. Results show that strong seasonal signal is present in the western equatorial Pacific and explains more than 50% of the thermal variance below 500 m. Lag-correlation tracing further shows that this sub-thermocline seasonal signal originates from the eastern equatorial Pacific via downward and southwestward propagation of annual Rossby waves. Possible mechanisms for the equatorward shift of Rossby wave path are also discussed.

  16. Dust-trapping Rossby vortices in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Meheut, H.; Meliani, Z.; Varniere, P.; Benz, W.

    2012-09-01

    Context. One of the most challenging steps in planet formation theory is the one leading to the formation of planetesimals of kilometre size. A promising scenario involves the existence of vortices able to concentrate a large amount of dust and grains in their centres. Up to now this scenario has mostly been studied in 2D razor thin disks. A 3D study including, simultaneously, the formation and resulting dust concentration of the vortices with vertical settling, is still missing. Aims: The Rossby wave instability self-consistently forms 3D vortices, which have the unique quality of presenting a large-scale vertical velocity in their centre. Here we aim to study how this newly discovered effect can alter the dynamic evolution of the dust. Methods: We performed global 3D simulations of the RWI in a radially and vertically stratified disk using the code MPI-AMRVAC. After the growth phase of the instability, the gas and solid phases are modelled by a bi-fluid approach, where the dust is considered as a fluid without pressure. Both the drag force of the gas on the dust and the back reaction of the dust on the gas are included. Multiple grain sizes from 1 mm to 5 cm are used with a constant density distribution. Results: We obtain in a short timescale a high concentration of the largest grains in the vortices. Indeed, in 3 rotations the dust-to-gas density ratio grows from 10-2 to unity leading to a concentration of mass up to that of Mars in one vortex. The presence of the radial drift is also at the origin of a dust pile-up at the radius of the vortices. Lastly, the vertical velocity of the gas in the vortex causes the sedimentation process to be reversed, the mm size dust is lifted and higher concentrations are obtained in the upper layer than in the midplane. Conclusions: The Rossby wave instability is a promising mechanism for planetesimal formation, and the results presented here can be of particular interest in the context of future observations of protoplanetary

  17. Investigation of Rossby-number similarity in the neutral boundary layer using large-eddy simulation

    SciTech Connect

    Ohmstede, W.D.; Cederwall, R.T.; Meyers, R.E.

    1988-01-01

    One special case of particular interest, especially to theoreticians, is the steady-state, horizontally homogeneous, autobarotropic (PLB), hereafter referred to as the neutral boundary layer (NBL). The NBL is in fact a 'rare' atmospheric phenomenon, generally associated with high-wind situations. Nevertheless, there is a disproportionate interest in this problem because Rossby-number similarity theory provides a sound approach for addressing this issue. Rossby-number similarity theory has rather wide acceptance, but because of the rarity of the 'true' NBL state, there remains an inadequate experimental database for quantifying constants associated with the Rossby-number similarity concept. Although it remains a controversial issue, it has been proposed that large-eddy simulation (LES) is an alternative to physical experimentation for obtaining basic atmospherc 'data'. The objective of the study reported here is to investigate Rossby-number similarity in the NBL using LES. Previous studies have not addressed Rossby-number similarity explicitly, although they made use of it in the interpretation of their results. The intent is to calculate several sets of NBL solutions that are ambiguous relative to the their respective Rossby numbers and compare the results for similarity, or the lack of it. 14 refs., 1 fig.

  18. Revisiting the Rossby Haurwitz wave test case with contour advection

    NASA Astrophysics Data System (ADS)

    Smith, Robert K.; Dritschel, David G.

    2006-09-01

    This paper re-examines a basic test case used for spherical shallow-water numerical models, and underscores the need for accurate, high resolution models of atmospheric and ocean dynamics. The Rossby-Haurwitz test case, first proposed by Williamson et al. [D.L. Williamson, J.B. Drake, J.J. Hack, R. Jakob, P.N. Swarztrauber, A standard test set for numerical approximations to the shallow-water equations on the sphere, J. Comput. Phys. (1992) 221-224], has been examined using a wide variety of shallow-water models in previous papers. Here, two contour-advective semi-Lagrangian (CASL) models are considered, and results are compared with previous test results. We go further by modifying this test case in a simple way to initiate a rapid breakdown of the basic wave state. This breakdown is accompanied by the formation of sharp potential vorticity gradients (fronts), placing far greater demands on the numerics than the original test case does. We also go further by examining other dynamical fields besides the height and potential vorticity, to assess how well the models deal with gravity waves. Such waves are sensitive to the presence or not of sharp potential vorticity gradients, as well as to numerical parameter settings. In particular, large time steps (convenient for semi-Lagrangian schemes) can seriously affect gravity waves but can also have an adverse impact on the primary fields of height and velocity. These problems are exacerbated by a poor resolution of potential vorticity gradients.

  19. Extratropical anticyclonic Rossby wave breaking and Indian summer monsoon failure

    NASA Astrophysics Data System (ADS)

    Samanta, Dhrubajyoti; Dash, M. K.; Goswami, B. N.; Pandey, P. C.

    2016-03-01

    Interactions between midlatitude disturbances and the monsoonal circulation are significant for the Indian summer monsoon (ISM) rainfall. This paper presents examples of monsoon-midlatitude linkage through anticyclonic Rossby wave breaking (RWB) over West Asia during June, July and August of the years 1998-2010. RWB events over West Asia are identified by the inversion of the potential vorticity air mass at three different isentropic levels (340, 350, and 360 K) using daily NCEP-NCAR reanalysis. It is observed that RWB took place over West Asia before/during breaks in the ISM. Further, these events occur on the anticyclonic shear side of the subtropical jet, where the gradient of the zonal wind is found to be high. RWB is responsible for the southward movement of high potential vorticity air from the westerly jet, leading to the formation of a blocking high over the Arabian region. In turn, this blocking high advects and causes the descent of upper tropospheric cold and dry air towards Central India. Such an air mass with low moist static energy inhibits deep monsoonal convection and thereby leads to a dry spell. In fact, we find that RWB induced blocking over West Asia to be one of the major causes of dry spell/break episodes in ISM. Additionally, the presence of cold air over Central India reduces the north-south thermal contrast over the monsoon region thereby modifying the local Hadley circulation over the region.

  20. Aspect ratio effects on revolving wings with Rossby number consideration.

    PubMed

    Lee, Y J; Lua, K B; Lim, T T

    2016-01-01

    Numerical simulations have been conducted to investigate the effect of aspect ratio (AR) on the mean lift generation of a revolving flat rectangular wing. The purpose of the study is to address some discrepancies reported in the literature regarding the influence of AR on mean lift coefficient. Here, we consider a range of AR from 1 to 10 and Rossby number (Ro) from 0.58 to 7.57, and our results show that different degrees of coupling between AR and Ro yield different trends of a mean lift coefficient with respect to increasing AR. The choice of reference velocity for the normalisation of mean lift forces also has a significant effect on the perceived AR effect. By isolating the effect of Ro, we found that higher AR produces higher mean lift coefficient until it plateaus at a sufficiently high AR. This finding is consistent with conventional fixed wing aerodynamics. Additionally, our results show that increasing AR reduces the three-dimensional wing tip effect and is beneficial to mean lift generation while higher Ro increases leading-edge vortex instability, which is detrimental to mean lift generation. Therefore, mean lift generation on revolving wings is dictated by the competition between these two factors, which represent two fundamentally independent phenomena. PMID:27608653

  1. Transiting exoplanets from the CoRoT space mission⋆. XXVIII. CoRoT-33b, an object in the brown dwarf desert with 2:3 commensurability with its host star

    NASA Astrophysics Data System (ADS)

    Csizmadia, Sz.; Hatzes, A.; Gandolfi, D.; Deleuil, M.; Bouchy, F.; Fridlund, M.; Szabados, L.; Parviainen, H.; Cabrera, J.; Aigrain, S.; Alonso, R.; Almenara, J.-M.; Baglin, A.; Bordé, P.; Bonomo, A. S.; Deeg, H. J.; Díaz, R. F.; Erikson, A.; Ferraz-Mello, S.; Tadeu dos Santos, M.; Guenther, E. W.; Guillot, T.; Grziwa, S.; Hébrard, G.; Klagyivik, P.; Ollivier, M.; Pätzold, M.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Mazeh, T.; Wuchterl, G.; Carpano, S.; Ofir, A.

    2015-12-01

    We report the detection of a rare transiting brown dwarf with a mass of 59 MJup and radius of 1.1 RJup around the metal-rich, [Fe/H] = +0.44, G9V star CoRoT-33. The orbit is eccentric (e = 0.07) with a period of 5.82 d. The companion, CoRoT-33b, is thus a new member in the so-called brown dwarf desert. The orbital period is within 3% to a 3:2 resonance with the rotational period of the star. CoRoT-33b may be an important test case for tidal evolution studies. The true frequency of brown dwarfs close to their host stars (P< 10 d) is estimated to be approximately 0.2% which is about six times smaller than the frequency of hot Jupiters in the same period range. We suspect that the frequency of brown dwarfs declines faster with decreasing period than that of giant planets. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Based on observations made with HARPS (High Accuracy Radial velocity Planet Searcher) spectrograph on the 3.6-m European Organisation for Astronomical Research in the Southern Hemisphere telescope at La Silla Observatory, Chile (ESO program 188.C-0779).Based on observations obtained with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, in time allocated by the Spanish Time Allocation Committee (CAT).

  2. Decrease of the Atmospheric Co-Rotation with Height

    ERIC Educational Resources Information Center

    Membrado, M.; Pacheco, A. F.

    2010-01-01

    Considering our atmosphere as a steady viscous gaseous envelope that co-rotates with the Earth, we obtain a solution for the form in which this induced rotational effect decreases as a function of the distances to the centre of the Earth and to the rotation axis. (Contains 1 figure.)

  3. Asteroseismology of OB stars with CoRoT

    NASA Astrophysics Data System (ADS)

    Degroote, P.; Aerts, C.; Samadi, R.; Miglio, A.; Briquet, M.; Auvergne, M.; Baglin, A.; Baudin, F.; Catala, C.; Michel, E.

    2010-12-01

    The CoRoT satellite is revolutionizing the photometric study of massive O-type and B-type stars. During its long runs, CoRoT observed the entire main sequence B star domain, from typical hot β Cep stars, via cooler hybrid p- and g-mode pulsators to the SPB stars near the edge of the instability strip. CoRoT lowers the sensitivity barrier from the typical mmag-precision reached from the ground, to the μmag-level reached from space. Within the wealth of detected and identified pulsation modes, relations have been found in the form of multiplets, combination of frequencies, and frequency- and period spacings. This wealth of observational evidence is finally providing strong constraints to test current models of the internal structure and pulsations of hot stars. Aside from the expected opacity driven modes with infinite lifetime, other unexpected types of variability are detected in massive stars, such as modes of stochastic nature. The simultaneous observation of all these light curve characteristics implies a challenge for both observational asteroseismology and stellar modelling. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.

  4. Can a minimalist model of wind forced baroclinic Rossby waves produce reasonable results?

    NASA Astrophysics Data System (ADS)

    Watanabe, Wandrey B.; Polito, Paulo S.; da Silveira, Ilson C. A.

    2016-04-01

    The linear theory predicts that Rossby waves are the large scale mechanism of adjustment to perturbations of the geophysical fluid. Satellite measurements of sea level anomaly (SLA) provided sturdy evidence of the existence of these waves. Recent studies suggest that the variability in the altimeter records is mostly due to mesoscale nonlinear eddies and challenges the original interpretation of westward propagating features as Rossby waves. The objective of this work is to test whether a classic linear dynamic model is a reasonable explanation for the observed SLA. A linear-reduced gravity non-dispersive Rossby wave model is used to estimate the SLA forced by direct and remote wind stress. Correlations between model results and observations are up to 0.88. The best agreement is in the tropical region of all ocean basins. These correlations decrease towards insignificance in mid-latitudes. The relative contributions of eastern boundary (remote) forcing and local wind forcing in the generation of Rossby waves are also estimated and suggest that the main wave forming mechanism is the remote forcing. Results suggest that linear long baroclinic Rossby wave dynamics explain a significant part of the SLA annual variability at least in the tropical oceans.

  5. The Superposition of Eastward and Westward Rossby Waves in Response to Localized Forcing

    NASA Astrophysics Data System (ADS)

    Shaman, J. L.; Tziperman, E.

    2015-12-01

    Rossby waves are a principal form of atmospheric communication between disparate parts of the climate system. These planetary waves are typically excited by diabatic or orographic forcing and can be subject to considerable downstream modification. Due to differences in wave properties, including vertical structure, phase speed and group velocity, Rossby waves exhibit a wide range of behaviors. Here we demonstrate the combined effects of eastward propagating stationary barotropic Rossby waves and westward propagating very low zonal wavenumber stationary barotropic Rossby waves on the atmospheric response to wintertime El Niño convective forcing over the tropical Pacific. Experiments are conducted using the Community Atmospheric Model 4.0 in which both diabatic forcing over the Pacific and localized relaxation outside the forcing region are applied. The localized relaxation is used to dampen Rossby wave propagation to either the west or east of the forcing region and isolate the alternate direction signal. Wave responses match theoretical expectations and clarify that observed downstream stationary responses to diabatic forcing result from the superposition of planetary wave signals emanating in alternate directions.

  6. Reflection of annual Rossby waves at the maritime western boundary of the tropical Pacific

    NASA Technical Reports Server (NTRS)

    White, Warren B.; Graham, Nicholas; Tai, C.-K.

    1990-01-01

    Results are presented of an examination of altimetric sea level time series from the first 17 months of the Geosat Geodetic Mission. The examination provides the first direct evidence of the Rossby wave reflection process operating in both hemispheres at the maritime western boundary of the tropical Pacific, in regard to annual Rossby activity. It is demonstrated that the Philippines in the Northern Hemisphere and the Solomon, the Bismarck, and the New Guinea islands in the Southern Hemisphere reflected the incident baroclinic Rossby wave activity of the one-year period, generating equatorial Kelvin wave activity that emanated from the maritime western boundary of the tropical Pacific, conducting the annual baroclinic signal along the equator into the eastern equatorial Pacific.

  7. The Mass of CoRoT-7b

    NASA Astrophysics Data System (ADS)

    Hatzes, Artie P.; Fridlund, Malcolm; Nachmani, Gil; Mazeh, Tsevi; Valencia, Diana; Hébrard, Guillaume; Carone, Ludmila; Pätzold, Martin; Udry, Stephane; Bouchy, Francois; Deleuil, Magali; Moutou, Claire; Barge, Pierre; Bordé, Pascal; Deeg, Hans; Tingley, Brandon; Dvorak, Rudolf; Gandolfi, Davide; Ferraz-Mello, Sylvio; Wuchterl, Günther; Guenther, Eike; Guillot, Tristan; Rauer, Heike; Erikson, Anders; Cabrera, Juan; Csizmadia, Szilard; Léger, Alain; Lammer, Helmut; Weingrill, Jörg; Queloz, Didier; Alonso, Roi; Rouan, Daniel; Schneider, Jean

    2011-12-01

    The mass of CoRoT-7b, the first transiting super-Earth exoplanet, is still a subject of debate. A wide range of masses have been reported in the literature ranging from as high as 8 M ⊕ to as low as 2.3 M ⊕. This range in mass is largely due to the activity level of the star that contributes a significant amount of radial velocity (RV) "jitter" and how the various methods correct this jitter. Although most mass determinations give a density consistent with a rocky planet, the lower value permits a bulk composition that can be up to 50% water. We present an analysis of the CoRoT-7b RV measurements that uses very few and simple assumptions in treating the activity signal. By analyzing those RV data for which multiple measurements were made in a given night, we remove the activity related RV contribution without any a priori model. We argue that the contribution of activity to the final RV curve is negligible and that the K-amplitude due to the planet is well constrained. This yields a mass of 7.42 ± 1.21 M ⊕ and a mean density of ρ = 10.4 ± 1.8 gm cm-3. CoRoT-7b is similar in mass and radius to the second rocky planet to be discovered, Kepler-10b, and within the errors they have identical bulk densities—they are virtual twins. These bulk densities lie close to the density-radius relationship for terrestrial planets similar to what is seen for Mercury. CoRoT-7b and Kepler-10b may have an internal structure more like Mercury than the Earth.

  8. Energetic particle acceleration at corotating interaction regions: Ulysses results

    SciTech Connect

    Desai, M.I.; Marsden, R.G.; Sanderson, T.R.; Gosling, J.T.

    1997-07-01

    We present here statistical properties of energetic ions (tilde 1 MeV) accelerated by corotating interaction regions observed at the Ulysses spacecraft. We have correlated the tilde 1 MeV proton intensity measured near the trailing edges of the interaction regions with their compression ratio. We interpret our results in terms of the plasma conditions experienced at Ulysses and identify a likely source of the low energy seed particles accelerated at the interaction regions.

  9. CoRoT space photometry of seven Cepheids

    NASA Astrophysics Data System (ADS)

    Poretti, E.; Le Borgne, J. F.; Rainer, M.; Baglin, A.; Benkő, J. M.; Debosscher, J.; Weiss, W. W.

    2015-11-01

    A few Galactic classical Cepheids were observed in the programmes of space missions as Coriolis, MOST, and Kepler. An appealing opportunity was to detect additional non-radial modes, thus opening the possibility to perform asteroseismic studies and making the pulsational content of Galactic Cepheids more similar to that of Magellanic Clouds ones. However, only hints of cycle-to-cycle variations were found, without any strict periodicity. In this context the potential of the CoRoT exoplanetary data base was not fully exploited despite the wide area covered on the Galactic plane. Therefore, we investigated all the candidate Cepheids pointed out by the automatic classification of the CoRoT curves. At the end, we could identify seven bona fide Cepheids. The light curves were investigated to remove some instrumental effects. The frequency analysis was particularly delicate since these small effects can be enhanced by the large amplitude, resulting in the presence of significant, but spurious, peaks in the power spectrum. Indeed, the careful evaluation of a very attracting peak in the spectra of CoRoT 0102618121 allowed us to certify its spurious origin. Once that the instrumental effects were properly removed, no additional mode was detected. On the other hand, cycle-to-cycle variations of the Fourier parameters were observed, but very small and always within ±3σ. Among the seven Cepheids, there are two Pop. I first-overtone pulsators, four Pop. I fundamental mode pulsators, and one Pop. II star. The CoRoT colours allowed us to measure that times of maximum brightness occur a little earlier (about 0.01 period) at short wavelengths than at long ones.

  10. THE MASS OF CoRoT-7b

    SciTech Connect

    Hatzes, Artie P.; Wuchterl, Guenther; Fridlund, Malcolm; Gandolfi, Davide; Nachmani, Gil; Mazeh, Tsevi; Valencia, Diana; Hebrard, Guillaume; Borde, Pascal; Carone, Ludmila; Paetzold, Martin; Udry, Stephane; Bouchy, Francois; Deleuil, Magali; Moutou, Claire; Barge, Pierre; Deeg, Hans; Tingley, Brandon; Dvorak, Rudolf; Ferraz-Mello, Sylvio E-mail: malcolm.fridlund@esa.int; and others

    2011-12-10

    The mass of CoRoT-7b, the first transiting super-Earth exoplanet, is still a subject of debate. A wide range of masses have been reported in the literature ranging from as high as 8 M{sub Circled-Plus} to as low as 2.3 M{sub Circled-Plus }. This range in mass is largely due to the activity level of the star that contributes a significant amount of radial velocity (RV) 'jitter' and how the various methods correct this jitter. Although most mass determinations give a density consistent with a rocky planet, the lower value permits a bulk composition that can be up to 50% water. We present an analysis of the CoRoT-7b RV measurements that uses very few and simple assumptions in treating the activity signal. By analyzing those RV data for which multiple measurements were made in a given night, we remove the activity related RV contribution without any a priori model. We argue that the contribution of activity to the final RV curve is negligible and that the K-amplitude due to the planet is well constrained. This yields a mass of 7.42 {+-} 1.21 M{sub Circled-Plus} and a mean density of {rho} = 10.4 {+-} 1.8 gm cm{sup -3}. CoRoT-7b is similar in mass and radius to the second rocky planet to be discovered, Kepler-10b, and within the errors they have identical bulk densities-they are virtual twins. These bulk densities lie close to the density-radius relationship for terrestrial planets similar to what is seen for Mercury. CoRoT-7b and Kepler-10b may have an internal structure more like Mercury than the Earth.

  11. Testing a Method of Detecting a Magnetic Field of Transiting Hot-Jupiter CoRot-1b

    NASA Astrophysics Data System (ADS)

    Biddle, Lauren I.; Turner, J.; Pearson, K.; Teske, J.

    2013-06-01

    In October of 2011 and December of 2012, exoplanet CoRot-1b was observed on the Steward Observatory 61” Kuiper Telescope using the Bessel-U filter to detect a possible magnetic field. In addition, the primary transit of CoRoT-1b was observed January 29, 2012 and February 2, 2012 using the medium resolution spectrograph on the 6.5 meter MMT Observatory. It is suggested by Vidotto et. al. (2011), that it is possible to detect a magnetic field of a transiting exoplanet in the near-UV photometric band by comparing asymmetry between the ingress and egress of the light curve. This effect is believed to be caused by a bow shock being formed in front of the planet as it transverses through the coronal plasma of its host star. CoRot-1b is a candidate for demonstrating this effect. We do not observe an early ingress in our near-UV broad-band light curves from the 61" Kuiper Telescope. We find an unexpected upper limit of 0.087-1.4 Gauss for the magnetic field strength of CoRoT-1b. This result is consistent with the near-UV observations by Turner et al. 2013 of another exoplanet predicted to show this effect, TrES-3b. It was suggested Vidotto et al 2011 and the finding of Turner et al. 2013 that an early near-UV might only happen at certain spectral resonance lines. Our observations from the MMT observatory hope to shed light on this possibly. Our spectral observations can constrain the composition of a possible bowshock and also investigate potential molecular features in the atmosphere of CoRoT-1b. To find the best fit to the light curves we used a modeling package called EXOMOP that uses the analytic equations of Mandel & Agol (2002) to generate a model transit, the Levenberg-Marquardt non-linear least squares minimization algorithm to find the best fit, the bootstrap Monte Carlo technique to calculate robust errors of the fitted parameters, and the residual permutation “rosary bead” method to access the importance of red noise. Several other parameters to confirm

  12. Corotating pressure waves without streams in the solar wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1983-01-01

    Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the Sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect; it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the Sun.

  13. First imaging of corotating interaction regions using the STEREO spacecraft

    NASA Astrophysics Data System (ADS)

    Rouillard, A. P.; Davies, J. A.; Forsyth, R. J.; Rees, A.; Davis, C. J.; Harrison, R. A.; Lockwood, M.; Bewsher, D.; Crothers, S. R.; Eyles, C. J.; Hapgood, M.; Perry, C. H.

    2008-05-01

    Plasma parcels are observed propagating from the Sun out to the large coronal heights monitored by the Heliospheric Imagers (HI) instruments onboard the NASA STEREO spacecraft during September 2007. The source region of these out-flowing parcels is found to corotate with the Sun and to be rooted near the western boundary of an equatorial coronal hole. These plasma enhancements evolve during their propagation through the HI cameras' fields of view and only becoming fully developed in the outer camera field of view. We provide evidence that HI is observing the formation of a Corotating Interaction Region (CIR) where fast solar wind from the equatorial coronal hole is interacting with the slow solar wind of the streamer belt located on the western edge of that coronal hole. A dense plasma parcel is also observed near the footpoint of the observed CIR at a distance less than 0.1AU from the Sun where fast wind would have not had time to catch up slow wind. We suggest that this low-lying plasma enhancement is a plasma parcel which has been disconnected from a helmet streamer and subsequently becomes embedded inside the corotating interaction region.

  14. Reflection of interannual Rossby waves at the maritime western boundary of the tropical Pacific

    NASA Astrophysics Data System (ADS)

    White, Warren B.; Tai, Chang-Kou

    1992-09-01

    The reflection of interannual Rossby waves over a 2.7-year period (i.e., November 1986 to August 1989) is examined in the western tropical Pacific utilizing altimetric sea level observations from the Geosat Exact Repeat Mission. In 1987 this reflection process generates upwelling Kelvin waves that tended to limit the growth of the 1986-1987 El Niño in the eastern equatorial Pacific. Two-dimensional autocorrelation and spectral analyses verify the existence of westward traveling Rossby waves in both the equatorial and off-equatorial domains, and eastward propagating Kelvin waves in the equatorial domain. Extended empirical orthogonal function (EEOF) analysis characterizes the time-space evolutionary behavior of the Rossby wave reflection process, extending from the El Niño in 1986-1987 toward the anti-El Niño in 1988-1989. Both the Philippines Archipelago in the northern hemisphere and the Solomon Archipelago/Bismarck Archipelago/New Guinea complex in the southern hemisphere appear to reflect incident Rossby waves, with maximum amplitude near 8°N and 8°S, generating Kelvin waves in the equatorial wave guide that conduct the anomalous signal eastward along the equator. This apparent reflection process is examined in terms of the linear theory, with sea level phase information in the northern hemisphere at the western boundary (130°W) expanded in terms of the Kelvin and symmetric Rossby meridional wave modes. These modes are formed as weighted sums of parabolic cylinder functions. This procedure, operating under the constraint that the reflection process occurred according to linear theory, determines the percent contribution that each incident Rossby wave mode amplitude has upon the amplitude of the reflected Kelvin wave. This percentage changed little over the evolution of the EEOF pattern. The amplitude of the first-mode Rossby wave (i.e., mode 2) accounts for most of the Kelvin wave amplitude (i.e., 70-80%), with the higher-mode Rossby wave amplitudes (i

  15. Planetary transit candidates in the CoRoT LRa01 field

    NASA Astrophysics Data System (ADS)

    Carone, L.; Gandolfi, D.; Cabrera, J.; Hatzes, A. P.; Deeg, H. J.; Csizmadia, Sz.; Pätzold, M.; Weingrill, J.; Aigrain, S.; Alonso, R.; Alapini, A.; Almenara, J.-M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Bruntt, H.; Carpano, S.; Cochran, W. D.; Deleuil, M.; Díaz, R. F.; Dreizler, S.; Dvorak, R.; Eislöffel, J.; Eigmüller, P.; Endl, M.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gazzano, J.-C.; Gibson, N.; Gillon, M.; Gondoin, P.; Grziwa, S.; Günther, E. W.; Guillot, T.; Hartmann, M.; Havel, M.; Hébrard, G.; Jorda, L.; Kabath, P.; Léger, A.; Llebaria, A.; Lammer, H.; Lovis, C.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.; Nortmann, L.; Ofir, A.; Ollivier, M.; Parviainen, H.; Pepe, F.; Pont, F.; Queloz, D.; Rabus, M.; Rauer, H.; Régulo, C.; Renner, S.; de La Reza, R.; Rouan, D.; Santerne, A.; Samuel, B.; Schneider, J.; Shporer, A.; Stecklum, B.; Tal-Or, L.; Tingley, B.; Udry, S.; Wuchterl, G.

    2012-02-01

    Context. CoRoT is a pioneering space mission whose primary goals are stellar seismology and extrasolar planets search. Its surveys of large stellar fields generate numerous planetary candidates whose lightcurves have transit-like features. An extensive analytical and observational follow-up effort is undertaken to classify these candidates. Aims: We present the list of planetary transit candidates from the CoRoT LRa01 star field in the Monoceros constellation toward the Galactic anti-center direction. The CoRoT observations of LRa01 lasted from 24 October 2007 to 3 March 2008. Methods: We acquired and analyzed 7470 chromatic and 3938 monochromatic lightcurves. Instrumental noise and stellar variability were treated with several filtering tools by different teams from the CoRoT community. Different transit search algorithms were applied to the lightcurves. Results: Fifty-one stars were classified as planetary transit candidates in LRa01. Thirty-seven (i.e., 73% of all candidates) are "good" planetary candidates based on photometric analysis only. Thirty-two (i.e., 87% of the "good" candidates) have been followed-up. At the time of writing twenty-two cases were solved and five planets were discovered: three transiting hot-Jupiters (CoRoT-5b, CoRoT-12b, and CoRoT-21b), the first terrestrial transiting planet (CoRoT-7b), and another planet in the same system (CoRoT-7c, detected by radial velocity survey only). Evidence of another non-transiting planet in the CoRoT-7 system, namely CoRoT-7d, was recently found as well. The CoRoT space mission, launched on December 27, 2006, has been developed and is operated by CNES, with contributions of Austria, Belgium, Brazil, ESA (RSSD and Science Program), Germany and Spain.

  16. Resonance

    NASA Astrophysics Data System (ADS)

    Perozzi, E.; Murdin, P.

    2000-11-01

    A resonance in CELESTIAL MECHANICS occurs when some of the quantities characterizing the motion of two or more celestial bodies can be considered as commensurable, i.e. their ratio is close to an integer fraction. In a simplified form, this can be expressed as ...

  17. Rossby wave radiation by an eddy on a beta-plane: Experiments with laboratory altimetry

    SciTech Connect

    Zhang, Y.; Afanasyev, Y. D.

    2015-07-15

    Results from the laboratory experiments on the evolution of vortices (eddies) generated in a rotating tank with topographic β-effect are presented. The focus of the experiments is on the far-field flow which contains Rossby waves emitted by travelling vortices. The surface elevation and velocity fields are measured by the altimetric imaging velocimetry. The experiments are supplemented by shallow water numerical simulations as well as a linear theory which describes the Rossby wave radiation by travelling vortices. The cyclonic vortices observed in the experiments travel to the northwest and continuously radiate Rossby waves. Measurements show that initially axisymmetric vortices develop a dipolar component which enables them to perform translational motion. A pattern of alternating zonal jets to the west of the vortex is created by Rossby waves with approximately zonal crests. Energy spectra of the flows in the wavenumber space indicate that a wavenumber similar to that introduced by Rhines for turbulent flows on the β-plane can be introduced here. The wavenumber is based on the translational speed of a vortex rather than on the root-mean-square velocity of a turbulent flow. The comparison between the experiments and numerical simulations demonstrates that evolving vortices also emit inertial waves. While these essentially three-dimensional non-hydrostatic waves can be observed in the altimetric data, they are not accounted for in the shallow water simulations.

  18. Reflection of annual Rossby waves at the maritime western boundary of the tropical Pacific

    NASA Astrophysics Data System (ADS)

    White, Warren B.; Graham, Nicholas; Tai, C.-K.

    1990-03-01

    In this study the examination of altimetric sea level time series from the first 17 months of the Geosat Geodetic Mission provides the first evidence of the Rossby wave reflection process operating at the maritime western boundary of the tropical Pacific in both the northern and southern hemispheres. In an earlier study, Tai et al. (1989) analyzed altimetric sea level time series derived from crossover differences during the first 17 months of the Geosat Geodetic Mission from April 1985 to September 1986, finding statistically significant agreement with in situ measurements of sea level differences (i.e., island sea level and relative dynamic height), In the present study, two-dimensional spectral analysis verified the existence of both off-equatorial baroclinic Rossby wave activity and equatorial baroclinic Kelvin wave activity in the altimetric sea level data set, establishing also that the annual cycle dominated the variability over this 17-month period. Next, extended empirical orthogonal function analysis (Graham et al., 1987) determined the evolutionary behavior of the readjustment process that occurred in the sea surface topography on the annual cycle over this 17-month period. Both the Philippines archipelago in the northern hemisphere and the Solomon archipelago-Bismarck archipelago-New Guinea complex in the southern hemisphere were found to reflect incident baroclinic Rossby wave activity of 1-year period, particularly manifested in the October-April transition, generating equatorial Kelvin wave activity that conducted the annual signal along the equatorial waveguide into the eastern equatorial Pacific. At the eastern boundary of South America, reflection of the incident equatorial Kelvin wave activity was associated with coastal Kelvin wave activity and equatorial-trapped Rossby wave activity in the equatorial waveguide, the latter propagating back to the west. However, the equatorial-trapped Rossby wave activity thus generated was not observed to

  19. Testing a Method of Detecting a Magnetic Field of Transiting Hot-Jupiter CoRot-1b

    NASA Astrophysics Data System (ADS)

    Biddle, Lauren; Turner, J.; Pearson, K.; Teske, J.

    2013-10-01

    In October of 2011 and December of 2012, exoplanet CoRot-1b was observed on the Steward Observatory 1.55m Kuiper Telescope using the Bessel-U filter to detect a possible magnetic field. It is suggested by Vidotto et. al. (2011), that it is possible to detect a magnetic field of a transiting exoplanet in the near-UV photometric band by comparing asymmetry between the ingress and egress of the light curve. This effect is believed to be caused by a bow shock being formed in front of a closely orbiting planet as it transverses through the coronal plasma of its host star. CoRot-1b is a candidate for demonstrating this effect. We do not observe an early ingress in our near-UV broad-band light curves from the 61" Kuiper Telescope. We find an unexpected upper limit of 0.087-1.4 Gauss for the magnetic field strength of CoRoT-1b. This result is consistent with the near-UV observations by Turner et al. (2013) of another exoplanet predicted to show this effect, TrES-3b. It was suggested by Vidotto et al. (2011) and the finding of Turner et al. (2013) that an early ingress observed in the near-UV might only happen at certain spectral resonance lines. To find the best fit to the light curves we used a modeling package called EXOMOP that uses the analytic equations of Mandel & Agol (2002) to generate a model transit, the Levenberg-Marquardt non-linear least squares minimization algorithm to find the best fit, the bootstrap Monte Carlo technique to calculate robust errors of the fitted parameters, and the residual permutation “rosary bead” method to access the importance of red noise. Several other parameters to confirm and amend can be derived from the light curve including the planet’s mass, radius, density, surface gravity, distance, and orbital inclination.

  20. Latitude dependence of co-rotating shock acceleration

    NASA Technical Reports Server (NTRS)

    Gold, R. E.; Lanzerotti, L. J.; Maclennan, C. G.; Krimigis, S. M.

