Search Publications
Generation of He+ and O+ EMIC waves by the bunch distribution of O+ ions associated with fast magnetosonic shocks in the magnetosphere
Lee, L. C.; Lee, K. H.
Electromagnetic ion cyclotron (EMIC) waves are often observed in the magnetosphere with frequency usually in the H+ and He+ cyclotron bands and sometimes in the O+ band. The temperature anisotropy, caused by injection of energetic ions or by compression of magnetosphere, can efficiently generate H+ EMIC …
Three-dimensional distribution of hydrogen fluoride gas toward NGC 6334 I and I(N)
Abergel, A.; van der Wiel, M. H. D.; Naylor, D. A. +2 more
Context. The HF molecule has been proposed as a sensitive tracer of diffuse interstellar gas, while at higher densities its abundance could be influenced heavily by freeze-out onto dust grains.
Aims: We investigate the spatial distribution of a collection of absorbing gas clouds, some associated with the dense, massive star-forming core NGC 6…
Analysis of spatially deconvolved polar faculae
Suematsu, Y.; Shimizu, T.; Ruiz Cobo, B. +2 more
Polar faculae are bright features that can be detected in solar limb observations and they are related to magnetic field concentrations. Although there are a large number of works studying them, some questions about their nature as their magnetic properties at different heights are still open. Thus, we aim to improve the understanding of solar pol…
The first transition Wolf-Rayet WN/C star in M31
Caldwell, Nelson; Iłkiewicz, Krystian; Mikołajewska, Joanna +3 more
Three decades of searches have revealed 154 Wolf-Rayet (WR) stars in M31, with 62 of WC type, 92 of WN type and zero of transition-type WN/C or WC/N. In apparent contrast, about two per cent of the WR stars in the Galaxy, the LMC and M33 simultaneously display strong lines of carbon and nitrogen, I.e. they are transition-type WN/C or WC/N stars. W…
Fine-pitch CdTe detector for hard X-ray imaging and spectroscopy of the Sun with the FOXSI rocket experiment
Takahashi, Tadayuki; Saito, Shinya; Watanabe, Shin +8 more
We have developed a fine-pitch hard X-ray (HXR) detector using a cadmium telluride (CdTe) semiconductor for imaging and spectroscopy for the second launch of the Focusing Optics Solar X-ray Imager (FOXSI). FOXSI is a rocket experiment to perform high sensitivity HXR observations from 4 to 15 keV using the new technique of HXR focusing optics. The …
Learning about stars from their colors
Allende Prieto, C.
Aims: We pose the question of how much information on the atmospheric parameters of late-type stars can be retrieved purely from color information using standard photometric systems.
Methods: We carried out numerical experiments using stellar fluxes from model atmospheres, injecting random noise before analyzing them. We examined the pre…
Thermodynamic performance of the 3-stage ADR for the Astro-H Soft-X-ray Spectrometer instrument
Kelley, Richard L.; Porter, Frederick S.; DiPirro, Michael J. +6 more
The Soft X-ray Spectrometer (SXS) instrument (Mitsuda et al., 2010) [1] on Astro-H (Takahashi et al., 2010) [2] will use a 3-stage ADR (Shirron et al., 2012) to cool the microcalorimeter array to 50 mK. In the primary operating mode, two stages of the ADR cool the detectors using superfluid helium at ⩽1.20 K as the heat sink (Fujimoto et al., 2010…
Transient effects in Herschel/PACS spectroscopy
Fadda, Dario; Appleton, Philip N.; Jacobson, Jeffery D.
Context. The Ge:Ga detectors used in the PACS spectrograph onboard the Herschel space telescope react to changes of the incident flux with a certain delay. This generates transient effects on the resulting signal which can be important and last for up to an hour.
Aims: The paper presents a study of the effects of transients on the detected si…
Suprathermal Electrons in Titan’s Sunlit Ionosphere: Model-Observation Comparisons
Coates, A. J.; Wahlund, J. -E.; Edberg, N. J. T. +8 more
The dayside ionosphere of the Saturnian satellite Titan is generated mainly from photoionization of N2 and CH4. We compare model-derived suprathermal electron intensities with spectra measured by the Cassini Plasma Spectrometer/Electron Spectrometer (CAPS/ELS) in Titan's sunlit ionosphere (altitudes of 970-1250 km) focusing o…
Ion injection at Quasi-parallel Shocks Seen by the Cluster Spacecraft
Dandouras, I.; Vaivads, A.; Khotyaintsev, Yu. V. +2 more
Collisionless shocks in space plasma are known to be capable of accelerating ions to very high energies through diffusive shock acceleration (DSA). This process requires an injection of suprathermal ions, but the mechanisms producing such a suprathermal ion seed population are still not fully understood. We study acceleration of solar wind ions re…