| 1. |
- Blazere, Aurore, et al.
(författare)
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Magnetic geometry and surface differential rotation of the bright Am star Alhena A
- 2020
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 492:4, s. 5794-5810
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Tidskriftsartikel (refereegranskat)abstract
- Alhena A (y Gem A) is a bright Am star, with the strongest disc -integrated magnetic field strength reported so far for an Am star. Its spectrum exhibits standard circularly polarized Zeeman signatures, contrary to all previously studied Am stars that display abnormal signatures dominated by a single -signed lobe. We present here the result of follow-up observations of Athena, using very high signal-to-noise spectropolarimetric data obtained over 25 observing nights with NARVAL at Telescope Bernard Lyot, in the frame of the BRITE (BRIght Target Explorer) spectropolarimetric survey. We confirm that Alhena A is magnetic and we determine its surface magnetic properties using different methods. Inclined dipole models are used to reproduce the longitudinal field measurements, as well as the Stokes V line profiles themselves. In both cases, the model is consistent with a polar field strength of 30 G. This is confirmed by a Zeeman -Doppler Imaging (ZDI) model, which also unveils smaller scale magnetic structures. A rotational period of 8.975 d was identified using intensity line profile variations. The ZDI inversion suggests that the surface magnetic field is sheared by differential rotation, with a difference in rotation rate between high and low latitudes at about 15 per cent of the solar value. This result challenges theories of the development of surface differential rotation in intermediate mass main -sequence stars.
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| 2. |
- Mathis, Lesley-Ann, et al.
(författare)
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Creating informed public acceptance by a user-centered human-machine interface for all automated transport modes
- 2020
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Ingår i: Proceedings of 8th Transport Research Arena TRA 2020. ; , s. 9-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Increasing automation is ongoing in all areas of transport. This raises new challenges for the design and training of Human-Machine Interfaces (HMI) for different user groups. The EU-project Drive2theFuture investigates the needs and wants of transportation users, operators, passengers and passersby to gain their acceptance and to set the ground for a sustainable market introduction of automated transport. This paper describes how HMI concepts for the transport modes road, rail, maritime and aviation in Drive2theFuture are developed and comparatively assessed in order to be able to support an educated use of automated transport. By relying on a stepwise process, adaptable HMI strategies for different user clusters and levels of automation are defined. As a universal method, a comprehensive HMI development toolkit is developed, which can be adopted as training tool to create realistic expectations and enhance acceptance among users, operators and drivers in light of the deployment of automated vehicles.
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| 3. |
- Pepin, Mathis, et al.
(författare)
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Multiplicity fluctuations and correlations in 5.02 TeV p+Pb collisions at zero impact parameter
- 2023
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Ingår i: Physical Review C. - 2469-9985. ; 107:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a Bayesian method to reconstruct event-by-event multiplicity fluctuations and rapidity correlations in p+Pb collisions at zero impact parameter from minimum-bias data, without assuming any model of the collision dynamics. We test it on Monte Carlo simulations with the Angantyr model, then apply it to ATLAS data on the distribution of charged multiplicity and transverse energy in p+Pb collisions at sNN=5.02 TeV. Fluctuations in b=0 collisions are quantum fluctuations which originate mostly from the proton wave function, and therefore have the potential to constrain the subnucleonic structure of the proton. The Angantyr model is found to overestimate fluctuations. In addition, we find that as the rapidity increases (towards the Pb-going side), not only the multiplicity density increases, but also its relative event-by-event fluctuation. This counterintuitive phenomenon is also observed in simulations with Angantyr, and with the quantum chromodynamics dipole model, where its origin can be traced back to the branching process through which gluons are produced.
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| 4. |
- Subjak, Jan, et al.
(författare)
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TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission
- 2020
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 159:4
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of an intermediate-mass transiting brown dwarf (BD), TOI-503b, from the TESS mission. TOI-503b is the first BD discovered by TESS, and it has circular orbit around a metallic-line A-type star with a period of P.=.3.6772.+/-.0.0001 days. The light curve from TESS indicates that TOI-503b transits its host star in a grazing manner, which limits the precision with which we measure the BD's radius ( = R 1.34+ R b 0.150.26 J). We obtained highresolution spectroscopic observations with the FIES, Ondr.ejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be Mb.=.53.7.+/-.1.2 MJ. The host star has a mass of Ma.=.1.80.+/-.0.06Me, a radius of Ra.=.1.70.+/-.0.05Re, an effective temperature of Teff.=.7650.+/-.160 K, and a relatively high metallicity of 0.61.+/-.0.07 dex. We used stellar isochrones to derive the age of the system to be 180 Myr, which places its age between that of RIK 72b (a 10 Myr old BD in the Upper Scorpius stellar association) and AD 3116b (a 600 Myr old BD in the Praesepe cluster). Given the difficulty in measuring the tidal interactions between BDs and their host stars, we cannot precisely say whether this BD formed in situ or has had its orbit circularized by its host star over the relatively short age of the system. Instead, we offer an examination of plausible values for the tidal quality factor for the star and BD. TOI-503b joins a growing number of known short-period, intermediate-mass BDs orbiting mainsequence stars, and is the second such BD known to transit an A star, after HATS-70b. With the growth in the population in this regime, the driest region in the BD desert (35-55MJ sin i) is reforesting.
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