    1985-01-01

    Energetic particle observations in the outer heliosphere (approx 12 A. U.) by the LECP instruments on the Voyager 1 and Voyager 2 spacecraft are discussed that show a definite latitude dependence of the number and intensity of particle enhancements produced by corotating interplanetary regions during an interval when no solar energetic particle events were observed. The particle enhancements are fewer in number and less intense at higher (approx 20 deg.) heliolatitudes. However, the similar spectral shapes of the accelerated particles at the two spacecraft indicate that the acceleration process is the same at the two latitudes, but less intense at the higher latitude.

  1. Departure from corotation of the Io plasma torus - Local plasma production

    NASA Technical Reports Server (NTRS)

    Pontius, D. H., Jr.; Hill, T. W.

    1982-01-01

    The departure of the Jovian magnetosphere from rigid corotation is adequately explained by outward plasma transport at distances where L is greater than approximately 10. The departure of 5% observed in the Io plasma torus, however, is too large to be accounted for simply by plasma transport. Local plasma production is proposed as the main factor determining the corotation lag in the torus. The outward pick-up current provided by ionization of neutral atoms is calculated and related to the current produced in the ionosphere by the corotation lag. This leads to an expression giving the corotation lag of the torus as a function of radial distance. Charge transfer is found to be an important process, allowing the majority of the torus mass to be ejected from the magnetosphere in a neutral state. Thus, the mass loading rate is found to be several times that inferred from examination of the corotation lag associated with outward plasma transport.

  2. Magnetic activity of the star Corot-Exo-2a

    NASA Astrophysics Data System (ADS)

    Savanov, I. S.

    2010-05-01

    Continuous photometric observations of the young active solar-type star Corot-Exo-2a using the “Corot” space telescope obtained over 142 days were used to analyze the star’s surface temperature inhomogeneities and to monitor their continuous evolution. This analysis was based on the iPH code, which reconstructs the distribution of temperature inhomogeneities on the surface of a star based on its light curve in a two-temperature approximation. We identified five time intervals in the positions of active areas, with corresponding flip-flop events, interpreted as activity periods. Their durations were between 55 and 15 days. The time scale for the active-longitude flip-flops of Corot-Exo-2a is a few tens of days, rather than years, as for other stars studied earlier. We detected motions of the active longitudes, possibly indicating differential rotation of the star. The phenomenon of flip-flops in the positions of active longitudes has a complex character. This is the first case apart fromthe Sun where we are able to follow the appearance and development of temperature inhomogeneities on a stellar surface in such detail. We determined typical timescales for variations of the activity parameter of the star in the ranges 17-20, 28-32, 33-38, and 51-55 days, which characterize changes of the brightness variation amplitude, the spotted surface area, positions of active areas, and brightness variations.

  3. DIRECT OBSERVATION OF A COROTATING INTERACTION REGION BY THREE SPACECRAFT

    SciTech Connect

    Tappin, S. J. Howard, T. A

    2009-09-10

    White-light observations of interplanetary disturbances have been dominated by interplanetary coronal mass ejections (ICMEs). This is because the other type of disturbance, the corotating interaction region (CIR), has proved difficult to detect using white-light imagers. Recently, a number of papers have appeared presenting CIR observations using the Solar Terrestrial Relations Observatory (STEREO) Heliospheric Imagers (HIs), but have mostly only focused on a single spacecraft and imager. In this paper, we present observations of a single CIR that was observed by all three current white-light heliospheric imagers (SMEI and both STEREO HIs), as well as the in situ instruments on both STEREO satellites and ACE. We begin with a discussion of the geometry of the CIR structure, and show how the apparent leading edge structure is expected to change as it corotates relative to the observer. We use these calculations to predict elongation-time profiles for CIRs of different speeds for each of the imagers, and also to predict the arrival times at the in situ instruments. We show that although all three measured different parts, they combine to produce a self-consistent picture of the CIR. Finally, we offer some thoughts on why CIRs have proved so difficult to detect in white-light heliospheric images.

  4. PRE-DISCOVERY OBSERVATIONS OF CoRoT-1b AND CoRoT-2b WITH THE BEST SURVEY

    SciTech Connect

    Rauer, H.; Erikson, A.; Kabath, P.; Hedelt, P.; Csizmadia, Sz.; Paris, P. v.; Renner, S.; Titz, R.; Voss, H.; Boer, M.; Tournois, G.; Carone, L.; Eigmueller, P.

    2010-01-15

    The Berlin Exoplanet Search Telescope (BEST) wide-angle telescope installed at the Observatoire de Haute-Provence and operated in remote control from Berlin by the Institut fuer Planetenforschung, DLR, has observed the CoRoT target fields prior to the mission. The resulting archive of stellar photometric light curves is used to search for deep transit events announced during CoRoT's alarm mode to aid in fast photometric confirmation of these events. The 'initial run' field of CoRoT (IRa01) was observed with BEST in 2006 November and December for 12 nights. The first 'long run' field (LRc01) was observed from 2005 June to September for 35 nights. After standard CCD data reduction, aperture photometry has been performed using the ISIS image subtraction method. About 30,000 light curves were obtained in each field. Transits of the first detected planets by the CoRoT mission, CoRoT-1b and CoRoT-2b, were found in archived data of the BEST survey and their light curves are presented here. Such detections provide useful information at the early stage of the organization of follow-up observations of satellite alarm-mode planet candidates. In addition, no period change was found over {approx}4 years between the first BEST observation and last available transit observations.

  5. The role of resonances in the evolution of galactic disks

    NASA Astrophysics Data System (ADS)

    Lepine, Jacques; Scarano, Sergio; Andrievsky, Sergei; de Barros, Douglas A.; Junqueira, Thiago C.

    2015-03-01

    Resonances play an important role in the evolution of the disks of spiral galaxies, and in particular in the chemical abundance evolution. The dominant effect is that of corotation; this effect can be even used as a tool to estimate the age of the present spiral arm pattern, which are usually found to be long-lived, contrary to a recent common belief. We investigated a sample of galaxies for which the corotation radius is known and for which there are available in the literature measurements of abundance gradients for Oxygen. A very good correlation is found between corotation radii and the radii at which there is a break in the slope of the gradients. The gradients are usually decreasing in the inner regions and become flat or rising at larger radii. In several galaxies, including the Milky Way, one observes not only a change in the slope of the abundance gradient, but also an abrupt step in metallicity, at corotation. This step is due to the fact that corotation separates the disk of a galaxy in two regions (inside corotation and outside corotation) which are isolated one from the other, so that the two sides evolve in an independent way. The barrier between the two regions is produced by the flow of gas in opposite directions in the two sides and by the ring-shaped void of gas observed at corotation. Besides this, an independent effect of corotation is a minimum of star formation associated with the minimum velocity at which the spiral arms (seen as potential wells) are fed with interstellar gas. Still another effect is the scattering of stars by the resonance, which causes their migration to different galactic radii. Other resonances, like 4:1, have properties almost opposite to corotation; they stimulate star-formation, and tend to gather the stars in the resonant orbit, instead of scattering them out, as shown by numerical simulations. Due to this property, one can see arms which have the shape of resonant stellar orbits, which depart from logarithmic spirals.

  6. Long-Range Radiation of Barotropic Rossby Waves from the Equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Farrar, J. T.; Durland, T.

    2014-12-01

    Analysis of sea-surface height (SSH) anomalies from satellite altimetry shows variability throughout the North Pacific that is coherent with Tropical Instability Waves. In the tropics (10N-20N) this variability has regular phase patterns that are consistent with barotropic Rossby waves having northward energy propagation (Farrar, J. Phys. Oceanogr., 2011). Further north, the phase patterns become confused and the variance decreases, but hot spots of coherent variability reemerge in the Gulf of Alaska and south of the Aleutian Islands. Ray-tracing calculations and comparisons with numerical simulations support the conclusion that this remote (and seemingly isolated) variability can indeed be attributed to barotropic Rossby waves generated near the equator and undergoing bathymetric refraction as they propagate northward.

  7. Rossby-Khantadze electromagnetic planetary vortical motions in the ionospheric E-layer

    NASA Astrophysics Data System (ADS)

    Kaladze, T. D.; Tsamalashvili, L. V.; Kahlon, L. Z.

    2011-12-01

    It is shown that in the earth's conductive ionospheric E-region, large-scale ultra low-frequency Rossby and Khantadze electromagnetic waves can propagate. Along with the prevalent effect of Hall conductivity for these waves, the latitudinal inhomogeneity of both the earth's angular velocity and the geomagnetic field becomes essential. Action of these effects leads to the coupled propagation of electromagnetic Rossby and Khantadze modes. Linear propagation properties of these waves are given in detail. It is shown that the waves lose the dispersing property for large values of wave numbers. Corresponding nonlinear solitary vortical structures are constructed. Conditions for such self-organization are given. It is shown that nonlinear large-scale vortices generate the stronger pulses of the geomagnetic field than the corresponding linear waves. Previous investigations are revised.

  8. The role of toroidal magnetic field on the Rossby wave instability

    NASA Astrophysics Data System (ADS)

    Gholipour, Mahmoud; Nejad-Asghar, Mohsen

    2015-05-01

    In the accretion discs, the toroidal magnetic fields and viscous stresses are directly connected to each other, because generation of the large-scale toroidal magnetic fields are produced by the magnetohydrodynamic (MHD) turbulence. Gholipour & Nejad-Asghar have recently shown that the effect of high turbulent viscosity on the Rossby wave instability (RWI) is important, while the effect of low turbulent viscosity can be ignored. In this paper, in addition of turbulent viscosity, we investigate the role of toroidal magnetic field on the non-axisymmetric RWI in the self-gravitating accretion discs. We use a numerical method to investigate stable and unstable modes. The results show that the perturbations of Rossby waves will be damped by both the viscosity and toroidal magnetic field, while the magnetic diffusivity acts vice versa. Also, occurrence of RWI depends on the turbulent magnetic Prandtl number (i.e. ratio of the turbulent viscosity to the turbulent magnetic diffusivity).

  9. (2+1)-dimensional dissipation nonlinear Schrödinger equation for envelope Rossby solitary waves and chirp effect

    NASA Astrophysics Data System (ADS)

    Jin-Yuan, Li; Nian-Qiao, Fang; Ji, Zhang; Yu-Long, Xue; Xue-Mu, Wang; Xiao-Bo, Yuan

    2016-04-01

    In the past few decades, the (1+1)-dimensional nonlinear Schrödinger (NLS) equation had been derived for envelope Rossby solitary waves in a line by employing the perturbation expansion method. But, with the development of theory, we note that the (1+1)-dimensional model cannot reflect the evolution of envelope Rossby solitary waves in a plane. In this paper, by constructing a new (2+1)-dimensional multiscale transform, we derive the (2+1)-dimensional dissipation nonlinear Schrödinger equation (DNLS) to describe envelope Rossby solitary waves under the influence of dissipation which propagate in a plane. Especially, the previous researches about envelope Rossby solitary waves were established in the zonal area and could not be applied directly to the spherical earth, while we adopt the plane polar coordinate and overcome the problem. By theoretical analyses, the conservation laws of (2+1)-dimensional envelope Rossby solitary waves as well as their variation under the influence of dissipation are studied. Finally, the one-soliton and two-soliton solutions of the (2+1)-dimensional NLS equation are obtained with the Hirota method. Based on these solutions, by virtue of the chirp concept from fiber soliton communication, the chirp effect of envelope Rossby solitary waves is discussed, and the related impact factors of the chirp effect are given. Project supported by the National Natural Science Foundation of China (Grant No. 41406018).

  10. Barotropic and baroclinic instability of Rossby waves on the infinite beta-plane

    NASA Astrophysics Data System (ADS)

    Anderson, Jeffrey L.

    The normal mode instability problem for a stationary Rossby wave of finite amplitude and arbitrary orientation in a two-level model with zonal mean shear in the vertical is examined on the infinite beta-plane using a Floquet technique. The results are compared to the instability of a finite amplitude stationary Rossby wave in a barotropic model. The instability of the barotropic model linearized about the upper level flow of the stationary two-level Rossby wave is also examined; forcing must be introduced to the barotropic equations in this case to balance the time tendency of the basic state. The instabilities of the three models are compared in an attempt to address two questions. First, are the barotropic instabilities related to any of the two-level model instabilities? Second, what are the consequences of introducing forcing in the stability problem? It is found that the barotropic models accurately reproduce those instabilities of the two-level model that have a nearly barotropic structure; these are not necessarily low-frequency instabilities. The introduction of forcing is found to have a significant impact on the barotropic instabilities. Special emphasis is placed on parameter ranges judged to be analogous to the mid-latitude atmosphere. Possible relevance of the results to geophysical flows and the instability problem on the sphere are discussed.

  11. Generalized Investigation of the Rotation-Activity Relation: Favoring Rotation Period instead of Rossby Number

    NASA Astrophysics Data System (ADS)

    Reiners, A.; Schüssler, M.; Passegger, V. M.

    2014-10-01

    Magnetic activity in Sun-like and low-mass stars causes X-ray coronal emission which is stronger for more rapidly rotating stars. This relation is often interpreted in terms of the Rossby number, i.e., the ratio of rotation period to convective overturn time. We reconsider this interpretation on the basis of the observed X-ray emission and rotation periods of 821 stars with masses below 1.4 M ⊙. A generalized analysis of the relation between X-ray luminosity normalized by bolometric luminosity, L X/L bol, and combinations of rotational period, P, and stellar radius, R, shows that the Rossby formulation does not provide the solution with minimal scatter. Instead, we find that the relation L X/L bolvpropP -2 R -4 optimally describes the non-saturated fraction of the stars. This relation is equivalent to L XvpropP -2, indicating that the rotation period alone determines the total X-ray emission. Since L X is directly related to the magnetic flux at the stellar surface, this means that the surface flux is determined solely by the star's rotation and is independent of other stellar parameters. While a formulation in terms of a Rossby number would be consistent with these results if the convective overturn time scales exactly as L_bol-1/2, our generalized approach emphasizes the need to test a broader range of mechanisms for dynamo action in cool stars.

  12. Suppression of Atlantic Tropical Cyclone Activity by Extratropical Rossby Wave Breaking

    NASA Astrophysics Data System (ADS)

    Zhang, G.; Wang, Z.

    2014-12-01

    With warm SST anomalies in the tropical Atlantic and cold SST anomalies in the East Pacific, the reduced Atlantic tropical cyclone activity from August to early September in 2013 was a surprise to the hurricane community. Our analyses suggest that the suppressed storm activity can be attributed to the frequent occurrence of dry air in the middle to upper troposphere along with strong vertical wind shear. Such unfavorable conditions are directly related to the equatorward propagation and breaking of midlatitude Rossby waves, which lead to the equatorward intrusions of cold and dry extratropical air. Further examination suggests the active anti-cyclonic Rossby wave breaking and frequent equatorward intrusions of extratropical air in August 2013 were associated with changes of the midlatitude jet stream (i.e., acceleration, eastward extension and greater strain rate). The EOF analysis of 200-hPa zonal wind identifies a recurrent mode of interannual variability over Atlantic, which is associated with the variations of the intensity and zonal extent of the mid-latitude jet. This mode is found significantly correlated to Atlantic hurricane frequency in August, with a coefficient higher than the Nino3.4 index and comparable to the (relative) SST of Major Development Region (MDR). Our analyses thus emphasize the extratropical impacts on Atlantic tropical cyclones via the Rossby wave breaking. This physical link is missing in most statistical and hybrid forecast schemes and may help explain the seasonal prediction bust in 2013.

  13. On the seasonal distribution on Rossby wave breaking and their impact on weather variables

    NASA Astrophysics Data System (ADS)

    Schneidereit, Andrea; Peters, Dieter

    2014-05-01

    Rossby wave breaking on tropopause level is determined by the objective method according to Gabriel and Peters (2007). This method assumes that during the irreversible meridional overturning of potential vorticity contours the meridional component of the wave activity flux reaches its maximum value. According to the background flow, two different types of anticyclonic and two different types of cyclonic Rossby wave breaking can be distinguished. Analyzing seasonal cycle of the re-analysis data of the ECMWF, ERA-Interim, showing that the mean distributions of RWB events result mainly from the winter. Evaluating the composite distribution of precipitation and wind, reveal all four types are related with a special precipitation distribution. On the example of poleward anticyclonic RWB events, RWB-P2, a region can be identified where also the generation of inertia-gravity waves is possible. This region is located on the exit part of the breaking induced jet streak. A GCM model study with zonal mean ozone and added zonally asymmetric ozone in stratosphere was performed. The induced radiative changes in the stratosphere are causing changes of the location of Rossby wave breaking events in the upper troposphere. This results from the changing background flow in the lower stratosphere, which induce more diffluence over the eastern North Atlantic. As a result, the distribution of RWB-P2 events is shifted significantly westwards.

  14. Inhomogeneous closure and statistical mechanics for Rossby wave turbulence over topography

    NASA Astrophysics Data System (ADS)

    Frederiksen, Jorgen S.; O'Kane, Terence J.

    2005-09-01

    The quasi-diagonal direct interaction approximation (QDIA) closure theory is formulated for the interaction of mean fields, Rossby waves and inhomogeneous turbulence over topography on a generalized beta-plane. An additional small term, corresponding to the solid-body rotation vorticity on the sphere, is included in the barotropic equation and it is shown that this results in a one-to-one correspondence between the dynamical equations, Rossby wave dispersion relations, nonlinear stability criteria and canonical equilibrium theory on the generalized beta-plane and on the sphere. The dynamics, kinetic energy spectra, mean field structures and mean streamfunction tendencies contributed by transient eddies are compared with the ensemble-averaged results from direct numerical simulations (DNS) at moderate resolution. A series of numerical experiments is performed to examine the generation of Rossby waves when eastward large-scale flows impinge on a conical mountain in the presence of moderate to strong two-dimensional turbulence. The ensemble predictability of northern hemisphere flows in 10-day forecasts is also examined on a generalized beta-plane. In all cases, the QDIA closure is found to be in very good agreement with the statistics of DNS except in situations of strong turbulence and weak mean fields where ensemble-averaged DNS fails to predict mean field amplitudes correctly owing to sampling problems even with as many as 1800 ensemble members.

  15. Observations of rossby wave propagation in the Northeast Atlantic with topex/poseidon altimetry

    NASA Astrophysics Data System (ADS)

    Cipollini, P.; Cromwell, D.; Quartly, G. D.

    1998-11-01

    A technique is described to observe Rossby waves in the oceans using altimeter data, which makes use of longitude/time diagrams of sea surface height anomalies at a given latitude, relying on the zonal propagation of those waves. By means of the Fast Fourier and Radon Transforms of the longitude/time diagrams it is possible to locate the spectral components corresponding to wave propagation and to give an approximate estimation of some of their characteristics such as their height and speed. The results obtained by using data from the TOPEX/POSEIDON radar altimeters in the Northeast Atlantic highlight a narrow `preferred' zonal band of propagation for Rossby waves around 33°-34° N. The speeds of the dominant signals at different latitudes have been computed both in Fourier space and in Radon space: they are in good agreement with the prediction of a revised theory of Rossby wave propagation, which has recently been introduced to explain the discrepancy between observed wave speeds and the speeds computed from the classical theory.

  16. Role of SST meridional structure in coupling the Kelvin and Rossby waves of the intraseasonal oscillation

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Huang, Gang; Yan, Mi

    2015-08-01

    The intraseasonal oscillation (ISO) is one of the most important modes of the tropical atmosphere, which influences global livelihood of hundreds of millions of people. The meridional structure of sea surface temperature (SST) has been found to be important for the ISO simulation in general circulation models (GCMs). Using a theoretical frictional skeleton model for the ISO, we investigate the effects of different SST structures on the ISO in this study. The model results show that the observed Madden-Julian oscillation (MJO), boreal summer ISO (BSISO) and quasi-biweekly oscillation can be simulated in this model with different SST structures. The Ekman pumping of the boundary layer associated with equatorially trapped SST favors the growth of eastward propagating Kelvin waves and prefers the fast eastward propagating signal. A broad SST provides a strong instability source for the Rossby waves, which will slow down the MJO. In the boreal summer, the high SST center in the off-equatorial region can trigger strong off-equatorial moisture pumping from the boundary layer, which enhances the Rossby waves and can simulate the northwest-southeast tilted rain band associated with the BSISO. When the Rossby component overwhelms the Kelvin component, the low-frequency westward component of the BSISO and the higher-frequency quasi-biweekly oscillation can be simulated.

  17. The CoRoT transit candidate catalog

    NASA Astrophysics Data System (ADS)

    Aigrain, S.; Deleuil, M.

    2013-09-01

    We present a full catalog of all the candidate transiting planets identified by the CoRoT space mission during its first 5 years of operations, including homogeneously derived transit parameters, validation diagnostics and a summary of the outcome of follow-up observations, where available.The catalog includes confirmed planets, clear false alarms (mainly blended or grazing eclipsing binaries), but also dozens of unconfirmed cases, where the follow-up was either inconclusive (hot stars, fast rotators) or incomplete (owing to limited telescope time and the relatively faint nature of the CoRoT targets). The catalog is intended primarily as a resource for the community, for example as a starting point for completeness and population studies. The candidate detection and selection processes have evolved significantly over the course of the mission. Several teams independently analyse the light curves from each observing run, searching for transits and providing ranked candidate lists, which are subsequently merged and ranked manually. This enables the use of some specialist methods, which are better suited to the detection of only certain types of transits, but makes it difficult to provide an overall assessment of the sensitivity of the mission to transits of different depths and periods. However, we note the transit search methods used by the different teams have gradually converged since launch, and there are now fewer teams actively involved in the transit search, with more overlap between the resulting candidate lists. For each CoRoT observing run, one team member coordinates the selection of candidates for followup, with input from the other team members. The set of criteria used to perform this selection have also evolved over the years, becoming more homogeneous. In particular, the light curve fitting tools used to produce the transit parameters and other diagnostics, which are included in the present catalog, are now routinely used to validate candidates and

  18. VizieR Online Data Catalog: CoRoT observation log (N2-4.4) (CoRoT 2016)

    NASA Astrophysics Data System (ADS)

    COROT Team

    2014-03-01

    CoRoT, a space astronomy mission, has measured photometric micro-variability of stars from minutes to months (up to 150 days) with a high duty cycle (more than 90%). The mission was led by CNES in association with four French laboratories and 7 participating countries and agencies (Austria, Belgium, Brazil, Germany, Spain, and the ESA Science Programme). The satellite was composed of a PROTEUS platform (the 3rd in the series) and a unique instrument: a stellar rapid photometer. It was launched on December 27th 2006 by a Soyuz Rocket, from Bakonour. The mission has lasted almost 6 years (the nominal 3-year duration and a 3-year extension) and has observed more than 160 000 stars. It stopped sending data on November 2nd 2012. Two regions of the sky were accessible for long period of time: circles of 10 degrees centered on the equator around alpha=06:50 and alpha=18:50. They were called the CoRoT eyes: the "anticenter" and the "center eye" (as they are approximately in these directions). Each pointing covers 1.4x2.8 square degrees within one of those CoRoT eyes. The original scientific objectives were focussed on the study of stellar pulsations (asteroseismology) to probe the internal structure of stars, and the detection of small exoplanets through their "transit" in front of their host star, and the measurement of their size. This lead to introduce two modes of observations, working simultaneously: - The "bright star" mode dedicated to very precise seismology of a small sample of bright and closeby stars - The "faint star" mode, observing a very large number of stars at the same time, to detect transits, which are rare events, as they imply the alignment of the star, the planet and the observer. The large amount of data gathered in this mode turned out to be extremely fruitful for many topics of stellar physics. Beyond these two initial objectives, CoRoT data revealed stellar variability associated with various other phenomena: granulation, rotational modulation by

  19. VizieR Online Data Catalog: CoRoT observation log (N2-4.4) (CoRoT 2016)

    NASA Astrophysics Data System (ADS)

    COROT Team

    2014-03-01

    CoRoT, a space astronomy mission, has measured photometric micro-variability of stars from minutes to months (up to 150 days) with a high duty cycle (more than 90%). The mission was led by CNES in association with four French laboratories and 7 participating countries and agencies (Austria, Belgium, Brazil, Germany, Spain, and the ESA Science Programme). The satellite was composed of a PROTEUS platform (the 3rd in the series) and a unique instrument: a stellar rapid photometer. It was launched on December 27th 2006 by a Soyuz Rocket, from Bakonour. The mission has lasted almost 6 years (the nominal 3-year duration and a 3-year extension) and has observed more than 160 000 stars. It stopped sending data on November 2nd 2012. Two regions of the sky were accessible for long period of time: circles of 10 degrees centered on the equator around alpha=06:50 and alpha=18:50. They were called the CoRoT eyes: the "anticenter" and the "center eye" (as they are approximately in these directions). Each pointing covers 1.4x2.8 square degrees within one of those CoRoT eyes. The original scientific objectives were focussed on the study of stellar pulsations (asteroseismology) to probe the internal structure of stars, and the detection of small exoplanets through their "transit” in front of their host star, and the measurement of their size. This lead to introduce two modes of observations, working simultaneously: - The “bright star” mode dedicated to very precise seismology of a small sample of bright and closeby stars - The “faint star” mode, observing a very large number of stars at the same time, to detect transits, which are rare events, as they imply the alignment of the star, the planet and the observer. The large amount of data gathered in this mode turned out to be extremely fruitful for many topics of stellar physics. Beyond these two initial objectives, CoRoT data revealed stellar variability associated

  20. The high-energy environment in the super-Earth system CoRoT-7

    NASA Astrophysics Data System (ADS)

    Poppenhaeger, K.; Czesla, S.; Schröter, S.; Lalitha, S.; Kashyap, V.; Schmitt, J. H. M. M.

    2012-05-01

    High-energy irradiation of exoplanets has been identified to be a key influence on the stability of these planets' atmospheres. So far, irradiation-driven mass-loss has been observed only in two Hot Jupiters, and the observational data remain even more sparse in the super-Earth regime. We present an investigation of the high-energy emission in the CoRoT-7 system, which hosts the first known transiting super-Earth. To characterize the high-energy XUV radiation field into which the rocky planets CoRoT-7b and CoRoT-7c are immersed, we analyzed a 25 ks XMM-Newton observation of the host star. Our analysis yields the first clear (3.5σ) X-ray detection of CoRoT-7. We determine a coronal temperature of ≈ 3 MK and an X-ray luminosity of 3 × 1028 erg s-1. The level of XUV irradiation on CoRoT-7b amounts to ≈37 000 erg cm-2 s-1. Current theories for planetary evaporation can only provide an order-of-magnitude estimate for the planetary mass loss; assuming that CoRoT-7b has formed as a rocky planet, we estimate that CoRoT-7b evaporates at a rate of about 1.3 × 1011 g s-1 and has lost ≈4-10 earth masses in total.

  1. GAUDI: A Preparatory Archive for the COROT Mission

    NASA Astrophysics Data System (ADS)

    Solano, E.; Catala, C.; Garrido, R.; Poretti, E.; Janot-Pacheco, E.; Gutiérrez, R.; González, R.; Mantegazza, L.; Neiner, C.; Fremat, Y.; Charpinet, S.; Weiss, W.; Amado, P. J.; Rainer, M.; Tsymbal, V.; Lyashko, D.; Ballereau, D.; Bouret, J. C.; Hua, T.; Katz, D.; Lignières, F.; Lüftinger, T.; Mittermayer, P.; Nesvacil, N.; Soubiran, C.; van't Veer-Menneret, C.; Goupil, M. J.; Costa, V.; Rolland, A.; Antonello, E.; Bossi, M.; Buzzoni, A.; Rodrigo, C.; Aerts, C.; Butler, C. J.; Guenther, E.; Hatzes, A.

    2005-01-01

    The GAUDI database (Ground-based Asteroseismology Uniform Database Interface) is a preparatory archive for the COROT (Convection, Rotation, and Planetary Transits) mission developed at the Laboratorio de Astrofísica Espacial y Física Fundamental (Laboratory for Space Astrophysics and Theoretical Physics, Spain). Its intention is to make the ground-based observations obtained in preparation of the asteroseismology program available in a simple and efficient way. It contains spectroscopic and photometric data together with inferred physical parameters for more than 1500 objects gathered since 1998 January 1998 in 6 years of observational campaigns. In this paper, the main functions and characteristics of the system are described. Based on observations collected at La Silla (ESO proposals 67.D-0169, 69.D-0166, and 70.D-0110), Telescopio Nazionale Galileo (proposal 6-20-068), Observatoire de Haute-Provence, the South African Astronomical Observatory, Tautenburg Observatory, and Sierra Nevada Observatory.

  2. Effects of corotating interaction regions on ULYSSES high energy particles

    SciTech Connect

    Droege, W.; Kunow, H.; Raviart, A.

    1995-09-01

    Since June 1992 the Kiel Electron Telescope on board ULYSSES measures variations of more than 10% in the fluxes of high energy H and He showing a periodicity of about 26 days in coincidence with the passage of corotating interaction regions. (CIR). At low energies MeV protons are accelerated at the shocks of the CIRs. These effects are observed up to high southern latitudes, where the signature of a CIR is no longer visible in plasma or magnetic field data. After passing over the south polar cap ULYSSES has now returned to the solar equator and climbs up to the north pole. In this paper we study the relative intensity variations with latitude and the latitude dependence at solar distances smaller than ever studied before.

  3. Transiting exoplanets from the CoRoT space mission. XXVI. CoRoT-24: a transiting multiplanet system

    NASA Astrophysics Data System (ADS)

    Alonso, R.; Moutou, C.; Endl, M.; Almenara, J.-M.; Guenther, E. W.; Deleuil, M.; Hatzes, A.; Aigrain, S.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Cavarroc, C.; Cabrera, J.; Carpano, S.; Csizmadia, Sz.; Cochran, W. D.; Deeg, H. J.; Díaz, R. F.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Fruth, T.; Gandolfi, D.; Gillon, M.; Grziwa, S.; Guillot, T.; Hébrard, G.; Jorda, L.; Léger, A.; Lammer, H.; Lovis, C.; MacQueen, P. J.; Mazeh, T.; Ofir, A.; Ollivier, M.; Pasternacki, T.; Pätzold, M.; Queloz, D.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Tadeu dos Santos, M.; Tingley, B.; Titz-Weider, R.; Weingrill, J.; Wuchterl, G.

    2014-07-01

    We present the discovery of a candidate multiply transiting system, the first one found in the CoRoT mission. Two transit-like features with periods of 5.11 and 11.76 d are detected in the CoRoT light curve around a main sequence K1V star of r = 15.1. If the features are due to transiting planets around the same star, these would correspond to objects of 3.7 ± 0.4 and 5.0 ± 0.5 R⊕ , respectively. Several radial velocities serve to provide an upper limit of 5.7 M⊕ for the 5.11 d signal and to tentatively measure a mass of 28+11-11 M⊕ for the object transiting with a 11.76 d period. These measurements imply low density objects, with a significant gaseous envelope. The detailed analysis of the photometric and spectroscopic data serves to estimate the probability that the observations are caused by transiting Neptune-sized planets as much as over 26 times higher than a blend scenario involving only one transiting planet and as much as over 900 times higher than a scenario involving two blends and no planets. The radial velocities show a long-term modulation that might be attributed to a 1.5 MJup planet orbiting at 1.8 AU from the host, but more data are required to determine the precise orbital parameters of this companion. The CoRoT space mission, launched on 27 December 2006, has been developed and is operated by the CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Program), Germany, and Spain. Some of the observations were made with the HARPS spectrograph at ESO La Silla Observatory (184.C-0639) and with the HIRES spectrograph at the Keck Telescope (N035Hr, N143Hr 260 and N095Hr). Partly based on observations obtained at ESO Paranal Observatory, Chile (086.C-0235(A) and B).Tables 2-4 and Fig. 12 are available in electronic form at http://www.aanda.org

  4. Expected Performance of the CoRoT Planet Search from Light Curve Beauty Contests

    NASA Astrophysics Data System (ADS)

    Moutou, C.; Aigrain, S.; Almenara, J.; Alonso, R.; Auvergne, M.; Barge, P.; Blouin, D.; Borde, P.; Cabrera, J.; Carone, L.; Cautain, R.; Deeg, H.; Erikson, A.; Fressin, F.; Guis, V.; Leger, A.; Guterman, P.; Irwin, M.; Kabath, P.; Lanza, A.; Maceroni, C.; Mazeh, T.; Ollivier, M.; Pont, F.; Paetzold, M.; Queloz, D.; Rauer, H.; Rouan, D.; Schneider, J.; Tamuz, O.; Voss, H.; Zucker, S.

    2007-07-01

    The CoRoT space mission, scheduled for launch in December 2006, has two primary science goals: asteroseismology and the detection of planetary transits, the latter being the subject of this contribution. Given its expected photometric performance and its 150 day observing window, CoRoT will detect planets with periods up to 75 days and radii down to 2 Earth radii. To prepare for the data analysis and evaluate the detection limits of the mission, a number of blind exercises to detect planets in simulated light curves have been carried out within the CoRoT exoplanet community, and their results to date are summarized here.

  5. WARM SPITZER PHOTOMETRY OF THE TRANSITING EXOPLANETS CoRoT-1 AND CoRoT-2 AT SECONDARY ECLIPSE

    SciTech Connect

    Deming, Drake; Knutson, Heather; Agol, Eric; Cowan, Nicolas B.; Desert, Jean-Michel; Charbonneau, David; Burrows, Adam; Fortney, Jonathan J.; Laughlin, Gregory; Langton, Jonathan; Showman, Adam P.; Lewis, Nikole K.

    2011-01-10

    We measure secondary eclipses of the hot giant exoplanets CoRoT-1 at 3.6 and 4.5 {mu}m, and CoRoT-2 at 3.6 {mu}m, both using Warm Spitzer. We find that the Warm Spitzer mission is working very well for exoplanet science. For consistency of our analysis we also re-analyze archival cryogenic Spitzer data for secondary eclipses of CoRoT-2 at 4.5 and 8 {mu}m. We compare the total data for both planets, including optical eclipse measurements by the CoRoT mission, and ground-based eclipse measurements at 2 {mu}m, to existing models. Both planets exhibit stronger eclipses at 4.5 than at 3.6 {mu}m, which is often indicative of an atmospheric temperature inversion. The spectrum of CoRoT-1 is best reproduced by a 2460 K blackbody, due either to a high altitude layer that strongly absorbs stellar irradiance, or an isothermal region in the planetary atmosphere. The spectrum of CoRoT-2 is unusual because the 8 {mu}m contrast is anomalously low. Non-inverted atmospheres could potentially produce the CoRoT-2 spectrum if the planet exhibits line emission from CO at 4.5 {mu}m, caused by tidal-induced mass loss. However, the viability of that hypothesis is questionable because the emitting region cannot be more than about 30% larger than the planet's transit radius, based on the ingress and egress times at eclipse. An alternative possibility to account for the spectrum of CoRoT-2 is an additional opacity source that acts strongly at wavelengths less than 5 {mu}m, heating the upper atmosphere while allowing the deeper atmosphere seen at 8 {mu}m to remain cooler. We obtain a similar result as Gillon et al. for the phase of the secondary eclipse of CoRoT-2, implying an eccentric orbit with e cos({omega}) = -0.0030 {+-} 0.0004.

