Search Publications
An improved age-activity relationship for cool stars older than a gigayear
Poppenhaeger, K.; Silva Aguirre, V.; Wolk, S. J. +2 more
Stars with convective envelopes display magnetic activity, which decreases over time due to the magnetic braking of the star. This age dependence of magnetic activity is well studied for younger stars, but the nature of this dependence for older stars is not well understood. This is mainly because absolute stellar ages for older stars are hard to …
Model-independent analyses of non-Gaussianity in Planck CMB maps using Minkowski functionals
Buchert, Thomas; France, Martin J.; Steiner, Frank
Despite the wealth of Planck results, there are difficulties in disentangling the primordial non-Gaussianity of the Cosmic Microwave Background (CMB) from the secondary and the foreground non-Gaussianity (NG). For each of these forms of NG the lack of complete data introduces model-dependences. Aiming at detecting the NGs of the CMB temperature an…
Extragalactic background light: a measurement at 400 nm using dark cloud shadow - II. Spectroscopic separation of the dark cloud's light, and results★
Leinert, Ch.; Väisänen, P.; Lehtinen, K. +2 more
In a project aimed at measuring the optical extragalactic background light (EBL), we are using the shadow of a dark cloud. We have performed, with the ESO VLT/FORS, spectrophotometry of the surface brightness towards the high-galactic-latitude dark cloud Lynds 1642. A spectrum representing the difference between the opaque core of the cloud and se…
Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations
Besla, Gurtina; Patel, Ekta; Mandel, Kaisey
In the era of high-precision astrometry, space observatories like the Hubble Space Telescope (HST) and Gaia are providing unprecedented 6D phase-space information of satellite galaxies. Such measurements can shed light on the structure and assembly history of the Local Group, but improved statistical methods are needed to use them efficiently. Her…
OCCASO - II. Physical parameters and Fe abundances of red clump stars in 18 open clusters
Jordi, C.; Casamiquela, L.; Anders, F. +13 more
Open clusters have long been used to study the chemodynamical evolution of the Galactic disc. This requires a homogeneously analysed sample covering a wide range of ages and distances. In this paper, we present the Open Clusters Chemical Abundances from Spanish Observatories (OCCASO) second data release. This comprises a sample of high-resolution …
The occurrence and wave properties of EMIC waves observed by the Magnetospheric Multiscale (MMS) mission
Allen, R. C.; Deng, X. H.; Torbert, R. B. +5 more
Electromagnetic ion cyclotron (EMIC) waves can precipitate the ring current ions and relativistic electrons and heat the cold electrons in the magnetosphere. This requires comprehensive knowledge of the occurrence and wave properties of EMIC waves. In the present study, we used the data from one new mission, the Magnetospheric Multiscale (MMS) mis…
What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?
Martínez-Sykora, Juan; De Pontieu, Bart; Chintzoglou, Georgios
Spicules are the most ubuiquitous type of jets in the solar atmosphere. The advent of high-resolution imaging and spectroscopy from the Interface Region Imaging Spectrograph (IRIS) and ground-based observatories has revealed the presence of very high apparent motions of order 100-300 km s-1 in spicules, as measured in the plane of the s…
Explosive events in active region observed by IRIS and SST/CRISP
Doyle, J. G.; Madjarska, M. S.; Huang, Z. +3 more
Transition-region explosive events (EEs) are characterized by non-Gaussian line profiles with enhanced wings at Doppler velocities of 50-150 km s-1. They are believed to be the signature of solar phenomena that are one of the main contributors to coronal heating. The aim of this study is to investigate the link of EEs to dynamic phenome…
Impact crater relaxation on Dione and Tethys and relation to past heat flow
Schenk, Paul M.; White, Oliver L.; Bray, Veronica J. +3 more
Relating relaxation of impact crater topography to past heat flow through the crusts of icy satellites is a technique that has been applied to satellites around Jupiter and Saturn. We use global digital elevation models of the surfaces of Dione and Tethys generated from Cassini data to obtain crater depth/diameter (d/D) data. Relaxation is found t…
Cometary dust: the diversity of primitive refractory grains
Wooden, D. H.; Ishii, H. A.; Zolensky, M. E.
Comet dust is primitive and shows significant diversity. Our knowledge of the properties of primitive cometary particles has expanded significantly through microscale investigations of cosmic dust samples (anhydrous interplanetary dust particles (IDPs), chondritic porous (CP) IDPs and UltraCarbonaceous Antarctic micrometeorites, Stardust and Roset…