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Four and one more: The formation history and total mass of globular clusters in the Fornax dSph
Fraser, M.; de Boer, T. J. L.
We have determined the detailed star formation history and total mass of the globular clusters in the Fornax dwarf spheroidal using archival HST WFPC2 data. Colour-magnitude diagrams were constructed in the F555W and F814W bands and corrected for the effect of Fornax field star contamination, after which we used the routine Talos to derive the qua…
Testing chirality of primordial gravitational waves with Planck and future CMB data: no hope from angular power spectra
Melchiorri, Alessandro; Shiraishi, Maresuke; Gerbino, Martina +2 more
We use the 2015 Planck likelihood in combination with the Bicep2/Keck likelihood (BKP and BK14) to constrain the chirality, χ, of primordial gravitational waves in a scale-invariant scenario. In this framework, the parameter χ enters theory always coupled to the tensor-to-scalar ratio, r, e.g. in combination of the form χ ṡ r. Thus, the capability…
Physical Properties of Spectroscopically Confirmed Galaxies at z ≥ 6. III. Stellar Populations from SED Modeling with Secure Lyα Emission and Redshifts
Ouchi, Masami; Shimasaku, Kazuhiro; Fan, Xiaohui +9 more
We present a study of stellar populations in a sample of spectroscopically confirmed Lyman-break galaxies (LBGs) and Lyα emitters (LAEs) at 5.7< z< 7. These galaxies have deep images from Subaru, the Hubble Space Telescope, and Spitzer/IRAC. We focus on 27 galaxies with IRAC detections, and characterize their stellar populations based on the…
Alluvial Fan Morphology, distribution and formation on Titan
Hayes, A. G.; Birch, S. P. D.; Radebaugh, J. +2 more
Titan is a hydrologically active world, with dozens of alluvial fans that are evidence of sediment transport from high to low elevations. However, the distribution and requirements for the formation of fans on Titan are not well understood. We performed the first global survey of alluvial fans on Titan using Cassini Synthetic Aperture Radar (SAR) …
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 …