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This poster presents new results derived from spectropolarimetric and photometric observations of the young weak line T Tauri star V410 Tau, collected respectively with the new near-infrared spectropolarimeter SPIRou at CFHT, and with the TESS space probe. For the first time, we combined high-resolution spectropolarimetry and high-precision photometry with Zeeman-Doppler Imaging, in order to reconstruct maps of the photospheric brightness and of the large-scale magnetic field at the surface of V410 Tau. Our results reveal a complex magnetic field, consistent with previous studies, and a high level of stellar activity. Our study also illustrates the benefits of near-infrared (vs optical) observations, to investigate the magnetic topologies of young stars and look for the potential presence of massive planets on close-in orbits through radial velocity measurements.

This poster presents the analysis of spectropolarimetric data of the pre-cataclysmic variable binary system V471 Tau obtained with ESPaDOnS at the Canada-France-Hawaii Telescope in two observational campaigns. We show first reconstructions of the large-scale magnetic field of the K2 dwarf, as well as new brightness maps and the amount of differential rotation by which surface maps are sheared. We compare the differential rotation fluctuations obtained for the K2 dwarf with those of the single-star analogue AB Dor. Finally, we argue that a slingshot mechanism likely sustains the prominence observed in 2004.

This poster presents the analysis of spectropolarimetric data of the pre-cataclysmic variable binary system V471 Tau obtained with ESPaDOnS at the Canada-France-Hawaii Telescope in two observational campaigns. We show first reconstructions of the large-scale magnetic field of the K2 dwarf, as well as new brightness maps and the amount of differential rotation by which surface maps are sheared. We compare the differential rotation fluctuations obtained for the K2 dwarf with those of the single-star analogue AB Dor. Finally, we argue that a slingshot mechanism likely sustains the prominence observed in 2004., {"references":["https://doi.org/10.1093/mnras/stz3173","https://doi.org/10.1046/j.1365-2966.2003.07101.x","https://doi.org/10.1111/j.1365-2966.2006.10073.x","https://doi.org/10.1111/j.1365-2966.2006.11154.x"]}

There have recently been detections of radio emission from low-mass stars, some of which are indicative of star-planet interactions. Motivated by these exciting new results, here we present stellar wind models for the active planet-hosting M dwarf AU Mic. Our models incorporate the large-scale photospheric magnetic field map of the star, reconstructed using the Zeeman-Doppler Imaging method. We use our models to assess if planet-induced radio emission could be generated in the corona of AU Mic, through a mechanism analogous to the sub-Alfv\'enic Jupiter-Io interaction. In the case that AU Mic has a mass-loss rate of 27 times that of the Sun, we find that both planets b and c in the system can induce radio emission from 10 MHz to 3 GHz in the corona of the host star for the majority of their orbits, with peak flux densities of 10 mJy. Our predicted emission bears a striking similarity to that recently reported from GJ 1151 by Vedantham et al. (2020), which is indicative of being induced by a planet. Detection of such radio emission would allow us to place an upper limit on the mass-loss rate of the star., Comment: 4 pages, 3 figures. Proceedings of the 20.5th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (CS20.5), March 2021. arXiv admin note: substantial text overlap with arXiv:2103.16318

