A5045985935- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Geomagnetism and Paleomagnetism Studies
- Computational Physics and Python Applications
- Impact of Light on Environment and Health
- Solar and Space Plasma Dynamics
- Distributed and Parallel Computing Systems
- Adaptive optics and wavefront sensing
- Modeling, Simulation, and Optimization
- Geological and Geophysical Studies
- Scientific Computing and Data Management
University of Groningen
2015-2022
Max Planck Society
2018
Astronomical Institute of the Slovak Academy of Sciences
2015-2017
University of Edinburgh
2012-2015
Royal Observatory
2013-2014
Scottish Universities Physics Alliance
2012
Context. The second Gaia data release (DR2) contains very precise astrometric and photometric properties for more than one billion sources, astrophysical parameters dozens of millions, radial velocities variability information half a million stars from selected classes, orbits thousands solar system objects. Aims. Before the catalogue was published, these have undergone dedicated validation processes. goal this paper is to describe results in terms completeness, accuracy, precision various...
Before the publication of Gaia Catalogue, contents first data release have undergone multiple dedicated validation tests. These tests aim at analysing in-depth Catalogue content to detect anomalies, individual problems in specific objects or overall statistical properties, either filter them before public release, describe different caveats for an optimal exploitation data. Dedicated methods using internal data, external catalogues models been developed processes. They are testing normal...
We report the discovery of 59 globular clusters (GCs) and two candidate GCs in a search halo M31, primarily via visual inspection CHFT/MegaCam imagery from Pan-Andromeda Archaeological Survey (PAndAS).The superior quality these data also allow us to check classification remote objects Revised Bologna Catalogue (RBC), plus subset GC candidates drawn SDSS imaging.We identify three additional new RBC, confirm nature 11 (8 which appear independently our catalogue); remaining 188 across both...
We present a detailed kinematic analysis of the outer halo globular cluster (GC) system M31. Our basis for this is set new spectroscopic observations 78 clusters lying at projected distances between Rproj ~20-140 kpc from M31 centre. These are largely drawn recent PAndAS catalogue; 63 our targets have no previous velocity data. Via Bayesian maximum likelihood we find that GCs with > 30 exhibit coherent rotation around minor optical axis M31, in same direction as more centrally- located GCs,...
We explore the phase-space structure of nearby halo stars identified kinematically from Gaia DR2 data. focus on their distribution in velocity and "integrals motion" space as well photometric properties. Our sample selected to be moving at a relative least 210 km/s with respect Local Standard Rest, contains an important contribution low rotational tail disk(s). The $V_R$-distribution these depicts small asymmetry similar that seen for faster rotating thin disk near Sun. also identify...
The hierarchical structure formation model predicts that stellar halos should form, at least partly, via mergers. If this was a predominant channel for the Milky Way's halo, imprints of merger history in form moving groups or streams exist also vicinity Sun. Here we study kinematics halo stars Solar neighbourhood using very recent first data release from Gaia mission, and particular TGAS dataset, combination with RAVE survey. Our aim is to determine amount substructure present phase-space...
We present a new Python library called vaex, to handle extremely large tabular datasets, such as astronomical catalogues like the Gaia catalogue, N-body simulations or any other regular datasets which can be structured in rows and columns. Fast computations of statistics on N-dimensional grids allows analysis visualization order billion per second. use streaming algorithms, memory mapped files zero copy policy allow exploration larger than memory, e.g. out-of-core algorithms. Vaex arbitrary...
We present the first kinematic analysis of far outer halo globular cluster (GC) population in Local Group galaxy M31. Our sample contains 53 objects with projected radii ~20-130 kpc, which 44 have no previous spectroscopic information. GCs >30 kpc are found to exhibit net rotation around minor axis M31, same sense as inner GCs, albeit a smaller amplitude 79 +/-19 km/s. The rotation-corrected velocity dispersion full GC is 106 +/-12 km/s, we observe decrease increasing radius. find compelling...
We utilize the final catalogue from Pan-Andromeda Archaeological Survey to investigate links between globular cluster system and field halo in M31 at projected radii Rproj = 25–150 kpc. In this region radial density profile exhibits a power-law decline with index Γ −2.37 ± 0.17, matching that for stellar component [Fe/H] < −1.1. Spatial maps reveal striking correspondence most luminous substructures metal-poor positions of many clusters. By comparing stars local each azimuthal distribution...
The third gaia data release (DR3) provides a wealth of new products. early part the release, Gaia EDR3, already provided astrometric and photometric for nearly two billion sources. full now adds improved parameters compared to DR2 radial velocities, astrophysical parameters, variability information, light curves, orbits Solar System objects. improvements are in terms number sources, variety parameter precision, accuracy. For first time, DR3 also sample spectrophotometry spectra obtained with...
