99 research outputs found
Characterization of TESS M-dwarfs with ExTrA
No full textExTrA (Exoplanets in Transits and their Atmospheres - Bonfils et al. 2015) is a new instrument composed of an array of three 60-cm telescopes capable of infrared photometry and located in La Silla, Chile. This instrument relies on a new approach that involves combining optical photometry with spectroscopic information in order to mitigate the disruptive effect of Earth’s atmosphere, as well as effects introduced by instruments and detectors. ExTrA is currently being used to confirm TESS planet detections around M-dwarfs, refine transit parameters, and search for additional exoplanets in the same systems. ExTrA obtains a better precision for the planetary radius and for the transit timings for late M-type stars with one or a few TESS transits. This work already led to the confirmation of a mini-Neptune around the M-dwarf TOI-269 (Cointepas et al. 2021). ExTrA will also work in tandem with NIRPS, a near-infrared spectrograph that will join HARPS (High Accuracy Radial velocity Planet Searcher) on the 3.6m ESO telescope to conduct a comprehensive radial-velocity survey on M dwarfs
Detection and characterization of exoplanets orbiting M dwarfs with two newnear-infrared instruments : ExTrA and NIRPS.
No full textSur les 5322 exoplanètes découvertes à ce jour, seulement 665 ont été bien caractérisées en mesurant précisément à la fois leur rayon et leur masse. La combinaison de la photométrie de transit et des mesures de vitesses radiales de haute précision permet de contraindre la densité moyenne des exoplanètes et d'obtenir une première estimation de leur composition et structure interne. Les étoiles de faible masse sont des cibles importantes pour caractériser les exoplanètes car les naines M représentent la majeure partie de la population stellaire de notre voisinage et sont connues pour héberger de multiples petites exoplanètes. En raison de leur faible luminosité intrinsèque aux longueurs d'onde visibles, le proche infrarouge est privilégié pour étudier ces étoiles froides car elles émettent la plupart de leur lumière dans cette région du spectre. ExTrA et NIRPS, deux nouveaux instruments proche infrarouge, représentent une chance d'améliorer notre compréhension des systèmes planétaires entourant les naines M.Au cours de mon doctorat, j'ai rassemblé toutes les candidats planétaires en orbite autour des naines M observées par la mission TESS, une étude globale du ciel à la recherche d'exoplanètes en transit autour d'étoiles brillantes et proches. À partir de cette liste, j'ai planifié les observations de suivi en utilisant ExTrA. À partir des données brutes, j'ai généré des courbes de lumière utilisables. J'ai ensuite analysé les courbes de lumière pour identifier les transits planétaires et je les ai modélisés pour obtenir les paramètres planétaires. Des observations supplémentaires avec des instruments au sol sont nécessaires pour confirmer la nature planétaire du compagnon car des compagnons stellaires peuvent être à l'origine de faux positifs, et la combinaison d'observations avec TESS dans le visible et avec ExTrA dans le proche infrarouge s'est avérée très utile pour valider le candidat planétaire et obtenir une mesure précise de son rayon. A partir de là, d'autres observations sont nécessaires pour caractériser complètement les exoplanètes. Pour les différents systèmes que j'ai publiés pendant ma thèse, j'ai rassemblé et modélisé des observations des spectrographes HARPS et ESPRESSO.Le spectrographe NIRPS sera bientôt également capable de fournir la masse des exoplanètes détectées en transits, en particulier autour des naines M. J'ai proposé deux programmes dans le cadre du temps garanti d'observations (GTO) de NIRPS. Le premier utilisera des mesures de vitesses radiale pour compléter notre photométrie ExTrA afin de peupler le diagramme masse-rayon pour les naines M moyennes à tardives. Le second vise à détecter des planètes supplémentaires dans des systèmes connus en calculant la probabilité d'existence de ces planètes non détectées et le coût de leur détection avec les instruments actuels comme NIRPS.Les synergies entre ces deux instruments dans le proche infrarouge nous permettront de caractériser les exoplanètes en orbite autour des naines M et offriront une opportunité unique d'étudier la formation et l'évolution des planètes autour de ces étoiles de faible masse, froides et à longue durée de vie.Out of the 5322 exoplanets discovered so far, only 665 have been well characterized by measuring precisely both their radius and mass. The combination of transit photometry and high-precision velocity measurements allows to constrain the mean bulk density of the exoplanets and obtain a first-order