Search Publications
Extending Gaia DR2 with HST narrow-field astrometry: the WISE J154151.65-225024.9 test case
Bedin, L. R.; Fontanive, C.
One field containing WISE J154151.65- 225024.9 was observed by Hubble Space Telescope at three different epochs taken in ∼5 yr. We measured positions of sources in all images and successfully linked these positions to the Gaia DR2 absolute system to derive the astrometric parameters for this faint close-by Y1 brown dwarf. The developed procedure a…
A new method for extracting seismic indices and granulation parameters: Results for more than 20,000 CoRoT and Kepler red giants
Michel, E.; Samadi, R.; de Assis Peralta, R.
We have developed a new automated method intended to perform the simultaneous—and thus more consistent—measurement of both the seismic indices characterizing the oscillations and the parameters characterizing the granulation signature of red giant stars. This method, called MLEUP, takes advantage of the Maximum Likelihood Estimate (MLE) algorithm …
Fluid simulations of plasma turbulence at ion scales: Comparison with Vlasov-Maxwell simulations
Passot, T.; Zouganelis, I.; Veltri, P. +5 more
Comparisons are presented between a hybrid Vlasov-Maxwell (HVM) simulation of turbulence in a collisionless plasma and fluid reductions. These include Hall-magnetohydrodynamics (HMHD) and Landau fluid (LF) or finite Larmor radius-Landau fluid (FLR-LF) models that retain pressure anisotropy and low-frequency kinetic effects such as Landau damping a…
In Search of Recent Disruption of (3200) Phaethon: Model Implication and Hubble Space Telescope Search
Ye, Quanzhi; Hui, Man-To; Wiegert, Paul A.
Near-Earth asteroid (3200) Phaethon is notable for its association with a strong annual meteor shower, the Geminids, indicative of one or more episodes of mass ejection in the past. The mechanism of Phaethon’s past activity is not yet understood. Here, we present a Hubble Space Telescope (HST) search of meter-sized fragments in the vicinity of Pha…
Intense Current Structures Observed at Electron Kinetic Scales in the Near-Earth Magnetotail During Dipolarization and Substorm Current Wedge Formation
Lavraud, B.; Malykhin, A. Yu.; Grigorenko, E. E. +4 more
We use data from the 2013-2014 Cluster Inner Magnetosphere Campaign, with its uniquely small spacecraft separations (less than or equal to electron inertia length, <fi>λ</fi>e), to study multiscale magnetic structures in 14 substorm-related prolonged dipolarizations in the near-Earth magnetotail. Three time scales of dipolar…
Connections between Star Cluster Populations and Their Host Galaxy Nuclear Rings
Ho, Luis C.; de Grijs, Richard; Ma, Chao
Nuclear rings are excellent laboratories for probing diverse phenomena such as the formation and evolution of young massive star clusters and nuclear starbursts, as well as the secular evolution and dynamics of their host galaxies. We have compiled a sample of 17 galaxies with nuclear rings, which are well resolved by high-resolution Hubble and Sp…
Spitzer Infrared Spectrograph Observations of the Galactic Center: Quantifying the Extreme Ultraviolet/Soft X-ray Fluxes
Simpson, Janet P.
It has long been shown that the extreme ultraviolet spectrum of the ionizing stars of H II regions can be estimated by comparing the observed line emission to detailed models. In the Galactic Center (GC), however, previous observations have shown that the ionizing spectral energy distribution (SED) of the local photon field is strange, producing b…
NuSTAR observations of Mrk 766: distinguishing reflection from absorption
Harrison, F. A.; Stern, D.; Zhang, W. W. +15 more
We present two new NuSTAR observations of the narrow-line Seyfert 1 (NLS1) galaxy Mrk 766 and give constraints on the two scenarios previously proposed to explain its spectrum and that of other NLS1s: relativistic reflection and partial covering. The NuSTAR spectra show a strong hard (>15 keV) X-ray excess, while simultaneous soft X-ray coverag…
Testing the equivalence principle in space after the MICROSCOPE mission
Nobili, Anna M.; Anselmi, Alberto
Tests of the weak equivalence principle (WEP) can reveal a new, composition dependent, force of nature, or disprove many models of new physics. For the first time, such a test is being successfully carried out in space by the MICROSCOPE satellite. Early results show no violation of the WEP sourced by the Earth for Pt and Ti test masses with random…
Responses of the Martian Magnetosphere to an Interplanetary Coronal Mass Ejection: MAVEN Observations and LatHyS Results
Holmström, M.; Luhmann, J. G.; Chaufray, J. -Y. +12 more
The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft observed a strong interplanetary coronal mass ejection (ICME) reaching Mars on 13 September 2017. In this work we analyze the interaction between such an extreme event and the Martian-induced magnetosphere by means of Laboratoire Atmosphères, Milieux et Observations Spatiales Hybrid Sim…