Search Publications
High-energy monitoring of NGC 4593 with XMM-Newton and NuSTAR. X-ray spectral analysis
Bianchi, S.; Cappi, M.; Ponti, G. +8 more
We present results from a joint XMM-Newton/NuSTAR monitoring of the Seyfert 1 NGC 4593, consisting of 5 × 20 ks simultaneous observations spaced by 2 d, performed in 2015 January. The source is variable, both in flux and spectral shape, on time-scales down to a few ks and with a clear softer-when-brighter behaviour. In agreement with past observat…
CME impact on comet 67P/Churyumov-Gerasimenko
Glassmeier, K. -H.; Behar, E.; Möstl, C. +23 more
We present Rosetta observations from comet 67P/Churyumov-Gerasimenko during the impact of a coronal mass ejection (CME). The CME impacted on 2015 Oct 5-6, when Rosetta was about 800 km from the comet nucleus, and 1.4 au from the Sun. Upon impact, the plasma environment is compressed to the level that solar wind ions, not seen a few days earlier wh…
A Hubble Space Telescope Study of the Enigmatic Milky Way Halo Globular Cluster Crater*
Dolphin, Andrew E.; Sills, Alison; Belokurov, Vasily +6 more
We analyze the resolved stellar populations of the faint stellar system, Crater, based on deep optical imaging taken with the Advanced Camera for Surveys on the Hubble Space Telescope. Crater’s color-magnitude diagram (CMD) extends ∼4 mag below the oldest main-sequence (MS) turnoff. Structurally, we find that Crater has a half-light radius of ∼20 …
NuSTAR and XMM-Newton Observations of the Neutron Star X-Ray Binary 1RXS J180408.9-34205
Harrison, F. A.; Fabian, A. C.; Miller, J. M. +8 more
We report on observations of the neutron star (NS) residing in the low-mass X-ray binary 1RXS J180408.9-34205 taken 2015 March by NuSTAR and XMM-Newton while the source was in the hard spectral state. We find multiple reflection features (Fe {{{K}}}α detected with NuSTAR; N vii, O vii, and O viii detected in the RGS) from different ion…
Acetylene on Titan’s Surface
Le Mouélic, S.; Cornet, T.; Rodriguez, S. +6 more
Titan’s atmosphere is opaque in the near-infrared due to gaseous absorptions, mainly by methane, and scattering by aerosols, except in a few “transparency windows.” Thus, the composition of Titan’s surface remains difficult to access from space and is still poorly constrained. Photochemical models suggest that most of the organic compounds formed …
Origin of low proton-to-electron temperature ratio in the Earth's plasma sheet
Zelenyi, L. M.; Sauvaud, J. -A.; Lavraud, B. +4 more
We study the proton-to-electron temperature ratio (Tp/Te) in the plasma sheet (PS) of the Earth's magnetotail using 5 years of Cluster observations (2001-2005). The PS intervals are searched within a region defined with -19 < X ≤ -7 RE and |Y| < 15 RE (GSM) under the condition |BX| ≤ 10 …
Variegation of comet 67P/Churyumov-Gerasimenko in regions showing activity
Jorda, L.; Lamy, P. L.; Lara, L. M. +49 more
Aims.We carried out an investigation of the surface variegation of comet 67P/Churyumov-Gerasimenko, the detection of regions showing activity, the determination of active and inactive surface regions of the comet with spectral methods, and the detection of fallback material.
Methods: We analyzed multispectral data generated with Optical, Spec…
New Parallaxes and a Convergence Analysis for the TW Hya Association
Faherty, J. K.; Weinberger, A. J.; Gagné, J. +3 more
The TW Hya Association (TWA) is a nearby stellar association with an age of ∼5-10 Myr. This is an important age for studying the late stages of star and planet formation. We measure the parallaxes of 14 candidate members of TWA. That brings to 38 the total number of individual stars with fully measured kinematics, I.e., proper motion, radial veloc…
Gamma-ray emission from SN2014J near maximum optical light
Sunyaev, R.; Churazov, E.; Hernanz, M. +17 more
Context. The optical light curve of Type Ia supernovae (SNIa) is powered by thermalized gamma-rays produced by the decay of 56Ni and 56Co, the main radioactive isotopes synthesized by the thermonuclear explosion of a C/O white dwarf.
Aims: Gamma-rays escaping the ejecta can be used as a diagnostic tool for studying the c…
Global Gradients for Cosmic-Ray Protons in the Heliosphere During the Solar Minimum of Cycle 23/24
Potgieter, M. S.; Vos, E. E.
Global gradients for cosmic-ray (CR) protons in the heliosphere are computed with a comprehensive modulation model for the recent prolonged solar minimum of Cycle 23/24. Fortunately, the PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) and Ulysses/KET (Kiel Electron Telescope) instruments simultaneously observed pro…