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Ion acceleration dependence on magnetic shear angle in dayside magnetopause reconnection
Fuselier, S. A.; Trattner, K. J.; Petrinec, S. M. +2 more
Magnetic reconnection at the Earth's magnetopause plays an important role in magnetospheric dynamics. Understanding the dynamics requires theory and observations. Previous theoretical work suggests that for no guide field, ions in the exhaust region on the magnetosheath side of the boundary counterstream with a velocity separation that is twice th…
Low CO/CO2 ratios of comet 67P measured at the Abydos landing site by the Ptolemy mass spectrometer
Mousis, O.; Andrews, D.; Morse, A. +4 more
Comets are generally considered to contain the best-preserved material from the beginning of our planetary system, although the mechanism of their formation and subsequent evolution are still poorly understood. Here we report the direct in situ measurement of H2O, CO, and CO2 by the Ptolemy mass spectrometer onboard the Phila…
Cassini INMS measurements of Enceladus plume density
McNutt, R. L.; Waite, J. H.; Teolis, B. D. +5 more
During six encounters between 2008 and 2013, the Cassini Ion and Neutral Mass Spectrometer (INMS) made in situ measurements deep within the Enceladus plumes. Throughout each encounter, those measurements contained density variations that reflected the nature of the source, particularly of the high-velocity jets. Since the dominant constituent of t…
Variability of the coronal line region in NGC 4151
Ferland, Gary J.; Steenbrugge, Katrien C.; Landt, Hermine +1 more
We present the first extensive study of the coronal line variability in an active galaxy. Our data set for the nearby source NGC 4151 consists of six epochs of quasi-simultaneous optical and near-infrared spectroscopy spanning a period of about 8 yr and five epochs of X-ray spectroscopy overlapping in time with it. None of the coronal lines showed…
The Born-again Planetary Nebula A78: An X-Ray Twin of A30
Gruendl, R. A.; Hamann, W. -R.; Chu, Y. -H. +8 more
We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar …
A radio and X-ray study of the merging cluster A2319
Rudnick, Lawrence; Jeltema, Tesla E.; Storm, Emma
A2319 is a massive, merging galaxy cluster with a previously detected radio halo that roughly follows the X-ray emitting gas. We present the results from recent observations of A2319 at ∼20 cm with the Karl G. Jansky Very Large Array and a re-analysis of the X-ray observations from XMM-Newton, to investigate the interactions between the thermal an…
Newly Determined Explosion Center of Tycho's Supernova and the Implications for Proposed Ex-companion Stars of the Progenitor
Schaefer, Bradley E.; Xue, Zhichao
“Star G,” near the center of the supernova remnant of Tycho’s SN 1572, has been claimed to be the ex-companion star of the exploding white dwarf, thus pointing to the progenitor being like a recurrent nova. This claim has been controversial, but there have been no confident proofs or disproofs. Previously, no one has seriously addressed the questi…
Object-based Dune Analysis: Automated dune mapping and pattern characterization for Ganges Chasma and Gale crater, Mars
Fenton, Lori K.; Michaels, Timothy I.; Vaz, David A. +2 more
A method that enables the automated mapping and characterization of dune fields on Mars is described. Using CTX image mosaics, the introduced Object-based Dune Analysis (OBDA) technique produces an objective and reproducible mapping of dune morphologies over extensive areas. The data set thus obtained integrates a large variety of data, allowing a…
The 1999aa-like Type Ia Supernova iPTF14bdn in the Ultraviolet and Optical
Suntzeff, Nicholas B.; Wang, Xiaofeng; Zhang, Jujia +5 more
We present ultraviolet (UV) and optical photometry and spectra of the 1999aa-like supernova (SN) iPTF14bdn. The UV data were observed using the Swift Ultraviolet/Optical Telescope and constitute the first UV spectral series of a 1999aa-like SN. From the photometry, we measure Δm15(B) = 0.84 ± 0.05 mag and blue UV colors at epochs earlie…
Plasma regions, charged dust and field-aligned currents near Enceladus
Gurnett, D. A.; Dougherty, M. K.; Kurth, W. S. +7 more
We use data from several instruments on board Cassini to determine the characteristics of the plasma and dust regions around Saturn's moon Enceladus. For this we utilize the Langmuir probe and the electric antenna connected to the wideband receiver of the radio and plasma wave science (RPWS) instrument package as well as the magnetometer (MAG). We…