publications

2024

1. MELCHIORS - The Mercator Library of High Resolution Stellar Spectroscopy

   Royer, P.,  Merle, T.,  Dsilva, K., and 72 more authors

   A&A, 2024

   DOI

2020

1. Integrating the OpenSky Network into GNSS-R Climate Monitoring Research

   Mike Laverick, Delwyn Moller, Christopher Ruf, and 6 more authors

   Proceedings, 2020

   Abs DOI

   Global Navigation Satellite System Reflectometry (GNSS-R) provides a unique means of inferring geophysical conditions of the Earth’s surface without the need for costly, and often infeasible, in-situ climate monitoring systems. As part of NASA’s Cyclone Global Navigation Satellite System (CYGNSS) mission, and in conjunction with Air New Zealand, we are taking the novel approach of mounting a GNSS-R receiver on a commercial aircraft, which shall allow for an unprecedented collection of climate data over and around the islands of New Zealand. Such data include inundation and coastal dynamics, and soil moisture content and variability. We report back to the community how the OpenSky Network data support our climate monitoring research. We discuss how we use the historical database state-vectors to simulate and visualise the predicted geographical coverage of the airborne GNSS-R receiver. We also discuss how the live API can help monitor our payload in-flight, our investigations into the OpenSky ADS-B coverage over New Zealand, and our plans to expand the coverage.

2019

1. The Belgian Repository of Fundamental Atomic Data and Stellar Spectra (BRASS)

   Alex Lobel, Pierre Royer, Christophe Martayan, and 7 more authors

   Atoms, 2019

   Abs DOI

   Background: BRASS (Belgian Repository of Fundamental Atomic Data and Stellar Spectra) is an international networking project for the development of a new public database providing accurate fundamental atomic data of vital importance for stellar spectroscopic research. We present an overview of research results obtained in the past four years. Methods: The BRASS database offers atomic line data we thoroughly tested by comparing theoretical and observed stellar spectra. We perform extensive quality assessments of selected atomic input data using advanced radiative transfer spectrum synthesis calculations, which we compare to high-resolution Mercator-HERMES and ESO-VLT-UVES spectra of F-, G-, and K-type benchmark stars observed with very high signal-to-noise ratios. We have retrieved about half a million atomic lines required for our detailed spectrum synthesis calculations from the literature and online databases such as VAMDC, NIST, VALD, CHIANTI, Spectr-W 3 , TIPbase, TOPbase, SpectroWeb. Results: The atomic datasets have been cross-matched based on line electronic configuration information and organized in a new online repository called BRASS. The validated atomic data, combined with the observed and theoretical spectra are also interactively offered in BRASS. The combination of these datasets is a novel approach for its development providing a universal reference for advanced stellar spectroscopic research. Conclusion: We present an overview of the BRASS Data Interface developments allowing online user interaction for the combined spectrum and atomic data display, line identification, atomic data accuracy assessments including line log(gf)-values, and line equivalent width measurements.

2. The Belgian repository of fundamental atomic data and stellar spectra (BRASS) - II. Quality assessment of atomic data for unblended lines in FGK stars

   Laverick, M.,  Lobel, A.,  Royer, P., and 7 more authors

   A&A, 2019

   DOI
3. The Belgian Repository of fundamental Atomic data and Stellar Spectra (BRASS)

   M. Laverick, A. Lobel, P. Royer, and 7 more authors

   Proceedings of the International Astronomical Union, 2019

   DOI
4. Fundamental atomic data deduced using stellar spectroscopy

   M. Laverick

   2019

2018

1. The Belgian Repository of fundamental Atomic data and Stellar Spectra (BRASS)

   T. Merle, M. Laverick, A. Lobel, and 9 more authors

   In SF2A-2018: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics, Dec 2018
2. The Belgian Repository of Fundamental Atomic Data and Stellar Spectra: An Insight into Systematic Line Selection

   M. Laverick, A. Lobel, P. Royer, and 7 more authors

   In Workshop on Astrophysical Opacities, Aug 2018
3. The Belgian Repository of Fundamental Atomic Data and Stellar Spectra: Atomic Line Data Validation

   A. Lobel, P. Royer, C. Martayan, and 7 more authors

   In Workshop on Astrophysical Opacities, Aug 2018
4. The ESO Diffuse Interstellar Band Large Exploration Survey (EDIBLES)

   J. Cami, N. L. Cox, A. Farhang, and 29 more authors

   The Messenger, Mar 2018
5. The Belgian repository of fundamental atomic data and stellar spectra (BRASS) - I. Cross-matching atomic databases of astrophysical interest

   Laverick, M.,  Lobel, A.,  Merle, T., and 5 more authors

   A&A, Mar 2018

   DOI
6. The Belgian Repository of Fundamental Atomic Data and Stellar Spectra (BRASS) Identifying Fruitful Methods for Producing Atomic Data

   Mike Laverick, Alex Lobel, Pierre Royer, and 7 more authors

   Galaxies, Mar 2018

   Abs DOI

   The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to provide the largest systematic and homogeneous quality assessment to-date of input atomic data required for stellar spectral synthesis. In addition to quality-assessed atomic data, BRASS shall also provide of a range of extremely high-quality benchmark stellar spectra spanning late B-type stars to early K-type stars. In this paper, we summarise the project’s progress and available results to-date. We provide a brief comparison between our results and the BRASS project’s compiled and cross-matched atomic literature, with the goal of providing useful feedback to the atomic community on which methods may produce more reliable and accurate atomic data. We hope that the examples presented here stimulate further investigation by the atomic physics community.

