Search Publications
Wavevector anisotropy of plasma turbulence at ion kinetic scales: solar wind observations and hybrid simulations
Narita, Y.; Motschmann, U.; Comişel, H.
Wavevector anisotropy of ion-scale plasma turbulence is studied at various values of ion beta. Two complementary methods are used. One is multi-point measurements of magnetic field in the near-Earth solar wind as provided by the Cluster spacecraft mission, and the other is hybrid numerical simulation of two-dimensional plasma turbulence. Both meth…
IP Eridani: A surprising long-period binary system hosting a He white dwarf
Jorissen, A.; Masseron, T.; Van Winckel, H. +3 more
We determine the orbital elements for the K0 IV + white dwarf (WD) system IP Eri, which appears to have a surprisingly long period of 1071 d and a significant eccentricity of 0.25. Previous spectroscopic analyses of the WD, based on a distance of 101 pc inferred from its Hipparcos parallax, yielded a mass of only 0.43 M⊙, implying it to…
CH4 mixing ratios at microbar pressure levels of Jupiter as constrained by 3-micron ISO data
Moses, J. I.; Sim, C. K.; Kim, Sang J. +1 more
Infrared Space Observatory (ISO) data of Jupiter are revisited in order to derive CH4 mixing ratios at microbar pressures in the atmosphere. We utilize the most updated radiative transfer programs to construct a 3-µm emission model of CH4 to be compared with the ISO data. From the model-data comparisons, we derive the h…
Saturn’s F Ring core: Calm in the midst of chaos
Scargle, J. D.; Showalter, M. R.; Colwell, J. E. +5 more
The long-term stability of the narrow F Ring core has been hard to understand. Instead of acting as “shepherds”, Prometheus and Pandora together stir the vast preponderance of the region into a chaotic state, consistent with the orbits of newly discovered objects like S/2004 S 6. We show how a comb of very narrow radial locations of high stability…
Circumnuclear Molecular Gas in Megamaser Disk Galaxies NGC 4388 and NGC 1194
Greene, Jenny E.; van de Ven, Glenn; Seth, Anil +3 more
We explore the warm molecular and ionized gas in the centers of two megamaser disk galaxies using K-band spectroscopy. Our ultimate goal is to determine how gas is funneled onto the accretion disk, here traced by megamaser spots on sub-parsec scales. We present NIR IFU data with a resolution of ~50 pc for two galaxies: NGC 4388 with VLT/SINFONI an…
A model of the magnetosheath magnetic field during magnetic clouds
Kilpua, E. K. J.; Turc, L.; Fontaine, D. +1 more
Magnetic clouds (MCs) are huge interplanetary structures which originate from the Sun and have a paramount importance in driving magnetospheric storms. Before reaching the magnetosphere, MCs interact with the Earth's bow shock. This may alter their structure and therefore modify their expected geoeffectivity. We develop a simple 3-D model of the m…
ALMA Observations of the Host Galaxy of GRB 090423 at z = 8.23: Deep Limits on Obscured Star Formation 630 Million Years after the Big Bang
Berger, E.; Chary, R. -R.; Chornock, R. +7 more
We present rest-frame far-infrared (FIR) and optical observations of the host galaxy of GRB 090423 at z = 8.23 from the Atacama Large Millimeter Array (ALMA) and the Spitzer Space Telescope, respectively. The host remains undetected to 3σ limits of F ν(222 GHz) <~ 33 µJy and F ν(3.6 µm) <~ 81 nJy. The FIR li…
Massive stars in the giant molecular cloud G23.3-0.3 and W41
Menten, Karl M.; Rich, R. Michael; MacKenty, John W. +7 more
Context. Young massive stars and stellar clusters continuously form in the Galactic disk, generating new Hii regions within their natal giant molecular clouds and subsequently enriching the interstellar medium via their winds and supernovae.
Aims: Massive stars are among the brightest infrared stars in such regions; their identification permi…
The Quest to Understand Supergranulation and Large-Scale Convection in the Sun
Hanasoge, Shravan M.; Sreenivasan, Katepalli R.
Surface granulation of the Sun is primarily a consequence of thermal transport in the outer 1 % of the radius. Its typical scale of about 1 - 2 Mm is set by the balance between convection, free-streaming radiation, and the strong density stratification in the surface layers. The physics of granulation is well understood, as demonstrated by the clo…
UV spectral analysis of very hot H-deficient [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6 and Sand 3
Bianchi, Luciana; Keller, Graziela R.; Maciel, Walter J.
We analysed ultraviolet Far Ultraviolet Spectroscopic Explorer, International Ultraviolet Explorer, and Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra of five of the hottest [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6, and Sand 3. The analysis leveraged on our grid of cmfgen synthetic spec…