Search Publications
Full 5D characterisation of the Sagittarius stream with Gaia DR2 RR Lyrae
Castro-Ginard, A.; Helmi, A.; Antoja, T. +4 more
Context. The Sagittarius (Sgr) stream is one of the best tools that we currently have to estimate the mass and shape of our Galaxy. However, assigning membership and obtaining the phase-space distribution of the stars that form the tails of the stream is quite challenging.
Aims: Our goal is to produce a catalogue of the RR Lyrae stars of Sgr …
Measuring bulk flows of the intracluster medium in the Perseus and Coma galaxy clusters using XMM-Newton
Fabian, A. C.; Pinto, C.; Eckert, D. +7 more
We demonstrate a novel technique for calibrating the energy scale of the EPIC-pn detector on XMM-Newton, which allows us to measure bulk flows in the intracluster medium (ICM) of the Perseus and Coma galaxy clusters. The procedure uses the fluorescent instrumental background lines present in all observations, in particular, Cu-Kα. By studying thei…
Mars' Ionopause: A Matter of Pressures
Holmstrom, Mats; Sánchez-Cano, Beatriz; Mayyasi, Majd +8 more
This study assesses under what circumstances the Martian ionopause is formed on the dayside, both in regions where there are strong crustal magnetic fields and areas where these fields are small (<30 nT). Multiple data sets from three MAVEN dayside deep dip campaigns are utilized between periapsis and 600-1,000 km, as well as solar wind observa…
Four Distinct Pathways to the Element Abundances in Solar Energetic Particles
Reames, Donald V.
Based upon recent evidence from abundance patterns of chemical elements in solar energetic particles (SEPs), and, ironically, the belated inclusion of H and He, we can distinguish four basic SEP populations: (1) SEP1—pure "impulsive" SEPs are produced by magnetic reconnection in solar jets showing steep power-law enhancements of 1 ≤Z ≤56 ions vers…
On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko
Morbidelli, Alessandro; Snodgrass, Colin; Altwegg, Kathrin +5 more
Primitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth- and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices …
Central molecular zones in galaxies: 12CO-to-13CO ratios, carbon budget, and X factors
Israel, F. P.
We present ground-based measurements of 126 nearby galaxy centers in 12CO and 92 in 13CO in various low-J transitions. More than 60 galaxies were measured in at least four lines. The average relative intensities of the first four J 12CO transitions are 1.00:0.92:0.70:0.57. In the first three J transitions, the aver…
A global geomorphologic map of Saturn's moon Titan
Williams, D. A.; Hayes, A. G.; Wall, S. D. +10 more
Titan has an active methane-based hydrologic cycle1 that has shaped a complex geologic landscape2, making its surface one of most geologically diverse in the Solar System. Despite the differences in materials, temperatures and gravity fields between Earth and Titan, many of their surface features are similar and can be interp…
The Gaia DR2 parallax zero-point: hierarchical modelling of red clump stars
Bovy, Jo; Chan, Victor C.
The systematic offset of Gaia parallaxes has been widely reported with Gaia's second data release, and it is expected to persist in future Gaia data. In order to use Gaia parallaxes to infer distances to high precision, we develop a hierarchical probabilistic model to determine the Gaia parallax zero-point offset along with the calibration of an e…
Improving transit characterisation with Gaussian process modelling of stellar variability
Cabrera, J.; Barros, S. C. C.; Santos, N. C. +4 more
Context. New photometric space missions to detect and characterise transiting exoplanets are focusing on bright stars to obtain high cadence, high signal-to-noise light curves. Since these missions will be sensitive to stellar oscillations and granulation even for dwarf stars, they will be limited by stellar variability. Therefore, it is crucial a…
Diagnosing the Stellar Population and Tidal Structure of the Blanco 1 Star Cluster
Tang, Shih-Yun; Chen, W. P.; Zhang, Yu +2 more
We present the stellar population, using Gaia DR2 parallax, kinematics, and photometry, of the young (∼100 Myr), nearby (∼230 pc) open cluster, Blanco 1. A total of 644 member candidates are identified via the unsupervised machine learning method StarGO to find the clustering in the five-dimensional position and proper motion parameter (X, Y, Z, $…