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Solar radiative output and its variability: evidence and mechanisms
Fröhlich, Claus; Lean, Judith
Electromagnetic radiation from the Sun is Earth’s primary energy source. Space-based radiometric measurements in the past two decades have begun to establish the nature, magnitude and origins of its variability. An 11-year cycle with peak-to-peak amplitude of order 0.1 % is now well established in recent total solar irradiance observations, as are…
Exploring The Saturn System In The Thermal Infrared: The Composite Infrared Spectrometer
Smith, M. D.; Showalter, M. R.; Lellouch, E. +42 more
The Composite Infrared Spectrometer (CIRS) is a remote-sensing Fourier Transform Spectrometer (FTS) on the Cassini orbiter that measures thermal radiation over two decades in wavenumber, from 10 to 1400 cm- 1 (1 mm to 7µ m), with a spectral resolution that can be set from 0.5 to 15.5 cm- 1. The far infrared portion of t…
Probing turbulence in the Coma galaxy cluster
Finoguenov, A.; Böhringer, H.; Miniati, F. +2 more
Spatially-resolved gas pressure maps of the Coma galaxy cluster are obtained from a mosaic of XMM-Newton observations in the scale range between a resolution of 20 kpc and an extent of 2.8 Mpc. A Fourier analysis of the data reveals the presence of a scale-invariant pressure fluctuation spectrum in the range between 40 and 90 kpc and is found to b…
Numerical simulation of the 12 May 1997 interplanetary CME event
Odstrcil, D.; Riley, P.; Zhao, X. P.
Numerical three-dimensional magnetohydrodynamic models are capable of predicting large-scale solar wind structures at Earth, provided that appropriate time-dependent boundary conditions are specified near the Sun. Since knowledge of such conditions is at present insufficient to directly drive the models, various approximations are used. In this pa…
The Anatomy of Star Formation in NGC 300
Helou, G.; Roussel, H.; Fazio, G. G. +19 more
The Spitzer Space Telescope was used to study the mid- to far-infrared properties of NGC 300 and to compare dust emission to Hα to elucidate the heating of the interstellar medium (ISM) and the star formation cycle at scales smaller than 100 pc. The new data allow us to discern clear differences in the spatial distribution of 8 µm dust emiss…
An Extended Scheme for Fitting X-Ray Data with Accretion Disk Spectra in the Strong Gravity Regime
Yaqoob, T.; Dovčiak, M.; Karas, V.
Accreting black holes are believed to emit X-rays, which then mediate information about strong gravity in the vicinity of the emission region. We report on a set of new routines for the XSPEC package for analyzing X-ray spectra of black-hole accretion disks. The new computational tool significantly extends the capabilities of the currently availab…
The Rest-Frame Optical Spectra of SCUBA Galaxies
Ivison, R. J.; Smail, Ian; Swinbank, A. M. +3 more
We present near-infrared spectroscopy and narrowband imaging at the wavelength of redshifted Hα for a sample of 30 high-redshift, far-infrared luminous galaxies. This sample is selected from surveys in the submillimeter, millimeter, and radio wave bands and has complete redshift coverage with a median redshift of z~2.4. We use our data to measure …
A Study of the Kinematic Evolution of Coronal Mass Ejections
Zhang, J.; Howard, R. A.; Dere, K. P. +1 more
We report the kinematic properties of a set of three coronal mass ejections (CMEs) observed with the LASCO (Large Angle and Spectrometric Coronagraph) on the Solar and Heliospheric Observatory (SOHO) spacecraft, which showed characteristics of impulsive, intermediate, and gradual acceleration, respectively. The first CME had a 30 minute long fast …
Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin?
Enßlin, T. A.; Pfrommer, C.
We wish to constrain the cosmic-ray proton (CRp) population in galaxy clusters. By hadronic interactions with the thermal gas of the intra-cluster medium (ICM), the CRp produce γ-rays for which we develop an analytic formalism to deduce their spectral distribution. Assuming the CRp-to-thermal energy density ratio XCRp and the CRp spectr…
Galaxy Size Evolution at High Redshift and Surface Brightness Selection Effects: Constraints from the Hubble Ultra Deep Field
Bouwens, R. J.; Illingworth, G. D.; Blakeslee, J. P. +2 more
We use the exceptional depth of the Ultra Deep Field (UDF) and UDF-parallel Advanced Camera for Surveys fields to study the sizes of high-redshift (z~2-6) galaxies and address long-standing questions about possible biases in the cosmic star formation rate due to surface brightness dimming. Contrasting B-, V-, and i-dropout samples culled from the …