7. Multi-technique investigation of the binary fraction of A-F type candidate hybrid variable stars discovered by Kepler

   Lampens, P.,  Frémat, Y.,  Vermeylen, L., and 14 more authors

   A&A, Mar 2018

   DOI

2017

1. The ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES) - I. Project description, survey sample, and quality assessment

   Cox, Nick L. J.,  Cami, Jan,  Farhang, Amin, and 27 more authors

   A&A, Mar 2017

   DOI
2. BRASS: Cross-match of atomic repositories and spectral line blending investigations

   M. Laverick, A. Lobel, P. Royer, and 2 more authors

   Canadian Journal of Physics, Mar 2017

   Abs DOI

   The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to critically evaluate atomic data, from publicly available repositories, by comparing state-of-the-art synthetic spectra against high-quality benchmark stellar spectra. In preparation for our assessment we have cross-matched atomic line transitions from several different databases. Our investigation revealed significant updates in log(gf) values, sometimes as large as 2–4 dex, that fully justify the need for systematic quality assessments of the atomic data. We have also investigated the spectral line blending of an initial subset of 2647 atomic lines using spectral synthesis calculations, for the spectral types BAFGK.

3. The Belgian repository of fundamental atomic data and stellar spectra

   A. Lobel, P. Royer, C. Martayan, and 5 more authors

   Canadian Journal of Physics, Mar 2017

   Abs DOI

   BRASS is an international networking project of the Federal Government of Belgium for the development of a new public database providing accurate fundamental atomic data of vital importance for stellar spectroscopic research. The BRASS database will offer atomic line data that is thoroughly tested by comparing theoretical and observed stellar spectra. We are in the course of performing extensive quality assessments of selected atomic input data with advanced radiative transfer spectrum synthesis calculations that we compare in detail to high-resolution Mercator-HERMES and ESO-VLT-UVES spectra of very high signal-to-noise ratios for about 30 hot and cool bright stars of B, A, F, G, and K spectral types. The new database will provide the tested and validated values of absorption lines we retrieve from various existing atomic repositories, such as NIST and VAMDC. The validated atomic datasets, combined with the observed and theoretical spectra, will be interactively offered online at brass.sdf.org. The combination of these datasets is a novel approach for its development, which will provide a universal reference for advanced stellar spectroscopic research. We present the atmospheric parameter results of a subset of five benchmark stars observed with signal-to-noise ratios of 800–1200. The observed and theoretical spectra of the Sun and 51 Peg between 4000 and 6800 Å are offered online in the BRASS Data Interface. It also incorporates a new list of ∼900 metal lines for which we compute blending below 5% of the equivalent width useful for detailed line profile modeling and synthetic spectrum fit quality assessments of atomic line data.

2016

1. The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370

   M. Hrudková, A. Hatzes, R. Karjalainen, and 20 more authors

   Monthly Notices of the Royal Astronomical Society, Sep 2016

   Abs DOI

   We report on the discovery of a planetary companion candidate with a minimum mass M sin i = 4.6 ± 1.0 MJupiter orbiting the K2 III giant star HD 175370 (KIC 007940959). This star was a target in our programme to search for planets around a sample of 95 giant stars observed with Kepler. This detection was made possible using precise stellar radial velocity measurements of HD 175370 taken over five years and four months using the coudé echelle spectrograph of the 2-m Alfred Jensch Telescope and the fibre-fed echelle spectrograph High Efficiency and Resolution Mercator Echelle Spectrograph of the 1.2-m Mercator Telescope. Our radial velocity measurements reveal a periodic (349.5 ± 4.5 d) variation with a semi-amplitude K = 133 ± 25 m s− 1, superimposed on a long-term trend. A low-mass stellar companion with an orbital period of ∼88 yr in a highly eccentric orbit and a planet in a Keplerian orbit with an eccentricity e = 0.22 are the most plausible explanation of the radial velocity variations. However, we cannot exclude the existence of stellar envelope pulsations as a cause for the low-amplitude radial velocity variations and only future continued monitoring of this system may answer this uncertainty. From Kepler photometry, we find that HD 175370 is most likely a low-mass red giant branch or asymptotic giant branch star.