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Unveiling shocks in planetary nebulae
Toalá, Jesús A.; Guerrero, Martín A.; Miranda, Luis F. +4 more
The propagation of a shock wave into a medium is expected to heat the material beyond the shock, producing noticeable effects in intensity line ratios such as [O iii]/Hα. To investigate the occurrence of shocks in planetary nebulae (PNe), we have used all narrow-band [O iii] and Hα images of PNe available in the HST archive to build their [O iii]/…
Ion temperature anisotropy instabilities in planetary magnetosheaths
Lakhina, G. S.; Tsurutani, B. T.; Echer, E. +2 more
There has been a lack of understanding why mirror modes are present in planetary magnetosheaths, at comets, and in the heliosheath. Linear theory indicates that the ion cyclotron instability should dominate over the mirror mode instability in electron-proton plasma. In this paper, we take a new approach. We examine the role of plasma electron temp…
Pillars and globules at the edges of H ii regions. Confronting Herschel observations and numerical simulations
Hill, T.; White, G. J.; Roussel, H. +24 more
Context. Herschel far-infrared imaging observations have revealed the density structure of the interface between H ii regions and molecular clouds in great detail. In particular, pillars and globules are present in many high-mass star-forming regions, such as the Eagle nebula (M 16) and the Rosette molecular cloud, and understanding their origin w…
OH/IR stars and their superwinds as observed by the Herschel Space Observatory
Waters, L. B. F. M.; Teyssier, D.; Justtanont, K. +4 more
Aims: In order to study the history of mass loss in extreme OH/IR stars, we observed a number of these objects using CO as a tracer of the density and temperature structure of their circumstellar envelopes.
Methods: Combining CO observations from the Herschel Space Observatory with those from the ground, we trace mass loss rates as a fun…
The use and calibration of read-out streaks to increase the dynamic range of the Swift Ultraviolet/Optical Telescope
Carter, M.; Page, M. J.; Symeonidis, M. +12 more
The dynamic range of photon counting micro-channel-plate (MCP) intensified charged-coupled device (CCD) instruments such as the Swift Ultraviolet/Optical Telescope (UVOT) and the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded by the CCD. …
Hot Water in the Inner 100 AU of the Class 0 Protostar NGC 1333 IRAS2A
Bergin, Edwin A.; van Dishoeck, Ewine F.; Visser, Ruud +2 more
Evaporation of water ice above 100 K in the inner few 100 AU of low-mass embedded protostars (the so-called hot core) should produce quiescent water vapor abundances of ~10-4 relative to H2. Observational evidence so far points at abundances of only a few 10-6. However, these values are based on spherical models, w…
Particle and magnetic field properties of the Saturnian magnetosheath: Presence and upstream escape of hot magnetospheric plasma
Coates, A. J.; Dougherty, M. K.; Thomsen, M. F. +6 more
We analyze plasma, energetic particle, and magnetic field data from all available Cassini passes through the Saturnian magnetosheath between July 2004 and July 2011 and provide a statistical overview of particle and field properties. The results show that magnetosheath plasma has an average number density of ~0.1 cm-3 and a temperature …
Stochastic Acceleration by Multi-Island Contraction during Turbulent Magnetic Reconnection
Kontar, Eduard P.; Bian, Nicolas H.
The acceleration of charged particles in magnetized plasmas is considered during turbulent multi-island magnetic reconnection. The particle acceleration model is constructed for an ensemble of islands which produce adiabatic compression of the particles. The model takes into account the statistical fluctuations in the compression rate experienced …
B- and A-type Stars in the Taurus-Auriga Star-forming Region
Padgett, Deborah; Rebull, Luisa; Mooley, Kunal +2 more
We describe the results of a search for early-type stars associated with the Taurus-Auriga molecular cloud complex, a diffuse nearby star-forming region noted as lacking young stars of intermediate and high mass. We investigate several sets of possible O, B, and early A spectral class members. The first is a group of stars for which mid-infrared i…
Spectral and Timing Properties of the Magnetar CXOU J164710.2-455216
An, Hongjun; Kaspi, Victoria M.; Archibald, Robert +1 more
We report on spectral and timing properties of the magnetar CXOU J164710.2-455216 in the massive star cluster Westerlund 1. Using 11 archival observations obtained with Chandra and XMM-Newton over approximately 1000 days after the source's 2006 outburst, we study the flux and spectral evolution of the source. We show that the hardness of the sourc…