Search Publications
Measurements of Rapid Density Fluctuations in the Solar Wind
Bale, S. D.; Kellogg, P. J.; Malaspina, D. M. +1 more
The power spectrum of density fluctuations in the solar wind is inferred by tracking small timescale changes in the electron plasma frequency during periods of strong Langmuir wave activity. STEREO electric field waveform data are used to produce time profiles of plasma density from which the density power spectrum is derived. The power spectra ob…
Investigating the driving mechanisms of coronal mass ejections
Gallagher, P. T.; Lin, C. -H.; Raftery, C. L.
Aims: The objective of this study was to examine the kinematics of coronal mass ejections (CMEs) using EUV and coronagraph images, and to make a quantitative comparison with a number of theoretical models. One particular aim was to investigate the acceleration profile of CMEs in the low corona.
Methods: We selected two CME events for thi…
XMM-Newton and INTEGRAL study of the SFXT IGR J18483-0311 in quiescence: hint of a cyclotron emission feature?
Sidoli, L.; Ducci, L.; Bassani, L. +2 more
We report the results from archival XMM-Newton and INTEGRAL observations of the Supergiant Fast X-ray Transient (SFXT) IGR J18483-0311 in quiescence. The 18-60 keV hard X-ray behaviour of the source is presented here for the first time; it is characterized by a spectral shape (Γ ~ 2.5) similar to that during outburst activity, and the lowest measu…
Observations of a stationary mid-latitude cloud system on Titan
Barnes, J. W.; de Pater, I.; Hartung, M. +1 more
We report the observation of a cloud system on Titan that remained localized near 40°S latitude and 60°W longitude for at least 34 h. Ground-based observations obtained with the SINFONI imaging spectrograph at the Very Large Telescope over four consecutive nights recorded the lifetime and altitude of the unresolved cloud system. Concomitant measur…
A study of the massive star-forming region M8 using images from the Spitzer Infrared Array Camera
Kumar, Dewangan Lokesh; Anandarao, B. G.
We present photometry and images (3.6, 4.5, 5.8 and 8.0 µm) from the Spitzer Infrared Array Camera (IRAC) of the star-forming region Messier 8 (M8). The IRAC photometry reveals ongoing star formation in the M8 complex, with 64 class 0/I and 168 class II sources identified in several locations in the vicinity of submm gas cores/clumps. Nearly…
Sounding of Titan’s atmosphere at submillimeter wavelengths from an orbiting spacecraft
Hartogh, P.; Lellouch, E.; Coustenis, A. +7 more
An investigation of the capabilities and science goals of a submillimeter-wave heterodyne sounder onboard a Titan orbiter is presented. Based on a model of Titan's submillimeter spectrum, and including realistic instrumental performances, we show that passive limb observations of Titan's submillimeter radiation would bring novel and unique informa…
A Direct Detection of Gas Accretion: The Lyman Limit System in 3C 232
Danforth, Charles W.; Stocke, John T.; Keeney, Brian A.
The gas added to and removed from galaxies over cosmic time greatly affects their stellar populations and star formation rates. QSO absorption line studies in close QSO/galaxy pairs create a unique opportunity to study the physical conditions and kinematics of this gas. Here we present new Hubble Space Telescope (HST) images of the QSO/galaxy pair…
The Accreting White Dwarf in SS Cygni Revealed
Blair, William P.; Sion, Edward M.; Godon, Patrick +1 more
We have carried out a combined Hubble Space Telescope (HST/GHRS) and Far Ultraviolet Spectroscopic Explorer (FUSE) analysis of the prototype dwarf nova SS Cygni during quiescence. The FUSE and HST spectra were obtained at comparable times after outburst and have matching flux levels where the two spectra overlap. In our synthetic spectral analysis…
The Relative Intensity Calibration of Hinode/EIS and SOHO/SUMER
Young, P. R.; Landi, E.
In this work, we have used simultaneous observations of the quiet Sun above the solar west limb obtained with the Hinode/Extreme ultraviolet Imaging Spectrograph and SOHO/SUMER instruments to determine their relative intensity calibration. We used two different methods: intensity ratios of lines emitted by the same upper level and observed in the …
Distance to the galaxy IC 342
Tikhonov, N. A.; Galazutdinova, O. A.
Based on archival Hubble Space Telescope images, we have performed stellar photometry for a region of the spiral galaxy IC 342 located in the Milky Way zone. On the constructed Hertzsprung-Russell diagram, we have identified the red giant branch and determined the distance modulus for the galaxy by the TRGB (tip of the red giant branch) method, ( …