Search Publications
Constraining dark sector perturbations II: ISW and CMB lensing tomography
Weller, J.; Giannantonio, T.; Battye, R. A. +1 more
Any Dark Energy (DE) or Modified Gravity (MG) model that deviates from a cosmological constant requires a consistent treatment of its perturbations, which can be described in terms of an effective entropy perturbation and an anisotropic stress. We have considered a recently proposed generic parameterisation of DE/MG perturbations and compared it t…
Periodic variations of oxygen EUV dayglow in the upper atmosphere of Venus: Hisaki/EXCEED observations
Fedorov, A.; Futaana, Y.; Zhang, T. L. +14 more
Using the Extreme Ultraviolet Spectroscope for Exospheric Dynamics (EXCEED) aboard Hisaki and the Solar Extreme Ultraviolet Monitor on the Solar and Heliospheric Observatory, we investigate variations of the extreme ultraviolet (EUV) dayglow brightness for OII 83.4 nm, OI 130.4 nm, and OI 135.6 nm in the Venusian upper atmosphere observed in March…
Calibration of Hinode/XRT for Coalignment
McKenzie, David E.; Yoshimura, Keiji
We present coalignment calibration procedures for the X-ray Telescope (XRT) onboard the Hinode satellite. We performed not only an XRT stand-alone calibration, but also cross calibration using data from the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). Several new me…
Simulated magnetic flows in the solar photosphere
Solanki, S. K.; Danilovic, S.; Cameron, R. H.
Context. Recent Sunrise/IMaX observations have revealed supersonic magnetic flows.
Aims: Our aim is to determine the origin of these flows by using realistic magnetohydrodynamics simulations.
Methods: We simulated cancellation and emergence of magnetic flux through the solar photosphere. Our first numerical experiment started with a magn…
Saturn's giant storm and global radiant energy
West, Robert A.; Baines, Kevin H.; Nixon, Conor A. +11 more
We analyze the relationship between Saturn's radiant energies and the 2010 giant storm with the Cassini observations. The storm increased the emitted power in a wide latitudinal band (20-55°N) with a maximum change of 9.2 ± 0.1% around 45°N from 2010 to 2011. Such a regional change caused the global-average emitted power to increase by ~2.0 ± 0.2%…
Empirical Relationship Between CME Parameters and Geo-effectiveness of Halo CMEs in the Rising Phase of Solar Cycle 24 (2011 - 2013)
Moon, Y. -J.; Shanmugaraju, A.; Umapathy, S. +2 more
We analyzed the physical characteristics of 40 halo coronal mass ejections (CMEs) and their geo-effective parameters observed during the period 2011 to 2013 in the rising phase of Solar Cycle 24. Out of all halo CMEs observed by SOHO/LASCO, we selected 40 halo CMEs and investigated their geomagnetic effects. In particular, we estimated the CME dir…
Co-spatial Long-slit UV/Optical Spectra of Ten Galactic Planetary Nebulae with HST/STIS. II. Nebular Models, Central Star Properties, and He+CNO Synthesis
Balick, B.; Corradi, R. L. M.; Dufour, R. J. +5 more
The goal of the present study is twofold. First, we employ new HST/STIS spectra and photoionization modeling techniques to determine the progenitor masses of eight planetary nebulae (IC 2165, IC 3568, NGC 2440, NGC 3242, NGC 5315, NGC 5882, NGC 7662, and PB 6). Second, for the first time we are able to compare each object’s observed nebular abunda…
The Volatile Composition of Comet C/2003 K4 (LINEAR) at Near-IR Wavelengths—Comparisons with Results from the NanÇay Radio Telescope and from the Odin, Spitzer, and SOHO Space Observatories
Villanueva, G. L.; Paganini, L.; Mumma, M. J. +2 more
We observed comet C/2003 K4 (LINEAR) using NIRSPEC at the Keck Observatory on UT 2004 November 28, when the comet was at 1.28 AU from the Sun (post-perihelion) and 1.38 AU from Earth. We detected six gaseous species (H2O, OH*, C2H6, CH3OH, CH4, and HCN) and obtained upper limits for three othe…
Earth's Magnetotail
McPherron, Robert L.
Earth's magnetic tail (magnetotail) was discovered 50 years ago by the first spacecraft to fly downstream of Earth. The magnetotail is a complex structure created by the solar wind. The tail is in fact a very dynamic structure with many internal processes and rapid changes. The magnetospheric substorm is the name given to the collection of phenome…
ULF wave electromagnetic energy flux into the ionosphere: Joule heating implications
Angelopoulos, V.; Bonnell, J. W.; Hartinger, M. D. +2 more
Ultralow-frequency (ULF) waves—in particular, Alfvén waves-transfer energy into the Earth's ionosphere via Joule heating, but it is unclear how much they contribute to global and local heating rates relative to other energy sources. In this study we use Time History of Events and Macroscale Interactions during Substorms satellite data to investiga…