  6. Transiting exoplanets from the CoRoT space mission. XXV. CoRoT-27b: a massive and dense planet on a short-period orbit

    NASA Astrophysics Data System (ADS)

    Parviainen, H.; Gandolfi, D.; Deleuil, M.; Moutou, C.; Deeg, H. J.; Ferraz-Mello, S.; Samuel, B.; Csizmadia, Sz.; Pasternacki, T.; Wuchterl, G.; Havel, M.; Fridlund, M.; Angus, R.; Tingley, B.; Grziwa, S.; Korth, J.; Aigrain, S.; Almenara, J. M.; Alonso, R.; Baglin, A.; Barros, S. C. C.; Bordé, P.; Bouchy, F.; Cabrera, J.; Díaz, R. F.; Dvorak, R.; Erikson, A.; Guillot, T.; Hatzes, A.; Hébrard, G.; Mazeh, T.; Montagnier, G.; Ofir, A.; Ollivier, M.; Pätzold, M.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.

    2014-02-01

    Aims: We report the discovery of a massive and dense transiting planet CoRoT-27b on a 3.58-day orbit around a 4.2 Gyr-old G2 star. The planet candidate was identified from the CoRoT photometry, and was confirmed as a planet with ground-based spectroscopy. Methods: The confirmation of the planet candidate is based on radial velocity observations combined with imaging to rule out blends. The characterisation of the planet and its host star was carried out using a Bayesian approach where all the data (CoRoT photometry, radial velocities, and spectroscopic characterisation of the star) are used jointly. The Bayesian analysis included a study whether the assumption of white normally distributed noise holds for the CoRoT photometry and whether the use of a non-normal noise distribution offers advantages in parameter estimation and model selection. Results: CoRoT-27b has a mass of 10.39 ± 0.55MJup, a radius of 1.01 ± 0.04RJup, a mean density of 12.6-1.67+1.92g cm-3, and an effective temperature of 1500 ± 130 K. The planet orbits around its host star, a 4.2 Gyr-old G2-star with a mass M⋆ = 1.06M⊙ and a radius R⋆ = 1.05R⊙, on a 0.048 ± 0.007 AU orbit of 3.58 days. The radial velocity observations allow us to exclude highly eccentric orbits, namely, e < 0.065 with 99% confidence. Given its high mass and density, theoretical modelling of CoRoT-27b is demanding. We identify two solutions with heavy element mass fractions of 0.11 ± 0.08M⊕ and 0.07 ± 0.06M⊕, but even solutions void of heavy elements cannot be excluded. We carry out a secondary eclipse search from the CoRoT photometry using a method based on Bayesian model selection, but conclude that the noise level is too high to detect eclipses shallower than 9% of the transit depth. Using a non-normal noise model was shown not to affect the parameter estimation results, but led to significant improvement in the sensitivity of the model selection process. The CoRoT space mission, launched on December 27, 2006

  7. CoRoT-7b: SUPER-EARTH OR SUPER-Io?

    SciTech Connect

    Barnes, Rory; Kaib, Nathan A.; Raymond, Sean N.; Greenberg, Richard; Jackson, Brian

    2010-02-01

    CoRoT-7b, a planet about 70% larger than the Earth orbiting a Sun-like star, is the first-discovered rocky exoplanet, and hence has been dubbed a 'super-Earth'. Some initial studies suggested that since the planet is so close to its host star, it receives enough insolation to partially melt its surface. However, these past studies failed to take into consideration the role that tides may play in this system. Even if the planet's eccentricity has always been zero, we show that tidal decay of the semimajor axis could have been large enough that the planet formed on a wider orbit which received less insolation. Moreover, CoRoT-7b could be tidally heated at a rate that dominates its geophysics and drives extreme volcanism. In this case, CoRoT-7b is a 'super-Io' that, like Jupiter's volcanic moon, is dominated by volcanism and rapid resurfacing. Such heating could occur with an eccentricity of just 10{sup -5}. This small value could be driven by CoRoT-7c if its own eccentricity is larger than {approx}10{sup -4}. CoRoT-7b may be the first of a class of planetary super-Ios likely to be revealed by the CoRoT and Kepler spacecraft.

  8. Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system

    NASA Astrophysics Data System (ADS)

    Haywood, R. D.; Cameron, A. C.; Queloz, D.; Barros, S. C. C.; Deleuil, M.; Fares, R.; Gillon, M.; Hatzes, A.; Lanza, A. F.; Lovis, C.; Moutou, C.; Pepe, F.; Pollacco, D.; Santerne, A.; Ségransan, D.; Unruh, Y.

    2014-01-01

    Since the discovery of the transiting Super-Earth CoRoT-7b, several investigations have been made of the number and precise masses of planets present in the system, but they all yield different results, owing to the star's high level of activity. Radial velocity (RV) variations induced by stellar activity therefore need to be modelled and removed to allow a reliable detection of all planets in the system. We re-observed CoRoT-7 in January 2012 with both HARPS and the CoRoT satellite, so that we now have the benefit of simultaneous RV and photometric data. We fitted the off-transit variations in the CoRoT lightcurve using a harmonic decomposition similar to that implemented in Queloz et al. (2009). This fit was then used to model the stellar RV contribution, according to the methods described by Aigrain et al. (2011). This model was incorporated into a Monte Carlo Markov Chain in order to make a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We also assess the evidence for the presence of one or two additional planetary companions.

  9. CoRoT-7b: Super-Earth or Super-Io?

    NASA Astrophysics Data System (ADS)

    Barnes, Rory; Raymond, Sean N.; Greenberg, Richard; Jackson, Brian; Kaib, Nathan A.

    2010-02-01

    CoRoT-7b, a planet about 70% larger than the Earth orbiting a Sun-like star, is the first-discovered rocky exoplanet, and hence has been dubbed a "super-Earth." Some initial studies suggested that since the planet is so close to its host star, it receives enough insolation to partially melt its surface. However, these past studies failed to take into consideration the role that tides may play in this system. Even if the planet's eccentricity has always been zero, we show that tidal decay of the semimajor axis could have been large enough that the planet formed on a wider orbit which received less insolation. Moreover, CoRoT-7b could be tidally heated at a rate that dominates its geophysics and drives extreme volcanism. In this case, CoRoT-7b is a "super-Io" that, like Jupiter's volcanic moon, is dominated by volcanism and rapid resurfacing. Such heating could occur with an eccentricity of just 10-5. This small value could be driven by CoRoT-7c if its own eccentricity is larger than ~10-4. CoRoT-7b may be the first of a class of planetary super-Ios likely to be revealed by the CoRoT and Kepler spacecraft.

  10. The Effect of Surface Topography on the Nonlinear Dynamics of Rossby Waves

    NASA Technical Reports Server (NTRS)

    Abarzhi, S. I.; Desjardins, O.; Pitsch, H.

    2003-01-01

    Boussinesq convection in rotating systems attracts a sustained attention of the fluid dynamics community, because it has intricate non-linear dynamics (Cross & Hohenberg 1993) and plays an important role in geophysical and astrophysical applications, such as the motion of the liquid outer core of Earth, the Red Spot in Jupiter, the giant cells in the Sun etc. (Alridge et al. 1990). A fundamental distinction between the real geo- and astrophysical problems and the idealized laboratory studies is that natural systems are inhomogeneous (Alridge et al. 1990). Heterogeneities modulate the flow and influence significantly the dynamics of convective patterns (Alridge et al. 1990; Hide 1971). The effect of modulations on pattern formation and transition to turbulence in Boussinesq convection is far from being completely understood (Cross & Hohenberg 1993; Aranson & Kramer 2002). It is generally accepted that in the liquid outer core of the Earth the transport of the angular momentum and internal heat occurs via thermal Rossby waves (Zhang et al. 2001; Kuang & Bloxham 1999). These waves been visualized in laboratory experiments in rotating liquid-filled spheres and concentric spherical shells (Zhang et al. 2001; Kuang & Bloxham 1999). The basic dynamical features of Rossby waves have been reproduced in a cylindrical annulus, a system much simpler than the spherical ones (Busse & Or 1986; Or & Busse 1987). For convection in a cylindrical annulus, the fluid motion is two-dimensional, and gravity is replaced by a centrifugal force, (Busse & Or 1986; Or & Busse 1987). Hide (1971) has suggested that the momentum and heat transport in the core might be influenced significantly by so-called bumps, which are heterogeneities on the mantle-core boundary. To model the effect of surface topography on the transport of momentum and energy in the liquid outer core of the Earth, Bell & Soward (1996), Herrmann & Busse (1998) and Westerburg & Busse (2001) have studied the nonlinear dynamics

  11. Generalized investigation of the rotation-activity relation: favoring rotation period instead of Rossby number

    SciTech Connect

    Reiners, A.; Passegger, V. M.; Schüssler, M.

    2014-10-20

    Magnetic activity in Sun-like and low-mass stars causes X-ray coronal emission which is stronger for more rapidly rotating stars. This relation is often interpreted in terms of the Rossby number, i.e., the ratio of rotation period to convective overturn time. We reconsider this interpretation on the basis of the observed X-ray emission and rotation periods of 821 stars with masses below 1.4 M {sub ☉}. A generalized analysis of the relation between X-ray luminosity normalized by bolometric luminosity, L {sub X}/L {sub bol}, and combinations of rotational period, P, and stellar radius, R, shows that the Rossby formulation does not provide the solution with minimal scatter. Instead, we find that the relation L {sub X}/L {sub bol}∝P {sup –2} R {sup –4} optimally describes the non-saturated fraction of the stars. This relation is equivalent to L {sub X}∝P {sup –2}, indicating that the rotation period alone determines the total X-ray emission. Since L {sub X} is directly related to the magnetic flux at the stellar surface, this means that the surface flux is determined solely by the star's rotation and is independent of other stellar parameters. While a formulation in terms of a Rossby number would be consistent with these results if the convective overturn time scales exactly as L{sub bol}{sup −1/2}, our generalized approach emphasizes the need to test a broader range of mechanisms for dynamo action in cool stars.

  12. Conservation laws of wave action and potential enstrophy for Rossby waves in a stratified atmosphere

    NASA Technical Reports Server (NTRS)

    Straus, D. M.

    1983-01-01

    The evolution of wave energy, enstrophy, and wave motion for atmospheric Rossby waves in a variable mean flow are discussed from a theoretical and pedagogic standpoint. In the absence of mean flow gradients, the wave energy density satisfies a local conservation law, with the appropriate flow velocity being the group velocity. In the presence of mean flow variations, wave energy is not conserved, but wave action is, provided the mean flow is independent of longitude. Wave enstrophy is conserved for arbitrary variations of the mean flow. Connections with Eiiassen-Palm flux are also discussed.

  13. Conservation laws of wave action and potential enstrophy for Rossby waves in a stratified atmosphere

    NASA Technical Reports Server (NTRS)

    Straus, D. M.

    1983-01-01

    The evolution of wave energy, enstrophy, and wave motion for atmospheric Rossby waves in a variable mean flow are discussed from a theoretical and pedagogic standpoint. In the absence of mean flow gradients, the wave energy density satisfies a local conservation law, with the appropriate flow velocity being the group velocity. In the presence of mean flow variations, wave energy is not conserved, but wave action is, provided the mean flow is independent of longitude. Wave enstrophy is conserved for arbitrary variations of the mean flow. Connections with Eliassen-Palm flux are also discussed.

  14. Shear flow driven Rossby-Khantadze electromagnetic planetary vortices in the ionospheric E-layer

    NASA Astrophysics Data System (ADS)

    Kaladze, T. D.; Kahlon, L. Z.; Horton, W.; Pokhotelov, O.; Onishchenko, O.

    2014-04-01

    A system of equations describing the nonlinear interaction of coupled Rossby-Khantadze electromagnetic waves with a sheared zonal flow in the Earth's ionospheric E-layer is obtained. For the linear regime the corresponding region of phase velocities is analyzed and the appropriate stability condition of zonal flow is deduced. It is shown that the sheared zonal flow may excite solitary vortical structures in the form of a row of counter-rotating vortices whose amplitudes decrease with the increase of the zonal flow parameter. This conclusion is consistent with the stabilizing idea of a sheared zonal flow. The possibility of an intense magnetic-field generation is shown.

  15. Nonaxisymmetric Rossby vortex instability with toroidal magnetic fields in structured disks

    SciTech Connect

    Yu, Cong; Li, Hui

    2009-01-01

    We investigate the global nonaxisymmetric Rossby vortex instability (RVI) in a differentially rotating, compressible magnetized accretion disk with radial density structures. Equilibrium magnetic fields are assumed to have only the toroidal component. Using linear theory analysis, we show that the density structure can be unstable to nonaxisymmetric modes. We find that, for the magnetic field profiles we have studied, magnetic fields always provide a stabilizing effect to the unstable RVI modes. We discuss the physical mechanism of this stabilizing effect. The threshold and properties of the unstable modes are also discussed in detail. In addition, we present linear stability results for the global magnetorotational instability when the disk is compressible.

  16. Corotation lag limit on mass-loss rate from Io

    NASA Technical Reports Server (NTRS)

    Huang, T. S.; Siscoe, G. L.

    1987-01-01

    Considering rapid escape of H2O from Io during an early hot evolutionary epoch, an H2O plasma torus is constructed by balancing dissociation and ionization products against centrifugally driven diffusion, including for the first time the effects of corotation lag resulting from mass loading. Two fundamental limits are found as the mass injection rate increases: (1) an 'ignition' limit of 1.1 x 10 to the 6th kg/s, beyond which the torus cannot ionize itself and photoionization dominates; and (2) the ultimate mass loading limit of 1.3 x 10 to the 7th kg/s, which occurs when neutrals newly created by charge exchange and recombination cannot leave the torus, thereby bringing magnetospherically driven transport to a halt. Connecting this limit with the variations of Io's temperature in its early evolution epoch gives an estimate of the upper limit on the total mass loss from Io, about 3.0 x 10 to the 20th kg (for high-opacity nebula) and about 8.9 x 10 to the 20th kg (for low-opacity nebula). These limits correspond to eroding 8 km and 22 km of H2O from the surface. It is concluded that compared to the other Galilean satellites, Io was created basically dry.

  17. Effects of corotating interaction regions on Ulysses high energy particles

    SciTech Connect

    Droege, W.; Kunow, H.; Heber, B.; Mueller-Mellin, R.; Sierks, H.; Wibberenz, G.; Raviart, A.; Ducros, R.; Ferrando, P.; Rastoin, C.; Gosling, J.T.

    1996-07-01

    We investigate the intensity variation of low energy ({approximately}6{endash}23MeV/N) heliospheric ions and of galactic protons (250{endash}2200 MeV) observed by the Kiel Electron Telescope onboard the Ulysses spacecraft associated with Corotating Interaction Regions (CIR) from mid-1992 to end of June 1995. This period covers Ulysses{close_quote} transit to high southern latitudes, the south polar pass, return to the solar equator and ascent to the north pole up to 70{degree}. We find that the flux of high energy protons exhibits a periodicity of about 26 days with a relative intensity variation of 10{percent}. At latitudes below {approximately}50{degree} the recurrent variations of galactic protons are in coincidence with the passage of CIRs and enhancements of low energies protons and alpha particles which are accelerated at the shocks of the CIRs. The modulation of galactic protons is observed up to high southern latitudes, where the signatures of a CIR are no longer visible in plasma or magnetic field data. The periodicity does not depend on latitude and its phase apparently remains constant during Ulysses{close_quote} pass over the south pole as well as through the solar equator. {copyright} {ital 1996 American Institute of Physics.}

  18. Suprathermal helium associated with corotating interaction regions: A case study

    NASA Astrophysics Data System (ADS)

    Yu, J.; Berger, L.; Wimmer-Schweingruber, R. F.; Hilchenbach, M.; Kallenbach, R.; Klecker, B.; Guo, J.

    2016-03-01

    Enhancements of suprathermal particles observed at 1AU often can be related to Corotating Interaction Regions (CIRs). The compression regions associated with CIRs and their driven shocks which typically form at a few AU distance to the Sun can efficiently accelerate particles. If accelerated at the trailing edge of a CIR these particles can travel sunward along the ambient magnetic field and thus enhanced fluxes can be observed even if the acceleration region has passed over the spacecraft. We have analysed a CIR that has been observed at L1 by ACE/SWICS and SOHO/CELIAS/STOF on days 207 and 208 in 2003. The combination of SWICS and STOF data allowed us to study suprathermal Helium ranging from its onset at solar wind bulk energies up to 330 keV/nuc. Here we present our results for the temporal evolution of the flux, energy spectra and the He+/He++ ratio. In particular we present observational evidence for a turnover of the energy spectra at lower energies after the CIR passage which has been theoretically predicted but never been observed so far.

  19. Effects of corotating interaction regions on Ulysses high energy particles

    SciTech Connect

    Droege, W.; Kunow, H.; Heber, B.; Mueller-Mellin, R.; Sierks, H.; Wibberenz, G.; Raviart, A.; Ducros, R.; Ferrando, P.; Rastoin, C.; Paizis, C.; Gosling, J. T.

    1996-07-20

    We investigate the intensity variation of low energy ({approx}6-23 MeV/N) heliospheric ions and of galactic protons (250-2200 MeV) observed by the Kiel Electron Telescope onboard the Ulysses spacecraft associated with Corotating Interaction Regions (CIR) from mid-1992 to end of June 1995. This period covers Ulysses' transit to high southern latitudes, the south polar pass, return to the solar equator and ascent to the north pole up to 70 deg. We find that the flux of high energy protons exhibits a periodicity of about 26 days with a relative intensity variation of 10%. At latitudes below {approx}50 deg. the recurrent variations of galactic protons are in coincidence with the passage of CIRs and enhancements of low energies protons and alpha particles which are accelerated at the shocks of the CIRs. The modulation of galactic protons is observed up to high southern latitudes, where the signatures of a CIR are no longer visible in plasma or magnetic field data. The periodicity does not depend on latitude and its phase apparently remains constant during Ulysses' pass over the south pole as well as through the solar equator.

  20. HELIUM ION ANISOTROPIES IN COROTATING INTERACTION REGIONS AT 1 AU

    SciTech Connect

    Ebert, R. W.; Desai, M. I.; Dayeh, M. A.; Mason, G. M.

    2012-08-01

    We investigated the first-order flow anisotropies in the solar wind frame of {approx}0.06-0.95 MeV nucleon{sup -1} He ions during three corotating interaction region (CIR)-associated particle intensity enhancements observed at 1 AU by Wind, examining CIRs with (1) a reverse shock, (2) a well-formed compression region, and (3) a weak compression region. We identified anti-sunward flows in the compression region downstream of the CIR trailing edge in the events with a reverse shock and well-formed compression that transitioned to sunward flows across and upstream of this boundary. These observations suggest that the trailing edge is organizing the He ion flows and is a local source for the particles in these events, this source being inside 1 AU prior to the trailing edge arrival and beyond 1 AU after its passage. The event with the weak compression region had predominantly sunward flows throughout, indicating that the source of the He ions was beyond 1 AU. These observations provide compelling evidence that He ions at 1 AU can be accelerated to suprathermal energies at the CIR trailing edge in events where the compression region is well formed.

  1. Energetic Particles and Upstream Waves at Co-rotating Shocks

    NASA Astrophysics Data System (ADS)

    Smith, Edward J.; Zhou, Xiaoyan

    2010-03-01

    We report a study of energetic ion acceleration at shocks bounding co-rotating interaction regions (CIRs). Archived data obtained by Ulysses magnetic field, solar wind and energetic particle investigations at low latitude CIRs have been assembled and analyzed. The statistical relations between various properties of 22 Forward shocks, energetic particles and upstream heliospheric magnetic field fluctuations are presented. No statistically significant correlations are found between the shock compression ratio, r, or the particle intensity, jp, or the energetic particle spectral index, s, and the shock normal-upstream field angle, θBn. Furthermore, a theoretical relation between the particle spectral index and shock compression is not consistent with the observed values of s and r. The particle intensities are poorly correlated with the power in upstream heliospheric magnetic field fluctuations contrary to our preliminary study of fewer shocks. We conclude that many of the expectations of Diffusive Shock Theory are not supported by this data set but it is too early to decide whether some key measurement is missing or the theory needs reconsideration.

  2. VizieR Online Data Catalog: Fourier analysis of HD 49330 CoRoT light curve (Huat+, 2009)

    NASA Astrophysics Data System (ADS)

    Huat, A.-L.; Hubert, A.-M.; Baudin, F.; Floquet, M.; Neiner, C.; Fremat, Y.; Gutierrez-Soto, J.; Andrade, L.; de Batz, B.; Diago, P. D.; Emilio, M.; Espinosa, F. Lara; Fabregat, J.; Janot-Pacheco, E.; Leroy, B.; Martayan, C.; Semaan, T.; Suso, J.; Auvergne, M.; Catala, C.; Michel, E.; Samadi, R.

    2009-09-01

    This work analyses the high precision photometric light curve obtained for the CoRoT target HD49330 (B0.5 IVe) which was observed during 136.886 days with a sample of 32s. During the CoRoT run the star underwent an outburst often observed in hot Be star. The CoRoT light curve was analysed using Fourier methods and non-linear least square fitting. (5 data files).

  3. QUASI-BIENNIAL OSCILLATIONS IN THE SOLAR TACHOCLINE CAUSED BY MAGNETIC ROSSBY WAVE INSTABILITIES

    SciTech Connect

    Zaqarashvili, Teimuraz V.; Carbonell, Marc; Oliver, Ramon; Ballester, Jose Luis E-mail: marc.carbonell@uib.e E-mail: joseluis.ballester@uib.e

    2010-11-20

    Quasi-biennial oscillations (QBOs) are frequently observed in solar activity indices. However, no clear physical mechanism for the observed variations has been suggested so far. Here, we study the stability of magnetic Rossby waves in the solar tachocline using the shallow water magnetohydrodynamic approximation. Our analysis shows that the combination of typical differential rotation and a toroidal magnetic field with a strength of {>=}10{sup 5} G triggers the instability of the m = 1 magnetic Rossby wave harmonic with a period of {approx}2 years. This harmonic is antisymmetric with respect to the equator and its period (and growth rate) depends on the differential rotation parameters and magnetic field strength. The oscillations may cause a periodic magnetic flux emergence at the solar surface and consequently may lead to the observed QBO in solar activity features. The period of QBOs may change throughout a cycle, and from cycle to cycle, due to variations of the mean magnetic field and differential rotation in the tachocline.

  4. A new model for algebraic Rossby solitary waves in rotation fluid and its solution

    NASA Astrophysics Data System (ADS)

    Chen, Yao-Deng; Yang, Hong-Wei; Gao, Yu-Fang; Yin, Bao-Shu; Feng, Xing-Ru

    2015-09-01

    A generalized Boussinesq equation that includes the dissipation effect is derived to describe a kind of algebraic Rossby solitary waves in a rotating fluid by employing perturbation expansions and stretching transformations of time and space. Using this equation, the conservation laws of algebraic Rossby solitary waves are discussed. It is found that the mass, the momentum, the energy, and the velocity of center of gravity of the algebraic solitary waves are conserved in the propagation process. Finally, the analytical solution of the equation is generated. Based on the analytical solution, the properties of the algebraic solitary waves and the dissipation effect are discussed. The results point out that, similar to classic solitary waves, the dissipation can cause the amplitude and the speed of solitary waves to decrease; however, unlike classic solitary waves, the algebraic solitary waves can split during propagation and the decrease of the detuning parameter can accelerate the occurrence of the solitary waves fission phenomenon. Project supported by the Shandong Provincial Key Laboratory of Marine Ecology and Environment and Disaster Prevention and Mitigation Project, China (Grant No. 2012010), the National Natural Science Foundation of China (Grant Nos. 41205082 and 41476019), the Special Funds for Theoretical Physics of the National Natural Science Foundation of China (Grant No. 11447205), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), China.

  5. Abrupt Cooling and the Oceanic Rossby Wave Observed during CINDY2011

    NASA Astrophysics Data System (ADS)

    Seiki, A.; Katsumata, M.; Horii, T.; Hasegawa, T.; Richards, K. J.; Yoneyama, K.; Shirooka, R.

    2012-12-01

    Cooperative Indian Ocean experiment on intraseasonal variability in the Year 2011 (CINDY 2011) was conducted to capture atmospheric and oceanic characteristics of the Madden-Julian Oscillation (MJO) in the central Indian Ocean. During CINDY, the research vessel MIRAI basically stayed at 8°S, 80.5°E from 1 October to 28 November 2011. Intraseasonal convection associated with MJO was organized in the central Indian Ocean twice in late October and late November during the period. In the southern hemisphere, however, it was weak and lagged the northern one by a week in the October and November events, respectively. In the middle of November, both sea surface temperature (SST) and mixed layer temperature decreased suddenly when cold low salinity water intruded in the surface layer around the MIRAI. This intrusion was accompanied by a surface current change from southwestward to northwestward associated with the passage of the downwelling Rossby wave. Advective cooling is shown to play an important role in the heat budget of the mixed layer. This is an interesting result because the associated downwelling Rossby wave is usually considered to increase SST. In addition, the cooling is suggested to suppress the convection, resulting in the lagged convective onset in the south Indian Ocean in late November.

  6. Propagation of Rossby-Khantadze Electromagnetic Planetary Waves in the Ionospheric E-Layer

    NASA Astrophysics Data System (ADS)

    Futatani, S.; Kaladze, T.; Horton, W.; Benkadda, S.

    2013-10-01

    Nonlinear vortex propagation of electromagnetic coupled Rossby and Khantadze planetary waves in the weakly ionized E-layer of the ionosphere are investigated with numerical simulations. For each k-vector the linear dispersion relation has two eigenmodes corresponding to the slow magnetized Rossby wave and the fast magnetic Khantadze wave. Both waves propagate westward with speeds of order 10-20 m/s for the slow wave and of order 500-1000 km/s for the fast wave. We show that for finite amplitudes there are dipole solitary vortex structures emitted from general initial conditions. These structures are the neutrally stable, nonlinear states that avoid radiating waves by propagating faster than the corresponding linear wave speeds. The condition for these coherent structures to occur is that their amplitudes be such that the nonlinear convection around the core of the disturbance is faster that the linear wave speed for the corresponding dominant Fourier components of the initial disturbance. The presence of the solitary vortex states are indicative of an initial strong disturbance such that arising from a solar storm, a tectonic plate movements or volcanic eruptions. Supported by NSF Grant 0964692 to the University of Texas at Austin; PIIM/CNRS at Aix-Marseille University, and by IMeRA Grant for Advanced Research.

  7. Nonlinear propagation of Rossby-Khantadze electromagnetic planetary waves in the ionospheric E-layer

    NASA Astrophysics Data System (ADS)

    Futatani, S.; Horton, W.; Kaladze, T. D.

    2013-10-01

    Nonlinear vortex propagation of electromagnetic coupled Rossby and Khantadze planetary waves in the weakly ionized ionospheric E-layer is investigated with numerical simulations. Large scale, finite amplitude vortex structures are launched as initial conditions at low, mid, and high latitudes. For each k-vector the linear dispersion relation has two eigenmodes corresponding to the slow magnetized Rossby wave and the fast magnetic Khantadze wave. Both waves propagate westward with local speeds of the order of 10-20 m/s for the slow wave and of the order of 500-1000 km/s for the fast wave. We show that for finite amplitudes there are dipole solitary structures emitted from the initial conditions. These structures are neutrally stable, nonlinear states that avoid radiating waves by propagating faster than the corresponding linear wave speeds. The condition for these coherent structures to occur is that their amplitudes are such that the nonlinear convection around the core of the disturbance is faster than the linear wave speed for the corresponding dominant Fourier components of the initial disturbance. The presence of the solitary vortex states is indicative of an initial strong disturbance such as that from a solar storm or a tectonic plate movement. We show that for generic, large amplitude initial disturbances both slow and fast vortex structures propagate out of the initial structure.

  8. Nonlinear propagation of Rossby-Khantadze electromagnetic planetary waves in the ionospheric E-layer

    SciTech Connect

    Futatani, S.; Horton, W.; Kaladze, T. D.

    2013-10-15

    Nonlinear vortex propagation of electromagnetic coupled Rossby and Khantadze planetary waves in the weakly ionized ionospheric E-layer is investigated with numerical simulations. Large scale, finite amplitude vortex structures are launched as initial conditions at low, mid, and high latitudes. For each k-vector the linear dispersion relation has two eigenmodes corresponding to the slow magnetized Rossby wave and the fast magnetic Khantadze wave. Both waves propagate westward with local speeds of the order of 10–20 m/s for the slow wave and of the order of 500–1000 km/s for the fast wave. We show that for finite amplitudes there are dipole solitary structures emitted from the initial conditions. These structures are neutrally stable, nonlinear states that avoid radiating waves by propagating faster than the corresponding linear wave speeds. The condition for these coherent structures to occur is that their amplitudes are such that the nonlinear convection around the core of the disturbance is faster than the linear wave speed for the corresponding dominant Fourier components of the initial disturbance. The presence of the solitary vortex states is indicative of an initial strong disturbance such as that from a solar storm or a tectonic plate movement. We show that for generic, large amplitude initial disturbances both slow and fast vortex structures propagate out of the initial structure.

  9. Resonance trapping in the primordial solar nebula - The case of a Stokes drag dissipation

    NASA Astrophysics Data System (ADS)

    Beauge, C.; Ferraz-Mello, S.

    1993-06-01

    An analytical and numerical study is conducted of the orbital evolution of solid particles in a gas-rich planetary nebula, in the presence of a planetary embryo, for the case of a Stokes drag. The equations of the averaged model for the motion of particles in resonance with the embryo have allowed corotation and libration solutions to be obtained for a wide range of drag coefficient values, thereby clarifying the role played by secular resonances. Effective resonance capture is shown by the numerical simulations for both librations and corotations.

  10. Transiting exoplanets from the CoRoT space mission. XXIV. CoRoT-25b and CoRoT-26b: two low-density giant planets

    NASA Astrophysics Data System (ADS)

    Almenara, J. M.; Bouchy, F.; Gaulme, P.; Deleuil, M.; Havel, M.; Gandolfi, D.; Deeg, H. J.; Wuchterl, G.; Guillot, T.; Gardes, B.; Pasternacki, T.; Aigrain, S.; Alonso, R.; Auvergne, M.; Baglin, A.; Bonomo, A. S.; Bordé, P.; Cabrera, J.; Carpano, S.; Cochran, W. D.; Csizmadia, Sz.; Damiani, C.; Diaz, R. F.; Dvorak, R.; Endl, M.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Hébrard, G.; Gillon, M.; Guenther, E.; Hatzes, A.; Léger, A.; Lammer, H.; MacQueen, P. J.; Mazeh, T.; Moutou, C.; Ollivier, M.; Ofir, A.; Pätzold, M.; Parviainen, H.; Queloz, D.; Rauer, H.; Rouan, D.; Santerne, A.; Samuel, B.; Schneider, J.; Tal-Or, L.; Tingley, B.; Weingrill, J.

    2013-07-01

    We report the discovery of two transiting exoplanets, CoRoT-25b and CoRoT-26b, both of low density, one of which is in the Saturn mass-regime. For each star, ground-based complementary observations through optical photometry and radial velocity measurements secured the planetary nature of the transiting body and allowed us to fully characterize them. For CoRoT-25b we found a planetary mass of 0.27 ± 0.04 MJup, a radius of 1.08-0.10+0.3 RJup and hence a mean density of 0.15-0.06+0.15 g cm-3. The planet orbits an F9 main-sequence star in a 4.86-day period, that has a V magnitude of 15.0, solar metallicity, and an age of 4.5-2.0+1.8-Gyr. CoRoT-26b orbits a slightly evolved G5 star of 9.06 ± 1.5-Gyr age in a 4.20-day period that hassolar metallicity and a V magnitude of 15.8. With a mass of 0.52 ± 0.05 MJup, a radius of 1.26-0.07+0.13 RJup, and a mean density of 0.28-0.07+0.09 g cm-3, it belongs to the low-mass hot-Jupiter population. Planetary evolution models allowed us to estimate a core mass of a few tens of Earth mass for the two planets with heavy-element mass fractions of 0.52-0.15+0.08 and 0.26-0.08+0.05, respectively, assuming that a small fraction of the incoming flux is dissipated at the center of the planet. In addition, these models indicate that CoRoT-26b is anomalously large compared with what standard models could account for, indicating that dissipation from stellar heating could cause this size. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Partly based on observations obtained at the European Southern Observatory at Paranal and La Silla, Chile in programs 083.C-0690(A), 184.C-0639.

  11. Particle acceleration at corotating interaction regions in the heliosphere

    SciTech Connect

    Tsubouchi, K.

    2014-11-01

    Hybrid simulations are performed to investigate the dynamics of both solar wind protons and interplanetary pickup ions (PUIs) around the corotating interaction region (CIR). The one-dimensional system is applied in order to focus on processes in the direction of CIR propagation. The CIR is bounded by forward and reverse shocks, which are responsible for particle acceleration. The effective acceleration of solar wind protons takes place when the reverse shock (fast wind side) favors a quasi-parallel regime. The diffusive process accounts for this acceleration, and particles can gain energy in a suprathermal range (on the order of 10 keV). In contrast, the PUI acceleration around the shock differs from the conventional model in which the motional electric field along the shock surface accelerates particles. Owing to their large gyroradius, PUIs can gyrate between the upstream and downstream, several proton inertial lengths away from the shock. This 'cross-shock' gyration results in a net velocity increase in the field-aligned component, indicating that the magnetic mirror force is responsible for acceleration. The PUIs that remain in the vicinity of the shock for a long duration (tens of gyroperiods) gain much energy and are reflected back toward the upstream. These reflected energetic PUIs move back and forth along the magnetic field between a pair of CIRs that are magnetically connected. The PUIs are repeatedly accelerated in each reflection, leading to a maximum energy gain close to 100 keV. This mechanism can be evaluated in terms of 'preacceleration' for the generation of anomalous cosmic rays.

