The paper outlines the space-weather-related observations, instrumentation, research and service developments carried out at the Geophysical Centre of the Royal Meteorological Institute (RMI) in Dourbes, Belgium.

Because of the significant dangers they pose, accurate forecasting of Solar Energetic Particle (SEP) events is vital. Whilst it has long been known that SEP-production is associated with high-energy solar events, forecasting algorithms based upon the observation of these types of solar event suffer from high false alarm rates. Here we analyse the parameters of 4 very high energy solar events which were false alarms, with a view to reaching an understanding as to why SEPs were not detected at Earth. We find that in each case at least two factors were present which have been shown to be detrimental to SEP production.

We present accurate methods of abundance determination based on the non-local thermodynamic equilibrium (NLTE) line formation for carbon, oxygen, calcium, titanium, and iron in the atmospheres of BAF-type stars. For C I-II, O I, Ca I-II, and Ti I-II, their comprehensive model atoms were described in our previous papers. A fairly complete model atom of Fe I-II is first applied in this study. We determine the NLTE abundances of the nine BAF-type stars with well-determined atmospheric parameters, using high-resolution and high signal-to-noise ratio spectral observations in the broad wavelength range, from the UV to the IR. For C, Ca, Ti, and Fe, NLTE leads to consistent abundances from the lines of the two ionisation stages. The C I, Ca II, and Fe II emission lines were detected in the near IR spectrum of the late B-type subgiant star HD 160762. They are well reproduced in the classical hydrostatic model atmosphere, when applying our NLTE methods.

Case studies show that some energetic particle flux enhancements up to MeV/nuc. observed at 1 AU cannot be treated as a consequence of particle acceleration at shocks or during flares. Atypical energetic particle events (AEPEs) are often detected during crossings of magnetic cavities formed by strong current sheets of various origins in the solar wind. Such cavities confine small-scale magnetic islands (SMIs) produced by magnetic reconnection. SMIs, in turn, trap and re-accelerate energetic particles according to predictions based on the theory of Zank et al. describing stochastic particle energization in the supersonic solar wind via numerous dynamically interacting SMIs. AEPEs possess energies that overlap SEP events and can be an important component in understanding space weather.

There is growing evidence that, among the various subclasses of carbon-enhanced metal-poor (CEMP) stars, the outer halo of the Milky Way exhibits a higher frequency of CEMP-no stars (those having no over-abundances of heavy neutron-capture elements) compared with the CEMP-s stars (those with over-enhancements of the s-process elements), while the inner halo shows a higher frequency of CEMP-s stars. We map out fractions of CEMP-no and CEMP-s stars in the inner- and outer-halo populations, separated by their spatial distribution of carbonicity ([C/Fe]), a so-called “carbonicity map”, based on a sample of over 100,000 main-sequence turnoff stars with available spectroscopy from the Sloan Digital Sky Survey. The CEMP-no and CEMP-s objects are classified by different levels of absolute carbon abundances for our sample, A(C). We also present kinematic and orbital characteristics of these subclasses for each population. The contrast appearing in these characteristics provides critical constraints on the assembly history of the two primary stellar components of the Galactic halo.

The space weather forecast can be conditionally divided into three components: 1) The forecast of recurrent slowly varying events which are associated with the topology of a large-scale magnetic field; 2) Evaluation of fluxes of ultraviolet and extreme radiation; 3) Detecting and determining the parameters of eruptions and CME. All three components can be observed and evaluated by ground-based telescopes. In this article we describe the telescopes of the space weather service in Kislovodsk Mountain Astronomical Station. Telescope-magnetograph STOP for the forecast of recurrent events and patrol telescopes-spectrographs for detecting CME and estimating hard radiation fluxes.

We report the results of abundance analysis for high-resolution spectra of eight extremely metal-poor turn-off stars selected from SDSS/SEGUE. Based on differential analysis adopting stellar parameters from Balmer line profiles, we obtain the following results: i) Statistically significant scatter is found in [X/Fe] (X=Na, Mg, Cr, Ti, Sr and Ba), among which [Na/Fe] shows an apparent bimodal distribution, ii) Li abundances are ~0.3 dex lower in [Fe/H]<−3.5 than the Spite plateau value without significant scatter.

