Search Publications
The Rotation of the Solar Photospheric Magnetic Field
Xu, J. C.; Gao, P. X.
The rotational characteristics of the solar photospheric magnetic field at four flux ranges are investigated together with the total flux of active regions (MFar) and quiet regions (MFqr). The first four ranges (MF1-4) are (1.5-2.9) × 1018, (2.9-32.0) × 1018, (3.20-4.27) × 1019, and…
A Deep X-Ray View of the Bare AGN Ark 120. I. Revealing the Soft X-Ray Line Emission
Turner, T. J.; Porquet, D.; Reeves, J. N. +3 more
The Seyfert 1 galaxy Ark 120 is a prototype example of the so-called class of bare nucleus active galactic nuclei (AGNs), whereby there is no known evidence for the presence of ionized gas along the direct line of sight. Here deep (>400 ks exposure), high-resolution X-ray spectroscopy of Ark 120 is presented from XMM-Newton observations that we…
A Deep X-Ray View of the Bare AGN Ark 120. II. Evidence for Fe K Emission Transients
Porquet, D.; Matt, G.; Reeves, J. N. +3 more
We report on the results from a large observational campaign on the bare Seyfert galaxy Ark 120, jointly carried out in 2014 with XMM-Newton, Chandra, and NuSTAR. The fortunate line of sight to this source, devoid of any significant absorbing material, provides an incomparably clean view to the nuclear regions of an active galaxy. Here we focus on…
Modeling the Initiation of the 2006 December 13 Coronal Mass Ejection in AR 10930: The Structure and Dynamics of the Erupting Flux Rope
Fan, Yuhong
We carry out a 3D magnetohydrodynamic simulation to model the initiation of the coronal mass ejection (CME) on 2006 December 13 in the emerging δ-sunspot active region NOAA 10930. The setup of the simulation is similar to a previous simulation by Fan, but with a significantly widened simulation domain to accommodate the wide CME. The simulation sh…
A low-luminosity soft state in the short-period black hole X-ray binary Swift J1753.5-0127
Altamirano, D.; Charles, P. A.; Gandhi, P. +6 more
We present results from the spectral fitting of the candidate black hole X-ray binary Swift J1753.5-0127 in an accretion state previously unseen in this source. We fit the 0.7-78 keV spectrum with a number of models, however the preferred model is one of a multitemperature disc with an inner disc temperature kTin = 0.252 ± 0.003 keV sca…
Saturn's icy satellites investigated by Cassini-VIMS. IV. Daytime temperature maps
Sotin, Christophe; Buratti, Bonnie J.; Clark, Roger N. +13 more
The spectral position of the 3.6 µm continuum peak measured on Cassini-VIMS I/F spectra is used as a marker to infer the temperature of the regolith particles covering the surfaces of Saturn's icy satellites. This feature is characterizing the crystalline water ice spectrum which is the dominant compositional endmember of the satellites' sur…
Modelling the evolution of a comet subsurface: implications for 67P/Churyumov-Gerasimenko
Guilbert-Lepoutre, Aurélie; Rosenberg, Eric D.; Prialnik, Dina +1 more
Modelling the evolution of comets is a complex task aiming at providing constraints on physical processes and internal properties that are inaccessible to observations, although they could potentially bring key elements to our understanding of the origins of these primitive objects. This field has made a tremendous step forward in the post-Giotto …
Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta
Jorda, L.; Lamy, P. L.; Lara, L. M. +58 more
Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study th…
Transition Region Abundance Measurements During Impulsive Heating Events
Warren, Harry P.; Doschek, George A.; Brooks, David H. +1 more
It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona, low-FIP elements such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements such as C, N, O, Ar, and Ne. In this paper we…
DC and low-frequency double probe electric field measurements in space
Mozer, F. S.
The double probe technique for measuring DC and low-frequency electric fields in space plasmas is described with an emphasis on uncertainties in the measurements, data analysis techniques, and methods for improving the electric field measurements in future missions.