Search Publications
AGB stars in Leo P and their use as metallicity probes
Lee, Chien-Hsiu
Leo P is the most metal-poor yet star-forming galaxy in the local volume, and has the potential to serve as a local counterpart to interpret the properties of distant galaxies in the early universe. We present a comprehensive search of asymptotic giant branch (AGB) stars in Leo P using deep infrared imaging. AGB stars are the major dust contributo…
Development of a formalism for computing transits of Earth-directed CMEs, plasma sheaths, and shocks. Towards a forecasting tool
Corona-Romero, P.; Gonzalez-Esparza, J. A.
Interplanetary Coronal mass ejections (ICMEs) (super-magnetosonically) faster than the ambient solar wind are preceded by shock waves. Earth-directed shock waves, plasma sheaths and ICMEs are precursors of the major geomagnetic storms. The plasma sheath between the shock and the ICME leading edge plays a very important role to determine the geoeff…
The Gaia Attitude Star Catalog
Smart, R. L.
We describe the Attitude Star Catalog produced for the Gaia mission. This catalog is being used by Gaia for the first on-ground attitude reconstruction. Originally it was simply a subset of the Initial Gaia Source List but this subset did not meet the isolation requirements and it contained a significant number of double entries. As a result durin…
A new characterization of the Compton process in the ULX spectra
Makishima, K.; Kobayashi, S.; Nakazawa, K.
Attempts were made to construct a unified description of the spectra of ULX (Ultra Luminous X-ray source) objects, including their power-law (PL) state and disk-like state. Among spectral models proposed to explain either state, the present work adopts the one which combines multi-color disk (MCD) emission and its thermal Comptonization (THC). Thi…
The nature of the cataclysmic variable PT Per
Watson, M. G.; Osborne, J. P.; Schwope, A. D. +2 more
We present a study of the cataclysmic variable star PT Per based on archival XMM-Newton X-ray data and new optical spectroscopy from the William Herschel Telescope (WHT) with Intermediate dispersion Spectrograph and Imaging System (ISIS). The X-ray data show deep minima which recur at a period of 82 min and a hard, unabsorbed X-ray spectrum. The o…
A Possible Cause of the Diminished Solar Wind During the Solar Cycle 23 - 24 Minimum
Wu, Chin-Chun; Liou, Kan
Interplanetary magnetic field and solar wind plasma density observed at 1 AU during Solar Cycle 23 - 24 (SC-23/24) minimum were significantly smaller than those during its previous solar cycle (SC-22/23) minimum. Because the Earth's orbit is embedded in the slow wind during solar minimum, changes in the geometry and/or content of the slow wind reg…
EMVIM: An empirical model for the magnetic field configuration near Venus
He, Maosheng; Vogt, Joachim; Zhang, Tielong +1 more
More than 2000 orbits of Venus Express magnetic field measurements are condensed into Empirical Model of Venusian Induced Magnetic fields (EMVIM), an empirical model to quantify the magnetic configuration in the Venusian magnetosphere at low altitude (<500 km) as a function of the upstream solar wind magnetic field (IMF components) and the sola…
Propagation of Solar Energetic Particles During Multiple Coronal Mass Ejection Events
Valtonen, Eino; Pohjolainen, Silja; Al-Hamadani, Firas
We study solar energetic particle (SEP) events during multiple solar eruptions. The analysed sequences, on 24 - 26 November 2000, 9 - 13 April 2001, and 22 - 25 August 2005, consisted of halo-type coronal mass ejections (CMEs) that originated from the same active region and were associated with intense flares, EUV waves, and interplanetary (IP) ra…
Mission accomplished: Rosetta crashes into comet
Gibney, Elizabeth
Craft sends back wealth of images in 19-kilometre descent.
Iron-rich solar particle events measured by SOHO/ERNE during two solar cycles
Vainio, R.; Valtonen, E.; Raukunen, O.
Aims: We study the differences in the heavy ion composition of solar energetic particle (SEP) events between solar cycles 23 and 24.
Methods: We have surveyed the SOHO/ERNE heavy ion data from the beginning of solar cycle 23 until the end of June 2015, that is, well into the declining phase of cycle 24. We used this long observation peri…