We report on observations of two newly discovered globular clusters in the outskirts M31 made using Gemini Multi-Object Spectrograph (GMOS) instrument North. These objects, PAndAS-7 (PA-7) and PAndAS-8 (PA-8), lie at a galactocentric radius ≈87 kpc are projected, with separation ≈19 kpc, to field halo substructure known as South-West Cloud. measure radial velocities for which confirm that they almost certainly physically associated this feature. Colour–magnitude diagrams reveal strikingly...
It is well accepted that ‘;hot Jupiters’ and other short-period planets did not form in situ, as the temperature protoplanetary disc at radius which they now orbit would have been too high for planet formation to occurred. These planets, instead, larger radii then move into region orbit. The exact process leads of these close-in is, however, unclear it seems there may be more than one mechanism can produce systems. Dynamical interactions multiple-planet systems scatter highly eccentric...
We study the dynamical properties of halo stars located in Solar Neighbourhood. Our goal is to explore how depend on selection criteria used for defining a sample stars. Once this understood we proceed measure shape and orientation halo's velocity ellipsoid use information put constraints gravitational potential Galaxy. recently released Gaia DR1 catalogue cross-matched RAVE dataset our analysis. develop criterion based distribution function various Galactic components, using action...
Using data from the Pan-Andromeda Archaeological Survey (PAndAS), we have discovered four new globular clusters (GCs) associated with M31 dwarf elliptical (dE) satellites NGC 147 and 185. Three of these are one All lie beyond main optical boundaries galaxies most remote yet known in systems. Radial velocities derived low-resolution spectra used to argue that GCs bound dwarfs not part halo population. Combining PAndAS United Kingdom Infrared Telescope (UKIRT)/WFCAM (Wide-Field Camera) data,...
We undertake the first detailed analysis of stellar population and spatial properties a diffuse substructure in outer halo M31. The South-West Cloud lies at projected distance ∼100 kpc from centre M31 extends for least ∼50 projection. use Pan-Andromeda Archaeological Survey photometry red giant branch stars to determine |$793^{+45}_{-45}$| kpc. metallicity cloud is found be [Fe/H] = −1.3 ± 0.1. This consistent with coincident globular clusters PAndAS-7 PAndAS-8, which have metallicities...
We present three newly discovered globular clusters (GCs) in the Local Group dwarf irregular NGC 6822. Two are luminous and compact, while third is a very low luminosity diffuse cluster. report integrated optical photometry of clusters, drawing on archival CFHT/Megacam data. The spatial positions new GCs consistent with linear alignment already-known clusters. most also highly elliptical, which we speculate may be due to tidal field its environment.
A central tenet of the current cosmological paradigm is that galaxies grow over time through accretion smaller systems. Here, we present new kinematic measurements near centre one densest pronounced substructures, South-West Cloud, in outer halo our nearest giant neighbour, Andromeda galaxy. These observations reveal properties this region Cloud are consistent with those PA-8, a globular cluster previously shown to be co-spatial stellar substructure. In sense situation reminiscent handful...
We present a comprehensive analysis of the globular cluster (GC) system Local Group dwarf irregular galaxy NGC 6822. Our study is based on homogeneous optical and near-IR photometry, as well long-slit spectroscopic observations which are used to determine new radial velocities for 6 GCs, two had no previous information. construct optical-near IR colour-colour diagrams through comparison simple stellar population models infer that GCs have old ages consistent with being 9 Gyr or older, while...
Extended stellar haloes are a natural by-product of the hierarchical formation massive galaxies. If merging is non-negligible factor in growth our Galaxy, evidence such events should be encoded its halo. Reliable identification genuine halo stars challenging task however. The 1st Gaia data release contains positions, parallaxes and proper motions for over 2 million stars, mostly Solar neighbourhood. DR2 will enlarge this sample to 1.5 billion brightest ~5 which have full phase-space...
This is a corrigendum to Gaia Collaboration (2018). It corrects errors in Appendix B, which describes the modelling of Large and Small Magellanic Clouds (LMC SMC). One these also affects Fig. 18 paper, shows rotation curve median radial motion LMC. No other results paper are affected. There should be no vector products everywhere product appears scalar product. Eqs. (B.5), (B.8), (B.10), (B.12), (B.13), (B.20). Equation defines one component position within plane galaxy, contains an...
An error occurred during the production process of original published version. The following names were omitted from the author list: R. Haigron, D. Hatzidimitriou, M. Hauser, Haywood, U. Heiter, J. Heu, T. Hilger. version has been corrected together with publication this corrigendum.
There is long tradition extending more than a century on the identification of moving groups in Solar neighborhood. However, with advent large kinematic surveys, and especially upcoming Gaia data releases there need for sophisticated automated substructure finders. We analyze TGASxRAVE dataset to identify Galactic disk. These stars may then be used map dynamical star formation processes vicinity Sun. use ROCKSTAR algorithm, "friends-of-friends"-like finder 6D phase-space, Hertzsprung-Russell...