  12. Revisiting the transits of CoRoT-7b at a lower activity level

    NASA Astrophysics Data System (ADS)

    Barros, S. C. C.; Almenara, J. M.; Deleuil, M.; Diaz, R. F.; Csizmadia, Sz.; Cabrera, J.; Chaintreuil, S.; Collier Cameron, A.; Hatzes, A.; Haywood, R.; Lanza, A. F.; Aigrain, S.; Alonso, R.; Bordé, P.; Bouchy, F.; Deeg, H. J.; Erikson, A.; Fridlund, M.; Grziwa, S.; Gandolfi, D.; Guillot, T.; Guenther, E.; Leger, A.; Moutou, C.; Ollivier, M.; Pasternacki, T.; Pätzold, M.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Wuchterl, G.

    2014-09-01

    The first super-Earth with measured radius discovered was CoRoT-7b and it has opened the new field of rocky exoplanet characterisation. To better understand this interesting system, new observations were taken with the CoRoT satellite. During this run 90 new transits were obtained in the imagette mode. These were analysed together with the previous 151 transits obtained in the discovery run and HARPS radial velocity observations to derive accurate system parameters. A difference is found in the posterior probability distribution of the transit parameters between the previous CoRoT run (LRa01) and the new run (LRa06). We propose that this is due to an extra noise component in the previous CoRoT run suspected of being transit spot occultation events. These lead to the mean transit shape becoming V-shaped. We show that the extra noise component is dominant at low stellar flux levels and reject these transits in the final analysis. We obtained a planetary radius, Rp = 1.585 ± 0.064 R⊕ , in agreement with previous estimates. Combining the planetary radius with the new mass estimates results in a planetary density of 1.19 ± 0.27 ρ⊕ which is consistent with a rocky composition. The CoRoT-7 system remains an excellent test bed for the effects of activity in the derivation of planetary parameters in the shallow transit regime.

  13. Data Analysis Provenance: Use Case for Exoplanet Search in CoRoT Database

    NASA Astrophysics Data System (ADS)

    de Souza, L.; Salete Marcon Gomes Vaz, M.; Emílio, M.; Ferreira da Rocha, J. C.; Janot Pacheco, E.; Carlos Boufleur, R.

    2012-09-01

    CoRoT (COnvection Rotation and Planetary Transits) is a mission led by the French national space agency CNES, in collaboration with Austria, Spain, Germany, Belgium and Brazil. The mission priority is dedicated to exoplanet search and stellar seismology. CoRoT light curves database became public after one year of their delivery to the CoRoT Co-Is, following the CoRoT data policy. The CoRoT archive contains thousands of light curves in FITS format. Several exoplanet search algorithms require detrend algorithms to remove both stellar and instrumental signal, improving the chance to detect a transit. Different detrend and transit detection algorithms can be applied to the same database. Tracking the origin of the information and how the data was derived in each level in the data analysis process is essential to allow sharing, reuse, reprocessing and further analysis. This work aims at applying a formalized and codified knowledge model by means of domain ontology. It allows to enrich the data analysis with semantic and standardization. It holds the provenance information in the database for a posteriori recovers by humans or software agents.

  14. The relation of objectively detected Rossby-Wave-Trains and extratropical cyclones in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Schuster, Mareike; Kirchner, Ingo; Lorenz, Philip; Ulbrich, Uwe; Will, Andreas

    2014-05-01

    Our current interest and topic of this poster is the relation of Rossby-Wave-Trains (RWTs) and cyclones in the North Atlantic. Northern Hemisphere extra-tropical cyclones, especially those systems that occur in winter, are known to have high socioeconomic impacts, e.g. through high windspeed and large amounts of precipitation. Recently, a specific interest in Rossby-Wave-Trains has arisen. Long lived RWTs have been shown to be precursors for extreme events and they may impact the predictability of mid-latitude weather systems. We therefore apply automated schemes for the identification of RWTs and cyclones, respectively and relate their characteristics, with the focus of the impact for European climate. Evaluating reanalysis and model data of historical runs, we aim to identify possible spatio-temporal connections between these objectively identified RWTs and cyclones. As our project "MesoTel", which is presented here, is part of a decadal prediction initiative from the German Federal Ministry of Education and Research called "MiKlip", we are additionally investigating the decadal variability of RWTs & cyclones within reanalyses and MiKlip simulations. Our long-term goal is to improve the predictability of seasonal means for Europe through a Two-Way-Nested (TWN) model setup. For this TWN model setup, the regional climate model COSMO-CLM (CCLM) is nested into the atmosphere-ocean general circulation model ECHAM6/MPI-OM (MPI-ESM) in order to investigate the feedback of the meso-scales on the large scales and vice versa. Focus is laid on the development and propagation of synoptic systems (e.g. Rossby Wave Trains and cyclones) that are affecting Europe. The Two-Way-Nested region, thus the CCLM domain, covers Central America and the North Atlantic (CANA) and therefore includes the Gulf stream region, whose prevalent strong meridional SST gradients favor the development of perturbations which then propagate downstream, commonly develop into extra-tropical cyclones and

  15. Short-scale convection and long-scale deformationally unstable Rossby wave in a rotating fluid layer heated from below

    NASA Astrophysics Data System (ADS)

    Tikhomolov, Evgeniy

    1996-12-01

    A rotating fluid layer, heated from below, with a deformable upper and nondeformable lower stress free surfaces is considered in the Boussinesq approximation. The system of the differential equations that governs the long-scale Rossby waves and short-scale convection is obtained in the rapid-rotation approximation. Long-scale flows are unstable due to heating and deformation of the upper surface. The neutral stability curves for Rossby waves and convection are obtained for linearized version of the equations. In a slightly supercritical regime the amplitude equations for convection and Rossby waves are derived by the use of the method of multiscale expansions. The properties of the amplitude equations are discussed. The existence of the two weakly supercritical stationary convection regimes is shown by numerical integration of the equations in the rapid-rotation approximation. In one of them, the amplitude of short-scale convection is modulated due to long-scale deformation of the upper surface associated with the excitation of the Rossby wave. In the other regime, the presence of deformation gives rise to alternating regions with and without convection.

  16. Onset and Forecast of the 1994-1995 El Nino Event: Equatorial Rossby Wave Reflection Evidenced by TOPEX/POSEIDON

    NASA Technical Reports Server (NTRS)

    Boulanger, Jean-Phillipe; Fu, L. L.; Perigaud, C.

    1996-01-01

    We found evidence in TOPEX/POSEIDON sea level data that equatorial first meridionsl mode Rossby waves reflected at the Pacific western boundary into Kelvin waves during the January-july 1994 period prior to the 1994-1995 El Nino event.

  17. Validation of the smallest CoRoT candidates using PASTIS

    NASA Astrophysics Data System (ADS)

    Díaz, R. F.; Almenara, J. M.; Santerne, A.; Moutou, C.; Lethuillier, A.; Deleuil, M.; Bouchy, F.; Hébrard, G.; Montagnier, G.

    2013-09-01

    The majority of the smallest transiting planet candidates detected by CoRoT could not be directly confirmed by a dynamical measurement of their mass. This is due mainly to the faintness of the typical stars observed by CoRoT and to the small reflex motion induced by low-mass planets on their host stars. These candidates have traditionally being labeled as "unresolved", and virtually forgotten in the hope that the new generation of ultra-precise spectrographs installed in large telescopes would permit their confirmation. A way out of this problem is to statistically validate these candidates. In this talk, I will present PASTIS, the validation tool developed in Marseille that is being used to study the CoRoT unresolved candidates.

  18. Observations of planetary mixed Rossby-gravity waves in the upper stratosphere

    NASA Technical Reports Server (NTRS)

    Randel, William J.; Boville, Byron A.; Gille, John C.

    1990-01-01

    Observational evidence is presented for planetary scale (zonal wave number 1-2) mixed Rossby-gravity (MRG) waves in the equatorial upper stratosphere (35-50 km). These waves are detected in LIMS measurements as coherently propagating temperature maxima of amplitude 0.1-0.3 K, which are antisymmetric (out of phase) about the equator, centered near 10-15 deg north and south latitude. These features have vertical wavelengths of order 10-15 km, periods near 2-3 days, and zonal phase velocities close to 200 m/s. Both eastward and westward propagating waves are found, and the observed vertical wavelengths and meridional structures are in good agreement with the MRG dispersion relation. Theoretical estimates of the zonal accelerations attributable to these waves suggest they do not contribute substantially to the zonal momentum balance in the middle atmosphere.

  19. Rossby normal modes in nonuniform background configurations. I Simple fields. II - Equinox and solstice conditions

    NASA Technical Reports Server (NTRS)

    Salby, M. L.

    1981-01-01

    An investigation is conducted regarding the influence of mean field variations on the realization of planetary normal modes, taking into account the mode response and structure in the presence of simple background nonuniformities. It is found that mean field variations have the combined effect of depressing, shifting, and broadening the characteristic response of Rossby normal modes. While nonuniformities in both the mean wind and temperature fields contribute to the reduction in peak response, the former are primarily responsible for translation and spectral broadening. An investigation is conducted to determine which modes may be realized in actual atmospheric configurations and which may be identified. For both the equinox and solstice configurations, response peaks corresponding to all of the first four modes of wavenumbers 1, 2, and 3 are readily visible above the noise.

  20. Transport out of the lower stratospheric Arctic vortex by Rossby wave breaking

    NASA Technical Reports Server (NTRS)

    Waugh, D. W.; Plumb, R. A.; Atkinson, R. J.; Schoeberl, M. R.; Lait, L. R.; Newman, P. A.; Loewenstein, M.; Toohey, D. W.; Avallone, L. M.; Webster, C. R.

    1994-01-01

    The fine-scale structure in lower stratospheric tracer transport during the period of the two Arctic Airborne Stratospheric Expeditions (January and February 1989; December 1991 to March 1992) is investigated using contour advection with surgery calculations. These calculations show that Rossby wave breaking is an ongoing occurrence during these periods and that air is ejected from the polar vortex in the form of long filamentary structures. There is good qualitative agreement between these filaments and measurements of chemical tracers taken aboard the NASA ER-2 aircraft. The ejected air generally remains filamentary and is stretched and mixed with midlatitude air as it is wrapped around the vortex. This process transfers vortex air into midlatitudes and also produces a narrow region of fine-scale filaments surrounding the polar vortex. Among other things, this makes it difficult to define a vortex edge. The calculations also show that strong stirring can occur inside as well as outside the vortex.

  1. Rossby vortex simulation on a paraboloidal coordinate system using the lattice Boltzmann method.

    PubMed

    Yu, H; Zhao, K

    2001-11-01

    In this paper, we apply our compressible lattice Boltzmann model to a rotating parabolic coordinate system to simulate Rossby vortices emerging in a layer of shallow water flowing zonally in a rotating paraboloidal vessel. By introducing a scaling factor, nonuniform curvilinear mesh can be mapped to a flat uniform mesh and then normal lattice Boltzmann method works. Since the mass per unit area on the two-dimensional (2D) surface varies with the thickness of the water layer, the 2D flow seems to be "compressible" and our compressible model is applied. Simulation solutions meet with the experimental observations qualitatively. Based on this research, quantitative solutions and many natural phenomena simulations in planetary atmospheres, oceans, and magnetized plasma, such as the famous Jovian Giant Red Spot, the Galactic Spiral-vortex, the Gulf Stream, and the Kuroshio Current, etc., can be expected. PMID:11736137

  2. Long-Time Sustainability of Rossby Wave Instability in Protoplanetary Disks with Dead Zone

    NASA Astrophysics Data System (ADS)

    Li, S.; Li, H.

    2015-10-01

    We have run 2D simulations to investigate the generation and sustainability of Rossby wave instability (RWI) in proto-planetary disks with constant viscosity and for disks with low viscosity regions (dead zone). For the constant viscosity case, the development of RWI requires a low viscosity and life time of the RWI is short. We also find that the vortex, when it migrates, does so much faster than the disk's viscous drift rate. For disks with dead zone case, a much larger viscosity can be used and the RWI vortex can be sustained for a long time, even the life time of the disk, depending on the width and depth of the dead zone. For a narrow dead zone, the vortex depicts a periodic pattern with a period inversely proportional to the viscosity. If the dead-zone width exceeds some threshold, the periodicity of the RWI disappears.

  3. Planets and stellar activity: hide and seek in the CoRoT-7 system

    NASA Astrophysics Data System (ADS)

    Haywood, R. D.; Collier Cameron, A.; Queloz, D.; Barros, S. C. C.; Deleuil, M.; Fares, R.; Gillon, M.; Lanza, A. F.; Lovis, C.; Moutou, C.; Pepe, F.; Pollacco, D.; Santerne, A.; Ségransan, D.; Unruh, Y. C.

    2014-09-01

    Since the discovery of the transiting super-Earth CoRoT-7b, several investigations have yielded different results for the number and masses of planets present in the system, mainly owing to the star's high level of activity. We re-observed CoRoT-7 in 2012 January with both HARPS and CoRoT, so that we now have the benefit of simultaneous radial-velocity and photometric data. This allows us to use the off-transit variations in the star's light curve to estimate the radial-velocity variations induced by the suppression of convective blueshift and the flux blocked by starspots. To account for activity-related effects in the radial velocities which do not have a photometric signature, we also include an additional activity term in the radial-velocity model, which we treat as a Gaussian process with the same covariance properties (and hence the same frequency structure) as the light curve. Our model was incorporated into a Monte Carlo Markov Chain in order to make a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We measure the masses of planets b and c to be 4.73 ± 0.95 and 13.56 ± 1.08 M⊕, respectively. The density of CoRoT-7b is (6.61 ± 1.72)(Rp/1.58 R⊕)-3 g cm-3, which is compatible with a rocky composition. We search for evidence of an additional planet d, identified by previous authors with a period close to 9 d. We are not able to confirm the existence of a planet with this orbital period, which is close to the second harmonic of the stellar rotation at ˜7.9 d. Using Bayesian model selection, we find that a model with two planets plus activity-induced variations is most favoured.

  4. Abrupt cooling associated with the oceanic Rossby wave and lateral advection during CINDY2011

    NASA Astrophysics Data System (ADS)

    Seiki, Ayako; Katsumata, Masaki; Horii, Takanori; Hasegawa, Takuya; Richards, Kelvin J.; Yoneyama, Kunio; Shirooka, Ryuichi

    2013-10-01

    The cooperative Indian Ocean experiment on intraseasonal variability in the Year 2011 (CINDY2011) was conducted to capture atmospheric and oceanic characteristics of the Madden-Julian Oscillation (MJO) in the central Indian Ocean from late 2011 to early 2012. During CINDY2011, the research vessel (R/V) MIRAI stayed at 8°S, 80.5°E for two months during the special observing period (SOP). Intraseasonal convection associated with the MJO was organized in the central Indian Ocean in late October and late November during the SOP. In the middle of November, both sea surface temperature (SST) and mixed layer temperature decreased suddenly when cold low salinity water intruded into the upper layer around the R/V MIRAI. This intrusion was accompanied by a surface current change from southwestward to westward/west-northwestward associated with the passage of the annual oceanic downwelling Rossby wave. The mixed layer heat budget analysis shows that horizontal advection plays an important role in the abrupt cooling whereas the net surface heat flux cannot account for the cooling. This is an interesting result because the associated downwelling Rossby wave is usually considered to increase SST through a reduction of entrainment cooling. In addition, for the second MJO event convection was activated around 20 November over the central north and equatorial Indian Ocean but not in the south. It is suggested that the cooler surface waters (as seen at the location of the R/V MIRAI) tended to suppress the initial atmospheric convection, resulting in the lagged convective onset in the end of November over the central south Indian Ocean.

  5. Long-term observations of transport, eddies, and Rossby waves in the Mozambique Channel

    NASA Astrophysics Data System (ADS)

    Harlander, U.; Ridderinkhof, H.; Schouten, M. W.; de Ruijter, W. P. M.

    2009-02-01

    Data from an array of current meter moorings covering a period of two and a half years are used to estimate the varying transport through the Mozambique Channel. The total transport during this period is small (8.6 · 106 m3 s-1 or 8.6 Sv southward). Below 1200 m the transport is weak but a prominent deep western boundary undercurrent with cores at 1700 and 2200 m is found that transports 1.5 Sv to the north. The transport shows a large temporal variability, and neither a continuous upper layer western boundary current nor a continuous deep undercurrent is found. The variability in the upper layer is dominated by a period of 68 days and results mainly from eddies that migrate southward through the Mozambique Channel. In addition to this southward propagation, a westward-propagating signal is evident from a space-time diagram of the throughflow. The signal is interpreted as a Mozambique Channel Rossby normal mode. This interpretation is consistent with results from a Principal Oscillation Pattern Analysis (that estimates normal modes from the data) and a quasi-geostrophic channel model. A detailed inspection of a single "eddy event" shows that a precursor of an anticyclone is a strong southward current along the Madagascar coast that propagates westward to the center of the Channel. During the westward propagation, the current becomes unstable inducing an anticyclone. This scenario connects the westward-propagating mode with the eddy growth and explains the coincidence of the eddy and Rossby mode frequency. Still, the type of instability that leads to eddy growth could not be determined yet.

  6. Transiting exoplanets from the CoRoT space mission. XXVII. CoRoT-28b, a planet orbiting an evolved star, and CoRoT-29b, a planet showing an asymmetric transit

    NASA Astrophysics Data System (ADS)

    Cabrera, J.; Csizmadia, Sz.; Montagnier, G.; Fridlund, M.; Ammler-von Eiff, M.; Chaintreuil, S.; Damiani, C.; Deleuil, M.; Ferraz-Mello, S.; Ferrigno, A.; Gandolfi, D.; Guillot, T.; Guenther, E. W.; Hatzes, A.; Hébrard, G.; Klagyivik, P.; Parviainen, H.; Pasternacki, Th.; Pätzold, M.; Sebastian, D.; Tadeu dos Santos, M.; Wuchterl, G.; Aigrain, S.; Alonso, R.; Almenara, J.-M.; Armstrong, J. D.; Auvergne, M.; Baglin, A.; Barge, P.; Barros, S. C. C.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Carpano, S.; Chaffey, C.; Deeg, H. J.; Díaz, R. F.; Dvorak, R.; Erikson, A.; Grziwa, S.; Korth, J.; Lammer, H.; Lindsay, C.; Mazeh, T.; Moutou, C.; Ofir, A.; Ollivier, M.; Pallé, E.; Rauer, H.; Rouan, D.; Samuel, B.; Santerne, A.; Schneider, J.

    2015-07-01

    Context. We present the discovery of two transiting extrasolar planets by the satellite CoRoT. Aims: We aim at a characterization of the planetary bulk parameters, which allow us to further investigate the formation and evolution of the planetary systems and the main properties of the host stars. Methods: We used the transit light curve to characterize the planetary parameters relative to the stellar parameters. The analysis of HARPS spectra established the planetary nature of the detections, providing their masses. Further photometric and spectroscopic ground-based observations provided stellar parameters (log g, Teff, v sin i) to characterize the host stars. Our model takes the geometry of the transit to constrain the stellar density into account, which when linked to stellar evolutionary models, determines the bulk parameters of the star. Because of the asymmetric shape of the light curve of one of the planets, we had to include the possibility in our model that the stellar surface was not strictly spherical. Results: We present the planetary parameters of CoRoT-28b, a Jupiter-sized planet (mass 0.484 ± 0.087 MJup; radius 0.955 ± 0.066 RJup) orbiting an evolved star with an orbital period of 5.208 51 ± 0.000 38 days, and CoRoT-29b, another Jupiter-sized planet (mass 0.85 ± 0.20 MJup; radius 0.90 ± 0.16 RJup) orbiting an oblate star with an orbital period of 2.850 570 ± 0.000 006 days. The reason behind the asymmetry of the transit shape is not understood at this point. Conclusions: These two new planetary systems have very interesting properties and deserve further study, particularly in the case of the star CoRoT-29. The CoRoT space mission, launched on December 27th 2006, was developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany, and Spain. Based on observations obtained with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland

  7. Dissipative Dynamics of a Corotating Vortex Pair in a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Kwon, Woo Jin; Moon, Geol; Seo, Sang Won; Kim, Minseok; Lee, Moosong; Han, Jeong Ho; Shin, Yong-Il

    2015-05-01

    We report on the long-time evolution of a corotating vortex pair in a highly oblate Bose-Einstein Condensate at finite temperature. We generate a doubly charged vortex in a condensate by a phase imprinting method using a magnetic quadrupole field and measure the temporal evolution of the inter-vortex distance between corotating vortices. We find that the vortex separation monotonically increases over the hold time and its increasing rate is almost linearly proportional to the temperature of the system. We discuss the thermal damping on the vortex motion in a condensate.

  8. Consistent linearization of the element-independent corotational formulation for the structural analysis of general shells

    NASA Technical Reports Server (NTRS)

    Rankin, C. C.

    1988-01-01

    A consistent linearization is provided for the element-dependent corotational formulation, providing the proper first and second variation of the strain energy. As a result, the warping problem that has plagued flat elements has been overcome, with beneficial effects carried over to linear solutions. True Newton quadratic convergence has been restored to the Structural Analysis of General Shells (STAGS) code for conservative loading using the full corotational implementation. Some implications for general finite element analysis are discussed, including what effect the automatic frame invariance provided by this work might have on the development of new, improved elements.

  9. The legacy of CoRoT and Kepler on the physics of stellar evolution

    NASA Astrophysics Data System (ADS)

    Chaplin, William

    2015-08-01

    It is a golden era for stellar astrophysics studies, driven by new satellite observations of unprecedented quality and scope. In this talk I will review advances in our understanding that have followed from asteroseismic studies with CoRoT and Kepler data, not only for stellar evolution theory but also in respect of the legacy for exoplanet and Galactic stellar population studies. I will also highlight the huge amount of work that remains to be performed to fully exploit the CoRoT and Kepler databases, and look to ongoing studies with K2, and the future promise of the NASA TESS and ESA PLATO Missions.

  10. Multiple star systems observed with CoRoT and Kepler

    NASA Astrophysics Data System (ADS)

    Southworth, John

    2015-09-01

    The CoRoT and Kepler satellites were the first space platforms designed to perform high-precision photometry for a large number of stars. Multiple systems display a wide variety of photometric variability, making them natural benefactors of these missions. I review the work arising from CoRoT and Kepler observations of multiple systems, with particular emphasis on eclipsing binaries containing giant stars, pulsators, triple eclipses and/or low-mass stars. Many more results remain untapped in the data archives of these missions, and the future holds the promise of K2, TESS and PLATO.

  11. How to separate the low amplitude delta Scuti variation in CoRoT data unambigousely?

    NASA Astrophysics Data System (ADS)

    Benko, Jozsef M.; Paparo, Margit

    2015-08-01

    Rich regular frequency patterns were found in the Fourier spectra of low-amplitude Delta Scuti stars observed by CoRoT satellite. The CoRoT observations are, however, influenced by the disturbing effect of the SAA. The effect is marginal for high amplitude variable stars but it could be dangerous in the case of low amplitude variables, especially if the frequency range of the intrinsic variation overlaps the instrumental frequencies. Systematic tests were carried out both on synthetic and real data. Our aim was to determine a limit amplitude above which we were sure that the frequency pattern belonged to the stars.

  12. Transiting exoplanets from the CoRoT space mission. VIII. CoRoT-7b: the first super-Earth with measured radius

    NASA Astrophysics Data System (ADS)

    Léger, A.; Rouan, D.; Schneider, J.; Barge, P.; Fridlund, M.; Samuel, B.; Ollivier, M.; Guenther, E.; Deleuil, M.; Deeg, H. J.; Auvergne, M.; Alonso, R.; Aigrain, S.; Alapini, A.; Almenara, J. M.; Baglin, A.; Barbieri, M.; Bruntt, H.; Bordé, P.; Bouchy, F.; Cabrera, J.; Catala, C.; Carone, L.; Carpano, S.; Csizmadia, Sz.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Foing, B.; Fressin, F.; Gandolfi, D.; Gillon, M.; Gondoin, Ph.; Grasset, O.; Guillot, T.; Hatzes, A.; Hébrard, G.; Jorda, L.; Lammer, H.; Llebaria, A.; Loeillet, B.; Mayor, M.; Mazeh, T.; Moutou, C.; Pätzold, M.; Pont, F.; Queloz, D.; Rauer, H.; Renner, S.; Samadi, R.; Shporer, A.; Sotin, Ch.; Tingley, B.; Wuchterl, G.; Adda, M.; Agogu, P.; Appourchaux, T.; Ballans, H.; Baron, P.; Beaufort, T.; Bellenger, R.; Berlin, R.; Bernardi, P.; Blouin, D.; Baudin, F.; Bodin, P.; Boisnard, L.; Boit, L.; Bonneau, F.; Borzeix, S.; Briet, R.; Buey, J.-T.; Butler, B.; Cailleau, D.; Cautain, R.; Chabaud, P.-Y.; Chaintreuil, S.; Chiavassa, F.; Costes, V.; Cuna Parrho, V.; de Oliveira Fialho, F.; Decaudin, M.; Defise, J.-M.; Djalal, S.; Epstein, G.; Exil, G.-E.; Fauré, C.; Fenouillet, T.; Gaboriaud, A.; Gallic, A.; Gamet, P.; Gavalda, P.; Grolleau, E.; Gruneisen, R.; Gueguen, L.; Guis, V.; Guivarc'h, V.; Guterman, P.; Hallouard, D.; Hasiba, J.; Heuripeau, F.; Huntzinger, G.; Hustaix, H.; Imad, C.; Imbert, C.; Johlander, B.; Jouret, M.; Journoud, P.; Karioty, F.; Kerjean, L.; Lafaille, V.; Lafond, L.; Lam-Trong, T.; Landiech, P.; Lapeyrere, V.; Larqué, T.; Laudet, P.; Lautier, N.; Lecann, H.; Lefevre, L.; Leruyet, B.; Levacher, P.; Magnan, A.; Mazy, E.; Mertens, F.; Mesnager, J.-M.; Meunier, J.-C.; Michel, J.-P.; Monjoin, W.; Naudet, D.; Nguyen-Kim, K.; Orcesi, J.-L.; Ottacher, H.; Perez, R.; Peter, G.; Plasson, P.; Plesseria, J.-Y.; Pontet, B.; Pradines, A.; Quentin, C.; Reynaud, J.-L.; Rolland, G.; Rollenhagen, F.; Romagnan, R.; Russ, N.; Schmidt, R.; Schwartz, N.; Sebbag, I.; Sedes, G.; Smit, H.; Steller, M. B.; Sunter, W.; Surace, C.; Tello, M.; Tiphène, D.; Toulouse, P.; Ulmer, B.; Vandermarcq, O.; Vergnault, E.; Vuillemin, A.; Zanatta, P.

    2009-10-01

    Aims: We report the discovery of very shallow (Δ F/F ≈ 3.4× 10-4), periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite, which we interpret as caused by a transiting companion. We describe the 3-colour CoRoT data and complementary ground-based observations that support the planetary nature of the companion. Methods: We used CoRoT colours information, good angular resolution ground-based photometric observations in- and out- of transit, adaptive optics imaging, near-infrared spectroscopy, and preliminary results from radial velocity measurements, to test the diluted eclipsing binary scenarios. The parameters of the host star were derived from optical spectra, which were then combined with the CoRoT light curve to derive parameters of the companion. Results: We examined all conceivable cases of false positives carefully, and all the tests support the planetary hypothesis. Blends with separation >0.40´´or triple systems are almost excluded with a 8 × 10-4 risk left. We conclude that, inasmuch we have been exhaustive, we have discovered a planetary companion, named CoRoT-7b, for which we derive a period of 0.853 59 ± 3 × 10-5 day and a radius of Rp = 1.68 ± 0.09 R_Earth. Analysis of preliminary radial velocity data yields an upper limit of 21 M_Earth for the companion mass, supporting the finding. Conclusions: CoRoT-7b is very likely the first Super-Earth with a measured radius. This object illustrates what will probably become a common situation with missions such as Kepler, namely the need to establish the planetary origin of transits in the absence of a firm radial velocity detection and mass measurement. The composition of CoRoT-7b remains loosely constrained without a precise mass. A very high surface temperature on its irradiated face, ≈1800-2600 K at the substellar point, and a very low one, ≈50 K, on its dark face assuming no atmosphere, have been derived. The CoRoT space mission, launched on 27

  13. Transiting exoplanets from the CoRoT space mission. XVIII. CoRoT-18b: a massive hot Jupiter on a prograde, nearly aligned orbit

    NASA Astrophysics Data System (ADS)

    Hébrard, G.; Evans, T. M.; Alonso, R.; Fridlund, M.; Ofir, A.; Aigrain, S.; Guillot, T.; Almenara, J. M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Cabrera, J.; Carone, L.; Carpano, S.; Cavarroc, C.; Csizmadia, Sz.; Deeg, H. J.; Deleuil, M.; Díaz, R. F.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Gandolfi, D.; Gibson, N.; Gillon, M.; Guenther, E.; Hatzes, A.; Havel, M.; Jorda, L.; Lammer, H.; Léger, A.; Llebaria, A.; Mazeh, T.; Moutou, C.; Ollivier, M.; Parviainen, H.; Pätzold, M.; Queloz, D.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Tingley, B.; Wuchterl, G.

    2011-09-01

    We report the detection of CoRoT-18b, a massive hot Jupiter transiting in front of its host star with a period of 1.9000693 ± 0.0000028 days. This planet was discovered thanks to photometric data secured with the CoRoT satellite combined with spectroscopic and photometric ground-based follow-up observations. The planet has a mass Mp = 3.47 ± 0.38 MJup, a radius Rp = 1.31 ± 0.18 RJup, and a density ρp = 2.2 ± 0.8 g cm-3. It orbits a G9V star with a mass M⋆ = 0.95 ± 0.15 M⊙, a radius R⋆ = 1.00 ± 0.13 R⊙, and arotation period Prot = 5.4 ± 0.4 days. The age of the system remains uncertain, with stellar evolution models pointing either to a few tens Ma or several Ga, while gyrochronology and lithium abundance point towards ages of a few hundred Ma. This mismatch potentially points to a problem in our understanding of the evolution of young stars, with possibly significant implications for stellar physics and the interpretation of inferred sizes of exoplanets around young stars. We detected the Rossiter-McLaughlin anomaly in the CoRoT-18 system thanks to the spectroscopic observation of a transit. We measured the obliquity ψ = 20° ± 20° (sky-projected value λ = -10° ± 20°), indicating that the planet orbits in the same way as the star is rotating and that this prograde orbit is nearly aligned with the stellar equator. The CoRoT space mission, launched on 2006 December 27, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain.Table 2 is available in electronic form at http://www.aanda.org

  14. Transiting exoplanets from the CoRoT space mission. XXIII. CoRoT-21b: a doomed large Jupiter around a faint subgiant star

    NASA Astrophysics Data System (ADS)

    Pätzold, M.; Endl, M.; Csizmadia, Sz.; Gandolfi, D.; Jorda, L.; Grziwa, S.; Carone, L.; Pasternacki, T.; Aigrain, S.; Almenara, J. M.; Alonso, R.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Cabrera, J.; Cavarroc, C.; Cochran, W. B.; Deleuil, M.; Deeg, H. J.; Díaz, R.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gillon, M.; Guillot, T.; Hatzes, A.; Hébrard, G.; Léger, A.; Llebaria, A.; Lammer, H.; MacQueen, P. J.; Mazeh, T.; Moutou, C.; Ofir, A.; Ollivier, M.; Parviainen, H.; Queloz, D.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Tingley, B.; Weingrill, J.; Wuchterl, G.

    2012-09-01

    CoRoT-21, a F8IV star of magnitude V = 16 mag, was observed by the space telescope CoRoT during the Long Run 01 (LRa01) in the first winter field (constellation Monoceros) from October 2007 to March 2008. Transits were discovered during the light curve processing. Radial velocity follow-up observations, however, were performed mainly by the 10-m Keck telescope in January 2010. The companion CoRoT-21b is a Jupiter-like planet of 2.26 ± 0.33 Jupiter masses and 1.30 ± 0.14 Jupiter radii in an circular orbit of semi-major axis 0.0417 ± 0.0011 AU and an orbital period of 2.72474 ± 0.00014 days. The planetary bulk density is (1.36 ± 0.48) × 103 kg m-3, very similar to the bulk density of Jupiter, and follows an M1/3 - R relation like Jupiter. The F8IV star is a sub-giant star of 1.29 ± 0.09 solar masses and 1.95 ± 0.2 solar radii. The star and the planet exchange extremetidal forces that will lead to orbital decay and extreme spin-up of the stellar rotation within 800 Myr if the stellar dissipation is Q∗/k2∗ ≤ 107. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain.

  15. Transiting exoplanets from the CoRoT space mission. XX. CoRoT-20b: A very high density, high eccentricity transiting giant planet

    NASA Astrophysics Data System (ADS)

    Deleuil, M.; Bonomo, A. S.; Ferraz-Mello, S.; Erikson, A.; Bouchy, F.; Havel, M.; Aigrain, S.; Almenara, J.-M.; Alonso, R.; Auvergne, M.; Baglin, A.; Barge, P.; Bordé, P.; Bruntt, H.; Cabrera, J.; Carpano, S.; Cavarroc, C.; Csizmadia, Sz.; Damiani, C.; Deeg, H. J.; Dvorak, R.; Fridlund, M.; Hébrard, G.; Gandolfi, D.; Gillon, M.; Guenther, E.; Guillot, T.; Hatzes, A.; Jorda, L.; Léger, A.; Lammer, H.; Mazeh, T.; Moutou, C.; Ollivier, M.; Ofir, A.; Parviainen, H.; Queloz, D.; Rauer, H.; Rodríguez, A.; Rouan, D.; Santerne, A.; Schneider, J.; Tal-Or, L.; Tingley, B.; Weingrill, J.; Wuchterl, G.

