Search Publications
Simultaneous absolute timing of the Crab pulsar at radio and optical wavelengths
Schulz, R.; Oosterbroek, T.; Golden, A. +7 more
Context: The Crab pulsar emits across a large part of the electromagnetic spectrum. Determining the time delay between the emission at different wavelengths will allow to better constrain the site and mechanism of the emission. We have simultaneously observed the Crab Pulsar in the optical with S-Cam, an instrument based on Superconducting Tunneli…
Forward Modeling of Active Region Coronal Emissions. II. Implications for Coronal Heating
Leka, K. D.; Lundquist, L. L.; Fisher, G. H. +2 more
In Paper I, we introduced and tested a method for predicting solar active region coronal emissions using magnetic field measurements and a chosen heating relationship. Here, we apply this forward-modeling technique to 10 active regions observed with the Mees Solar Observatory Imaging Vector Magnetograph and the Yohkoh Soft X-ray Telescope. We prod…
The plasma sheet and boundary layers under northward IMF: A multi-point and multi-instrument perspective
Escoubet, C. P.; Pitout, F.; Zhang, T. L. +23 more
During conditions of northward interplanetary magnetic field (IMF), the near-tail plasma sheet is known to become denser and cooler, and is described as the cold-dense plasma sheet (CDPS). While its source is likely the solar wind, the prominent penetration mechanisms are less clear. The two main candidates are solar wind direct capture via double…
Plasma temperatures in Saturn's ionosphere
Galand, Marina; Moore, Luke; Yelle, Roger +2 more
We have calculated self-consistent electron and ion temperatures in Saturn's ionosphere using a series of coupled fluid and kinetic models developed to help interpret Cassini observations and to examine the energy budget of Saturn's upper atmosphere. Electron temperatures in the midlatitude topside ionosphere during solar maximum are calculated to…
The directivity of solar type III bursts at hectometer and kilometer wavelengths: Wind-Ulysses observations
Maksimovic, M.; Bonnin, X.; Hoang, S.
We investigate the directivity of solar type III radio bursts at hectometer and kilometer wavelengths using radio data recorded simultaneously by the Wind and Ulysses spacecraft which are widely separated in heliocentric longitude and latitude. From the positions of the associated flares and the solar wind speed and plasma density measured aboard …
Isolated OB Associations in Stripped H I Gas Clouds
Freeman, K. C.; Ryan-Weber, E. V.; Oey, M. S. +4 more
HST ACS HRC images in UV (F250W), V (F555W), and I (F814W) resolve three isolated OB associations that lie up to 30 kpc from the stellar disk of the S0 galaxy NGC 1533. Previous narrowband Hα imaging and optical spectroscopy showed these objects as unresolved intergalactic H II regions having Hα luminosities consistent with single early-type O sta…
Extending the baseline: Spitzer mid-infrared photometry of globular cluster systems in the Centaurus A and Sombrero Galaxies
Spitler, Lee R.; Forbes, Duncan A.; Beasley, Michael A.
Spitzer IR Array Camera (IRAC) mid-infrared photometry is presented for the globular cluster (GC) systems of the NGC 5128 (`Centaurus A') and NGC 4594 (`Sombrero') galaxies. Existing optical photometric and spectroscopic are combined with this new data in a comprehensive optical-to-mid-IR colour catalogue of 260 GCs. Empirical colour-metallicity r…
First observations of SO2 above Venus' clouds by means of Solar Occultation in the Infrared
Montmessin, F.; Fedorova, A.; Korablev, O. +6 more
Solar Occultation in the Infrared (SOIR) is a part of the Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV)/SOIR occultation experiment on board Venus Express dedicated to the study of gaseous and aerosol vertical structure of Venus' mesosphere. SOIR is an echelle spectrometer with acoustooptic selection of diff…
Multiscale Analysis of Active Region Evolution
Maguire, K.; Gallagher, P. T.; Young, C. A. +4 more
Flows in the photosphere of solar active regions are turbulent in nature. Because magnetic fields are frozen into the plasma on the solar surface, magnetograms can be used to investigate the processes responsible for structuring active regions. Here, a continuous wavelet technique is developed, analyzed, and used to investigate the multiscale stru…
Observations of Doppler Shift Oscillations with the EUV Imaging Spectrometer on Hinode
Warren, Harry P.; Watanabe, Tetsuya; Mariska, John T. +1 more
Damped Doppler shift oscillations have been observed in emission lines from ions formed at flare temperatures with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory and with the Bragg Crystal Spectrometer on Yohkoh. This Letter reports the detection of low-amplitude damped oscillations i…