estimate of their composition and inner structure. Cool, low mass stars are important targets to characterize exoplanets as M dwarfs represent most of the stellar population in our solar neighborhood, and are known to frequently host multiple small exoplanets. Due to the intrinsic faintness of M dwarfs at visible wavelengths, the near-infrared spectral range is preferred to study these cool stars as they emit most of their light in this region of the spectrum. ExTrA, a new near-infrared photometer and NIRPS, a new near-infrared spectrograph, both located at La Silla Observatory in Chile represent a chance to improve our understanding of planetary systems surrounding M dwarfs by measuring with precision both the planetary radius and the planetary mass.During my PhD, I collected all potential exoplanets orbiting M dwarfs observed by the TESS mission, an all-sky survey for transiting exoplanets orbiting bright and nearby stars. From these targets, I scheduled the follow-up observations using the ExTrA facility. Started from the raw data, I generated usable light curves. I then analyzed the light curves to identify any planetary transits and modeled them to obtain the planetary parameters. While M dwarfs are good candidates for exoplanet detection, their stellar companions can cause false positives. This is why additional observations with ground-based instruments are required to confirm the companion's planetary nature, and the combination of observations with TESS in the visible and with ExTrA in the near-infrared turned out to be very useful to validate the planetary candidate and obtain a precise radius measurement. From there, more observations are needed to fully characterize exoplanets. For the different systems I published during my thesis, I gathered and modeled observations from the HARPS and ESPRESSO spectrographs.The NIRPS spectrograph will soon also be able to provide the mass of the exoplanets detected in transits, especially around M dwarfs. I proposed two programs as part of the NIRPS Guaranteed Time Observations. The first program will use radial velocity measurements to complement our ExTrA photometry in order to populate the mass-radius diagram for mid-to-late M dwarfs. The second program attempts to discover additional planets in known systems by calculating the probability of these undetected planets' existence and the cost of detected them with current instruments like NIRPS.The synergies between both near-infrared instruments will allow us to characterize exoplanets orbiting M dwarfs and offer a unique opportunity to study planetary formation and evolution processes around these low-mass, cool, long-lived stars
Détection et caractérisation d'exoplanètes en orbite autour des naines M avec deux nouveaux instruments proche infrarouge : ExTrA et NIRPS
No full textOut of the 5322 exoplanets discovered so far, only 665 have been well characterized by measuring precisely both their radius and mass. The combination of transit photometry and high-precision velocity measurements allows to constrain the mean bulk density of the exoplanets and obtain a first-order estimate of their composition and inner structure. Cool, low mass stars are important targets to characterize exoplanets as M dwarfs represent most of the stellar population in our solar neighborhood, and are known to frequently host multiple small exoplanets. Due to the intrinsic faintness of M dwarfs at visible wavelengths, the near-infrared spectral range is preferred to study these cool stars as they emit most of their light in this region of the spectrum. ExTrA, a new near-infrared photometer and NIRPS, a new near-infrared spectrograph, both located at La Silla Observatory in Chile represent a chance to improve our understanding of planetary systems surrounding M dwarfs by measuring with precision both the planetary radius and the planetary mass.During my PhD, I collected all potential exoplanets orbiting M dwarfs observed by the TESS mission, an all-sky survey for transiting exoplanets orbiting bright and nearby stars. From these targets, I scheduled the follow-up observations using the ExTrA facility. Started from the raw data, I generated usable light curves. I then analyzed the light curves to identify any planetary transits and modeled them to obtain the planetary parameters. While M dwarfs are good candidates for exoplanet detection, their stellar companions can cause false positives. This is why additional observations with ground-based instruments are required to confirm the companion's planetary nature, and the combination of observations with TESS in the visible and with ExTrA in the near-infrared turned out to be very useful to validate the planetary candidate and obtain a precise radius