    2012-02-01

    We report the discovery by the CoRoT space mission of a new giant planet, CoRoT-20b. The planet has a mass of 4.24 ± 0.23 MJup and a radius of 0.84 ± 0.04 RJup. With a mean density of 8.87 ± 1.10 g cm-3, it is among the most compact planets known so far. Evolutionary models for the planet suggest a mass of heavy elements of the order of 800 M⊕ if embedded in a central core, requiring a revision either of the planet formation models or both planet evolution and structure models. We note however that smaller amounts of heavy elements are expected by more realistic models in which they are mixed throughout the envelope. The planet orbits a G-type star with an orbital period of 9.24 days and an eccentricity of 0.56.The star's projected rotational velocity is vsini = 4.5 ± 1.0 km s-1, corresponding to a spin period of 11.5 ± 3.1 days if its axis of rotation is perpendicular to the orbital plane. In the framework of Darwinian theories and neglecting stellar magnetic breaking, we calculate the tidal evolution of the system and show that CoRoT-20b is presently one of the very few Darwin-stable planets that is evolving toward a triple synchronous state with equality of the orbital, planetary and stellar spin periods. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany, and Spain.

  16. Spectral characterization and differential rotation study of active CoRoT stars

    NASA Astrophysics Data System (ADS)

    Nagel, E.; Czesla, S.; Schmitt, J. H. M. M.

    2016-05-01

    The CoRoT space telescope observed nearly 160 000 light curves. Among the most outstanding is that of the young, active planet host star CoRoT-2A. In addition to deep planetary transits, the light curve of CoRoT-2A shows strong rotational variability and a superimposed beating pattern. To study the stars that produce such an intriguing pattern of photometric variability, we identified a sample of eight stars with rotation periods between 0.8 and 11 days and photometric variability amplitudes of up to 7.5%, showing a similar CoRoT light curve. We also obtained high-resolution follow-up spectroscopy with TNG/SARG and carried out a spectral analysis with SME and MOOG. We find that the color dependence of the light curves is consistent with rotational modulation due to starspots and that latitudinal differential rotation provides a viable explanation for the light curves, although starspot evolution is also expected to play an important role. Our MOOG and SME spectral analyses provide consistent results, showing that the targets are dwarf stars with spectral types between F and mid-K. Detectable Li i absorption in four of the targets confirms a low age of 100-400 Myr also deduced from gyrochronology. Our study indicates that the photometric beating phenomenon is likely attributable to differential rotation in fast-rotating stars with outer convection zones.

  17. Transiting exoplanets from the CoRoT space mission . XIX. CoRoT-23b: a dense hot Jupiter on an eccentric orbit

    NASA Astrophysics Data System (ADS)

    Rouan, D.; Parviainen, H.; Moutou, C.; Deleuil, M.; Fridlund, M.; Ofir, A.; Havel, M.; Aigrain, S.; Alonso, R.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Cabrera, J.; Cavarroc, C.; Csizmadia, Sz.; Deeg, H. J.; Diaz, R. F.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Gandolfi, D.; Gillon, M.; Guillot, T.; Hatzes, A.; Hébrard, G.; Jorda, L.; Léger, A.; Llebaria, A.; Lammer, H.; Lovis, C.; Mazeh, T.; Ollivier, M.; Pätzold, M.; Queloz, D.; Rauer, H.; Samuel, B.; Santerne, A.; Schneider, J.; Tingley, B.; Wuchterl, G.

    2012-01-01

    We report the detection of CoRoT-23b, a hot Jupiter transiting in front of its host star with a period of 3.6314 ± 0.0001 days. This planet was discovered thanks to photometric data secured with the CoRoT satellite, combined with spectroscopic radial velocity (RV) measurements. A photometric search for possible background eclipsing binaries conducted at CFHT and OGS concluded with a very low risk of false positives. The usual techniques of combining RV and transit data simultaneously were used to derive stellar and planetary parameters. The planet has a mass of Mp = 2.8 ± 0.3 MJup, a radius of Rpl= 1.05 ± 0.13RJup, a density of ≈ 3 g cm-3. RV data also clearly reveal a nonzero eccentricity of e = 0.16 ± 0.02. The planet orbits a mature G0 main sequence star of V = 15.5 mag, with a mass M⋆ = 1.14 ± 0.08 M⊙, a radius R ⋆ = 1. 61 ± 0.18 R⊙ and quasi-solarabundances. The age of the system is evaluated to be 7 Gyr, not far from the transition to subgiant, in agreement with the rather large stellar radius. The two features of a significant eccentricity of the orbit and of a fairly high density are fairly uncommon for a hot Jupiter. The high density is, however, consistent with a model of contraction of a planet at this mass, given the age of the system. On the other hand, at such an age, circularization is expected to be completed. In fact, we show that for this planetary mass and orbital distance, any initial eccentricity should not totally vanish after 7 Gyr, as long as the tidal quality factor Qp is more than a few 105, a value that is the lower bound of the usually expected range. Even if CoRoT-23b features a density and an eccentricity that are atypical of a hot Jupiter, it is thus not an enigmatic object. The CoRoT space mission, launched on 27 December 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA, Germany, and Spain. First CoRoT data are available to the public from the CoRoT archive: http://idoc-corot

  18. Long-Term Tracking of Corotating Density Structures Using Heliospheric Imaging

    NASA Astrophysics Data System (ADS)

    Plotnikov, I.; Rouillard, A. P.; Davies, J. A.; Bothmer, V.; Eastwood, J. P.; Gallagher, P.; Harrison, R. A.; Kilpua, E.; Möstl, C.; Perry, C. H.; Rodriguez, L.; Lavraud, B.; Génot, V.; Pinto, R. F.; Sanchez-Diaz, E.

    2016-08-01

    The systematic monitoring of the solar wind in high-cadence and high-resolution heliospheric images taken by the Solar-Terrestrial Relation Observatory (STEREO) spacecraft permits the study of the spatial and temporal evolution of variable solar wind flows from the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7) Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project, we have generated a catalog listing the properties of 190 corotating structures well-observed in images taken by the Heliospheric Imager (HI) instruments onboard STEREO-A (ST-A). Based on this catalog, we present here one of very few long-term analyses of solar wind structures advected by the background solar wind. We concentrate on the subset of plasma density structures clearly identified inside corotating structures. This analysis confirms that most of the corotating density structures detected by the heliospheric imagers comprises a series of density inhomogeneities advected by the slow solar wind that eventually become entrained by stream interaction regions. We have derived the spatial-temporal evolution of each of these corotating density structures by using a well-established fitting technique. The mean radial propagation speed of the corotating structures is found to be 311 ±31 km s^{-1}. Such a low mean value corresponds to the terminal speed of the slow solar wind rather than the speed of stream interfaces, which is typically intermediate between the slow and fast solar wind speeds ({˜} 400 km s^{-1}). Using our fitting technique, we predicted the arrival time of each corotating density structure at different probes in the inner heliosphere. We find that our derived speeds are systematically lower by {˜} 100 km s^{-1} than those measured in situ at the predicted impact times. Moreover, for cases when a stream interaction region is clearly detected in situ at the estimated impact time, we find that our derived speeds are lower than the speed of the

  19. Long-Term Tracking of Corotating Density Structures Using Heliospheric Imaging

    NASA Astrophysics Data System (ADS)

    Plotnikov, I.; Rouillard, A. P.; Davies, J. A.; Bothmer, V.; Eastwood, J. P.; Gallagher, P.; Harrison, R. A.; Kilpua, E.; Möstl, C.; Perry, C. H.; Rodriguez, L.; Lavraud, B.; Génot, V.; Pinto, R. F.; Sanchez-Diaz, E.

    2016-06-01

    The systematic monitoring of the solar wind in high-cadence and high-resolution heliospheric images taken by the Solar-Terrestrial Relation Observatory (STEREO) spacecraft permits the study of the spatial and temporal evolution of variable solar wind flows from the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7) Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project, we have generated a catalog listing the properties of 190 corotating structures well-observed in images taken by the Heliospheric Imager (HI) instruments onboard STEREO-A (ST-A). Based on this catalog, we present here one of very few long-term analyses of solar wind structures advected by the background solar wind. We concentrate on the subset of plasma density structures clearly identified inside corotating structures. This analysis confirms that most of the corotating density structures detected by the heliospheric imagers comprises a series of density inhomogeneities advected by the slow solar wind that eventually become entrained by stream interaction regions. We have derived the spatial-temporal evolution of each of these corotating density structures by using a well-established fitting technique. The mean radial propagation speed of the corotating structures is found to be 311 ±31 km s^{-1}. Such a low mean value corresponds to the terminal speed of the slow solar wind rather than the speed of stream interfaces, which is typically intermediate between the slow and fast solar wind speeds ( {˜} 400 km s^{-1}). Using our fitting technique, we predicted the arrival time of each corotating density structure at different probes in the inner heliosphere. We find that our derived speeds are systematically lower by {˜} 100 km s^{-1} than those measured in situ at the predicted impact times. Moreover, for cases when a stream interaction region is clearly detected in situ at the estimated impact time, we find that our derived speeds are lower than the speed of the

  20. Noise properties of the CoRoT data. A planet-finding perspective

    NASA Astrophysics Data System (ADS)

    Aigrain, S.; Pont, F.; Fressin, F.; Alapini, A.; Alonso, R.; Auvergne, M.; Barbieri, M.; Barge, P.; Bordé, P.; Bouchy, F.; Deeg, H.; de La Reza, R.; Deleuil, M.; Dvorak, R.; Erikson, A.; Fridlund, M.; Gondoin, P.; Guterman, P.; Jorda, L.; Lammer, H.; Léger, A.; Llebaria, A.; Magain, P.; Mazeh, T.; Moutou, C.; Ollivier, M.; Pätzold, M.; Queloz, D.; Rauer, H.; Rouan, D.; Schneider, J.; Wuchter, G.; Zucker, S.

    2009-10-01

    In this short paper, we study the photometric precision of stellar light curves obtained by the CoRoT satellite in its planet-finding channel, with a particular emphasis on the time scales characteristic of planetary transits. Together with other articles in the same issue of this journal, it forms an attempt to provide the building blocks for a statistical interpretation of the CoRoT planet and eclipsing binary catch to date. After pre-processing the light curves so as to minimise long-term variations and outliers, we measure the scatter of the light curves in the first three CoRoT runs lasting more than 1 month, using an iterative non-linear filter to isolate signal on the time scales of interest. The behaviour of the noise on 2 h time scales is described well by a power-law with index 0.25 in R-magnitude, ranging from 0.1 mmag at R=11.5 to 1 mmag at R=16, which is close to the pre-launch specification, though still a factor 2-3 above the photon noise due to residual jitter noise and hot pixel events. There is evidence of slight degradation in the performance over time. We find clear evidence of enhanced variability on hour time scales (at the level of 0.5 mmag) in stars identified as likely giants from their R magnitude and B-V colour, which represent approximately 60 and 20% of the observed population in the directions of Aquila and Monoceros, respectively. On the other hand, median correlated noise levels over 2 h for dwarf stars are extremely low, reaching 0.05 mmag at the bright end. The CoRoT space mission, launched on December 27, 2006, has been developed and is operated by the CNES, with the contribution of Austria, Belgium, Brazil, ESA, Germany, and Spain. CoRoT data become publicly available one year after release to the Co-Is of the mission from the CoRoT archive: http://idoc-corot.ias.u-psud.fr/.

  1. Detection of Rossby Waves in Multi-Parameters in Multi-Mission Satellite Observations and HYCOM Simulations in the Indian Ocean

    NASA Technical Reports Server (NTRS)

    Subrahmanyam, Bulusu; Heffner, David M.; Cromwell, David; Shriver, Jay F.

    2009-01-01

    Rossby waves are difficult to detect with in situ methods. However, as we show in this paper, they can be clearly identified in multi-parameters in multi-mission satellite observations of sea surface height (SSH), sea surface temperature (SST) and ocean color observations of chlorophyll-a (chl-a), as well as 1/12-deg global HYbrid Coordinate Ocean Model (HYCOM) simulations of SSH, SST and sea surface salinity (SSS) in the Indian Ocean. While the surface structure of Rossby waves can be elucidated from comparisons of the signal in different sea surface parameters, models are needed to gain direct information about how these waves affect the ocean at depth. The first three baroclinic modes of the Rossby waves are inferred from the Fast Fourier Transform (FFT), and two-dimensional Radon Transform (2D RT). At many latitudes the first and second baroclinic mode Rossby wave phase speeds from satellite observations and model parameters are identified.

  2. First observational Evidence of Rossby Wave Signatures in Spectral Aerosol Optical Depths over Central Himalayas

    NASA Astrophysics Data System (ADS)

    Devulapalli, P. V.; Kondapalli, N. K.; Krishna, S.; Ratnam, M.; Naja, M. K.; Kishore, R.

    2013-12-01

    retrieved AOD (550nm). These signatures are also observed in background winds with westward propagation at a speed of ~ 2ms-1. Further, the Hovmoller diagram obtained from MODIS AOD also showed westward propagation through the observational site, re-confirming that these modulations are associated with Rossby waves of extra-tropical region. It is shown that inclusion of the Rossby wave modulation can cause an additional warming of ~ 4.07×0.98 Wm-2 over Central Himalayan region. The present study finds important implications in terms of wave induced dynamics of aerosols which have immense impact on atmospheric radiative forcing.

  3. The transport of angular momentum by gravitational instabilities and Rossby vortices in accretion disks

    NASA Astrophysics Data System (ADS)

    Currier, Nathaniel W.

    We propose a model for the birth of spiral galaxies and the supermassive black holes (SMBHs) at their centers. It all starts when a galaxy-mass gas condensation collapses to ~ 200 × the background density. It experiences weak tidal torques from similar condensations, which establish its spin parameter l. It forms a Lyman-a (Lya) cloud, then undergoes an inviscid, angular-momentum- preserving collapse to a Mestel disk with a flat rotation curve (FRCD). A FRCD has v ~ const, M Rossby vortex instability (RVI). Both mechanisms transport angular momentum coherently, so they easily dominate turbulent mechanisms wherever the disk is thin. The popular magneto-rotational instability (MRI) is semi-coherent, but it's not required for our model, so we leave it for further study. We use a 2-D Eulerian hydro code to simulate the SGI and RVI in both FRCDs and Keplerian disks. We explore the triggers of these instabilities, namely, the Toomre parameter Q in SGI-unstable FRCDs and pressure jumps in RVI-unstable Keplerian disks. We confirm that Q [Special characters omitted.] 1 triggers the SGI in FRCDs and that D P/P [Special characters omitted.] 5 generates robust Rossby vortices in Keplerian disks. We also find that these instabilities interact in the transition region between these two types of disks. We relate all this to our self-consistent model

  4. Excitation of zonal flow and magnetic field by Rossby-Khantadze electromagnetic planetary waves in the ionospheric E-layer

    NASA Astrophysics Data System (ADS)

    Kaladze, T. D.; Kahlon, L. Z.; Tsamalashvili, L. V.

    2012-02-01

    Nonlinear dynamics of Rossby-Khantadze electromagnetic planetary waves in the weakly ionized ionospheric E-layer is investigated. Along with the prevalent effect of Hall conductivity for these waves, the latitudinal inhomogeneity of both the Earth's angular velocity and the geomagnetic field becomes essential. It is shown that such short wavelength turbulence of Rossby-Khantadze waves is unstable with respect to the excitation of low-frequency and large-scale perturbations of the zonal flow and magnetic field. The nonlinear mechanism of the instability is driven by the advection of vorticity, leading to the inverse energy cascade toward the longer wavelength. The growth rate of the corresponding instability is found. It is shown that the generation of the intense mean magnetic field is caused by the latitudinal gradient of the geomagnetic field.

  5. VizieR Online Data Catalog: Planetary transit candidates in CoRoT LRa01 field (Carone+, 2012)

    NASA Astrophysics Data System (ADS)

    Carone, L.; Gandolfi, D.; Cabrera, J.; Hatzes, A. P.; Deeg, H. J.; Csizmadia, Sz.; Paetzold, M.; Weingrill, J.; Aigrain, S.; Alonso, R.; Alapini, A.; Almenara, J.-M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Borde, P.; Bouchy, F.; Bruntt, H.; Carpano, S.; Cochran, W. D.; Deleuil, M.; Diaz, R. F.; Dreizler, S.; Dvorak, R.; Eisloeffel, J.; Eigmueller, P.; Endl, M.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gazzano, J.-C.; Gibson, N.; Gillon, M.; Gondoin, P.; Grziwa, S.; Guenther, E. W.; Guillot, T.; Hartmann, M.; Havel, M.; Hebrard, G.; Jorda, L.; Kabath, P.; Leger, A.; Llebaria, A.; Lammer, H.; Lovis, C.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.; Nortmann, L.; Ofir, A.; Ollivier, M.; Parviainen, H.; Pepe, F.; Pont, F.; Queloz, D.; Rabus, M.; Rauer, H.; Regulo, C.; Renner, S.; de La, Reza R.; Rouan, D.; Santerne, A.; Samuel, B.; Schneider, J.; Shporer, A.; Stecklum, B.; Tal-Or, L.; Tingley, B.; Udry, S.; Wuchterl, G.

    2012-04-01

    We present the list of planetary transit candidates from the CoRoT LRa01 star field in the Monoceros constellation toward the Galactic anti-center direction. The CoRoT observations of LRa01 lasted from 24 October 2007 to 3 March 2008. We acquired and analyzed 7470 chromatic and 3938 monochromatic lightcurves. Instrumental noise and stellar variability were treated with several filtering tools by different teams from the CoRoT community. Different transit search algorithms were applied to the lightcurves. (4 data files).

  6. A Possible Rossby Wave Instability Origin for the Flares in Sagittarius A*

    NASA Astrophysics Data System (ADS)

    Tagger, Michel; Melia, Fulvio

    2006-01-01

    In recent years, near-IR and X-ray flares have been detected from the Galaxy's central radio point source, Sagittarius A* (Sgr A*), believed to be an ~3×106 Msolar supermassive black hole. In some cases, the transient emission appears to be modulated with a (quasi-)periodic oscillation (QPO) of ~17-20 minutes. The implied ~3rS size of the emitter (where rS≡2GM/c2 is the Schwarzschild radius) points to an instability-possibly induced by accretion-near the marginally stable orbit (MSO) of a slowly spinning object. But Sgr A* is not accreting via a large, ``standard'' disk; instead, the low-density environment surrounding it apparently feeds the black hole with low angular momentum clumps of plasma that circularize within ~(10-300)rS and merge onto a compact, hot disk. In this Letter, we follow the evolution of the disk following such an event, and we show that a Rossby wave instability, particularly in its magnetohydrodynamic (MHD) form, grows rapidly and produces a period of enhanced accretion lasting several hours. Both the amplitude of this response and its duration match the observed flare characteristics rather well.

  7. Rossby wave energy dispersion from tropical cyclone in zonal basic flows

    NASA Astrophysics Data System (ADS)

    Shi, Wenli; Fei, Jianfang; Huang, Xiaogang; Liu, Yudi; Ma, Zhanhong; Yang, Lu

    2016-04-01

    This study investigates tropical cyclone energy dispersion under horizontally sheared flows using a nonlinear barotropic model. In addition to common patterns, unusual features of Rossby wave trains are also found in flows with constant vorticity and vorticity gradients. In terms of the direction of the energy dispersion, the wave train can rotate clockwise and elongate southwestward under anticyclonic circulation (ASH), which contributes to the reenhancement of the tropical cyclone (TC). The wave train even splits into two obvious wavelike trains in flows with a southward vorticity gradient (WSH). Energy dispersed from TCs varies over time, and variations in the intensity of the wave train components typically occur in two stages. Wave-activity flux diagnosis and ray tracing calculations are extended to the frame that moves along with the TC to reveal the concrete progress of wave propagation. The direction of the wave-activity flux is primarily determined by the combination of the basic flow and the TC velocity. Along the flux, the distribution of pseudomomentum effectively illustrates the development of wave trains, particularly the rotation and split of wave propagation. Ray tracing involves the quantitative tracing of wave features along rays, which effectively coincide with the wave train regimes. Flows of a constant shear (parabolic meridional variation) produce linear (nonlinear) wave number variations. For the split wave trains, the real and complex wave number waves move along divergent trajectories and are responsible for different energy dispersion ducts.

  8. Persistent and energetic bottom-trapped topographic Rossby waves observed in the southern South China Sea

    NASA Astrophysics Data System (ADS)

    Shu, Yeqiang; Xue, Huijie; Wang, Dongxiao; Chai, Fei; Xie, Qiang; Cai, Shuqun; Chen, Rongyu; Chen, Ju; Li, Jian; He, Yunkai

    2016-04-01

    Energetic fluctuations with periods of 9–14 days below a depth of 1400 m were observed in the southern South China Sea (SCS) from 5 years of direct measurements. We interpreted such fluctuations as topographic Rossby waves (TRWs) because they obey the dispersion relation. The TRWs persisted from May 24, 2009 to August 23, 2013, and their bottom current speed with a maximum of ~10 cm/s was one order of magnitude greater than the mean current and comparable to the tidal currents near the bottom. The bottom-trapped TRWs had an approximate trapping depth of 325 m and reference wavelength of ~82 km, which were likely excited by eddies above. Upper layer current speed that peaked approximately every 2 months could offer the energy sources for the persistent TRWs in the southern SCS. Energetic bottom-trapped TRWs may have a comparable role in deep circulation to tides in areas with complex topography.

  9. Persistent and energetic bottom-trapped topographic Rossby waves observed in the southern South China Sea

    PubMed Central

    Shu, Yeqiang; Xue, Huijie; Wang, Dongxiao; Chai, Fei; Xie, Qiang; Cai, Shuqun; Chen, Rongyu; Chen, Ju; Li, Jian; He, Yunkai

    2016-01-01

    Energetic fluctuations with periods of 9–14 days below a depth of 1400 m were observed in the southern South China Sea (SCS) from 5 years of direct measurements. We interpreted such fluctuations as topographic Rossby waves (TRWs) because they obey the dispersion relation. The TRWs persisted from May 24, 2009 to August 23, 2013, and their bottom current speed with a maximum of ~10 cm/s was one order of magnitude greater than the mean current and comparable to the tidal currents near the bottom. The bottom-trapped TRWs had an approximate trapping depth of 325 m and reference wavelength of ~82 km, which were likely excited by eddies above. Upper layer current speed that peaked approximately every 2 months could offer the energy sources for the persistent TRWs in the southern SCS. Energetic bottom-trapped TRWs may have a comparable role in deep circulation to tides in areas with complex topography. PMID:27075644

  10. Atmospheric Transport and Mixing linked to Rossby Wave Breaking in GFDL Dynamical Core

    NASA Astrophysics Data System (ADS)

    Liu, C.; Barnes, E. A.

    2015-12-01

    Atmospheric transport and mixing plays an important role in the global energy balance and the distribution of health-related chemical constituents. Previous studies suggest a close linkage between large-scale transport and Rossby wave breaking (RWB). In this work, we use the GFDL spectral dynamical core to investigate this relationship and study the response of RWB-related transport in different climate scenarios. In a standard control run, we quantify the contribution of RWB to the total transport and mixing of an idealized tracer. In addition, we divide the contribution further into the two types of RWB - anticyclonic wave breaking (AWB) and cyclonic wave breaking (CWB) -- and contrast their efficiency at transport and mixing. Our results are compared to a previous study in which the transport ability of the two types of RWB is studied for individual baroclinic wave life-cycles. In a series of sensitivity runs, we study the response of RWB-related transport and mixing to various states of the jet streams. The responses of the mean strength, frequency, and the efficiency of RWB-related transport are documented and the implications for the transport and mixing in a warmer climate are discussed.

  11. The Rossby Centre Regional Atmospheric Climate Model part II: application to the Arctic climate.

    PubMed

    Jones, Colin G; Wyser, Klaus; Ullerstig, Anders; Willén, Ulrika

    2004-06-01

    The Rossby Centre regional climate model (RCA2) has been integrated over the Arctic Ocean as part of the international ARCMIP project. Results have been compared to observations derived from the SHEBA data set. The standard RCA2 model overpredicts cloud cover and downwelling longwave radiation, during the Arctic winter. This error was improved by introducing a new cloud parameterization, which significantly improves the annual cycle of cloud cover. Compensating biases between clear sky downwelling longwave radiation and longwave radiation emitted from cloud base were identified. Modifications have been introduced to the model radiation scheme that more accurately treat solar radiation interaction with ice crystals. This leads to a more realistic representation of cloud-solar radiation interaction. The clear sky portion of the model radiation code transmits too much solar radiation through the atmosphere, producing a positive bias at the top of the frequent boundary layer clouds. A realistic treatment of the temporally evolving albedo, of both sea-ice and snow, appears crucial for an accurate simulation of the net surface energy budget. Likewise, inclusion of a prognostic snow-surface temperature seems necessary, to accurately simulate near-surface thermodynamic processes in the Arctic. PMID:15264599

  12. Penetration of nonlinear Rossby eddies into South China Sea evidenced by cruise data

    NASA Astrophysics Data System (ADS)

    Hu, Jianyu; Zheng, Quanan; Sun, Zhenyu; Tai, Chang-Kuo

    2012-03-01

    From the analyses of the cruise conductivity-temperature-depth profiler and acoustic Doppler current profiler data combined with simultaneous satellite altimeter data and Argo float profiling data, this paper provides evidence for the nonlinear Rossby eddies (NREs) penetrating through the Kuroshio and the Luzon Strait and entering the South China Sea (SCS). A high-salinity water prism in the subsurface layer west of the Luzon Strait was observed in January 2010. The salty prism centered at around 21°N and 118°E has a salinity higher than 34.8 and co-locates with an anticyclonic eddy with a diameter of about 150 km. The water properties of the salty prism are close to those of the Northwest Pacific (NWP) water. The time series of altimeter data and Argo float profiling data indicate that the anticyclonic eddy originates from an NRE that propagates westward from the NWP. The eddy penetrates the Luzon Strait at a speed of about 0.6 m s-1 because of the effects of the narrow strait and the Kuroshio-eddy interaction and carries the high-salinity subsurface water from the NWP into the northern SCS.

  13. Persistent and energetic bottom-trapped topographic Rossby waves observed in the southern South China Sea.

    PubMed

    Shu, Yeqiang; Xue, Huijie; Wang, Dongxiao; Chai, Fei; Xie, Qiang; Cai, Shuqun; Chen, Rongyu; Chen, Ju; Li, Jian; He, Yunkai

    2016-01-01

    Energetic fluctuations with periods of 9-14 days below a depth of 1400 m were observed in the southern South China Sea (SCS) from 5 years of direct measurements. We interpreted such fluctuations as topographic Rossby waves (TRWs) because they obey the dispersion relation. The TRWs persisted from May 24, 2009 to August 23, 2013, and their bottom current speed with a maximum of ~10 cm/s was one order of magnitude greater than the mean current and comparable to the tidal currents near the bottom. The bottom-trapped TRWs had an approximate trapping depth of 325 m and reference wavelength of ~82 km, which were likely excited by eddies above. Upper layer current speed that peaked approximately every 2 months could offer the energy sources for the persistent TRWs in the southern SCS. Energetic bottom-trapped TRWs may have a comparable role in deep circulation to tides in areas with complex topography. PMID:27075644

  14. Transiting exoplanets from the CoRoT space mission. XVII. The hot Jupiter CoRoT-17b: a very old planet

    NASA Astrophysics Data System (ADS)

    Csizmadia, Sz.; Moutou, C.; Deleuil, M.; Cabrera, J.; Fridlund, M.; Gandolfi, D.; Aigrain, S.; Alonso, R.; Almenara, J.-M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Bruntt, H.; Carone, L.; Carpano, S.; Cavarroc, C.; Cochran, W.; Deeg, H. J.; Díaz, R. F.; Dvorak, R.; Endl, M.; Erikson, A.; Ferraz-Mello, S.; Fruth, Th.; Gazzano, J.-C.; Gillon, M.; Guenther, E. W.; Guillot, T.; Hatzes, A.; Havel, M.; Hébrard, G.; Jehin, E.; Jorda, L.; Léger, A.; Llebaria, A.; Lammer, H.; Lovis, C.; MacQueen, P. J.; Mazeh, T.; Ollivier, M.; Pätzold, M.; Queloz, D.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Tingley, B.; Titz-Weider, R.; Wuchterl, G.

    2011-07-01

    We report on the discovery of a hot Jupiter-type exoplanet, CoRoT-17b, detected by the CoRoT satellite. It has a mass of 2.43 ± 0.30 MJup and a radius of 1.02 ± 0.07 RJup, while its mean density is 2.82 ± 0.38 g/cm3. CoRoT-17b is in a circular orbit with a period of 3.7681 ± 0.0003 days. The host star is an old (10.7 ± 1.0 Gyr) main-sequence star, which makes it an intriguing object for planetary evolution studies. The planet's internal composition is not well constrained and can range from pure H/He to one that can contain ~380 earth masses of heavier elements. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Part of the observations were obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. Based on observations made with HARPS spectrograph on the 3.6-m European Organisation for Astronomical Research in the Southern Hemisphere telescope at La Silla Observatory, Chile (ESO program 184.C-0639). Based on observations made with the IAC80 telescope operated on the island of Tenerife by the Instituto de Astrofísica de Canarias in the Spanish Observatorio del Teide. Part of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  15. VizieR Online Data Catalog: Algorithm for correcting CoRoT raw light curves (Mislis+, 2010)

    NASA Astrophysics Data System (ADS)

    Mislis, D.; Schmitt, J. H. M. M.; Carone, L.; Guenther, E. W.; Patzold, M.

    2010-10-01

    Requirements : gfortran (or g77, ifort) compiler Input Files : The input files sould be raw CoRoT txt files (http://idoc-corot.ias.u-psud.fr/index.jsp) with names CoRoT*.txt Run the cda by typing C>: ./cda.csh (code and data sould be in the same directory) Output files : CDA creates one ascii output file with name - CoRoT*.R.cor for R filter (2 data files).

  16. Corotating MeV/amu ion enhancements at 1 AU or less from 1978 to 1986

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Barbier, L. M.; Reames, D. V.; Von Rosenvinge, T. T.

    1993-01-01

    The properties of MeV/amu ions in 64 corotating streams at and inside 1 AU associated with corotating high-speed streams from 1978 to 1986 during presolar maximum to near solar minimum conditions are discussed. Around 50 percent of the streams include significant ion intensity enhancements not associated with solar particle events or traveling interplanetary shocks. The ions stream nearly along the E x B drift direction in the spacecraft frame, corresponding to a weak sunward field-aligned streaming in the solar wind frame. The sunward streaming is consistent with particle acceleration in the outer heliosphere followed by diffusion into the inner heliosphere. The ion intensity is not correlated with the stream solar wind speed or with the increase in solar wind speed at the leading edge of the high-speed stream, suggesting that the local shock strength alone may not play a dominant role in determining the intensity.

  17. Global regularity for the 2D Oldroyd-B model in the corotational case

    NASA Astrophysics Data System (ADS)

    Ye, Zhuan; Xu, Xiaojing

    2016-09-01

    This paper is dedicated to the Oldroyd-B model with fractional dissipation $(-\\Delta)^{\\alpha}\\tau$ for any $\\alpha>0$. We establish the global smooth solutions to the Oldroyd-B model in the corotational case with arbitrarily small fractional powers of the Laplacian in two spatial dimensions. The methods described here are quite different from the tedious iterative approach used in recent paper \\cite{XY}. Moreover, in the Appendix we provide some a priori estimates to the Oldroyd-B model in the critical case which may be useful and of interest for future improvement. Finally, the global regularity to to the Oldroyd-B model in the corotational case with $-\\Delta u$ replaced by $(-\\Delta)^{\\gamma}u$ for $\\gamma>1$ are also collected in the Appendix. Therefore our result is more closer to the resolution of the well-known global regularity issue on the critical 2D Oldroyd-B model.

  18. Stellar parameters for stars of the CoRoT exoplanet field

    NASA Astrophysics Data System (ADS)

    Cortés, C.; Maciel, S. C.; Vieira, S.; Ferreira Lopes, C. E.; Leão, I. C.; de Oliveira, G. P.; Correia, C.; Canto Martins, B. L.; Catelan, M.; De Medeiros, J. R.

    2015-09-01

    Context. Spectroscopic observations represent a fundamental step in the physical characterization of stars and, in particular, in the precise location of stars in the HR diagram. Rotation is also a key parameter, impacting stellar properties and evolution, which modulates the interior and manifests itself on the surface of stars. To date, the lack of analysis based on large samples has prevented our understanding of the real impact of stellar parameters and rotation on the stellar evolution as well as on the behavior of surface abundances. The space missions, CoRoT and Kepler, are providing us with rotation periods for thousands of stars, thus enabling a robust assessment of the behavior of rotation for different populations and evolutionary stages. For these reasons, the follow-up programs are fundamental to increasing the returns of these space missions. An analysis that combines spectroscopic data and rotation/modulation periods obtained from these space missions provides the basis for establishing the evolutionary behavior of the angular momentum of solar-like stars at different evolutionary stages, and the relation of rotation with other relevant physical and chemical parameters. Aims: To support the computation and evolutionary interpretation of periods associated with the rotational modulation, oscillations, and variability of stars located in the CoRoT fields, we are conducting a spectroscopic survey for stars located in the fields already observed by the satellite. These observations allow us to compute physical and chemical parameters for our stellar sample. Methods: Using spectroscopic observations obtained with UVES/VLT and Hydra/Blanco, and based on standard analysis techniques, we computed physical and chemical parameters (Teff, log (g), [Fe/H], vmic, vrad, vsin (i), and A(Li)) for a large sample of CoRoT targets. Results: We provide physical and chemical parameters for a sample comprised of 138 CoRoT targets. Our analysis shows the stars in our

  19. The Transit Detection Algorithm DST and its application to CoRoT and Kepler data

    NASA Astrophysics Data System (ADS)

    Cabrera, J.; Rauer, H.; Erikson, A.; Csizmadia, S.