A number of recent studies have claimed that the double red clump observed in the Milky Way bulge is a consequence of an X-shaped structure. In particular, Ness & Lang (2016) report a direct detection of a faint X-shaped structure in the bulge from the residual map of the Wide-Field Infrared Survey Explorer (WISE) image. Here we show, however, that their result is seriously affected by a bulge model subtracted from the original image. When a boxy bulge model is subtracted, instead of a simple exponential bulge model as has been done by Ness & Lang, we find that most of the X-shaped structure in the residuals disappears. Furthermore, even if real, the stellar density in the claimed X-shaped structure is way too low to be observed as a strong double red clump (dRC) at l = 0°.

We show how to capture the behaviour of the phase-space distribution function (DF) of a Galactic disc stellar population at a resonance. This is done by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. We then assign to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits only depends on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of distribution functions in action space.

Our back-tracing code (GeoMagSphere) reconstructs the cosmic ray trajectories inside the Earth’s magnetosphere. GeoMagSphere gets the incoming directions of particles entering the magnetopause and disentangles primary from secondary particles (produced in atmosphere) or even particles trapped inside the Earth’s magnetic field. The separation of these particle families allows us to evaluate the geomagnetic rigidity cutoff. The model can be used considering the internal symmetric (IGRF-12) magnetic field only, or adding the asymmetric external one (Tsyganenko models: T89, T96 or TS05). A quantitative comparison among these models is presented for quiet (solar pressure Pdyn < 4 nPa) and disturbed (Pdyn > 4 nPa) periods of solar activity, as well as during solar events like flares, CMEs. In this analysis we focused our attention on magnetic field data in magnetosphere, from Cluster, and simulated cosmic rays for a generic detector on the ISS as for example AMS-02. We found that high solar activity periods, like a large fraction of the period covering years 2011-2015, are better described using IGRF+TS05 model. Results, i.e. the average vertical rigidity cutoff at the ISS orbit, are shown in geographic maps of 2° × 2° cells.

Modelling of Solar Energetic Particles (SEPs) is usually carried out by means of the 1D focused transport equation and the same approach is adopted within several SEP Space Weather forecasting frameworks. We present an alternative approach, based on test particle simulations, which naturally describes 3D particle propagation. The SPARX forecasting system is an example of how test particle simulations can be used in real time in a Space Weather context. SPARX is currently operational within the COMESEP Alert System. The performance of the system, which is triggered by detection of a solar flare of class >M1.0 is evaluated by comparing forecasts for flare events between 1997 and 2017 with actual SEP data from the GOES spacecraft.

Early Warning of Space Weather phenomena is one of the most important products produced by Mexican Space Weather Service (SCiESMEX). The aim is to deliver a verified warning to Mexican National Center for Disaster Prevention (CENAPRED) as well as to general public in near-real time automatically. First, the international pubic warning (or alert) is produced by Space Weather Prediction Center of National Oceanic and Atmospheric Administration, U.S.A. Further, the alert is received by SCiESMEX system, decodified, translated in Spanish and put in the context of local current conditions. The alerts are transformed and validated in agreement to Mexican policies of civil protection and CENAPRED protocols. The automatic system segments the information and delivers the corresponding web- page-alerts, emails, twits, facebook messages and SMS. The latency of the alert is 5 minutes. The code is running since January of 2015 without major interruptions.

We present results of an on-going effort to identify the minimum level of systematic, purely numerical differences in low-mass stellar models on the Red Giant Branch, by comparing models in selected phases for pre-defined physical input assumptions.

The Pristine survey uses narrow-band photometry on the region of the Ca II H & K absorption lines to find extremely metal-poor stars. With a spectroscopic follow-up sample of 205 stars in the magnitude range 14 < V < 18, we compute the success rates for finding extremely metal-poor stars and modify the selection criteria used to select stars for follow-up. This reduces the sample to 149 stars, and from these we report success rates of 22% for recovering stars with [Fe/H] < −3.0 and 70% for [Fe/H] < −2.5. When compared to previous works that search for extremely metal-poor stars, the success rates of Pristineshow an improvement in efficiency by a factor of ~4 − 5.