measurement. From there, more observations are needed to fully characterize exoplanets. For the different systems I published during my thesis, I gathered and modeled observations from the HARPS and ESPRESSO spectrographs.The NIRPS spectrograph will soon also be able to provide the mass of the exoplanets detected in transits, especially around M dwarfs. I proposed two programs as part of the NIRPS Guaranteed Time Observations. The first program will use radial velocity measurements to complement our ExTrA photometry in order to populate the mass-radius diagram for mid-to-late M dwarfs. The second program attempts to discover additional planets in known systems by calculating the probability of these undetected planets' existence and the cost of detected them with current instruments like NIRPS.The synergies between both near-infrared instruments will allow us to characterize exoplanets orbiting M dwarfs and offer a unique opportunity to study planetary formation and evolution processes around these low-mass, cool, long-lived stars.Sur les 5322 exoplanètes découvertes à ce jour, seulement 665 ont été bien caractérisées en mesurant précisément à la fois leur rayon et leur masse. La combinaison de la photométrie de transit et des mesures de vitesses radiales de haute précision permet de contraindre la densité moyenne des exoplanètes et d'obtenir une première estimation de leur composition et structure interne. Les étoiles de faible masse sont des cibles importantes pour caractériser les exoplanètes car les naines M représentent la majeure partie de la population stellaire de notre voisinage et sont connues pour héberger de multiples petites exoplanètes. En raison de leur faible luminosité intrinsèque aux longueurs d'onde visibles, le proche infrarouge est privilégié pour étudier ces étoiles froides car elles émettent la plupart de leur lumière dans cette région du spectre. ExTrA et NIRPS, deux nouveaux instruments proche infrarouge, représentent une chance d'améliorer notre compréhension des systèmes planétaires entourant les naines M.Au cours de mon doctorat, j'ai rassemblé toutes les candidats planétaires en orbite autour des naines M observées par la mission TESS, une étude globale du ciel à la recherche d'exoplanètes en transit autour d'étoiles brillantes et proches. À partir de cette liste, j'ai planifié les observations de suivi en utilisant ExTrA. À partir des données brutes, j'ai généré des courbes de lumière utilisables. J'ai ensuite analysé les courbes de lumière pour identifier les transits planétaires et je les ai modélisés pour obtenir les paramètres planétaires. Des observations supplémentaires avec des instruments au sol sont nécessaires pour confirmer la nature planétaire du compagnon car des compagnons stellaires peuvent être à l'origine de faux positifs, et la combinaison d'observations avec TESS dans le visible et avec ExTrA dans le proche infrarouge s'est avérée très utile pour valider le candidat planétaire et obtenir une mesure précise de son rayon. A partir de là, d'autres observations sont nécessaires pour caractériser complètement les exoplanètes. Pour les différents systèmes que j'ai publiés pendant ma thèse, j'ai rassemblé et modélisé des observations des spectrographes HARPS et ESPRESSO.Le spectrographe NIRPS sera bientôt également capable de fournir la masse des exoplanètes détectées en transits, en particulier autour des naines M. J'ai proposé deux programmes dans le cadre du temps garanti d'observations (GTO) de NIRPS. Le premier utilisera des mesures de vitesses radiale pour compléter notre photométrie ExTrA afin de peupler le diagramme masse-rayon pour les naines M moyennes à tardives. Le second vise à détecter des planètes supplémentaires dans des systèmes connus en calculant la probabilité d'existence de ces planètes non détectées et le coût de leur détection avec les instruments actuels comme NIRPS.Les synergies entre ces deux instruments dans le proche infrarouge nous permettront de caractériser les exoplanètes en orbite autour des naines M et offriront une opportunité unique d'étudier la formation et l'évolution des planètes autour de ces étoiles de faible masse, froides et à longue durée de vie
Détection et caractérisation d'exoplanètes en orbite autour des naines M avec deux nouveaux instruments proche infrarouge : ExTrA et NIRPS