    2011-10-01

    Transit detection algorithms are mathematical tools used to detect the presence of planets in the photometric data of transit surveys. Space missions are exploring the parameter space of transit surveys towards small planets where classical algorithms do not perform optimally, either due to the low signal to noise ratio of the signal or to its non-periodic characteristics. We present an algorithm addressing these challenges and its performance in an application to CoRoT and Kepler data.

  20. A rotating Michelson interferometer from the co-rotating point of view

    NASA Astrophysics Data System (ADS)

    Maraner, Paolo

    2016-06-01

    The phase shift induced by a uniform rotation in a Michelson interferometer is re-derived in the geometrical framework of the coordinate-free formalism of general relativity from the co-rotating point of view. The effect is second order in the ratio of the interferometer's speed to the speed of light and further suppressed by the ratio of the length of the interferometer's arms to the radius of rotation. The relation of the effect to gravitational time dilation is discussed.

  1. VizieR Online Data Catalog: CoRoT 105906206 frequencies analysis (da Silva+, 2014)

    NASA Astrophysics Data System (ADS)

    da Silva, R.; Maceroni, C.; Gandolfi, D.; Lehmann, H.; Hatzes, A. P.

    2014-03-01

    The file frequenc.dat contains the table with 220 frequencies, amplitudes, and phases, together with their uncertainties, derived for the light curve of CoRoT 105906206 with pulsations only (after subtracting the best binary model). The uncertainties are the formal values computed using equations (4), (10), and (11) of Montgomery & O'Donoghue (1999DSSN...13...28M). (1 data file).

  2. Observed departure of the Io plasma torus from rigid corotation with Jupiter

    NASA Technical Reports Server (NTRS)

    Brown, R. A.

    1983-01-01

    A study of forbidden S II red doublet spectra indicates that the Io plasma torus at 5.9 Jupiter radii does not corotate rigidly with Jupiter. The lag is found to be 6 percent + or 4 percent, where the variability range, not the uncertainty, is indicated. Comparison with existing models indicates the lag may be due primarily to ion creation in the Io torus.

  3. THE FUTURE OF THE SUN: AN EVOLVED SOLAR TWIN REVEALED BY CoRoT

    SciTech Connect

    Do Nascimento, J.-D. Jr.; Da Costa, J. S.; Castro, M.; Takeda, Y.; Melendez, J.

    2013-07-10

    The question of whether the Sun is peculiar within the class of solar-type stars has been the subject of active investigation over the past three decades. Although several solar twins have been found with stellar parameters similar to those of the Sun (albeit in a range of Li abundances and with somewhat different compositions), their rotation periods are unknown, except for 18 Sco, which is younger than the Sun and with a rotation period shorter than solar. It is difficult to obtain rotation periods for stars of solar age from ground-based observations, as a low-activity level implies a shallow rotational modulation of their light curves. CoRoT has provided space-based long time series from which the rotation periods of solar twins as old as the Sun could be estimated. Based on high-signal-to-noise, high-resolution spectroscopic observations gathered at the Subaru Telescope, we show that the star CoRoT ID 102684698 is a somewhat evolved solar twin with a low Li abundance. Its rotation period is 29 {+-} 5 days, compatible with its age (6.7 Gyr) and low lithium content, A{sub Li} {approx}< 0.85 dex. Interestingly, our CoRoT solar twin seems to have enhanced abundances of the refractory elements with respect to the Sun, a typical characteristic of most nearby twins. With a magnitude V {approx_equal} 14.1, ID 102684698 is the first solar twin revealed by CoRoT, the farthest field solar twin so far known, and the only solar twin older than the Sun for which a rotation period has been determined.

  4. On the mechanism of self gravitating Rossby interfacial waves in proto-stellar accretion discs

    NASA Astrophysics Data System (ADS)

    Yellin-Bergovoy, Ron; Heifetz, Eyal; Umurhan, Orkan M.

    2016-05-01

    The dynamical response of edge waves under the influence of self-gravity is examined in an idealized two-dimensional model of a proto-stellar disc, characterized in steady state as a rotating vertically infinite cylinder of fluid with constant density except for a single density interface at some radius r0. The fluid in basic state is prescribed to rotate with a Keplerian profile $\\Omega_k(r)\\sim r^{-3/2}$ modified by some additional azimuthal sheared flow. A linear analysis shows that there are two azimuthally propagating edge waves, kin to the familiar Rossby waves and surface gravity waves in terrestrial studies, which move opposite to one another with respect to the local basic state rotation rate at the interface. Instability only occurs if the radial pressure gradient is opposite to that of the density jump (unstably stratified) where self-gravity acts as a wave stabilizer irrespective of the stratification of the system. The propagation properties of the waves are discussed in detail in the language of vorticity edge waves. The roles of both Boussinesq and non-Boussinesq effects upon the stability and propagation of these waves with and without the inclusion of self-gravity are then quantified. The dynamics involved with self-gravity non- Boussinesq effect is shown to be a source of vorticity production where there is a jump in the basic state density, in addition, self-gravity also alters the dynamics via the radial main pressure gradient, which is a Boussinesq effect . Further applications of these mechanical insights are presented in the conclusion including the ways in which multiple density jumps or gaps may or may not be stable.

  5. North and South Atlantic Bidecadal SL variability: Rossby Waves, AMOC fingerprints and Regime Shifts

    NASA Astrophysics Data System (ADS)

    Vianna, M. L.; Menezes, V. V.

    2014-12-01

    The relationship between the North and South Atlantic bidecadal sea level (SL) oscillations in the twentieth century (1908-2008) is investigated using SODA 2.2.4 reanalysis and 102 monthly mean SL time series from TG stations provided by PSMSL. Bidecadal SL signal extraction was done using our method of subjectively choosing groupings of space-time data into non-overlapping period bands by use of Singular Spectrum Analysis (SSA)/ Maximum Entropy Method (MEM) analysis. A CEOF analysis of the SODA bidecadal band shows dominance of 22-24 year periods. Propagating bidecadal mode expansions were then determined through this analysis, which gives two principal modes. The first mode is dominant from 1915 to 1965 and the second from 1970 onward. The amplitude variabilities obtained suggests the presence of regime shifts, which coincide in time with shifts actually observed in European climate and South African lobster fisheries. The first mode is characterized by states with North and South Atlantic subtropical gyres in phase, while tropical and subpolar regions are in opposite phase relative to them. The second mode is characterized by the subpolar gyre and North subtropical gyre almost in quadrature, with North and South subtropical gyres out of phase. The evolution mechanism of this latter mode is related to east-west density contrasts and westward propagating Rossby waves. These waves show phase speeds dominated by geostrophic self-advection of density anomalies relative to the mean meridional density gradient as known from previous studies, but are shown to be additionally influenced by bottom topography. The oscillations caused by these waves are shown to have phase differences (quadrature in the North Atlantic) with regional indices of bidecadal AMOC oscillations. A number of SL-AMOC fingerprints are also reviewed, and a new eastern equatorial fingerprint is proposed.

  6. Rossby wave instability and long-term evolution of dead zones in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Miranda, Ryan; Lai, Dong; Méheut, Héloïse

    2016-04-01

    The physical mechanism of angular momentum transport in poorly ionized regions of protoplanetary discs, the dead zones (DZs), is not understood. The presence of a DZ naturally leads to conditions susceptible to the Rossby wave instability (RWI), which produces vortices and spiral density waves that may revive the DZ and be responsible for observed large-scale disc structures. We present a series of two-dimensional hydrodynamic simulations to investigate the role of the RWI in DZs, including its impact on the long-term evolution of the disc and its morphology. The non-linear RWI can generate Reynolds stresses (effective α parameter) as large as 0.01-0.05 in the DZ, helping to sustain quasi-steady accretion throughout the disc. It also produces novel disc morphologies, including azimuthal asymmetries with m = 1, 2, and atypical vortex shapes. The angular momentum transport strength and morphology are most sensitive to two parameters: the radial extent of the DZ and the disc viscosity. The largest Reynolds stresses are produced when the radial extent of the DZ is less than its distance to the central star. Such narrow DZs lead to a single vortex or two coherent antipodal vortices in the quasi-steady state. The edges of wider DZs evolve separately, resulting in two independent vortices and reduced angular momentum transport efficiency. In either case, we find that, because of the Reynolds stresses generated by the non-linear RWI, gravitational instability is unlikely to play a role in angular momentum transport across the DZ, unless the accretion rate is sufficiently high.

  7. Extreme Moisture Transport into the Arctic Linked to Rossby Wave Breaking

    NASA Astrophysics Data System (ADS)

    Liu, C.; Barnes, E. A.

    2014-12-01

    Water vapor plays an important role in the energetics of the Arctic. We demonstrate that the bulk of the poleward moisture transport by transients across 60N is driven by extreme transport events. These events are shown to be closely related to two types of Rossby wave breaking (RWB) - anticyclonic wave breaking (AWB) and cyclonic wave breaking (CWB). Using a RWB tracking algorithm, we determine that these two types can account for 47% of the total poleward moisture transport by transients across 60∘^circN in winter and 37% in summer. Additional analysis suggests that the seasonality of this RWB-related moisture transport is determined equally by the strength of RWB transport, and the frequency of RWB occurrence. The seasonality of RWB occurrence is, in turn, dictated by the seasonal variation of the latitude of the jet-streams - AWB (CWB) related transport occurs more frequently when the jet is shifted poleward (equatorward). The interannual variability of RWB-related transport across 60N in winter is shown to be strongly influenced by climate variability captured by ENSO and the NAO. In the positive (negative) phase of ENSO, AWB transports less (more) moisture through the Bering Strait and CWB transports more (less) through Canada. In the positive (negative) phase of the NAO, AWB transports more (less) moisture through the Norwegian Sea and CWB transports less (more) along the west coast of Greenland. These results highlight how low-frequency climate variability outside of the polar region can influence Arctic water vapor by modulating extreme synoptic transport events.

  8. Extreme moisture transport into the Arctic linked to Rossby wave breaking

    NASA Astrophysics Data System (ADS)

    Liu, Chengji; Barnes, Elizabeth A.

    2015-05-01

    The transport of moisture into the Arctic is tightly connected to midlatitude dynamics. We show that the bulk of the transient poleward moisture transport across 60°N is driven by extreme transport (fluxes greater than the 90th percentile) events. We demonstrate that these events are closely related to the two types of Rossby wave breaking (RWB)-anticyclonic wave breaking (AWB) and cyclonic wave breaking (CWB). Using a RWB tracking algorithm, we determine that RWB can account for approximately 68% of the extreme poleward moisture transport by transients across 60°N in winter and 56% in summer. Additional analysis suggests that the seasonality of such RWB-related moisture transport is determined approximately equally by (1) the magnitude of transport (which is largely a function of the background moisture gradient) and (2) the frequency of RWB occurrence. The seasonality of RWB occurrence is, in turn, tied to the seasonal variation of the latitude of the jet streams-AWB-related (CWB-related) transport occurs more frequently when the jet is shifted poleward (equatorward). The interannual variability of RWB-related transport across 60°N in winter is shown to be strongly influenced by climate variability captured by the El Niño/Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). In the positive (negative) phase of ENSO, AWB transports less (more) moisture through the Bering Strait and CWB transports more (less) through western Canada. In the positive (negative) phase of the NAO, AWB transports more (less) moisture through the Norwegian Sea and CWB transports less (more) along the west coast of Greenland. These results highlight that low-frequency climate variability outside of the polar regions can influence the Arctic water vapor by modulating extreme synoptic transport events.

  9. Uncovering the planets and stellar activity of CoRoT-7 using only radial velocities

    NASA Astrophysics Data System (ADS)

    Faria, J. P.; Haywood, R. D.; Brewer, B. J.; Figueira, P.; Oshagh, M.; Santerne, A.; Santos, N. C.

    2016-04-01

    Stellar activity can induce signals in the radial velocities of stars, complicating the detection of orbiting low-mass planets. We present a method to determine the number of planetary signals present in radial-velocity datasets of active stars, using only radial-velocity observations. Instead of considering separate fits with different number of planets, we use a birth-death Markov chain Monte Carlo algorithm to infer the posterior distribution for the number of planets in a single run. In a natural way, the marginal distributions for the orbital parameters of all planets are also inferred. This method is applied to HARPS data of CoRoT-7. We confidently recover the orbits of both CoRoT-7b and CoRoT-7c although the data show evidence for the presence of additional signals. All data and software presented in this article are available online at http://https://github.com/j-faria/exoBD-CoRoT7

  10. The CoRoT Discovery of a Unique Triple-mode Cepheid in the Galaxy

    NASA Astrophysics Data System (ADS)

    Poretti, E.; Baglin, A.; Weiss, W. W.

    2014-11-01

    The exploitation of the CoRoT treasure of stars observed in the exoplanetary field allowed the detection of a unusual triple-mode Cepheid in the Milky Way, CoRoT 0223989566. The two modes with the largest amplitudes and a period ratio of 0.80 are identified with the first (P 1 = 1.29 days) and second (P 2 = 1.03 days) radial overtones. The third period, which has the smallest amplitude but is able to produce combination terms with the other two, is the longest one (P 3 = 1.89 days). The ratio of 0.68 between the first-overtone period and the third period is the unusual feature. Its identification with the fundamental radial or a nonradial mode is discussed with respect to similar cases in the Magellanic Clouds. In both cases, the period triplet and the respective ratios make the star unique in our Galaxy. The distance derived from the period-luminosity relation and the galactic coordinates put CoRoT 0223989566 in the metal-rich environment of the "outer arm" of the Milky Way.

  11. A theoretical perspective on the ultra-compact systems of CoRoT and Kepler

    NASA Astrophysics Data System (ADS)

    Wuchterl, G.

    2011-10-01

    CoRoT and Kepler discovered closely spaced short period planetary systems. We investigate into the physics of these systems by combining an approach that was developed for the CoRoT mission to determine the distributions of planetary masses and radii based on a minimum number of basic physical principles with the classical approach of Hill-exclusion volumes to estimate dynamical stability. We discuss to what extent the discovered systems can be understood as a random draw from the theoretical mass and/or radius distributions with Hill-exclusion stability as a constraint. We point to the bi-modality of the theoretical planetary mass-function as a key factor in shaping the architecture of the presently known systems. Given the first-time availability of new high-resolution epoch-of observation theoretical radius distributions for the entire present period sensitivity of CoRoT and Keplerreleases, we take the opportunity to confront the various radius anomalies — 'styrofoam' planets, inflated Jupiters and Neptunes — to our statistical approach.

  12. THE CoRoT DISCOVERY OF A UNIQUE TRIPLE-MODE CEPHEID IN THE GALAXY

    SciTech Connect

    Poretti, E.; Baglin, A.; Weiss, W. W.

    2014-11-10

    The exploitation of the CoRoT treasure of stars observed in the exoplanetary field allowed the detection of a unusual triple-mode Cepheid in the Milky Way, CoRoT 0223989566. The two modes with the largest amplitudes and a period ratio of 0.80 are identified with the first (P {sub 1} = 1.29 days) and second (P {sub 2} = 1.03 days) radial overtones. The third period, which has the smallest amplitude but is able to produce combination terms with the other two, is the longest one (P {sub 3} = 1.89 days). The ratio of 0.68 between the first-overtone period and the third period is the unusual feature. Its identification with the fundamental radial or a nonradial mode is discussed with respect to similar cases in the Magellanic Clouds. In both cases, the period triplet and the respective ratios make the star unique in our Galaxy. The distance derived from the period-luminosity relation and the galactic coordinates put CoRoT 0223989566 in the metal-rich environment of the ''outer arm'' of the Milky Way.

  13. BEER analysis of Kepler and CoRoT light curves. III. Spectroscopic confirmation of seventy new beaming binaries discovered in CoRoT light curves

    NASA Astrophysics Data System (ADS)

    Tal-Or, L.; Faigler, S.; Mazeh, T.

    2015-08-01

    Context. The BEER algorithm searches stellar light curves for the BEaming, Ellipsoidal, and Reflection photometric modulations that are caused by a short-period companion. These three effects are typically of very low amplitude and can mainly be detected in light curves from space-based photometers. Unlike eclipsing binaries, these effects are not limited to edge-on inclinations. Aims: Applying the algorithm to wide-field photometric surveys such as CoRoT and Kepler offers an opportunity to better understand the statistical properties of short-period binaries. It also widens the window for detecting intrinsically rare systems, such as short-period brown-dwarf and massive-planetary companions to main-sequence stars. Methods: Applying the search to the first five long-run center CoRoT fields, we identified 481 non-eclipsing candidates with periodic flux amplitudes of 0.5-87 mmag. Optimizing the Anglo-Australian-Telescope pointing coordinates and the AAOmega fiber-allocations with dedicated softwares, we acquired six spectra for 231 candidates and seven spectra for another 50 candidates in a seven-night campaign. Analysis of the red-arm AAOmega spectra, which covered the range of 8342-8842 Å, yielded a radial-velocity precision of ~1 km s-1. Spectra containing lines of more than one star were analyzed with the two-dimensional correlation algorithm TODCOR. Results: The measured radial velocities confirmed the binarity of seventy of the BEER candidates - 45 single-line binaries, 18 double-line binaries, and 7 diluted binaries. We show that red giants introduce a major source of false candidates and demonstrate a way to improve BEER's performance in extracting higher fidelity samples from future searches of CoRoT light curves. The periods of the confirmed binaries span a range of 0.3-10 days and show a rise in the number of binaries per ΔlogP toward longer periods. The estimated mass ratios of the double-line binaries and the mass ratios assigned to the single

  14. An Analytic Model for Buoyancy Resonances in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Lubow, Stephen H.; Zhu, Zhaohuan

    2014-04-01

    Zhu et al. found in three-dimensional shearing box simulations a new form of planet-disk interaction that they attributed to a vertical buoyancy resonance in the disk. We describe an analytic linear model for this interaction. We adopt a simplified model involving azimuthal forcing that produces the resonance and permits an analytic description of its structure. We derive an analytic expression for the buoyancy torque and show that the vertical torque distribution agrees well with the results of the Athena simulations and a Fourier method for linear numerical calculations carried out with the same forcing. The buoyancy resonance differs from the classic Lindblad and corotation resonances in that the resonance lies along tilted planes. Its width depends on damping effects and is independent of the gas sound speed. The resonance does not excite propagating waves. At a given large azimuthal wavenumber ky > h -1 (for disk thickness h), the buoyancy resonance exerts a torque over a region that lies radially closer to the corotation radius than the Lindblad resonance. Because the torque is localized to the region of excitation, it is potentially subject to the effects of nonlinear saturation. In addition, the torque can be reduced by the effects of radiative heat transfer between the resonant region and its surroundings. For each azimuthal wavenumber, the resonance establishes a large scale density wave pattern in a plane within the disk.

  15. An analytic model for buoyancy resonances in protoplanetary disks

    SciTech Connect

    Lubow, Stephen H.; Zhu, Zhaohuan E-mail: zhzhu@astro.princeton.edu

    2014-04-10

    Zhu et al. found in three-dimensional shearing box simulations a new form of planet-disk interaction that they attributed to a vertical buoyancy resonance in the disk. We describe an analytic linear model for this interaction. We adopt a simplified model involving azimuthal forcing that produces the resonance and permits an analytic description of its structure. We derive an analytic expression for the buoyancy torque and show that the vertical torque distribution agrees well with the results of the Athena simulations and a Fourier method for linear numerical calculations carried out with the same forcing. The buoyancy resonance differs from the classic Lindblad and corotation resonances in that the resonance lies along tilted planes. Its width depends on damping effects and is independent of the gas sound speed. The resonance does not excite propagating waves. At a given large azimuthal wavenumber k{sub y} > h {sup –1} (for disk thickness h), the buoyancy resonance exerts a torque over a region that lies radially closer to the corotation radius than the Lindblad resonance. Because the torque is localized to the region of excitation, it is potentially subject to the effects of nonlinear saturation. In addition, the torque can be reduced by the effects of radiative heat transfer between the resonant region and its surroundings. For each azimuthal wavenumber, the resonance establishes a large scale density wave pattern in a plane within the disk.

  16. Constraints on the exosphere of CoRoT-7b

    NASA Astrophysics Data System (ADS)

    Guenther, E. W.; Cabrera, J.; Erikson, A.; Fridlund, M.; Lammer, H.; Mura, A.; Rauer, H.; Schneider, J.; Tulej, M.; von Paris, Ph.; Wurz, P.

    2011-01-01

    Context. The small radius and high density of CoRoT-7b implies that this transiting planet belongs to a different species than all transiting planets previously found. Current models suggest that this is the first transiting rocky planet found outside the solar system. Given that the planet orbits a solar-like star at a distance of only 4.5 R*, it is expected that material released from its surface may then form an exosphere. Aims: We constrain the properties of the exosphere by observing the planet in- and out-of-transit. Detecting the exosphere of CoRoT-7b would for the first time allow us to study the material originating in the surface of a rocky extrasolar planet. We scan the entire optical spectrum for any lines originating from the planet, focusing particularly on spectral lines such as those detected in Mercury and Io in our solar system. Methods: Since lines originating in the exosphere are expected to be narrow, we observed CoRoT-7b at high resolution with UVES on the VLT. By subtracting the two spectra from each other, we search for emission and absorption lines originating in the exosphere of CoRoT-7b. Results: In the first step, we focus on Ca I, Ca II, and Na, because these lines have been detected in Mercury. Since the signal-to-noise ratio (S/N) of the spectra is as high as 300, we derive firm upper limits for the flux-range between 1.6 × 10-18 and 3.2 × 10-18 W m-2. For CaO, we find an upper limit of 10-17 W m-2. We also search for emission lines originating in the plasma torus fed by volcanic activity and derive upper limits for these lines. In the whole spectrum we finally try to identify other lines originating in the planet. Conclusions: Except for CaO, the upper limits derived correspond to 2-6 × 10-6 L*, demonstrating the capability of UVES to detect very weak lines. Our observations certainly exclude the extreme interpretations of data for CoRoT-7b, such as an exosphere that emits 2000 times as brightly as Mercury. Based on observations

  17. Study of HD 169392A observed by CoRoT and HARPS

    NASA Astrophysics Data System (ADS)

    Mathur, S.; Bruntt, H.; Catala, C.; Benomar, O.; Davies, G. R.; García, R. A.; Salabert, D.; Ballot, J.; Mosser, B.; Régulo, C.; Chaplin, W. J.; Elsworth, Y.; Handberg, R.; Hekker, S.; Mantegazza, L.; Michel, E.; Poretti, E.; Rainer, M.; Roxburgh, I. W.; Samadi, R.; Stȩślicki, M.; Uytterhoeven, K.; Verner, G. A.; Auvergne, M.; Baglin, A.; Barceló Forteza, S.; Baudin, F.; Roca Cortés, T.

    2013-01-01

    Context. The results obtained by asteroseismology with data from space missions such as CoRoT and Kepler are providing new insights into stellar evolution. After five years of observations, CoRoT is continuing to provide high-quality data and we here present an analysis of the CoRoT observations of the double star HD 169392, complemented by ground-based spectroscopic observations. Aims: This work aims at characterising the fundamental parameters of the two stars, their chemical composition, the acoustic-mode global parameters including their individual frequencies, and their dynamics. Methods: We analysed HARPS observations of the two stars to derive their chemical compositions. Several methods were used and compared to determine the global properties of stars' acoustic modes and their individual frequencies from the photometric data of CoRoT. Results: The new spectroscopic observations and archival astrometric values suggest that HD 169392 is a weakly bound wide binary system. We obtained spectroscopic parameters for both components which suggest that they originate from the same interstellar cloud. However, only the signature of oscillation modes of HD 169392 A was measured; the signal-to-noise ratio of the modes in HD 169392B is too low to allow any confident detection. For HD 169392 A we were able to extract parameters of modes for ℓ = 0, 1, 2, and 3. The analysis of splittings and inclination angle gives two possible solutions: one with with splittings and inclination angles of 0.4-1.0 μHz and 20 - 40°, the other with 0.2-0.5 μHz and 55-86°. Modelling this star using the Asteroseismic Modeling Portal (AMP) gives a mass of 1.15 ± 0.01 M⊙, a radius of 1.88 ± 0.02 R⊙, and an age of 4.33 ± 0.12 Gyr. The uncertainties come from estimated errors on the observables but do not include uncertainties on the surface layer correction or the physics of stellar models. The CoRoT space mission, launched on December 27 2006, has been developed and is operated by

  18. HD 50844: a new look at δ Scuti stars from CoRoT space photometry

    NASA Astrophysics Data System (ADS)

    Poretti, E.; Michel, E.; Garrido, R.; Lefèvre, L.; Mantegazza, L.; Rainer, M.; Rodríguez, E.; Uytterhoeven, K.; Amado, P. J.; Martín-Ruiz, S.; Moya, A.; Niemczura, E.; Suárez, J. C.; Zima, W.; Baglin, A.; Auvergne, M.; Baudin, F.; Catala, C.; Samadi, R.; Alvarez, M.; Mathias, P.; Paparò, M.; Pápics, P.; Plachy, E.

    2009-10-01

    Context: Aims: This work presents the results obtained by CoRoT on HD 50844, the only δ Sct star observed in the CoRoT initial run (57.6 d). The aim of these CoRoT observations was to investigate and characterize for the first time the pulsational behaviour of a δ Sct star, when observed at a level of precision and with a much better duty cycle than from the ground. Methods: The 140 016 datapoints were analysed using independent approaches (SigSpec software and different iterative sine-wave fittings) and several checks performed (splitting of the timeseries in different subsets, investigation of the residual light curves and spectra). A level of 10-5 mag was reached in the amplitude spectra of the CoRoT timeseries. The space monitoring was complemented by ground-based high-resolution spectroscopy, which allowed the mode identification of 30 terms. Results: The frequency analysis of the CoRoT timeseries revealed hundreds of terms in the frequency range 0-30 d-1. All the cross-checks confirmed this new result. The initial guess that δ Sct stars have a very rich frequency content is confirmed. The spectroscopic mode identification gives theoretical support since very high-degree modes (up to ℓ=14) are identified. We also prove that cancellation effects are not sufficient in removing the flux variations associated to these modes at the noise level of the CoRoT measurements. The ground-based observations indicate that HD 50844 is an evolved star that is slightly underabundant in heavy elements, located on the Terminal Age Main Sequence. Probably due to this unfavourable evolutionary status, no clear regular distribution is observed in the frequency set. The predominant term (f_1=6.92 d-1) has been identified as the fundamental radial mode combining ground-based photometric and spectroscopic data. Conclusions: The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria

  19. Warm Season Subseasonal Variability and Climate Extremes in the Northern Hemisphere: The Role of Stationary Rossby Waves

    NASA Technical Reports Server (NTRS)

    Schubert, Siegfried; Wang, Hailan; Suarez, Max

    2010-01-01

    This study examines the nature of boreal summer subseasonal atmospheric variability based on the new NASA Modern-Era Retrospective analysis for Research and Applications (MERRA) for the period 1979-2010. An analysis of the June, July and August subseasonal 250hPa v-wind anomalies shows distinct Rossby wave-like structures that appear to be guided by the mean jets. On monthly subseasonal time scales, the leading waves (the first 10 rotated empirical orthogonal functions or REOFs of the 250hPa v-wind) explain about 50% of the Northern Hemisphere vwind variability, and account for more than 30% (60%) of the precipitation (surface temperature) variability over a number of regions of the northern middle and high latitudes, including the U.S. northern Great Plains, parts of Canada, Europe, and Russia. The first REOF in particular, consists of a Rossby wave that extends across northern Eurasia where it is a dominant contributor to monthly surface temperature and precipitation variability, and played an important role in the 2003 European and 2010 Russian heat waves. While primarily subseasonal in nature, the Rossby waves can at times have a substantial seasonal mean component. This is exemplified by REOF 4 which played a major role in the development of the most intense anomalies of the U.S. 1988 drought (during June) and the 1993 flooding (during July), though differed in the latter event by also making an important contribution to the seasonal mean anomalies. A stationary wave model (SWM) is used to reproduce some of the basic features of the observed waves and provide insight into the nature of the forcing. In particular, the responses to a set of idealized forcing functions are used to map the optimal forcing patterns of the leading waves. Also, experiments to reproduce the observed waves with the SWM using MERRA-based estimates of the forcing indicate that the wave forcing is dominated by sub-monthly vorticity transients.

  20. Using a new algorithm to track mixed-Rossby gravity waves (MRG) waves in reanalysis data

    NASA Astrophysics Data System (ADS)

    Au-Yeung, A. Y. M.; Tam, C. Y.

    2015-12-01

    A new algorithm has been developed to track westward travelling mixed-Rossby gravity waves (MRG) waves in the western Pacific based on the theoretical meridional wind structure stated in the shallow water equation (SWE) solutions. Applied to space-time filtered (period=3 to 8 days and wavenumber =-20 to 0), asymmetric meridional wind data at the 850hPa level from the NCEP CFS reanalysis, the algorithm finds locations with Gaussian-shaped meridional wind structure stated in SWE solutions through space and time. Two groups of MRG waves were found: one with higher wavenumber (11) and another one with lower-wavenumber (6). Moreover, the MRG waves show very different dispersive properties and occurrence behavior in the western and eastern equatorial Pacific. While both groups appear in the western Pacific, mainly 6 waves were found in the eastern Pacific. The fact that both 6 and 11 waves appear in the western Pacific agrees with past discussions on the co-existence of MRG waves and tropical-disturbance type (TD-type) waves. Also, the high wavenumber wave activities mainly appear west of the dateline, meaning that some triggering process may have taken place there. Northwestward wave train movement was found west of 140E in the low-level wind composites. On the other hand, negative correlation between meridional wind and temperature (negative) found in the vertical composites indicates downward vertical wave activity flux prior to the occurrences of MRG waves. Finally, in the western Pacific, kinetic energy energetics suggests that energy source of transient eddies is from the confluent background flow and also the zonal wind shear terms in the western Pacific. Overall, our method provides a way to identify the MRG waves instantaneously; in contrast, most of the methods employed in the past (e.g., spectral analysis or lag correlation/regression) are based on aggregates of data and they can only examine wave properties averaged over a certain period of time. Since MRG

  1. CoRoT light curves of Blazhko RR Lyrae stars. Evidence of a strong correlation between phase and amplitude modulations of CoRoT ID 0105288363

    NASA Astrophysics Data System (ADS)

    Chadid, M.; Perini, C.; Bono, G.; Auvergne, M.; Baglin, A.; Weiss, W. W.; Deboscher, J.

    2011-03-01

    Context. The CoRoT - Convection Rotation and planetary Transits - space mission provides a unique opportunity to monitor RR Lyrae stars with excellent time-sampling, unprecedented photometric precision, and a long time base of 150 days. Aims: The pulsation characteristics of RR Lyrae stars rely on robust physics, but we still lack a firm quantitative understanding of the physical mechanisms driving the Blazhko modulation and the long-term changes in their pulsation behavior. We use the high-precision space data of an unknown RR Lyrae star CoRoT ID 0105288363 observed during a second long run centered on the Galaxy - LRc02 -, to improve our understanding of the pulsation properties of RR Lyrae stars. Methods: The CoRoT data were corrected using a jump and trend filtering code. We applied different period-finding techniques including Period04, MuFrAn, PDM, and SigSpec. Amplitude and phase modulation were investigated using an analytical function method as well as traditional O-C diagrams. Results: For the first time, we detect significant cycle-to-cycle changes in the Blazhko modulation, which appear to be analogous to those predicted by Stothers - owing to the suppression of turbulent convection - to explain this phenomenon. We discuss the clear correlations between the phase and the amplitude of the bump, and the skewness and acuteness of the light curve during different Blazhko cycles. We find that these quantities are strongly anticorrelated with the fundamental pulsation period. This provides a strong support to the slow convective cycle model suggested by Stothers. We also detect a long-term modulation period in the maximum brightness spectrum. A more extended coverage of the long-term modulation is required to constrain its period. Seventh-order side peaks of the pulsation multiplet structure are also visible with the left-side peak amplitudes being higher than those of the right. This has never previously been detected. Future theoretical investigations are

  2. CoRoT-7b: Convection in a Tidally Locked Planet

    NASA Astrophysics Data System (ADS)

    Noack, Lena; Stamenkovic, Vlada; Wagner, Frank W.; Sohl, Frank; Breuer, Doris

    2010-05-01

    The number of terrestrial extrasolar planets found in the past few years is increasing rapidly. Some have masses ranging from 2 to 10 Earth masses, and the habitability of these planets is widely discussed in the planetary community. Due to observational limitations we will mostly be able to observe planets that are very close to its host star, resulting in a potentially tidally locked orbit. Our goal is to investigate if such planets can be habitable at all. But to do so, we first have to understand the convection behaviour of such planets. In this work we model the mantle convection of the recently discovered exoplanet CoRoT-7b [1], which is a planet believed to be tidally locked. The extreme intense insolation in the vicinity of its host star heats the day-side of CoRoT-7b, leading to surface temperatures about 2000 Kelvin higher than on the night-side [1]. CoRoT-7b is about 5 times more massive than the Earth and predominantly composed of dry silicate rock similar to Earth's Moon. A central iron core, if present, would be relatively small [2] with a core mass fraction of no more than 15 wt%. The mantle convection is modelled in a spherical shell [3] using a temperature- and pressure-dependent viscosity. We use a radioactive heat source density similar to present Earth. Coriolis forces are neglected and we assume that CoRoT-7b has no atmosphere. The results show that the lower mantle above the core-mantle boundary is in a more sluggish convection regime as a consequence of the viscosity increase with pressure. Depending on the strength of the viscosity increase, even a so-called low-lid [4] can form and conductive heat transport dominates from the core to the upper part of the mantle. The thermal state of such a deeply situated, conductive lower mantle of CoRoT-7b is not much influenced by the strongly laterally varying surface temperature. However, the temperatures of the upper convecting mantle are found to strongly vary from one side of the planet to the

  3. Development of corotational formulated FEM for application to 30m class large deployable reflector

    NASA Astrophysics Data System (ADS)

    Ozawa, Satoru; Fujiwara, Yuuichi; Tsujihata, Akio

    2010-06-01

    JAXA, Japan Aerospace Exploration Agency, is now developing a corotational formulated finite element analysis method and its software "Origami/ETS" for the development of 30m class large deployable reflectors. For the reason that the deployable reflector is composed of beams, cables and mesh, this analysis method is generalized for finite elements with multiple nodes, which are commonly used in linear finite element analyses. The large displacement and rotation are taken into account by the corotational formulation. The tangent stiffness matrix for finite elements with multiple nodes is obtained as follows; the geometric stiffness matrix of two node elements is derived by taking variation of the element's corotational matrix from the virtual work of finite elements with large displacement; similarly the geometric stiffness matrix for three node elements is derived; as the extension of two and three node element theories, the geometric stiffness matrix for multiple node elements is derived; with the geometric stiffness matrix for multiple node elements, the tangent stiffness matrix is obtained. The analysis method is applied for the deployment analysis and static structural analysis of the 30m class large deployable reflector. In the deployment analysis, it is confirmed that this method stably analyzes the deployment motion from the deployment configuration to the stowed configuration of the reflector. In the static analysis, it is confirmed that the mesh structure is analyzed successfully. The 30m class large deployable reflector is now still being developed and is about to undergo several tests with its prototypes. This analysis method will be used in the tests and verifications of the reflector.

