Search Publications
Solar energetic particle warnings from a coronagraph
St. Cyr, O. C.; Burkepile, J. T.; Posner, A.
We report here the concept of using near-real time observations from a coronagraph to provide early warning of a fast coronal mass ejection (CME) and the possible onset of a solar energetic particle (SEP) event. The 1 January 2016, fast CME, and its associated SEP event are cited as an example. The CME was detected by the ground-based K-Cor corona…
A Survey for Planetary-mass Brown Dwarfs in the Chamaeleon I Star-forming Region
Luhman, K. L.; Faherty, J. K.; Esplin, T. L. +2 more
We have performed a search for planetary-mass brown dwarfs in the Chamaeleon I star-forming region using proper motions and photometry measured from optical and infrared images from the Spitzer Space Telescope, the Hubble Space Telescope, and ground-based facilities. Through near-IR spectroscopy at Gemini Observatory, we have confirmed six of the …
Dynamics of aspherical dust grains in a cometary atmosphere: I. axially symmetric grains in a spherically symmetric atmosphere
Fulle, M.; Della Corte, V.; Rotundi, A. +3 more
In-situ measurements of individual dust grain parameters in the immediate vicinity of a cometary nucleus are being carried by the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko. For the interpretations of these observational data, a model of dust grain motion as realistic as possible is requested. In particular, the results of the Stardust …
H2O and O2 absorption in the coma of comet 67P/Churyumov-Gerasimenko measured by the Alice far-ultraviolet spectrograph on Rosetta
Parker, Joel Wm.; Bertaux, Jean-Loup; Stern, S. Alan +10 more
We have detected H2O and O2 absorption against the far-UV continuum of stars located on lines of sight near the nucleus of Comet 67P/Churyumov-Gerasimenko using the Alice imaging spectrograph on Rosetta. These stellar appulses occurred at impact parameters of ρ = 4-20 km, and heliocentric distances ranging from Rh …
Anisotropies of the Magnetic Field Fluctuations at Kinetic Scales in the Solar Wind: Cluster Observations
Alexandrova, Olga; Matteini, Lorenzo; Lacombe, Catherine
We present the first statistical study of the anisotropy of the magnetic field turbulence in the solar wind between 1 and 200 Hz, I.e., from proton to sub-electron scales. We consider 93 ten-minute intervals of the Cluster/STAFF measurements. We find that the fluctuations δ {B}\perp 2 are not gyrotropic at a given frequency f…
The Presence of Thermally Unstable X-Ray Filaments and the Production of Cold Gas in the NGC 5044 Group
Jones, Christine; David, Laurence P.; Sun, Ming +3 more
We present the results of a deep Chandra observation of the X-ray bright moderate-cooling flow group NGC 5044 along with the observed correlations between the ionized, atomic, and molecular gas in this system. The Chandra observation shows that the central AGN has undergone two outbursts in the past 108 years, based on the presence of t…
Testing the Recovery of Intrinsic Galaxy Sizes and Masses of z ∼ 2 Massive Galaxies Using Cosmological Simulations
Barro, Guillermo; Faucher-Giguère, Claude-André; Kriek, Mariska +5 more
Accurate measurements of galaxy masses and sizes are key to tracing galaxy evolution over time. Cosmological zoom-in simulations provide an ideal test bed for assessing the recovery of galaxy properties from observations. Here, we utilize galaxies with {M}* ∼ {10}10{--}{10}11.5 {M}⊙ at z ∼ 1.7-2 from th…
Recurrence rate and magma effusion rate for the latest volcanism on Arsia Mons, Mars
Richardson, Jacob A.; Wilson, James A.; Connor, Charles B. +2 more
Magmatism and volcanism have evolved the Martian lithosphere, surface, and climate throughout the history of Mars. Constraining the rates of magma generation and timing of volcanism on the surface clarifies the ways in which magma and volcanic activity have shaped these Martian systems. The ages of lava flows on other planets are often estimated u…
The Green Bank Ammonia Survey: Observations of Hierarchical Dense Gas Structures in Cepheus-L1251
Caselli, Paola; Di Francesco, James; Rosolowsky, Erik +20 more
We use Green Bank Ammonia Survey observations of NH3 (1, 1) and (2, 2) emission with 32″ FWHM resolution from a ∼10 pc2 portion of the Cepheus-L1251 molecular cloud to identify hierarchical dense gas structures. Our dendrogram analysis of the NH3 data results in 22 top-level structures, which reside within 13 lower…
Sagittarius A* High-energy X-Ray Flare Properties during NuSTAR Monitoring of the Galactic Center from 2012 to 2015
Hailey, Charles J.; Mori, Kaya; Zhang, Shuo +17 more
Understanding the origin of the flaring activity from the Galactic center supermassive black hole Sagittarius A* is a major scientific goal of the NuSTAR Galactic plane survey campaign. We report on the data obtained between 2012 July and 2015 April, including 27 observations on Sgr A*, with a total exposure of ≃ 1 Ms. We found a total of 10 X-ray…