No full textOut of the 5322 exoplanets discovered so far, only 665 have been well characterized by measuring precisely both their radius and mass. The combination of transit photometry and high-precision velocity measurements allows to constrain the mean bulk density of the exoplanets and obtain a first-order estimate of their composition and inner structure. Cool, low mass stars are important targets to characterize exoplanets as M dwarfs represent most of the stellar population in our solar neighborhood, and are known to frequently host multiple small exoplanets. Due to the intrinsic faintness of M dwarfs at visible wavelengths, the near-infrared spectral range is preferred to study these cool stars as they emit most of their light in this region of the spectrum. ExTrA, a new near-infrared photometer and NIRPS, a new near-infrared spectrograph, both located at La Silla Observatory in Chile represent a chance to improve our understanding of planetary systems surrounding M dwarfs by measuring with precision both the planetary radius and the planetary mass.During my PhD, I collected all potential exoplanets orbiting M dwarfs observed by the TESS mission, an all-sky survey for transiting exoplanets orbiting bright and nearby stars. From these targets, I scheduled the follow-up observations using the ExTrA facility. Started from the raw data, I generated usable light curves. I then analyzed the light curves to identify any planetary transits and modeled them to obtain the planetary parameters. While M dwarfs are good candidates for exoplanet detection, their stellar companions can cause false positives. This is why additional observations with ground-based instruments are required to confirm the companion's planetary nature, and the combination of observations with TESS in the visible and with ExTrA in the near-infrared turned out to be very useful to validate the planetary candidate and obtain a precise radius measurement. From there, more observations are needed to fully characterize exoplanets. For the different systems I published during my thesis, I gathered and modeled observations from the HARPS and ESPRESSO spectrographs.The NIRPS spectrograph will soon also be able to provide the mass of the exoplanets detected in transits, especially around M dwarfs. I proposed two programs as part of the NIRPS Guaranteed Time Observations. The first program will use radial velocity measurements to complement our ExTrA photometry in order to populate the mass-radius diagram for mid-to-late M dwarfs. The second program attempts to discover additional planets in known systems by calculating the probability of these undetected planets' existence and the cost of detected them with current instruments like NIRPS.The synergies between both near-infrared instruments will allow us to characterize exoplanets orbiting M dwarfs and offer a unique opportunity to study planetary formation and evolution processes around these low-mass, cool, long-lived stars.Sur les 5322 exoplanètes découvertes à ce jour, seulement 665 ont été bien caractérisées en mesurant précisément à la fois leur rayon et leur masse. La combinaison de la photométrie de transit et des mesures de vitesses radiales de haute précision permet de contraindre la densité moyenne des exoplanètes et d'obtenir une première estimation de leur composition et structure interne. Les étoiles de faible masse sont des cibles importantes pour caractériser les exoplanètes car les naines M représentent la majeure partie de la population stellaire de notre voisinage et sont connues pour héberger de multiples petites exoplanètes. En raison de leur faible luminosité intrinsèque aux longueurs d'onde visibles, le proche infrarouge est privilégié pour étudier ces étoiles froides car elles émettent la plupart de leur lumière dans cette région du spectre. ExTrA et NIRPS, deux nouveaux instruments proche infrarouge, représentent une chance d'améliorer notre compréhension des systèmes planétaires entourant les naines M.Au cours de mon doctorat, j'ai rassemblé toutes les candidats planétaires en orbite autour des naines M observées par la mission TESS, une étude globale du ciel à la recherche d'exoplanètes en transit autour d'étoiles brillantes et proches. À partir de cette liste, j'ai planifié les observations de suivi en utilisant ExTrA. À partir des données brutes, j'ai généré des courbes de lumière utilisables. J'ai ensuite analysé les courbes de lumière pour identifier les transits planétaires et je les ai modélisés pour obtenir les paramètres planétaires. Des observations supplémentaires avec des instruments au sol sont nécessaires pour confirmer la nature planétaire du compagnon car des compagnons stellaires peuvent être à l'origine de faux positifs, et la combinaison d'observations avec TESS dans le visible et avec ExTrA dans le proche infrarouge s'est avérée très utile pour valider le candidat planétaire et obtenir une mesure précise de son rayon. A partir de là, d'autres observations sont nécessaires pour caractériser complètement les exoplanètes. Pour les différents systèmes que j'ai publiés pendant ma thèse, j'ai rassemblé et modélisé des observations des spectrographes