  4. A 6-node co-rotational triangular elasto-plastic shell element

    NASA Astrophysics Data System (ADS)

    Li, Zhongxue; Xiang, Yu; Izzuddin, Bassam A.; Vu-Quoc, Loc; Zhuo, Xin; Zhang, Chuanjie

    2015-05-01

    A 6-node co-rotational triangular elasto-plastic shell element is developed. The local coordinate system of the element is defined by the vectors directing from one vertex to the other two vertices and their cross product. Based on such a co-rotational framework, the element rigid-body rotations are excluded in calculating the local nodal variables from the global nodal variables. The two smallest components of each nodal orientation vector are defined as rotational variables, resulting in the desired additive property for all nodal variables in a nonlinear incremental solution procedure. Different from other existing co-rotational finite element formulations, both the element tangent stiffness matrices in the local and in the global coordinate systems are symmetric owing to the commutativity of the nodal variables in calculating the second derivatives of the strain energy with respect to the local nodal variables and, through chain differentiation, with respect to the global nodal variables. For elasto-plastic analysis, the Maxwell-Huber-Hencky-von Mises yield criterion is employed together with the backward-Euler return-mapping method for the evaluation of the elasto-plastic stress state, where a consistent tangent modulus matrix is employed. To overcome locking problems, the assumed linear membrane strains and shear strains are obtained by using the line integration method proposed by MacNeal, and the assumed higher-order membrane strains are obtained by enforcing the stationarity of the mixed displacement-strain canonical functional, these assumed strains are then employed to replace the corresponding conforming strains. The reliability and convergence of the present 6-node triangular shell element formulation are verified through two elastic plate patch tests as well as two elastic and five elasto-plastic plate/shell problems undergoing large displacements and large rotations.

  5. Presenting new exoplanet candidates for the CoRoT chromatic light curves

    NASA Astrophysics Data System (ADS)

    Boufleur, Rodrigo; Emilio, Marcelo; Andrade, Laerte; Janot-Pacheco, Eduardo; De La Reza, Ramiro

    2015-08-01

    One of the most promising topics of modern Astronomy is the discovery and characterization of extrasolar planets due to its importance for the comprehension of planetary formation and evolution. Missions like MOST (Microvariability and Oscillations of Stars Telescope) (Walker et al., 2003) and especially the satellites dedicated to the search for exoplanets CoRoT (Convection, Rotation and planetary Transits) (Baglin et al., 1998) and Kepler (Borucki et al., 2003) produced a great amount of data and together account for hundreds of new discoveries. An important source of error in the search for planets with light curves obtained from space observatories are the displacements occuring in the data due to external causes. This artificial charge generation phenomenon associated with the data is mainly caused by the impact of high energy particles onto the CCD (Pinheiro da Silva et al. 2008), although other sources of error, not as well known also need to be taken into account. So, an effective analysis of the light curves depends a lot on the mechanisms employed to deal with these phenomena. To perform our research, we developed and applied a different method to fix the light curves, the CDAM (Corot Detrend Algorithm Modified), inspired by the work of Mislis et al. (2012). The paradigms were obtained using the BLS method (Kovács et al., 2002). After a semiautomatic pre-analysis associated with a visual inspection of the planetary transits signatures, we obtained dozens of exoplanet candidates in very good agreement with the literature and also new unpublished cases. We present the study results and characterization of the new cases for the chromatic channel public light curves of the CoRoT satellite.

  6. MOST detects corotating bright spots on the mid-O-type giant ξ Persei

    NASA Astrophysics Data System (ADS)

    Ramiaramanantsoa, Tahina; Moffat, Anthony F. J.; Chené, André-Nicolas; Richardson, Noel D.; Henrichs, Huib F.; Desforges, Sébastien; Antoci, Victoria; Rowe, Jason F.; Matthews, Jaymie M.; Kuschnig, Rainer; Weiss, Werner W.; Sasselov, Dimitar; Rucinski, Slavek M.; Guenther, David B.

    2014-06-01

    We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broad-band visual photometry of the O7.5III(n)((f)) star ξ Persei in 2011 November. This star is well known from previous work to show prominent DACs (discrete absorption components) on time-scales of about 2 d from UV spectroscopy and non-radial pulsation with one (l = 3) p-mode oscillation with a period of 3.5 h from optical spectroscopy. Our MOST-orbit (101.4 min) binned photometry fails to reveal any periodic light variations above the 0.1 mmag 3σ noise level for periods of a few hours, while several prominent Fourier peaks emerge at the 1 mmag level in the two-day period range. These longer period variations are unlikely due to pulsations, including gravity modes. From our simulations based upon a simple spot model, we deduce that we are seeing the photometric modulation of several corotating bright spots on the stellar surface. In our model, the starting times (random) and lifetimes (up to several rotations) vary from one spot to another yet all spots rotate at the same period of 4.18 d, the best-estimated rotation period of the star. This is the first convincing reported case of corotating bright spots on an O star, with important implications for drivers of the DACs (resulting from corotating interaction regions) with possible bright-spot generation via a breakout at the surface of a global magnetic field generated by a subsurface convection zone.

  7. Transiting exoplanets from the CoRoT space mission. XIV. CoRoT-11b: a transiting massive ``hot-Jupiter'' in a prograde orbit around a rapidly rotating F-type star

    NASA Astrophysics Data System (ADS)

    Gandolfi, D.; Hébrard, G.; Alonso, R.; Deleuil, M.; Guenther, E. W.; Fridlund, M.; Endl, M.; Eigmüller, P.; Csizmadia, Sz.; Havel, M.; Aigrain, S.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Bruntt, H.; Cabrera, J.; Carpano, S.; Carone, L.; Cochran, W. D.; Deeg, H. J.; Dvorak, R.; Eislöffel, J.; Erikson, A.; Ferraz-Mello, S.; Gazzano, J.-C.; Gibson, N. B.; Gillon, M.; Gondoin, P.; Guillot, T.; Hartmann, M.; Hatzes, A.; Jorda, L.; Kabath, P.; Léger, A.; Llebaria, A.; Lammer, H.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.; Ollivier, M.; Pätzold, M.; Pepe, F.; Queloz, D.; Rauer, H.; Rouan, D.; Samuel, B.; Schneider, J.; Stecklum, B.; Tingley, B.; Udry, S.; Wuchterl, G.

    2010-12-01

    The CoRoT exoplanet science team announces the discovery of CoRoT-11b, a fairly massive hot-Jupiter transiting a V = 12.9 mag F6 dwarf star (M_* = 1.27±0.05 M⊙, R_* = 1.37±0.03 R⊙, Teff = 6440±120 K), with an orbital period of P = 2.994329±0.000011 days and semi-major axis a = 0.0436±0.005 AU. The detection of part of the radial velocity anomaly caused by the Rossiter-McLaughlin effect shows that the transit-like events detected by CoRoT are caused by a planet-sized transiting object in a prograde orbit. The relatively high projected rotational velocity of the star (v sin i = 40±5 km s-1) places CoRoT-11 among the most rapidly rotating planet host stars discovered so far. With a planetary mass of Mp = 2.33±0.34 MJup and radius Rp =1.43±0.03 RJup, the resulting mean density of CoRoT-11b (ρp = 0.99±0.15 g/cm3) can be explained with a model for an inflated hydrogen-planet with a solar composition and a high level of energy dissipation in its interior. The CoRoT space mission, launched on 2006 December 27, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain.

  8. Affirmation of triggered Jovian radio emissions and their attribution to corotating radio lasers

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1985-01-01

    It is argued that the original statistical evidence for the existence of triggered radio emissions and corotating radio lasers on Jupiter remains valid notwithstanding the critique of Desch and Kaiser (1985). The Voyager radio spectrograms used to identify the triggered emissions are analyzed and the results are discussed. It is shown that the critique by Desch and Kaiser is unjustified because it is not based on the original event criteria, i.e., the correlation between the occurrence of Jovian auroral kilometric radiation and fast-drift type III solar bursts in the same frequency.

  9. Rotation period distribution of CoRoT and Kepler Sun-like stars

    NASA Astrophysics Data System (ADS)

    Leão, I. C.; Pasquini, L.; Ferreira Lopes, C. E.; Neves, V.; Valcarce, A. A. R.; de Oliveira, L. L. A.; Freire da Silva, D.; de Freitas, D. B.; Canto Martins, B. L.; Janot-Pacheco, E.; Baglin, A.; De Medeiros, J. R.

    2015-10-01

    Aims: We study the distribution of the photometric rotation period (Prot), which is a direct measurement of the surface rotation at active latitudes, for three subsamples of Sun-like stars: one from CoRoT data and two from Kepler data. For this purpose, we identify the main populations of these samples and interpret their main biases specifically for a comparison with the solar Prot. Methods: Prot and variability amplitude (A) measurements were obtained from public CoRoT and Kepler catalogs, which were combined with public data of physical parameters. Because these samples are subject to selection effects, we computed synthetic samples with simulated biases to compare with observations, particularly around the location of the Sun in the Hertzsprung-Russel (HR) diagram. Publicly available theoretical grids and empirical relations were used to combine physical parameters with Prot and A. Biases were simulated by performing cutoffs on the physical and rotational parameters in the same way as in each observed sample. A crucial cutoff is related with the detectability of the rotational modulation, which strongly depends on A. Results: The synthetic samples explain the observed Prot distributions of Sun-like stars as having two main populations: one of young objects (group I, with ages younger than ~1 Gyr) and another of main-sequence and evolved stars (group II, with ages older than ~1 Gyr). The proportions of groups I and II in relation to the total number of stars range within 64-84% and 16-36%, respectively. Hence, young objects abound in the distributions, producing the effect of observing a high number of short periods around the location of the Sun in the HR diagram. Differences in the Prot distributions between the CoRoT and Kepler Sun-like samples may be associated with different Galactic populations. Overall, the synthetic distribution around the solar period agrees with observations, which suggests that the solar rotation is normal with respect to Sun

  10. Modelling Flow and Heat Transfer in Co-Rotating Twin-Screw Extruders

    NASA Astrophysics Data System (ADS)

    Teixeira, C.; Faria, R.; Covas, J. A.; Gaspar-Cunha, A.

    2007-04-01

    This work presents a modelling routine of co-rotating twin-screw extrusion, from hopper to die. The program accounts for a sequence of individual stages linked together by boundary conditions, namely starve-fed solids conveying, solids conveying under pressure, delay, melting, melt conveying without pressure and melt conveying under pressure. It predicts the evolution along the screw and die of temperature, shear rate, residence time, viscosity, mechanical power consumption, pressure and fill ratio. The results obtained showed adequate sensitivity to changes in operating conditions and screw geometry and are in agreement with current theoretical and experimental knowledge.

  11. Zonal Wave Number 2 Rossby Wave (3.5-day oscillation) Over The Martian Lower Atmosphere

    NASA Astrophysics Data System (ADS)

    Ghosh, P.; Thokuluwa, R. K.

    2013-12-01

    to get decreasing monotonously to the statistically significant lowest power of 20 K^2 in the height of 450 Pascal level. Similar to the 0-30E longitude region, there is no significant wave in all the heights above the 450 Pascal level. The 190-230 E region shows similar wave characteristics (both the power and height structure) as observed for the 0-30 E region. This would indicate that the here reporting 3.5 day wave might be associated with eastward propagating (observed the zonal phase speed of ~0.5 days per 30 degree longitude) wave number 2 Rossby wave as the wave shows similar characteristics in the two longitude regions of 0-30E and 190-230 E with the longitudinal interval of 180 degrees. Peculiarly, in the 250-280 E region, the wave shows maximum power (120 K^2) in the two heights of 550 and 700 Pascal levels. As a further support for the zonal wave number 2 structure, there is no significant 3.5-day oscillation in all the height levels in the 290-320 E longitude region which is similar to what observed in the 35-60E longitude sector. A detailed investigation of this 3.5 day oscillation will be presented also for other periods of different years.

  12. Structure and Dynamics of the Sub-corotating Region of Saturn's Magnetosphere: Cassini Magnetic Field Observations.

    NASA Astrophysics Data System (ADS)

    Smith, E. J.; Dougherty, M. K.

    2014-12-01

    Measurements of the azimuthal magnetic field component, BΦ, enable the study of the sub-corotating magnetosphere, the associated global current system, the ionospheric Pedersen current, IP, and a comparison with the Cowley-Vasyliunas model. The study is strongly dependent on Cassini's highly elliptical orbits that restrict useful observations to specific orbits and parts of orbits to avoid weak azimuthal fields associated with the magnetopause or other magnetospheric currents. An example is the selection of thirteen identical orbits near 22 +/- 2 hours Local Time and restriction of the data to 4 to 10 Saturn radii. Inferred IP profiles between 10° and 25° ionospheric co-latitude, θi , when averaged, are similar in shape to model predictions with a peak value of 5 million amperes. However, the individual profiles vary significantly, the result of dynamics associated with large-scale motions of the magnetospheric field. The Cowley-Vasyliunas model also relates IP(θi) to magnetospheric rotation rates, ΩS, equivalent to the SKR period, and the sub-corotation rate, ω, and provides a means of estimating ω / ΩS in the night-side magnetosphere as compared to the dayside rotation rates obtained from azimuthal plasma velocity measurements, VΦ. Other carefully- selected orbits extend these results to different ranges in θi and Local Times and provide further values of important magnetospheric parameters and allow additional testing of the model.

  13. Physical state of the deep interior of the CoRoT-7b exoplanet

    NASA Astrophysics Data System (ADS)

    Wagner, Frank W.; Sohl, Frank; Rückriemen, Tina; Rauer, Heike

    2011-11-01

    The present study takes the CoRoT-7b exoplanet as an analogue for massive terrestrial planets to investigate conditions, under which intrinsic magnetic fields could be sustained in liquid cores. We examine the effect of depth-dependent transport parameters (e.g., activation volume of mantle rock) on a planet's thermal structure and the related heat flux across the core mantle boundary. For terrestrial planets more massive than the Earth, our calculations suggest that a substantial part of the lowermost mantle is in a sluggish convective regime, primarily due to pressure effects on viscosity. Hence, we find substantially higher core temperatures than previously reported from parameterized convection models. We also discuss the effect of melting point depression in the presence of impurities (e.g., sulfur) in iron-rich cores and compare corresponding melting relations to the calculated thermal structure. Since impurity effects become less important at the elevated pressure and temperature conditions prevalent in the deep interior of CoRoT-7b, iron-rich cores are likely solid, implying that a self-sustained magnetic field would be absent.

  14. Optical and mechanical design of a straylight rejection baffle for CoRoT

    NASA Astrophysics Data System (ADS)

    Plesseria, Jean-Yves; Mazy, Emmanuel; Defise, Jean-Marc; Rochus, Pierre; Lemmens, Els; Vrancken, Davy

    2003-11-01

    The COROT mission is part of the program "Petites Missions" of CNES (French space agency). It implies international cooperation between France, Belgium, Germany, Austria, Spain and the European Space Agency (ESA). COROT aims to perform astroseismology measurements and to detect exoplanets. Long duration observations of stars will be used to detect periodic variations with an afocal telescope followed by a dioptric objective and 4 CCDs. Due to the orbit of the spacecraft (low altitude polar orbit) and even if the observation are performed in a direction perpendicular to orbit plane, the measurements can be disturbed by the straylight reflected on the earth (albedo) that can generate periodic perturbation. CSL is in charge of the design and procurement, with the help of Belgian industries, of a baffle and its protective cover that will be mounted on top of the afocal entrance telescope. The requirements are very stringent from the optical point of view as well as from the mechanical point of view. The rejection of the baffle must be of the order of 1013 for field angles above 20 degrees while the allocated mass is 19 kilograms.

  15. Modeling transport of energetic particles in corotating interaction regions: A case study

    NASA Astrophysics Data System (ADS)

    Zhao, Lulu; Li, Gang; Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; Mason, G. M.; Wu, Z.; Chen, Y.

    2016-01-01

    We investigate energetic particle transport in corotating interaction regions (CIRs) through a case study. The CIR event we study occurred on 8 February 2008 and was observed by both the Advanced Composition Explorer (ACE) and the twin Solar TErrestrial RElations Observatory (STEREO) B spacecraft. An in situ reverse shock was observed by STEREO B (1.0 AU) but not ACE (0.98 AU). Using STEREO B observations and assuming the CIR structure does not vary significantly in the corotating frame, we estimate the shock location at later times for both the STEREO B and ACE observations. Further assuming the accelerated particle spectral shape at the shock does not vary with shock location, we calculate the particle differential intensities as observed by ACE and STEREO B at two different times by solving the focused transport equation using a Monte Carlo simulation. We assume that particles move along Parker's field and experience no cross-field diffusion. We find that the modulation of sub-MeV/nucleon particles is significant. To obtain reasonable comparisons between the simulations and the observations by both ACE and STEREO B, one has to assume that the CIR shock can accelerate more particles at a larger heliocentric distance than at a smaller heliocentric distance.

  16. Solar Wind Interaction with Comet 67P/C-G: Impact of Corotating Interaction Regions

    NASA Astrophysics Data System (ADS)

    Edberg, N. J. T.; Eriksson, A. I.; Odelstad, E.; Vigren, E.; Burch, J. L.; Carr, C.; Cupido, E.; Glassmeier, K. H.; Goldstein, R.; Halekas, J. S.; Pierre, H.; Lebreton, J. P.; Mandt, K.; Mokashi, P.; Nemeth, Z.; Nilsson, H.; Ramstad, R.; Richter, I.; Stenberg Wieser, G.

    2015-12-01

    We present observations from the Rosetta Plasma Consortium (RPC) of impacts of corotating interaction regions (CIRs) on comet 67P. Corotating interaction regions build up in the solar wind when slow flow is caught up by faster flow. A pressure pulse is then formed, which propagates outward in interplanetary space and impacts on e.g. planets, moons and comet in its path. In the interval October to December 2014 four such CIRs are traced from Earth (using ACE) to Mars (using Mars Express and MAVEN) and to comet 67P (using Rosetta). As the CIRs impact on the cometary coma the ionospheric low-energy plasma density in the ionosphere increases by roughly one order of magnitude in the first three events. The increased density is possibly caused by sweeping up of more upstream plasma in combination with increased impact ionization and charge exchange processes. Increased fluxes of ~100 eV electrons are observed concurrently and the magnetic field strength typically doubles as more interplanetary magnetic field piles up around of the comet.

  17. Implications of the Corotation Theorem on the MRI in Axial Symmetry

    NASA Astrophysics Data System (ADS)

    Montani, G.; Cianfrani, F.; Pugliese, D.

    2016-08-01

    We analyze the linear stability of an axially symmetric ideal plasma disk, embedded in a magnetic field and endowed with a differential rotation. This study is performed by adopting the magnetic flux function as the fundamental dynamical variable, in order to outline the role played by the corotation theorem on the linear mode structure. Using some specific assumptions (e.g., plasma incompressibility and propagation of the perturbations along the background magnetic field), we select the Alfvénic nature of the magnetorotational instability, and, in the geometric optics limit, we determine the dispersion relation describing the linear spectrum. We show how the implementation of the corotation theorem (valid for the background configuration) on the linear dynamics produces the cancellation of the vertical derivative of the disk angular velocity (we check such a feature also in the standard vector formalism to facilitate comparison with previous literature, in both the axisymmetric and three-dimensional cases). As a result, we clarify that the unstable modes have, for a stratified disk, the same morphology, proper of a thin-disk profile, and the z-dependence has a simple parametric role.

  18. The variability behaviour of CoRoT M-giant stars⋆

    NASA Astrophysics Data System (ADS)

    Ferreira Lopes, C. E.; Neves, V.; Leão, I. C.; de Freitas, D. B.; Canto Martins, B. L.; da Costa, A. D.; Paz-Chinchón, F.; Das Chagas, M. L.; Baglin, A.; Janot-Pacheco, E.; De Medeiros, J. R.

    2015-11-01

    Context. For six years the Convection, Rotation, and planetary Transits (CoRoT) space mission has been acquiring photometric data from more than 100 000 point sources towards and directly opposite the inner and outer regions of the Galaxy. The high temporal resolution of the CoRoT data, combined with the wide time span of the observations, enabled the study of short- and long-time variations in unprecedented detail. Aims: The aim of this work is to study the variability and evolutionary behaviour of M-giant stars using CoRot data. Methods: From the initial sample of 2534 stars classified as M giants in the CoRoT databases, we selected 1428 targets that exhibit well defined variability, by visual inspection. Then, we defined three catalogues: C1 - stars with Teff< 4200 K and LCs displaying semi-sinusoidal signatures; C2 - rotating variable candidates with Teff> 4200 K; C3 - long-period variable candidates (with LCs showing a variability period up to the total time span of the observations). The variability period and amplitude of C1 stars were computed using Lomb-Scargle and harmonic fit methods. Finally, we used C1 and C3 stars to study the variability behaviour of M-giant stars. Results: The trends found in the V-I vs. J-K colour-colour diagram are in agreement with standard empirical calibrations for M giants. The sources located towards the inner regions of the Galaxy are distributed throughout the diagram, while the majority of the stars towards the outer regions of the Galaxy are spread between the calibrations of M giants and the predicted position for carbon stars. The stars classified as supergiants follow a different sequence from the one found for giant stars. We also performed a Kolmogorov-Smirnov (KS) test of the period and amplitude of stars towards the inner and outer regions of the Galaxy. We obtained a low probability that the two samples came from the same parent distribution. The observed behaviour of the period-amplitude and period

  19. Rossby-Khantadze Electromagnetic Planetary Waves Driven by Sheared Zonal Winds in the E-Layer Ionosphere

    NASA Astrophysics Data System (ADS)

    Futatani, S.; Horton, W.; Kahlon, L. Z.; Kaladze, T.

    2014-10-01

    Nonlinear simulations are carried out for planetary scale [ >1000 km] electromagnetic Rossby and Khantadze planetary waves in the presence of a sheared zonal flow in the weakly ionized ionospheric E-layer. A variety of sheared flow profiles are studied. We shown that the nonlinear dynamics with the sheared zonal flows provides an energy source into the vortex structures. The energy transfer through the Reynolds stress tensor produces growth of the stable vortices under a variety of conditions. The energy accumulation breaks the vortex structure into multiple species according to the non-uniformity of profile of the external zonal shear flows. S. Futatani, W. Horton, T. D. Kaladze, Phys. Plasmas 20, 102903 (2013). T. D. Kaladze, L. Z. Kahlon, W. Horton. O Pokhotelov, and O. Onishenchenko, EPL 106, A05302 (2014).

  20. Rossby-Khantadze electromagnetic planetary waves driven by sheared zonal winds in the E-layer ionosphere

    NASA Astrophysics Data System (ADS)

    Futatani, S.; Horton, W.; Kahlon, L. Z.; Kaladze, T. D.

    2015-01-01

    Nonlinear simulations of electromagnetic Rossby and Khantadze planetary waves in the presence of a shearless and sheared zonal flows in the weakly ionized ionospheric E-layer are carried out. The simulations show that the nonlinear action of the vortex structures keeps the solitary character in the presence of shearless zonal winds as well as the ideal solutions of solitary vortex in the absence of zonal winds. In the presence of sheared zonal winds, the zonal flows result in breaking into separate multiple smaller pieces. A passively convected scalar field is shown to clarify the transport associated with the vortices. The work shows that the zonal shear flows provide an energy source into the vortex structure according to the shear rate of the zonal winds.

  1. Observations by GLORIA of stirring and mixing in the UTLS following Rossby wave breaking in winter 2015/2016

    NASA Astrophysics Data System (ADS)

    Ungermann, Joern; Friedl-Vallon, Felix; Höpfner, Michael; Preusse, Peter; Riese, Martin

    2016-04-01

    The Gimbaled Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an airborne infrared limb-imager combining a 2-D infrared detector with a Fourier transform spectrometer. It was operated aboard the German Gulfstream G550 research aircraft HALO during a series of simultaneous campaigns (POLSTRACC, SALSA, GWLCYCLE, GWEX) during the winter of 2015/2016 over Europe and the Arctic. This poster shows a set of GLORIA observations and analyses of 2-D trace gas cross-sections in the extratropical upper troposphere / lower stratosphere (UTLS). The spatially highly-resolved temperature, H2O, O3 and HNO3 data reveal an intricate layered structure in the extratropical Transition Layer (exTL). This heterogeneous structure was caused by Rossby wave breaking and is similar to the state found during previous measurements in summer 2012 over Europe. This study presents first analyses of the stirring and stratosphere-troposphere-exchange by means of backward-trajectory calculation.

  2. Rossby-Khantadze electromagnetic planetary waves driven by sheared zonal winds in the E-layer ionosphere

    SciTech Connect

    Futatani, S.; Horton, W.; Kahlon, L. Z.; Kaladze, T. D.

    2015-01-15

    Nonlinear simulations of electromagnetic Rossby and Khantadze planetary waves in the presence of a shearless and sheared zonal flows in the weakly ionized ionospheric E-layer are carried out. The simulations show that the nonlinear action of the vortex structures keeps the solitary character in the presence of shearless zonal winds as well as the ideal solutions of solitary vortex in the absence of zonal winds. In the presence of sheared zonal winds, the zonal flows result in breaking into separate multiple smaller pieces. A passively convected scalar field is shown to clarify the transport associated with the vortices. The work shows that the zonal shear flows provide an energy source into the vortex structure according to the shear rate of the zonal winds.

  3. Transiting exoplanets from the CoRoT space mission. XXI. CoRoT-19b: a low density planet orbiting an old inactive F9V-star

    NASA Astrophysics Data System (ADS)

    Guenther, E. W.; Díaz, R. F.; Gazzano, J.-C.; Mazeh, T.; Rouan, D.; Gibson, N.; Csizmadia, Sz.; Aigrain, S.; Alonso, R.; Almenara, J. M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Bruntt, H.; Cabrera, J.; Carone, L.; Carpano, S.; Cavarroc, C.; Deeg, H. J.; Deleuil, M.; Dreizler, S.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gandolfi, D.; Gillon, M.; Guillot, T.; Hatzes, A.; Havel, M.; Hébrard, G.; Jehin, E.; Jorda, L.; Lammer, H.; Léger, A.; Moutou, C.; Nortmann, L.; Ollivier, M.; Ofir, A.; Pasternacki, Th.; Pätzold, M.; Parviainen, H.; Queloz, D.; Rauer, H.; Samuel, B.; Santerne, A.; Schneider, J.; Tal-Or, L.; Tingley, B.; Weingrill, J.; Wuchterl, G.

    2012-01-01

    Context. Observations of transiting extrasolar planets are of key importance to our understanding of planets because their mass, radius, and mass density can be determined. These measurements indicate that planets of similar mass can have very different radii. For low-density planets, it is generally assumed that they are inflated owing to their proximity to the host-star. To determine the causes of this inflation, it is necessary to obtain a statistically significant sample of planets with precisely measured masses and radii. Aims: The CoRoT space mission allows us to achieve a very high photometric accuracy. By combining CoRoT data with high-precision radial velocity measurements, we derive precise planetary radii and masses. We report the discovery of CoRoT-19b, a gas-giant planet transiting an old, inactive F9V-type star with a period of four days. Methods: After excluding alternative physical configurations mimicking a planetary transit signal, we determine the radius and mass of the planet by combining CoRoT photometry with high-resolution spectroscopy obtained with the echelle spectrographs SOPHIE, HARPS, FIES, and SANDIFORD. To improve the precision of its ephemeris and the epoch, we observed additional transits with the TRAPPIST and Euler telescopes. Using HARPS spectra obtained during the transit, we then determine the projected angle between the spin of the star and the orbit of the planet. Results: We find that the host star of CoRoT-19b is an inactive F9V-type star close to the end of its main-sequence life. The host star has a mass M∗ = 1.21 ± 0.05 M⊙ and radius R∗ = 1.65 ± 0.04 R⊙. The planet has a mass of MP = 1.11 ± 0.06 MJup and radius of RP = 1.29 ± 0.03 RJup. The resulting bulk density is only ρ = 0.71 ± 0.06 g cm-3, which is much lower than that for Jupiter. Conclusions: The exoplanet CoRoT-19b is an example of a giant planet of almost the same mass as Jupiter but a ≈30% larger radius. The CoRoT space mission, launched on

  4. Transiting exoplanets from the CoRoT space mission. XXII. CoRoT-16b: a hot Jupiter with a hint of eccentricity around a faint solar-like star

    NASA Astrophysics Data System (ADS)

    Ollivier, M.; Gillon, M.; Santerne, A.; Wuchterl, G.; Havel, M.; Bruntt, H.; Bordé, P.; Pasternacki, T.; Endl, M.; Gandolfi, D.; Aigrain, S.; Almenara, J. M.; Alonso, R.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bouchy, F.; Cabrera, J.; Carone, L.; Carpano, S.; Cavarroc, C.; Cochran, W. D.; Csizmadia, Sz.; Deeg, H. J.; Deleuil, M.; Diaz, R. F.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gazzano, J.-C.; Grziwa, S.; Guenther, E.; Guillot, T.; Guterman, P.; Hatzes, A.; Hébrard, G.; Lammer, H.; Léger, A.; Lovis, C.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.; Ofir, A.; Pätzold, M.; Queloz, D.; Rauer, H.; Rouan, D.; Samuel, B.; Schneider, J.; Tadeu dos Santos, M.; Tal-Or, L.; Tingley, B.; Weingrill, J.

    2012-05-01

    Aims: We report the discovery of CoRoT-16b, a low density hot jupiter that orbits a faint G5V star (mV = 15.63) in 5.3523 ± 0.0002 days with slight eccentricity. A fit of the data with no a priori assumptions on the orbit leads to an eccentricity of 0.33 ± 0.1. We discuss this value and also derive the mass and radius of the planet. Methods: We analyse the photometric transit curve of CoRoT-16 given by the CoRoT satellite, and radial velocity data from the HARPS and HIRES spectrometers. A combined analysis using a Markov chain Monte Carlo algorithm is used to get the system parameters. Results: CoRoT-16b is a 0.535 -0.083/+0.085 MJ, 1.17 -0.14/+0.16 RJ hot Jupiter with a density of 0.44 -0.14/+0.21 g cm-3. Despite its short orbital distance (0.0618 ± 0.0015 AU) and the age of the parent star (6.73 ± 2.8 Gyr), the planet orbit exhibits significantly non-zero eccentricity. This is very uncommon for this type of objects as tidal effects tend to circularise the orbit. This value is discussed taking into account the characteristics of the star and the observation accuracy. The CoRoT space mission, launched on December 27, 2006, has been developed and is operated by the CNES with the contribution of Austria, Belgium, Brasil, ESA, Germany, and Spain.Observations made with the HARPS spectrograph at ESO La Silla Observatory (HARPS programs 083.C-0186 and 184.C-0639) and the HIRES spectrograph at the Keck Observatory (NASA-Keck programs N035Hr, N143Hr and N095Hr).

  5. Finest light curve details, physical parameters, and period fluctuations of CoRoT RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Benkő, J. M.; Szabó, R.; Derekas, A.; Sódor, Á.

    2016-08-01

    The CoRoT satellite supplied the scientific community with a huge data base of variable stars. Among them the RR Lyrae stars have intensively been discussed in numerous papers in the last few years, but the latest runs have not been checked to find RR Lyrae stars up to now. Our main goal was to fill this gap and complete the CoRoT RR Lyrae sample. We found nine unstudied RR Lyrae stars. Seven of them are new discoveries. We identified three new Blazhko stars. The Blazhko effect shows non-strictly repetitive nature for all stars. The frequency spectrum of the Blazhko star CoRoT 104948132 contains second overtone frequency with the highest known period ratio. The harmonic amplitude and phase declines with the harmonic order were studied for non-Blazhko stars. We found a period dependent but similar shape amplitude decline for all stars. We discovered significant random period fluctuation for one of the two oversampled target, CM Ori. After a successful transformation of the CoRoT band parameters to the Johnson V values we estimated the basic physical properties such as mass, luminosity, metallicity. The sample can be divided into two subgroups with respect to the metallicity but otherwise the physical parameters are in the canonical range of RR Lyrae stars.

  6. VizieR Online Data Catalog: Stellar parameters for CoRoT exoplanet field stars (Cortes+, 2015)

    NASA Astrophysics Data System (ADS)

    Cortes, C.; Maciel, S. C.; Vieira, S.; Ferreira Lopes, C. E.; Leao, I. C.; de Oliveira, G. P.; Correia, C.; Canto Martins, B. L.; Catelan, M.; de Medeiros, J. R.

    2016-08-01

    The present stellar sample is composed of 138 stars of spectral types F, G, and K, with visual magnitudes V between 10 to 14, located in two exoplanet fields observed by CoRoT, namely the Galactic center (LRc01: Long Run Center 01) and the Galactic anticenter (LRa01: Long Run Anticenter 01) fields. (4 data files).

  7. Accretion dynamics and disk evolution in NGC 2264: a study based on CoRoT photometric observations

    NASA Astrophysics Data System (ADS)

    Alencar, S. H. P.; Teixeira, P. S.; Guimarães, M. M.; McGinnis, P. T.; Gameiro, J. F.; Bouvier, J.; Aigrain, S.; Flaccomio, E.; Favata, F.

