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An XMM-Newton Study of the 401 Hz Accreting Pulsar SAX J1808.4-3658 in Quiescence
Campana, S.; Mereghetti, S.; Stella, L. +6 more
SAX J1808.4-3658 is a unique source, being the first low-mass X-ray binary showing coherent pulsations at a spin period comparable to that of millisecond radio pulsars. Here we present an XMM-Newton observation of SAX J1808.4-3658 in quiescence, the first that assessed its quiescent luminosity and spectrum with a good signal-to-noise ratio. XMM-Ne…
The initial conditions of isolated star formation - V. ISOPHOT imaging and the temperature and energy balance of pre-stellar cores
Ward-Thompson, D.; André, P.; Kirk, J. M.
ISO data taken with the long-wavelength imaging photo-polarimeter ISOPHOT are presented of 18 pre-stellar cores at three far-infrared wavelengths, 90, 170 and 200µm. Most of the cores are detected clearly at 170 and 200µm, but only one is detected strongly at 90µm, indicating that mostly they are very cold, with typical temperatu…
XMM-Newton observation of the distant (z=0.6}) galaxy cluster RX J1120.1+4318
Aghanim, N.; Arnaud, M.; Giard, M. +11 more
We report on a 20 ks XMM observation of the distant cluster RX J1120.1+4318, discovered at z=0.6 in the SHARC survey. The cluster has a regular spherical morphology, suggesting it is in a relaxed state. The combined fit of the EPIC/MOS&pn camera gives a cluster mean temperature of kT= 5.3+/-0.5 kev with an iron abundance of 0.47+/-0.19. The te…
Chandra Observations of the X-Ray Jet in Centaurus A
Hardcastle, M. J.; Worrall, D. M.; Forman, W. R. +3 more
We present high angular resolution X-ray images and spectra from two Chandra AXAF CCD Imaging Spectrometer (ACIS-I) observations of the X-ray jet in the nearby radio galaxy Cen A. We find that the X-ray emission from the jet is composed of a low surface brightness diffuse component extending continuously from within at least 60 pc of the active nu…
A Hubble Space Telescope Survey of the Mid-Ultraviolet Morphology of Nearby Galaxies
de Jong, Roelof S.; Conselice, Christopher J.; de Grijs, Richard +12 more
We present a systematic imaging survey of 37 nearby galaxies observed with the Hubble Space Telescope (HST) Wide Field and Planetary Camera 2 (WFPC2) in the mid-UV F300W filter, centered at 2930 Å, as well as in the I-band (F814W) filter at 8230 Å. Eleven of these galaxies were also imaged in the F255W filter, centered at 2550 Å. Our sample is car…
The profiles of the aromatic infrared bands explained with molecular carriers
Joblin, C.; Boissel, P.; Pech, C.
Using a compilation of the photophysical properties of molecules such as coronene, C24H12, we have constructed a numerical model to calculate the IR emission spectrum of a population of polycyclic aromatic hydrocarbon (PAH) species subjected to UV photons. The model enables us to calculate not only the energy emitted in the I…
High-resolution X-ray spectroscopy of Procyon by Chandra and XMM-Newton
Kaastra, J. S.; Raassen, A. J. J.; Mewe, R. +6 more
We report the analysis of the high-resolution soft X-ray spectrum of the nearby F-type star Procyon in the wavelength range from 5 to 175 Å obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board Chandra and with the Reflection Grating Spectrometers (RGS) and the EPIC-MOS CCD spectrometers on board XMM-Newton. Line fluxes h…
The blue compact dwarf galaxy I Zw 18: A comparative study of its low-surface-brightness component
Thuan, T. X.; Izotov, Y. I.; Green, R. F. +4 more
Using HST and ground-based optical and NIR imaging data we investigate whether the blue compact dwarf (BCD) galaxy I Zw 18 possesses an extended low-surface-brightness (LSB) old stellar population underlying its star-forming regions, as is the case in the majority of BCDs. This question is central to the long-standing debate on the evolutionary st…
The Hydromagnetic Origin of the Two Dynamical Types of Solar Coronal Mass Ejections
Zhang, M.; Low, B. C.
We propose a qualitative theory relating flux rope coronal mass ejections (CMEs) to initial states, represented by inverse or normal quiescent prominences corresponding to whether the flux rope magnetic field circulates in the same or opposite sense relative to the surrounding coronal magnetic field. Our theory explains the observed dual character…
Spectroscopic diagnostics of stellar transition regions and coronae in the XUV: AU Mic in quiescence
Mason, H. E.; Landini, M.; Del Zanna, G.
In this paper we review the spectroscopic diagnostic techniques that can be applied to XUV observations of active stars. In particular, we discuss methods for the determination of electron densities, emission measures and the chemical composition of the stellar transition regions and coronae. We pay particular attention to the atomic data used and…