HARPS et ESPRESSO.Le spectrographe NIRPS sera bientôt également capable de fournir la masse des exoplanètes détectées en transits, en particulier autour des naines M. J'ai proposé deux programmes dans le cadre du temps garanti d'observations (GTO) de NIRPS. Le premier utilisera des mesures de vitesses radiale pour compléter notre photométrie ExTrA afin de peupler le diagramme masse-rayon pour les naines M moyennes à tardives. Le second vise à détecter des planètes supplémentaires dans des systèmes connus en calculant la probabilité d'existence de ces planètes non détectées et le coût de leur détection avec les instruments actuels comme NIRPS.Les synergies entre ces deux instruments dans le proche infrarouge nous permettront de caractériser les exoplanètes en orbite autour des naines M et offriront une opportunité unique d'étudier la formation et l'évolution des planètes autour de ces étoiles de faible masse, froides et à longue durée de vie
Détection et caractérisation d'exoplanètes en orbite autour des naines M avec deux nouveaux instruments proche infrarouge : ExTrA et NIRPS
No full textOut of the 5322 exoplanets discovered so far, only 665 have been well characterized by measuring precisely both their radius and mass. The combination of transit photometry and high-precision velocity measurements allows to constrain the mean bulk density of the exoplanets and obtain a first-order estimate of their composition and inner structure. Cool, low mass stars are important targets to characterize exoplanets as M dwarfs represent most of the stellar population in our solar neighborhood, and are known to frequently host multiple small exoplanets. Due to the intrinsic faintness of M dwarfs at visible wavelengths, the near-infrared spectral range is preferred to study these cool stars as they emit most of their light in this region of the spectrum. ExTrA, a new near-infrared photometer and NIRPS, a new near-infrared spectrograph, both located at La Silla Observatory in Chile represent a chance to improve our understanding of planetary systems surrounding M dwarfs by measuring with precision both the planetary radius and the planetary mass.During my PhD, I collected all potential exoplanets orbiting M dwarfs observed by the TESS mission, an all-sky survey for transiting exoplanets orbiting bright and nearby stars. From these targets, I scheduled the follow-up observations using the ExTrA facility. Started from the raw data, I generated usable light curves. I then analyzed the light curves to identify any planetary transits and modeled them to obtain the planetary parameters. While M dwarfs are good candidates for exoplanet detection, their stellar companions can cause false positives. This is why additional observations with ground-based instruments are required to confirm the companion's planetary nature, and the combination of observations with TESS in the visible and with ExTrA in the near-infrared turned out to be very useful to validate the planetary candidate and obtain a precise radius measurement. From there, more observations are needed to fully characterize exoplanets. For the different systems I published during my thesis, I gathered and modeled observations from the HARPS and ESPRESSO spectrographs.The NIRPS spectrograph will soon also be able to provide the mass of the exoplanets detected in transits, especially around M dwarfs. I proposed two programs as part of the NIRPS Guaranteed Time Observations. The first program will use radial velocity measurements to complement our ExTrA photometry in order to populate the mass-radius diagram for mid-to-late M dwarfs. The second program attempts to discover additional planets in known systems by calculating the probability of these undetected planets' existence and the cost of detected them with current instruments like NIRPS.The synergies between both near-infrared instruments will allow us to characterize exoplanets orbiting M dwarfs and offer a unique opportunity to study planetary formation and evolution processes around these low-mass, cool, long-lived stars.Sur les 5322 exoplanètes découvertes à ce jour, seulement 665 ont été bien caractérisées en mesurant précisément à la fois leur rayon et leur masse. La combinaison de la photométrie de transit et des mesures de vitesses radiales de haute précision permet de contraindre la densité moyenne des exoplanètes et d'obtenir une première estimation de leur composition et structure interne. Les étoiles de faible masse sont des cibles importantes pour caractériser les exoplanètes car les naines M représentent la majeure partie de la population stellaire de notre voisinage et sont connues pour héberger de multiples petites exoplanètes. En raison de leur faible luminosité intrinsèque