Search Publications
Exploring the Circular Polarisation of Low-Frequency Solar Radio Bursts with LOFAR
Kumari, Anshu; Zucca, Pietro; Vocks, Christian +9 more
The Sun is an active star that often produces numerous bursts of electromagnetic radiation at radio wavelengths. Low frequency radio bursts have recently been brought back to light with the advancement of novel radio interferometers. However, their polarisation properties have not yet been explored in detail, especially with the Low Frequency Arra…
Ensemble-based unsupervised machine learning method for membership determination of open clusters using Mahalanobis distance
Deb, Sukanta; Baruah, Amiya; Kumar, Subhash
We present an improved method for the determination of membership of an open cluster using ensemble-based unsupervised machine learning techniques. The working principle of this method relies on two stages: (i) choosing a suitable range of three astrometric parameters (π, µαcos δ, µδ) using k-nearest neighbour (kN…
The importance of Fe fragmentation for LiBeB analyses. Is a Li primary source needed to explain AMS-02 data?
Maurin, D.; Ferronato Bueno, E.; Génolini, Y. +2 more
Context. High-precision data from AMS-02 on Li, Be, and B provide the best constraints on Galactic cosmic-ray transport parameters.
Aims: We re-evaluate the impact of Fe fragmentation on the Li, Be, and B modelling. We discuss the consequences on the transport parameter determination and reassess whether a primary source of Li is needed to ma…
TYC 2990-127-1: An Algol-type SB2 binary system of subgiant and red giant with a probable ongoing mass-transfer
Han, Zhanwen; Kovalev, Mikhail; Chen, Xuefei +3 more
We present a study of the spectroscopic binary TYC 2990-127-1 from the LAMOST survey. We use full-spectrum fitting to derive radial velocities and spectral parameters. The high mass ratio indicates that the system underwent mass transfer in the past. We compute the orbital solution and find that it is a very close sub-giant/red giant pair on circu…
Measuring weak lensing masses on individual clusters
Melin, Jean-Baptiste; Bartlett, James G.; Murray, Calum +1 more
We present weak lensing mass estimates for a sample of 458 galaxy clusters from the redMaPPer Sloan Digital Sky Survey DR8 catalogue using Hyper Suprime-Cam weak lensing data. We develop a method to quickly estimate cluster masses from weak lensing shear and use this method to estimate weak lensing masses for each of the galaxy clusters in our sam…
GJ 229B: Solving the Puzzle of the First Known T Dwarf with the APOLLO Retrieval Code
Mandell, Avi M.; McElwain, Michael W.; Howe, Alex R.
GJ 229B was the first T dwarf to be discovered in 1995, and its spectrum has been more thoroughly observed than that of most other brown dwarfs. Yet a full spectroscopic analysis of its atmosphere has not been done with modern techniques. This spectrum has several peculiar features, and recent dynamical estimates of GJ 229B's mass and orbit have d…
MICROSCOPE mission scenario, ground segment and data processing
Bergé, Joel; Chhun, Ratana; Métris, Gilles +9 more
Testing the weak equivalence principle to a precision of 10-15 requires a quantity of data that give enough confidence on the final result: ideally, the longer the measurement the better the rejection of the statistical noise. The science sessions had a duration of 120 orbits maximum and were regularly repeated and spaced out to accommo…
A Deep View into the Nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. III. Discrete Multicomponent Population-dynamical Models Based on the Jeans Equations
Lützgendorf, Nora; Böker, Torsten; Kamann, Sebastian +12 more
We present comprehensive multicomponent dynamical models of M54 (NGC 6715), the nuclear star cluster of the Sagittarius (Sgr) dwarf galaxy, which is undergoing a tidal disruption in the Milky Way halo. Previous papers in this series used a large MUSE mosaic data set to identify multiple stellar populations in the system and study their kinematic d…
OCCASO. IV. Radial velocities and open cluster kinematics
Jordi, C.; Casamiquela, L.; Cantat-Gaudin, T. +8 more
Context. Open clusters (OCs) are widely used as test particles to investigate a variety of astrophysical phenomena, from stellar evolution to Galactic evolution. Gaia and the complementary massive spectroscopic surveys are providing an unprecedented wealth of information about these systems.
Aims: The Open Cluster Chemical Abundances from Spa…
Assessing the role of clay and salts on the origin of MARSIS basal bright reflections
Orosei, Roberto; Caprarelli, Graziella; Pettinelli, Elena +7 more
Anomalously bright basal reflections detected by MARSIS at Ultimi Scopuli have been interpreted to indicate the presence of water-saturated materials or ponded liquid water at the base of the South Polar Layered Deposits (SPLD). Because conventional models assume basal temperatures (≤200 K) much lower than the melting point of water, this interpre…