The points where the horizontal component of the geomagnetic field vanishes are located in polar areas, far away from the geomagnetic (analytic) poles and the poles of rotation of the Earth and, differently from the geomagnetic poles, can be found experimentally with a magnetic survey to determine where the field is vertical. The experimental determination of the area where the total field is perfectly vertical, commonly known as dip pole, is not simple, due to the remoteness and harsh climatic conditions; another difficulty is related to the short term geomagnetic field variations, due to the interaction with the external solar wind, which causes the magnetospheric dynamics, particularly evident at high latitude, and as a consequence a displacement of the dip pole. Actually, the study of the dip pole displacements over short time scales can be an important tool for monitoring the magnetospheric dynamics at high latitude. In this study we present the updated location of the the dip poles, using data from the Swarm ESA’s constellation of satellites along their almost polar orbits. We also analyse the spatial shift of these areas during different seasons and interplanetary magnetic field orientations.

The RAVE survey obtains moderate-resolution (R ~ 7500) spectroscopy of relatively bright stars in the region of the Ca triplet, and derives estimates of stellar atmospheric parameters (Teff, log g, and [Fe/H]) and abundance estimates for a limited number of elements. The RAVE sample is selected on apparent magnitude, effectively removing the biases typically associated with searches for metal-poor stars such as metallicity, evolutionary status, or Galactic population membership. For the past several years, we have been obtaining medium-resolution (R ~ 1800) spectroscopy over a much wider wavelength range, from 3700 Å to 5500 Å, for RAVE stars with estimated metallicities from the RAVE pipeline of [Fe/H] < −1.8.

Based on these observations, we use the well-tested n-SSPP pipeline to obtain atmospheric parameter estimates, as well as measurements of [C/Fe], for over 1,700 metal-poor star candidates. We present an analysis of the distribution of carbon-enhancement in the relatively local volume of the Galaxy as a function of metallicity, location, and kinematics. Our results are useful to test the RAVE parameter estimates, and add to the growing number of known carbon-enhanced metal-poor (CEMP) stars for future high-resolution follow-up.

We present a comparison of previous simulations of the interaction of the Galactic disc with the Milky Way (MW) satellites using superbox-10 with new simulations performed with gadget-2 and ChaNGa. The robust performance of gadget-2 motivates us to employ more recent versions of gadgetto identify the satellite debris in the MW halo, disc and bulge.

By applying Principal Components Analysis (PCA) to solar magnetic synoptic maps in cycle 21-23 obtained with Wilcox Solar Observatory we derived analytical expressions for two principal components and their summary curve of solar magnetic field oscillations defined by dipole magnetic sources. In this paper we extrapolate backwards three millennia the summary curve describing solar activity and compare it with the relevant historic data. The extrapolated summary curve shows a remarkable resemblance to the sunspot and terrestrial activity reported in the past millennia: the Maunder Minimum (1645-1715), Wolf minimum (1200), Oort minimum (1010-1050), Homer minimum (800-900 BC), the medieval warm period (900-1200), the Roman warm period (400-10BC). We note that Sporer minimum (1460-1550) derived from the increased abundance of isotope Δ14C is likely produced by a strong increase of galactic cosmic rays caused by a supernova Vela Junior occurred in the Southern hemisphere.

It is generally accepted to use the solar wind ram pressure ρV2 and the IMF Bz component for empirical description of the geo-magnetopause position and shape. A specific feature of the present paper is not to use the solar wind ρV2 but the thermal Pth and magnetic field Pmag pressures adjacent to the magnetopause for proper modelling. These pressures are deduced from the results of 3-D MHD runs and analytic solutions for post bow shock MHD flow in Lagrangian variables. The magnetopause shape variation due to Bz component changes the so called ‘doubling factor’ fd, which can be analytically deduced from a Tsyganenko magnetospheric field ellipsoidal model. Including all the above effects in our analytical model leads to a good description of ‘rapid’ magnetopause approach to the Earth for southward IMF and to its ‘stagnant’ behaviour with the increase of northward IMF component.

We use the principal component analysis to study geomagnetic activity at annual resolution using a network of 26 magnetic stations in 1966-2015, and an extended network of 40 stations in 1980-2015. The first principal component describes the long-term evolution of global geomagnetic activity, and has an excellent correlation with indices like the Kp/Ap index. The two networks give identical results for the first principal component. The second principal component is highly correlated with the annual percentage of high-speed streams (HSS). The extended network has a slightly higher sensitivity to HSSs. We verify the non-trivial latitudinal distribution of the second empirical orthogonal function. We find that the amplitude of the 22-year variation of geomagnetic activity has a closely similar latitudinal distribution as the second empirical orthogonal function. This verifies that the 22-year variation of geomagnetic activity is related to HSSs. The most likely cause is the Russell-McPherron mechanism.