aux longueurs d'onde visibles, le proche infrarouge est privilégié pour étudier ces étoiles froides car elles émettent la plupart de leur lumière dans cette région du spectre. ExTrA et NIRPS, deux nouveaux instruments proche infrarouge, représentent une chance d'améliorer notre compréhension des systèmes planétaires entourant les naines M.Au cours de mon doctorat, j'ai rassemblé toutes les candidats planétaires en orbite autour des naines M observées par la mission TESS, une étude globale du ciel à la recherche d'exoplanètes en transit autour d'étoiles brillantes et proches. À partir de cette liste, j'ai planifié les observations de suivi en utilisant ExTrA. À partir des données brutes, j'ai généré des courbes de lumière utilisables. J'ai ensuite analysé les courbes de lumière pour identifier les transits planétaires et je les ai modélisés pour obtenir les paramètres planétaires. Des observations supplémentaires avec des instruments au sol sont nécessaires pour confirmer la nature planétaire du compagnon car des compagnons stellaires peuvent être à l'origine de faux positifs, et la combinaison d'observations avec TESS dans le visible et avec ExTrA dans le proche infrarouge s'est avérée très utile pour valider le candidat planétaire et obtenir une mesure précise de son rayon. A partir de là, d'autres observations sont nécessaires pour caractériser complètement les exoplanètes. Pour les différents systèmes que j'ai publiés pendant ma thèse, j'ai rassemblé et modélisé des observations des spectrographes HARPS et ESPRESSO.Le spectrographe NIRPS sera bientôt également capable de fournir la masse des exoplanètes détectées en transits, en particulier autour des naines M. J'ai proposé deux programmes dans le cadre du temps garanti d'observations (GTO) de NIRPS. Le premier utilisera des mesures de vitesses radiale pour compléter notre photométrie ExTrA afin de peupler le diagramme masse-rayon pour les naines M moyennes à tardives. Le second vise à détecter des planètes supplémentaires dans des systèmes connus en calculant la probabilité d'existence de ces planètes non détectées et le coût de leur détection avec les instruments actuels comme NIRPS.Les synergies entre ces deux instruments dans le proche infrarouge nous permettront de caractériser les exoplanètes en orbite autour des naines M et offriront une opportunité unique d'étudier la formation et l'évolution des planètes autour de ces étoiles de faible masse, froides et à longue durée de vie
Detection and Characterization of Exoplanets Orbiting M Dwarfs with Two New Near-Infrared Instruments: ExTrA and NIRPS
No full textOut of the 5322 exoplanets discovered so far, only 665 have been well characterized by measuring precisely both their radius and mass. The combination of transit photometry and high-precision velocity measurements allows to constrain the mean bulk density of the exoplanets and obtain a first-order estimate of their composition and inner structure. Cool, low mass stars are important targets to characterize exoplanets as M dwarfs represent most of the stellar population in our solar neighborhood, and are known to frequently host multiple small exoplanets. Due to the intrinsic faintness of M dwarfs at visible wavelengths, the near-infrared spectral range is preferred to study these cool stars as they emit most of their light in this region of the spectrum. ExTrA, a new near-infrared photometer and NIRPS, a new near-infrared spectrograph, both located at La Silla Observatory in Chile represent a chance to improve our understanding of planetary systems surrounding M dwarfs by measuring with precision both the planetary radius and the planetary mass.
During my PhD, I collected all potential exoplanets orbiting M dwarfs observed by the TESS mission, an all-sky survey for transiting exoplanets orbiting bright and nearby stars. From these targets, I scheduled the follow-up observations using the ExTrA facility. Started from the raw data, I generated usable light curves. I then analyzed the light curves to iden- tify any planetary transits and modeled them to obtain the planetary parameters. While M dwarfs are good candidates for exoplanet detection, their stellar companions can cause false positives. This is why additional observations with ground-based instruments are required to confirm the companion’s planetary nature, and the combination of observations with TESS in the visible and with ExTrA in the near-infrared turned out to be very useful to validate the planetary candidate and obtain a precise radius measurement. From there, more observations are needed to fully characterize exoplanets. For the different systems I published during my thesis, I gathered and modeled observations from the HARPS and ESPRESSO spectrographs.
