arXiv subjects

J-B Le Bouquin

Publications and source records attributed to J-B Le Bouquin.

4 recordsLinked to original sources

arXiv2026

An interferometric study of B star multiplicity

Massive stars can have extreme effects on their environments from local to galactic scales. While O star multiplicity has been studied over a broad separation range (to the point where absolute masses of these systems have been determined and investigations into multiple system formation and interactions have been performed), studies of B star multiplicity are lacking. Using interferometry, we investigated the multiplicity of a statistically significant sample of B stars over a range of separations (~0.5-35 au, given that the average distance to our sample is 412 pc). We analysed high angular resolution interferometric data taken with VLTI/PIONIER for a sample of 32 B stars. Using parametric modelling of the closure phases and visibilities, we determined best-fitting models to each of the systems and investigated whether each source was best represented by a single star or a higher-order system. The detection limits were calculated for companions to determine whether they were significant. We then combined our findings from the interferometric data with results from a literature search to determine whether other companions were reported at different separation ranges. Within the interferometric range 72+/-8% of the B stars are resolved as multiple systems. The most common type of system is a binary system, followed by single stars, triple systems, and quadruple systems. The interferometric companion fraction derived for the sample is 1.88+/-0.24. When we accounted for spectroscopic companions that have been confirmed in the literature and wide companions inferred from Gaia data in addition to the companions we found with interferometry, we obtain multiplicity and companion fractions of 0.88+/-0.06 and 2.31+/-0.27, respectively, for our sample. The number of triple systems increases to the second-most populous type of system when accounting for spectroscopic companions.

astro-ph.SR↗

arXiv2025

HD 143006: Interferometric Confirmation of Misaligned Protoplanetary Disc with CHARA/MIRCX and VLTI/PIONIER

The outer regions of the protoplanetary disc surrounding the T Tauri star HD 143006 show rings, dust asymmetries and shadows. Whilst rings and dust asymmetries can arise from companions and other mechanisms, shadows and misaligned discs in particular are typically attributed to the presence of misaligned planets or stellar-mass companions. To understand the mechanisms that drive these traits, the innermost regions of discs need to be studied. Using CHARA/MIRCX and VLTI/PIONIER, we observed the sub-au region of HD 143006. We constrain the orientation of the inner disc of HD 143006 and probe whether a misalignment between the inner and outer disc could be the cause of the shadows. Modelling the visibilities using a geometric model, the inclination and position angle are found to be $i=22^\circ\pm 3^\circ$ and $\mathrm{PA}=158^\circ\pm 8^\circ$ respectively, with an inner dust sublimation radius of $\sim0.04$ au. The inner disc is misaligned by $39^\circ\pm4^\circ$ with respect to the outer disc, with the far side of the inner disc to the east and the far side of the outer disc to the west. We constrain $h/R$ (scattering surface/radius of scattered light) of the outer disc at $18$ au to be about $13\%$ by calculating the offset between the shadow position and the central star. No companion was detected, with a magnitude contrast of $4.4$ in the H-band and placing an upper mass limit of $0.17 M_\odot$ at separations of $0-8$ au. Therefore, we cannot confirm or rule out that a low-mass star or giant planet is responsible for the misalignment and dust sub-structures.

astro-ph.EP↗

arXiv2024

Multiplicity of Galactic Cepheids from long-baseline interferometry V. High-accuracy orbital parallax and mass of SU Cygni

Cepheid masses are particularly necessary to help solving the mass discrepancy, while independent distance determinations provide crucial test of the period-luminosity relation and Gaia parallaxes. We used CHARA/MIRC to measure the astrometric positions of the high-contrast companion orbiting the Cepheid SU Cygni. We also present new radial velocity measurements from the HST. The combination of interferometric astrometry with optical and ultraviolet spectroscopy provides the full orbital elements of the system, in addition to component masses and the distance to the Cepheid system. We measured the mass of the Cepheid, $M_A = 4.859\pm0.058M_\odot$, and its two companions, $M_{Ba} = 3.595 \pm 0.033 M_\odot$ and $M_{Bb} = 1.546 \pm 0.009 M_\odot$. This is the most accurate existing measurement of the mass of a Galactic Cepheid (1.2%). Comparing with stellar evolution models, we show that the mass predicted is higher than the measured mass of the Cepheid, similar to conclusions of our previous work. We also measured the distance to the system to be $926.3 \pm 5.0$pc, i.e. an unprecedented parallax precision of $6μ$as (0.5%), being the most precise and accurate distance for a Cepheid. Such precision is similar to what is expected by Gaia for the last data release (DR5 in $\sim$ 2030) for single stars fainter than G = 13, but is not guaranteed for stars as bright as SU Cyg. We demonstrated that evolutionary models remain inadequate in accurately reproducing the measured mass, often predicting higher masses for the expected metallicity, even when factors such as rotation or convective core overshooting are taken into account. Our precise distance measurement allowed us to compare prediction period-luminosity relations. We found a disagreement of 0.2-0.5 mag with relations calibrated from photometry, while relations calibrated from direct distance measurement are in better agreement.

astro-ph.SR↗

arXiv2024

GRAVITY+ Wavefront Sensors: High-Contrast, Laser Guide Star, Adaptive Optics systems for the VLTI

We present the Wavefront Sensor units of the Gravity Plus Adaptive Optics (GPAO) system, which will equip all 8m class telescopes of the VLTI and is an instrumental part of the GRAVITY+ project. It includes two modules for each Wavefront Sensor unit: a Natural Guide Star sensor with high-order 40x40 Shack-Hartmann and a Laser Guide Star 30x30 sensor. The state-of-the-art AO correction will considerably improve the performance for interferometry, in particular high-contrast observations for NGS observations and all-sky coverage with LGS, which will be implemented for the first time on VLTI instruments. In the following, we give an overview of the Wavefront Sensor units system after completion of their integration and characterization.

astro-ph.IM↗