    2010-09-01

    Context. The young cluster NGC 2264 was observed with the CoRoT satellite for 23 days uninterruptedly in March 2008 with unprecedented photometric accuracy. We present the first results of our analysis of the accreting population belonging to the cluster as observed by CoRoT. Aims: We search for possible light curve variability of the same nature as that observed in the classical T Tauri star AA Tau, which was attributed to a magnetically controlled inner disk warp. The inner warp dynamics is supposed to be directly associated with the interaction between the stellar magnetic field and the inner disk region. Methods: We analyzed the CoRoT light curves of 83 previously known classical T Tauri stars that belong to NGC 2264 classifying them according to their light-curve morphology. We also studied the CoRoT light-curve morphology as a function of a Spitzer-based classification of the star-disk systems. Results: The classification derived on the basis of the CoRoT light-curve morphology agrees very well with the Spitzer IRAC-based classification of the systems. The percentage of AA Tau-like light curves decreases as the inner disk dissipates, from 40% ± 10% in systems with thick inner disks to 36% ± 16% in systems with anemic disks and zero in naked photosphere systems. Indeed, 91% ± 29% of the CTTS with naked photospheres exhibit pure spot-like variability, while only 18% ± 7% of the thick disk systems do so, presumably those seen at low inclination and thus free of variable obscuration. Conclusions: AA Tau-like light curves are found to be fairly common, with a frequency of at least ~30 to 40% in young stars with inner dusty disks. The temporal evolution of the light curves indicates that the structure of the inner disk warp, located close to the corotation radius and responsible for the obscuration episodes, varies over a timescale of a few (~1-3) rotational periods. This probably reflects the highly dynamical nature of the star-disk magnetospheric interaction

  8. The evolution of corotating stream fronts near the ecliptic plane in the inner solar system, 1. Two-dimensional fronts

    SciTech Connect

    Pizzo, V.J. )

    1989-07-01

    Numerical models of corotating solar wind flows have enjoyed considerable success in simulating the evolution of shocks and corotating interaction regions (CIRs) in the region beyond 1 AU, but their performance with respect to stream fronts located nearer the Sun has been somewhat disappointing. In particular, they tend to predict erroneously that corotating shock pairs should occur relatively frequently within 1 AU, given the sort of sharp boundaries between slow and fast flows observed at stream fronts near 0.3 AU by Helios. We use an existing two-dimensional MHD numerical model for corotating flow in the supersonic, superalfvenic solar wind to show that the predictions of premature shock pair formation are due to improper specification of flow conditions on the initial surface (inner boundary) used as the starting point in such models. This faulty initialization leads to the generation of a physically extraneous strong compression along the stream interface just outside the initial surface, which results in the appearance of evolutionary artifacts (like spurious discontinuities) further on in the solution. We describe an initialization scheme incorporating flow conditions more appropriate to stream fronts near the Sun and demonstrate that it produces the smooth initial behavior expected on physical grounds. Thus free of the evolutionary artifacts, we see that the shear flow at the stream interface approximately balances the kinematic steepening near the Sun, which for typical input conditions keeps the corotating shock pair from forming before about 1.5 AU. We describe the criteria for shock formation in terms of the interface dynamics and show that the steepening process cannot be treated even approximately with conventional kinematic techniques. In a subsequent paper we investigate how the three-dimensional geometry of the stream front affects the dynamical evolution and the resulting CIR structure.

  9. Numerical study of mixed convection between two corotating symmetrically heated disks

    SciTech Connect

    Soong, C.Y.; Yan, W.M. Hua Fan Inst. of Technology, Taipei )

    1993-03-01

    This article is concerned with a numerical study of mixed convection between two symmetrically heated corotating disks. Both thermal boundary conditions of constant wall temperature and uniform heat flux are considered. By applying the boundary-layer approximation and a linear relation for density variation in centrifugal force term, the governing equations reduce to a Boussinesq system of parabolic nature. The spatially developing flow and heat transfer are studied numerically. The effects of centrifugal buoyancy, Coriolis force, radial through-flow, and wall-heating on the flow structure and heat transfer performance are examined in detail. The results reveal that the centrifugal buoyancy, which was ignored in prior studies, is indeed a significant effect in this class of rotating flows. 19 refs.

  10. Mirroring of fast solar flare electrons on a downstream corotating interaction region

    NASA Technical Reports Server (NTRS)

    Anderson, K. A.; Sommers, J.; Lin, R. P.; Pick, M.; Chaizy, P.; Murphy, N.; Smith, E. J.; Phillips, J. L.

    1995-01-01

    We discuss an example of confinement of fast solar electrons by a discrete solar wind-interplanetary magnetic field structure on February 22, 1991. The structure is about 190,000 km in width and is clearly defined by changes in the direction of the magnetic field at the Ulysses spacecraft. This structure carries electrons moving toward the Sun as well as away from the Sun. A loss cone in the angular distribution of the fast electrons shows that mirroring, presumably magnetic, takes place downstream from the spacecraft. Following passage of this narrow structure, the return flux vanishes for 21 min after which time the mirroring resumes and persists for several hours. We identify the enhanced magnetic field region lying downstream from the Ulysses spacecraft that is responsible for the mirroring to be a corotating stream interaction region. Backstreaming suprathermal electron measurements by the Los Alamos National Laboratory plasma experiment on the Ulysses spacecraft support this interpretation.

  11. A three-dimensional model of corotating streams in the solar wind. 1: Theoretical foundations

    NASA Technical Reports Server (NTRS)

    Pizzo, V. J.

    1978-01-01

    The theoretical and mathematical background pertinent to the study of steady, corotating solar wind structure in all three spatial dimensions (3-D) is discussed. The dynamical evolution of the plasma in interplanetary space (defined as the region beyond roughly 35 solar radii where the flow is supersonic) is approximately described by the nonlinear, single fluid, polytropic (magneto-) hydrodynamic equations. Efficient numerical techniques for solving this complex system of coupled, hyperbolic partial differential equations are outlined. The formulation is inviscid and nonmagnetic, but methods allow for the potential inclusion of both features with only modest modifications. One simple, highly idealized, hydrodynamic model stream is examined to illustrate the fundamental processes involved in the 3-D dynamics of stream evolution. Spatial variations in the rotational stream interaction mechanism were found to produce small nonradial flows on a global scale that lead to the transport of mass, energy, and momentum away from regions of relative compression and into regions of relative rarefaction.

  12. Shock acceleration of energetic particles in corotating interaction regions in the solar wind

    SciTech Connect

    Fisk, L.A.; Lee, M.A.

    1980-04-15

    A simple shock model for the acceleration of energetic particles in corotating interaction regions (CIRs) in the solar wind is presented. Particles are accelerated at the forward and reverse shocks which bound the CIR by being compressed between the shock fronts and magnetic irregularities upstream from the shocks, or by being compressed between upstream irregularities and those downstream from the shocks. Particles also suffer adiabatic deceleration in the expanding solar wind, an effect not included in previous shock models for acceleration in CIRs. The model is able to account for the observed exponential spectra at Earth, the observed behavior of the spectra with radial distance, the observed radial gradients in the intensity, and the observed differences in the intensity and spectra at the forward and reverse shocks.

  13. Structure of a Magnetic Decrease Observed in a Corotating Interaction Region

    NASA Astrophysics Data System (ADS)

    Lee, Ensang; Parks, George K.

    2016-02-01

    Magnetic decreases are often observed in various regions of interplanetary space. Many studies are devoted to reveal the physical nature and generation mechanism of the magnetic decreases, but still we do not fully understand magnetic decreases. In this study, we investigate the structure of a magnetic decrease observed in a corotating interaction region using multi-spacecraft measurements. We use three spacecraft, ACE, Cluster, and Wind, which were widely separated in the x- and y-directions in the geocentric solar ecliptic (GSE) coordinates. The boundaries of the magnetic decrease are the same at the three locations and can be identified as tangential discontinuities. A notable feature is that the magnetic decrease has very large dimension, ≳268 R_{E}, along the boundary, which is much larger than the size, ˜6 R_{E}, along the normal direction. This suggests that the magnetic decrease has a shape of a long, thin rod or a wide slab.

  14. The Domain of δ Scuti Stars: First CoRoT IRa01 Results

    NASA Astrophysics Data System (ADS)

    Kaiser, Alexander; Weiss, Werner; Guenther, Eike; Balaguer, Lola; Maceroni, Carla; Ribas, Ignasi

    2009-09-01

    We present the first results of determing the δ Scuti population observed with CoRoT during the Initial Run (IRa01). From more than 10000 stars observed continuously in the exoplanet-channel during 58 days, 397 stars show pulsation in the δ Scuti domain. For 39 of the 397 stars low resolution classification spectra and Strömgren uvby photometry were available; thus fundamental parameters like effective temperature and surface gravity could be derived. Classical Fourier techniques and least squares multi-sine fits were applied to identify the pulsation frequencies. For additional 90 stars a pair of radial modes were found and by comparing with pulsation models it was possible to estimate the corresponding fundamental parameters.

  15. Angular velocity of gravitational radiation from precessing binaries and the corotating frame

    NASA Astrophysics Data System (ADS)

    Boyle, Michael

    2013-05-01

    This paper defines an angular velocity for time-dependent functions on the sphere and applies it to gravitational waveforms from compact binaries. Because it is geometrically meaningful and has a clear physical motivation, the angular velocity is uniquely useful in helping to solve an important—and largely ignored—problem in models of compact binaries: the inverse problem of deducing the physical parameters of a system from the gravitational waves alone. It is also used to define the corotating frame of the waveform. When decomposed in this frame, the waveform has no rotational dynamics and is therefore as slowly evolving as possible. The resulting simplifications lead to straightforward methods for accurately comparing waveforms and constructing hybrids. As formulated in this paper, the methods can be applied robustly to both precessing and nonprecessing waveforms, providing a clear, comprehensive, and consistent framework for waveform analysis. Explicit implementations of all these methods are provided in accompanying computer code.

  16. Mirroring of fast solar flare electrons on a downstream corotating interaction region

    SciTech Connect

    Anderson, K.A.; Sommers, J.; Lin, R.P.; Pick, M.; Chaizy, P.; Murphy, N.; Smith, E.J.; Phillips, J.L.

    1995-01-01

    The authors discuss an example of confinement of fast solar electrons by a discrete solar wind-interplanetary magnetic field structure on February 22, 1991. The structure is about 190,000 km in width and is clearly defined by changes in the direction of the magnetic field at the Ulysses spacecraft. This structure carries electrons moving toward the Sun as well as away from the Sun. A loss cone in the angular distribution of the fast electrons shows that mirroring, presumably magnetic, takes place downstream from the spacecraft. Following passage of this narrow structure, the return flux vanishes for 21 min after which time the mirroring resumes and persists for several hours. The authors identify the enhanced magnetic field region lying downstream from the Ulysses spacecraft that is responsible for the mirroring to be a corotating stream interaction region. Backstreaming suprathermal electron measurements by the Los Alamos National Laboratory plasma experiment on the Ulysses spacecraft support this interpretation. 12 refs., 9 figs.

  17. The extreme physical properties of the CoRoT-7b super-Earth

    NASA Astrophysics Data System (ADS)

    Léger, A.; Grasset, O.; Fegley, B.; Codron, F.; Albarede, A. F.; Barge, P.; Barnes, R.; Cance, P.; Carpy, S.; Catalano, F.; Cavarroc, C.; Demangeon, O.; Ferraz-Mello, S.; Gabor, P.; Grießmeier, J.-M.; Leibacher, J.; Libourel, G.; Maurin, A.-S.; Raymond, S. N.; Rouan, D.; Samuel, B.; Schaefer, L.; Schneider, J.; Schuller, P. A.; Selsis, F.; Sotin, C.

    2011-05-01

    The search for rocky exoplanets plays an important role in our quest for extra-terrestrial life. Here, we discuss the extreme physical properties possible for the first characterised rocky super-Earth, CoRoT-7b ( R pl = 1.58 ± 0.10 R Earth, M pl = 6.9 ± 1.2 M Earth). It is extremely close to its star ( a = 0.0171 AU = 4.48 R st), with its spin and orbital rotation likely synchronised. The comparison of its location in the ( M pl, R pl) plane with the predictions of planetary models for different compositions points to an Earth-like composition, even if the error bars of the measured quantities and the partial degeneracy of the models prevent a definitive conclusion. The proximity to its star provides an additional constraint on the model. It implies a high extreme-UV flux and particle wind, and the corresponding efficient erosion of the planetary atmosphere especially for volatile species including water. Consequently, we make the working hypothesis that the planet is rocky with no volatiles in its atmosphere, and derive the physical properties that result. As a consequence, the atmosphere is made of rocky vapours with a very low pressure ( P ⩽ 1.5 Pa), no cloud can be sustained, and no thermalisation of the planet is expected. The dayside is very hot (2474 ± 71 K at the sub-stellar point) while the nightside is very cold (50-75 K). The sub-stellar point is as hot as the tungsten filament of an incandescent bulb, resulting in the melting and distillation of silicate rocks and the formation of a lava ocean. These possible features of CoRoT-7b could be common to many small and hot planets, including the recently discovered Kepler-10b. They define a new class of objects that we propose to name " Lava-ocean planets".

  18. The CoRoT and Kepler Revolution in Stellar Variability Studies

    NASA Astrophysics Data System (ADS)

    Degroote, Pieter; Debosscher, Jonas

    2012-04-01

    Space-based observations of variable stars have revolutionized the field of variability studies. Dedicated satellites such as the CoRoT and Kepler missions have duty cycles which are unachievable from the ground, and effectively solve many of the aliasing problems prevalent in ground-based observation campaigns. Moreover, the location above the Earth's atmosphere eliminates a major source of scatter prevalent in observations from the ground. These two major improvements in instrumentation have triggered significant increases in our knowledge of the stars, but in order to reap the full benefits they are also obliging the community to adopt more efficient techniques for handling, analysing and interpreting the vast amounts of new, high-precision data in an effective yet comprehensive manner. This workshop heard an outline of the history and development of asteroseismology, and descriptions of the two space missions (CoRoT and Kepler) which have been foremost in accelerating those recent developments. Informal discussions on numerous points peppered the proceedings, and involved the whole audience at times. The conclusions which the workshop reached have been distilled into a list of seven recommendations (Section 5) for the asteroseismology community to study and absorb. In fact, while addressing activities (such as stellar classification or analysing and modelling light curves) that could be regarded as specific to the community in question, the recommendations include advice on matters such as improving communication, incorporating trans-disciplinary knowledge and involving the non-scientific public that are broad enough to serve as guidelines for the astrophysical community at large.

  19. The CoRoT chemical peculiar target star HD 49310

    NASA Astrophysics Data System (ADS)

    Paunzen, E.; Fröhlich, H.-E.; Netopil, M.; Weiss, W. W.; Lüftinger, T.

    2015-02-01

    Context. The magnetic chemically peculiar (CP) stars of the upper main sequence are well-suited laboratories for investigating the influence of local magnetic fields on the stellar surface because they produce inhomogeneities (spots) that can be investigated in detail as the star rotates. Aims: We studied the inhomogeneous surface structure of the CP2 star HD 49310 based on high-quality CoRoT photometry obtained during 25 days. The data have nearly no gaps. This analysis is similar to a spectroscopic Doppler-imaging analysis, but it is not a tomographic method. Methods: We performed detailed light-curve fitting in terms of stationary circular bright spots. Furthermore, we derived astrophysical parameters with which we located HD 49310 within the Hertzsprung-Russell diagram. We also investigated the possible connection of this star to the nearby young open cluster NGC 2264. Results: With a Bayesian technique, we produced a surface map that shows six bright spots. After removing some artefacts, the residuals of the observed and synthetic photometric data are ± 0.123 mmag. The rotational period of the star is P = 1.91909 ± 0.00001 days. Our photometric observations therefore cover about 13 full rotational cycles. Three spots are very large with diameters of ≃ 40deg. The spots are brighter by 40% than the unperturbed stellar photosphere. Conclusions: HD 49310 is a classical silicon (CP2) star with a mass of about 3 M⊙. It is not a member of NGC 2264. Our analysis shows the potential of using high-quality photometric data to analyse the surface structure of CP stars. A comprehensive analysis of similar archival data, preferrably from space missions, would contribute significantly to our understanding of surface phenomena of CP stars and their temporal evolution. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.

  20. The CoRoT satellite in flight: description and performance

    NASA Astrophysics Data System (ADS)

    Auvergne, M.; Bodin, P.; Boisnard, L.; Buey, J.-T.; Chaintreuil, S.; Epstein, G.; Jouret, M.; Lam-Trong, T.; Levacher, P.; Magnan, A.; Perez, R.; Plasson, P.; Plesseria, J.; Peter, G.; Steller, M.; Tiphène, D.; Baglin, A.; Agogué, P.; Appourchaux, T.; Barbet, D.; Beaufort, T.; Bellenger, R.; Berlin, R.; Bernardi, P.; Blouin, D.; Boumier, P.; Bonneau, F.; Briet, R.; Butler, B.; Cautain, R.; Chiavassa, F.; Costes, V.; Cuvilho, J.; Cunha-Parro, V.; de Oliveira Fialho, F.; Decaudin, M.; Defise, J.-M.; Djalal, S.; Docclo, A.; Drummond, R.; Dupuis, O.; Exil, G.; Fauré, C.; Gaboriaud, A.; Gamet, P.; Gavalda, P.; Grolleau, E.; Gueguen, L.; Guivarc'h, V.; Guterman, P.; Hasiba, J.; Huntzinger, G.; Hustaix, H.; Imbert, C.; Jeanville, G.; Johlander, B.; Jorda, L.; Journoud, P.; Karioty, F.; Kerjean, L.; Lafond, L.; Lapeyrere, V.; Landiech, P.; Larqué, T.; Laudet, P.; Le Merrer, J.; Leporati, L.; Leruyet, B.; Levieuge, B.; Llebaria, A.; Martin, L.; Mazy, E.; Mesnager, J.-M.; Michel, J.-P.; Moalic, J.-P.; Monjoin, W.; Naudet, D.; Neukirchner, S.; Nguyen-Kim, K.; Ollivier, M.; Orcesi, J.-L.; Ottacher, H.; Oulali, A.; Parisot, J.; Perruchot, S.; Piacentino, A.; Pinheiro da Silva, L.; Platzer, J.; Pontet, B.; Pradines, A.; Quentin, C.; Rohbeck, U.; Rolland, G.; Rollenhagen, F.; Romagnan, R.; Russ, N.; Samadi, R.; Schmidt, R.; Schwartz, N.; Sebbag, I.; Smit, H.; Sunter, W.; Tello, M.; Toulouse, P.; Ulmer, B.; Vandermarcq, O.; Vergnault, E.; Wallner, R.; Waultier, G.; Zanatta, P.

    2009-10-01

    Context: CoRoT is a space telescope dedicated to stellar seismology and the search for extrasolar planets. The mission is led by the CNES in association with French laboratories and has a large international participation. The European Space Agency (ESA), Austria, Belgium, and Germany contribute to the payload, and Spain and Brazil contribute to the ground segment. Development of the spacecraft, which is based on a PROTEUS low earth orbit (LEO) recurrent platform, commenced in October 2000, and the satellite was launched on December 27, 2006. Aims: The instrument and platform characteristics prior to launch have been described in ESA publication (SP-1306). In the present paper we explain the behaviour in flight, based on raw and corrected data. Methods: Five runs have been completed since January 2007. The data used here are essentially those acquired during the commissioning phase and from a long run that lasted 146 days. These enable us to give a complete overview of the instrument and platform behaviour for all environmental conditions. The ground based data processing is not described in detail because the most important method has been published elsewhere. Results: We show that the performance specifications are easily satisfied when the environmental conditions are favourable. Most of the perturbations, hence data corrections, are related to LEO perturbations: high energy particles inside the South Atlantic Anomaly (SAA), eclipses and temperature variations, and line of sight fluctuations due to the attitude control system. Straylight due to the reflected light from the earth, which is controlled by the telescope and baffle design, appears to be negligible. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with contributions from Austria, Belgium, Brazil, ESA, Germany and Spain. Four French laboratories associated with the CNRS (LESIA, LAM, IAS, OMP) collaborate with CNES on the satellite development. The

  1. The Berlin Exoplanet Search Telescope II Catalog of Variable Stars. II. Characterization of the CoRoT SRc02 Field

    NASA Astrophysics Data System (ADS)

    Klagyivik, P.; Csizmadia, Sz.; Pasternacki, T.; Cabrera, J.; Chini, R.; Eigmüller, P.; Erikson, A.; Fruth, T.; Kabath, P.; Lemke, R.; Murphy, M.; Rauer, H.; Titz-Weider, R.

    2016-05-01

    Time-series photometry of the CoRoT field SRc02 was obtained by the Berlin Exoplanet Search Telescope II (BEST II) in 2009. The main aim was to conduct a ground-based follow-up of the CoRoT field in order to detect variable stars with better spatial resolution than what can be achieved with the CoRoT Space Telescope. A total of 1846 variable stars were detected, of which only 30 have been previously known. For nine eclipsing binaries the stellar parameters were determined by modeling their light curves.

  2. Rossby and drift wave turbulence and zonal flows: The Charney-Hasegawa-Mima model and its extensions

    NASA Astrophysics Data System (ADS)

    Connaughton, Colm; Nazarenko, Sergey; Quinn, Brenda

    2015-12-01

    A detailed study of the Charney-Hasegawa-Mima model and its extensions is presented. These simple nonlinear partial differential equations suggested for both Rossby waves in the atmosphere and drift waves in a magnetically-confined plasma, exhibit some remarkable and nontrivial properties, which in their qualitative form, survive in more realistic and complicated models. As such, they form a conceptual basis for understanding the turbulence and zonal flow dynamics in real plasma and geophysical systems. Two idealised scenarios of generation of zonal flows by small-scale turbulence are explored: a modulational instability and turbulent cascades. A detailed study of the generation of zonal flows by the modulational instability reveals that the dynamics of this zonal flow generation mechanism differ widely depending on the initial degree of nonlinearity. The jets in the strongly nonlinear case further roll up into vortex streets and saturate, while for the weaker nonlinearities, the growth of the unstable mode reverses and the system oscillates between a dominant jet, which is slightly inclined to the zonal direction, and a dominant primary wave. A numerical proof is provided for the extra invariant in Rossby and drift wave turbulence-zonostrophy. While the theoretical derivations of this invariant stem from the wave kinetic equation which assumes weak wave amplitudes, it is shown to be relatively well-conserved for higher nonlinearities also. Together with the energy and enstrophy, these three invariants cascade into anisotropic sectors in the k-space as predicted by the Fjørtoft argument. The cascades are characterised by the zonostrophy pushing the energy to the zonal scales. A small scale instability forcing applied to the model has demonstrated the well-known drift wave-zonal flow feedback loop. The drift wave turbulence is generated from this primary instability. The zonal flows are then excited by either one of the generation mechanisms, extracting energy from

  3. Evidence of Boundary Reflection of Kelvin and First-Mode Rossby Waves from Topex/Poseidon Sea Level Data

    NASA Technical Reports Server (NTRS)

    Boulanger, Jean-Philippe; Fu, Lee-Lueng

    1996-01-01

    The TOPEX/POSEIDON sea level data lead to new opportunities to investigate some theoretical mechanisms suggested to be involved in the El Nino-Southern Oscillation phenomenon in the tropical Pacific ocean. In particular, we are interested in studying the western boundary reflection, a process crucial for the delayed action oscillator theory, by using the TOPEX/POSEIDON data from November 1992 to May 1995. We first projected the sea level data onto Kelvin and first-mode Ross waves. Then we estimated the contribution of wind forcing to these waves by using a single baroclinic mode simple wave model forced by the ERS-1 wind data. Wave propagation was clearly observed with amplitudes well explained by the wind forcing in the ocean interior. Evidence of wave reflection was detected at both the western and eastern boundaries of the tropical Pacific ocean. At the eastern boundary, Kelvin waves were seen to reflect as first-mode Rossby waves during the entire period. The reflection efficiency (in terms of wave amplitude) of the South American coasts was estimated to be 80% of that of an infinite meridional wall. At the western boundary, reflection was observed in April-August 1993, in January-June 1994, and, later, in December 1994 to February 1995. Although the general roles of these reflection events in the variability observed in the equatorial Pacific ocean are not clear, the data suggest that the reflections in January-June 1994 have played a role in the onset of the warm conditions observed in late 1994 to early 1995. Indeed, during the January-June 1994 period, as strong downwelling first-mode Rossby waves reflected into downwelling Kelvin waves, easterly wind and cold sea surface temperature anomalies located near the date line weakened and eventually reversed in June-July 1994. The presence of the warm anomalies near the date line then favored convection and westerly wind anomalies that triggered strong downwelling Kelvin waves propagating throughout the basin

  4. Zonal flows and magnetic fields driven by large-amplitude Rossby-Alfvén-Khantadze waves in the E-layer ionosphere

    NASA Astrophysics Data System (ADS)

    Kaladze, T. D.; Horton, W.; Kahlon, L. Z.; Pokhotelov, O.; Onishchenko, O.

    2013-12-01

    waves and vortices in the weakly ionized ionospheric E layer are dominated by the Hall conductivity that couples the Rossby and Alfvén dynamics giving rise to what are called Rossby-Alfvén-Khantadze electromagnetic structures. At finite amplitudes we show that the nonlinearities in the dynamics generate sheared zonal-flow velocities and zonal magnetic field fluctuations. The zonal-flow mechanism is based on the parametric excitation of the zonal variations through three-wave mode coupling in the planetary-scale waves. The coupled dynamics of the nonlinear 3-D incompressible flows and the magnetic field fluctuations are derived and used to derive the structure and growth rates for the zonal flows and zonal magnetic fields. Large-amplitude planetary waves are shown to drive up magnetic fluctuations up to 100 nT.

  5. Temporal Spectral Analysis of Be stars observed with CoRoT satellite

    NASA Astrophysics Data System (ADS)

    Emilio, Marcelo; Janot Pacheco, Eduardo; Andrade, Laerte

    . Nevertheless, to measure frequencies with great accuracy in stars requires both high photometric precision and high time-frequency resolution. The CoRoT (Convection, Rotation and planetary Transits) satellite opens for the first time in history the possibility of fulfilling this goal. CoRoT is an experiment of astronomy dedicated to seismology and the detection of extrasolar planet transits. It was launched on December 2006 in an inertial polar orbit at an altitude of 897 mathrm{km}. The instrument is fed by a phi=27 textrm{cm} telescope. Its scientific program is three-fold consisting of: (1) The seismology core program (SISMO), which concerns the seismic study of ˜10 bright (6CoRoT ID 102761769 observed by CoRoT satellite. We found two close frequencies related to the .CoRoT ID 102761769 star. They are 2.465 c d(-1) (28.5 mathrm{mu Hz}) and 2.441 c d(-1) (28.2 mathrm{mu Hz}). The precision to which those frequencies were found is 0.018 c d(-1) (0.2 mathrm{mu Hz}). The projected stellar rotation was estimated to be 120 km s(-1) from the Fourier transform of spectral lines. If CoRoT-ID 102761769 is a typical Galactic Be star it rotates near the critical velocity. The critical rotation frequency of a typical B5-6 star is about 3.5 c d(-1) (40.5 mathrm{mu Hz}), which implies that the above frequencies are really caused by stellar pulsations rather than star's rotation. HD 171219 frequencies 1.113, 1.130, 1.146 c * d(-1) form a triplet with the

  6. Feature-based verification of synoptic-scale Rossby wave breaking in the ECHAM5-HAM model

    NASA Astrophysics Data System (ADS)

    Béguin, A.; Martius, O.; Sprenger, M.; Spichtinger, P.; Folini, D.; Werlni, H.

    2010-09-01

    Breaking synoptic-scale Rossby waves (RWB) are central to the daily weather evolution of the extratropics and subtropics and for the meridional transport of chemical constituents and momentum. Synoptic-scale RWB events are manifest as elongated and narrow structures in the tropopause level potential vorticity (PV) field. A feature-based verification approach is used to assess the representation of these structures in present day climate simulations carried out with the ECHAM5-HAM climate model with different resolutions (T42L19, T63L31 and T106L31) in comparison to the ERA-40 data set. The algorithm extracts RWB objects from the tropopause-level PV field and allows verifying the frequency of occurrence of RWB objects. The model captures the location of the RWB frequency maxima in the northern hemisphere well in all resolutions. However, in the T42L19 simulation the frequency of events is underestimated in the entire northern hemisphere by 28% (averaged over all seasons and grid-points). The higher-resolution simulations capture the overall frequency of RWB much better, with a fairly small improvement from the T63L31 to the T106L31 run. In the higher-resolution simulations significant differences to the ERA-40 data are regionally confined and vary with the season. The most striking feature is that the model overestimates the frequency of RWB in the subtropical Atlantic in all seasons except for spring.

  7. Retrograde rotation of the large-scale flow in turbulent rotating Rayleigh-Benard convection with high Rossby number

    NASA Astrophysics Data System (ADS)

    Zhong, Jin-Qiang; Li, Hui-Min; Wang, Xue-Ying

    2015-11-01

    We present measurements of the azimuthal orientation θ (t) of the large-scale circulation (LSC) for turbulent Rayleigh-Bénard convection in the presence of week rotations Ω . Linear retrograde rotations of the LSC circulating plane are observed over the entire Rossby-number range (1 <= Ro <= 300) studied. When the Ro increases, the ratio of the retrograde rotation rate, γ = - < . θ > / Ω remains nearly a constant 0.12 in the range of (1 <= Ro <= 80) and starts to increases when Ro > 80 . When Ro ~= 300 , γ approaches a value of 0.36 close to the prediction from previous theoretical models. In a background of linear rotations, erratic changes in θ (t) accompanied by decreasing in the LSC amplitude δ are observed. These small- δ events give rise to the increasing γ with very high Ro numbers (80 <= Ro <= 300). In this range, the diffusivity of θ is proportional to δ-2 . Moreover, the occurrence frequency of the small- δ events, and their average duration are independent on Ro. We propose a model to include additional viscous damping for the LSC azimuthal motion due to turbulent viscosity and provide theoretical interpretations of the experimental results. Work supported by NSFC Grant No. 11202151.

  8. From Land-surface Snow Cover To Routed River Discharge In The Rossby Centre Regional Climate Model

    NASA Astrophysics Data System (ADS)

    Samuelsson, P.; Gollvik, S.; Graham, L. P.; Bringfelt, B.

    The purpose of a land-surface scheme (LSS) in a coupled atmosphere- land-ocean model system is in general to provide the atmosphere with correct turbulent and radia- tion fluxes and to provide the routing scheme with correct water runoff flux. ``Correct" includes both amounts and time distributions. Snow is a very important process to con- sider in a LSS used for simulations at high latitudes. Snow has extreme radiation and heat transfer properties and it accumulates water during the winter season. Therefore, both amount and distribution of snow have to be carefully simulated. The LSS in the Rossby Centre Regional Climate Model (RCA) separates snow storage on open land and in forest. Both storages are single-layered, include liquid water and use the en- ergy balance to solve for time changes in temperature and water storage. The runoff generated from i.e. snow melt in each grid cell is used in a routing scheme to produce river discharge for the ocean model. The routing scheme is based on the hydrological HBV model which means that it is separately calibrated for each individual sub-basin. Validations of snow cover and river discharge simulations will be presented.

  9. The coupling of mixed Rossby-gravity waves with diabatic heating during the TRMM-KWAJEX field campaign

    NASA Astrophysics Data System (ADS)

    Wang, Xiaocong; Zhang, Minghua

    2015-10-01

    Composite dynamic and thermodynamic structures of mixed Rossby-gravity (MRG) waves are presented with their coupling with diabatic heating and moisture sources/sinks, using Tropical Rainfall Measuring Mission-Kwajalein Experiment (TRMM-KWAJEX) field campaign data. A significant departure of convectively coupled waves from dry waves exists in the phases of wave component: maximum low-level wind convergence is accompanied by midtropospheric divergence and upper tropospheric convergence that is preceded by increase of moisture in the boundary layer. These phases correspond to surface turbulent transport, shallow and midlevel convections that cause moistening and heating of the lower and middle troposphere. They are followed by deep convection with maximum heating centered in the upper troposphere. The deep convective heating evolves to stratiform-like upper tropospheric heating and lower tropospheric cooling that precedes the quick demise of convection. Such a structure on convectively coupled MRG waves is summarized by four phases, which sheds lights on how tropical waves are coupled with convective processes in all their phases.

  10. Transiting exoplanets from the CoRoT space mission Resolving the nature of transit candidates for the LRa03 and SRa03 fields

    NASA Astrophysics Data System (ADS)

    Cavarroc, C.; Moutou, C.; Gandolfi, D.; Tingley, B.; Ollivier, M.; Aigrain, S.; Alonso, R.; Almenara, J.-M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Cabrera, J.; Carpano, S.; Carone, L.; Cochran, W. D.; Csizmadia, S.; Deeg, H. J.; Deleuil, M.; Díaz, R. F.; Dvorak, R.; Endl, M.; Erikson, A.; Fridlund, M.; Gillon, M.; Guenther, E. W.; Guillot, T.; Hatzes, A.; Hébrard, G.; Jorda, L.; Léger, A.; Lammer, H.; Lev, T.-O.; Lovis, C.; MacQueen, P. J.; Mazeh, T.; Ofir, A.; Parviainen, H.; Pasternacki, T.; Pätzold, M.; Queloz, D.; Rauer, H.; Rouan, D.; Samuel, B.; Santerne, A.; Schneider, J.; Weingrill, J.; Wuchterl, G.

    2012-02-01

    CoRoT is a space telescope which aims at studying internal structure of stars and detecting extrasolar planets. We present here a list of transits detected in the light curves of stars observed by CoRoT in two fields in the anti-center direction: the LRa03 one observed during 148 days from 3 October 2009 to 1 March 2010 followed by the SRa03 one from the 5 March 2010 to the 29 March 2010 during 25 days. 5329 light curves for the LRa03 field and 4169 for the SRa03 field were analyzed by the detection team of CoRoT. Then some of the selected exoplanetary candidates have been followed up from the ground. In the LRa03 field, 19 exoplanet candidates have been found, 8 remain unsolved. No secured planet has been found yet. In the SRa03 field, there were 11 exoplanetary candidates among which 6 cases remain unsolved and 3 planets have been found: CoRoT-18b, CoRoT-19b, CoRoT-20b.