The NIRPS spectrograph will soon also be able to provide the mass of the exoplanets detected in transits, especially around M dwarfs. I proposed two programs as part of the NIRPS Guaranteed Time Observations. The first program will use radial velocity measurements to complement our ExTrA photometry in order to populate the mass-radius diagram for mid-to-late M dwarfs. The second program attempts to discover additional planets in known systems by calculating the probability of these undetected planets’ existence and the cost of detected them with current instruments like NIRPS.
The synergies between both near-infrared instruments will allow us to characterize exoplanets orbiting M dwarfs and offer a unique opportunity to study planetary formation and evolution processes around these low-mass, cool, long-lived stars. </p
Fiber tracking in q-ball fields using regularized particle trajectories
No full textMost of the approaches dedicated to fiber tracking from diffusion-weighted MR data rely on a tensor model. However, the tensor model can only resolve a single fiber orientation within each imaging voxel. New emerging approaches have been proposed to obtain a better representation of the diffusion process occurring in fiber crossing. In this paper, we adapt a tracking algorithm to the q-ball representation, which results from a spherical Radon transform of high angular resolution data. This algorithm is based on a Monte-Carlo strategy, using regularized particle trajectories to sample the white matter geometry. The method is validated using a phantom of bundle crossing made up of haemodialysis fibers. The method is also applied to the detection of the auditory tract in three human subjects
Two temperate super-Earths transiting a nearby late-type M dwarf
No full textpeer reviewedIn the age of JWST, temperate terrestrial exoplanets transiting nearby late-type M dwarfs provide unique opportunities for characterising their atmospheres, as well as searching for biosignature gases. We report here the discovery and validation of two temperate super-Earths transiting LP 890-9 (TOI-4306, SPECULOOS-2), a relatively low-activity nearby (32 pc) M6V star. The inner planet, LP 890-9b, was first detected by TESS (and identified as TOI-4306.01) based on four sectors of data. Intensive photometric monitoring of the system with the SPECULOOS Southern Observatory then led to the discovery of a second outer transiting planet, LP 890-9c (also identified as SPECULOOS-2c), previously undetected by TESS. The orbital period of this second planet was later confirmed by MuSCAT3 follow-up observations. With a mass of 0.118±0.002 M⊙, a radius of 0.1556±0.0086 R⊙, and an effective temperature of 2850±75 K, LP 890-9 is the second-coolest star found to host planets, after TRAPPIST-1. The inner planet has an orbital period of 2.73 d, a radius of 1.320+0.053−0.027 R⊕, and receives an incident stellar flux of 4.09±0.12 S⊕. The outer planet has a similar size of 1.367+0.055−0.039 R⊕ and an orbital period of 8.46 d. With an incident stellar flux of 0.906 ± 0.026 S⊕, it is located within the conservative habitable zone, very close to its inner limit. Although the masses of the two planets remain to be measured, we estimated their potential for atmospheric characterisation via transmission spectroscopy using a mass-radius relationship and found that, after the TRAPPIST-1 planets, LP 890-9c is the second-most favourable habitable-zone terrestrial planet known so far. The discovery of this remarkable system offers another rare opportunity to study temperate terrestrial planets around our smallest and coolest neighbours
TOI 762 A b and TIC 46432937 b: Two Giant Planets Transiting M-dwarf Stars
No full textHartman, Joel D. et al.--Full list of authors: Hartman, Joel D.; Bayliss, Daniel; Brahm, Rafael; Bryant, Edward M.; Jordán, Andrés; Bakos, Gáspár Á.; Hobson, Melissa J.; Sedaghati, Elyar; Bonfils, Xavier; Cointepas, Marion; Almenara, Jose Manuel; Barkaoui, Khalid; Timmermans, Mathilde; Dransfield, George; Ducrot, Elsa; Zúñiga-Fernández, Sebastián; Hooton, Matthew J.; Pedersen, Peter Pihlmann; Pozuelos, Francisco J.; Triaud, Amaury H. M. J.; Gillon, Michaël; Jehin, Emmanuel; Waalkes, William C.; Berta-Thompson, Zachory K.; Howell, Steve B.; Furlan, Elise; Ricker, George R.; Vanderspek, Roland; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Rapetti, David; Collins, Karen A.; Charbonneau, David; Burke, Christopher J.; Rodriguez, David R.We present the discovery of TOI 762 A b and TIC 46432937 b, two giant planets transiting M-dwarf stars. Transits of both systems were first detected from observations by the NASA TESS mission, and the transiting objects are confirmed as planets through high-precision radial velocity observations carried out with Very Large Telescope/ESPRESSO. TOI 762 A b is a warm sub-Saturn with a mass of 0.251 ± 0.042 MJ, a radius of 0.744 ± 0.017 RJ, and an orbital period of 3.4717 days. It transits a mid-M-dwarf star with a mass of 0.442 ± 0.025 M☉ and a radius of 0.4250 ± 0.0091 R☉. The star TOI 762 A has a resolved binary star companion, TOI 762 B, that is separated from TOI 762 A by 3farcs2 (∼319 au) and has an estimated mass of 0.227 ± 0.010 M☉. The planet TIC 46432937 b is a warm super-Jupiter with a mass of 3.20 ± 0.11 MJ and radius of 1.188 ± 0.030 RJ. The planet's orbital period is P = 1.4404 days, and it undergoes grazing transits of its early M-dwarf host star, which has a mass of 0.563 ± 0.029 M☉ and a radius of 0.5299 ± 0.0091 R☉. TIC 46432937 b is one of the highest-mass planets found to date transiting an M-dwarf star. TIC 46432937 b is also a promising target for atmospheric observations, having the highest transmission spectroscopy metric or emission spectroscopy metric value of any known warm super-Jupiter (mass greater than 3.0 MJ, equilibrium temperature below 1000 K). © 2024. The Author(s). Published by the American Astronomical Society.We thank the anonymous referee for their careful reading this paper, and helpful comments that have improved the quality of the work. J.H. and G.B. acknowledge funding from NASA grant No. 80NSSC22K0315. A.J. and R.B. acknowledge support from ANID—Millennium Science Initiative—ICN12_009. R.B. acknowledges support from FONDECYT Project 11200751. A.J. acknowledges support from FONDECYT project 1210718. We acknowledge funding from the European Research Council under the ERC Grant Agreement No. 337591-ExTrA. This research has made use of the Exoplanet Follow-up Observation Program (ExoFOP; DOI:10.26134/ExoFOP5) website, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This paper made use of data collected by the TESS mission and which are publicly available from the Mikulski Archive for Space Telescopes (MAST) operated by the Space Telescope Science Institute (STScI). Funding for the TESS mission is provided by NASA's Science Mission Directorate. The specific observations from MAST analyzed in this paper can be accessed from DOI:10.17909/e3cp-9907. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. The contributions at the Mullard Space Science Laboratory by EMB have been supported by STFC through the consolidated grant ST/W001136/1. The postdoctoral fellowship of K.B. is funded by F.R.S.-FNRS grant T.0109.20 and by the Francqui Foundation. This publication benefits from the support of the French Community of Belgium in the context of the FRIA Doctoral Grant awarded to M.T. M.G. is F.R.S.-FNRS Research Director and E.J. is F.R.S.-FNRS Senior Research Associate. F.J.P. acknowledges financial support from the grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033 and through projects PID2019-109522GB-C52 and PID2022-137241NB-C43. Based on data collected by the SPECULOOS-South Observatory at the ESO Paranal Observatory in Chile. The ULiege's contribution to SPECULOOS has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013; grant Agreement No. 336480/SPECULOOS), from the Balzan Prize and Francqui Foundations, from the Belgian Scientific Research Foundation (F.R.S.-FNRS; grant No. T.0109.20), from the University of Liege, and from the ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. This work is supported by a grant from the Simons Foundation (PI: Queloz; grant No. 327127). Based on data collected by the TRAPPIST-South telescope at the ESO La Silla Observatory. TRAPPIST is funded by the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, FNRS) under the grant No. PDR T.0120.21, with the participation of the Swiss National Science Fundation (SNF). D.R. was supported by NASA under award number NNA16BD14C for NASA Academic Mission Services.With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).Peer reviewe
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