There have recently been detections of radio emission from low-mass stars, some of which are indicative of star-planet interactions. Motivated by these exciting new results, here we present stellar wind models for the active planet-hosting M dwarf AU Mic. Our models incorporate the large-scale photospheric magnetic field map of the star, reconstructed using the Zeeman-Doppler Imaging method. We use our models to assess if planet-induced radio emission could be generated in the corona of AU Mic, through a mechanism analogous to the sub-Alfvénic Jupiter-Io interaction. In the case that AU Mic has a mass-loss rate of 27 times that of the Sun, we find that both planets b and c in the system can induce radio emission from 10 MHz to 3 GHz in the corona of the host star for the majority of their orbits, with peak flux densities of 10 mJy. Our predicted emission bears a striking similarity to that recently reported from GJ 1151 by Vedantham et al. (2020), which is indicative of being induced by a planet. Detection of such radio emission would allow us to place an upper limit on the mass-loss rate of the star., {"references":["Carolan, S. et al. (2020). The dichotomy of atmospheric escape in AU Mic b","Chiang, E. & Fung, J. (2017). Stellar Winds and Dust Avalanches in the AU Mic Debris Disk","Grießmeier, J. M. et al. (2007). Predicting low-frequency radio fluxes of known extrasolar planets","Ip, W.-H. et al. (2004). On the Star-Magnetosphere Interaction of Close-in Exoplanets","Kavanagh, R. D. & Vidotto, A. A. (2020). Radio eclipses of exoplanets by the winds of their host stars","Kavanagh, R. D. et al. (2021). Planet-induced radio emission from the coronae of M dwarfs: the case of Prox Cen and AU Mic","Kavanagh, R. D. et al. (2019). MOVES - II. Tuning in to the radio environment of HD189733b","Klein, B. et al. (2021). Investigating the young AU Mic system with SPIRou: large-scale stellar magnetic field and close-in planet mass","Lanza, A. F. (2012). Star-planet magnetic interaction and activity in late-type stars with close-in planets","Mahadevan, S. et al. (2021). The Habitable-zone Planet Finder Detects a Terrestrial-mass Planet Candidate Closely Orbiting Gliese 1151: The Likely Source of Coherent Low-frequency Radio Emission from an Inactive Star","Martioli, E. et al. (2021). New constraints on the planetary system around the young active star AU Mic. Two transiting warm Neptunes near mean-motion resonance","McIvor, T., et al. (2006). Extrasolar planets, stellar winds and chromospheric hotspots","Neubauer, F. M. (1980). Nonlinear standing Alfvén wave current system at Io: Theory","Perger, M. et al. (2021). The CARMENES search for exoplanets around M dwarfs, No evidence for a super-Earth in a 2-day orbit around GJ 1151","Plavchan, P. et al. (2020). A planet within the debris disk around the pre-main-sequence star AU Microscopii","Plavchan, P. et al. (2009). New Debris Disks Around Young, Low-Mass Stars Discovered with the Spitzer Space Telescope","Powell, K. G. et al. (1999). A Solution-Adaptive Upwind Scheme for Ideal Magnetohydrodynamics","Saur, J. et al. (2013). Magnetic energy fluxes in sub-Alfvénic planet star and moon planet interactions","Saur, J. et al. (2004). Plasma interaction of Io with its plasma torus","Strugarek, A. et al. (2019). Chasing Star-Planet Magnetic Interactions: The Case of Kepler-78","Turnpenney, S. et al. (2018). Exoplanet-induced Radio Emission from M Dwarfs","van der Holst, B. et al. (2014). Alfvén Wave Solar Model (AWSoM): Coronal Heating","Vedantham, H. K. et al. (2020). Coherent radio emission from a quiescent red dwarf indicative of star-planet interaction","Vidotto, A. A. & Donati, J. F. (2017). Predicting radio emission from the newborn hot Jupiter V830 Tauri b and its host star","Vidotto, A. A. et al. (2015). On the environment surrounding close-in exoplanets","Zarka, P. (1998). Auroral radio emissions at the outer planets: Observations and theories","Zarka, P. (2007). Plasma interactions of exoplanets with their parent star and associated radio emissions","Zarka, P. et al. (2004). Jupiter's low-frequency radio spectrum from Cassini/Radio and Plasma Wave Science (RPWS) absolute flux density measurements"]}

There have recently been detections of radio emission from low-mass stars, some of which are indicative of star-planet interactions. Motivated by these exciting new results, here we present stellar wind models for the active planet-hosting M dwarf AU Mic. Our models incorporate the large-scale photospheric magnetic field map of the star, reconstructed using the Zeeman-Doppler Imaging method. We use our models to assess if planet-induced radio emission could be generated in the corona of AU Mic, through a mechanism analogous to the sub-Alfvénic Jupiter-Io interaction. In the case that AU Mic has a mass-loss rate of 27 times that of the Sun, we find that both planets b and c in the system can induce radio emission from 10 MHz to 3 GHz in the corona of the host star for the majority of their orbits, with peak flux densities of 10 mJy. Our predicted emission bears a striking similarity to that recently reported from GJ 1151 by Vedantham et al. (2020), which is indicative of being induced by a planet. Detection of such radio emission would allow us to place an upper limit on the mass-loss rate of the star.

There have recently been detections of radio emission from low-mass stars, some of which are indicative of star-planet interactions. Motivated by these exciting new results, here we present stellar wind models for the active planet-hosting M dwarf AU Mic. Our models incorporate the large-scale photospheric magnetic field map of the star, reconstructed using the Zeeman-Doppler Imaging method. We use our models to assess if planet-induced radio emission could be generated in the corona of AU Mic, through a mechanism analogous to the sub-Alfvénic Jupiter-Io interaction. In the case that AU Mic has a mass-loss rate of < 590 times that of the Sun, we find that both planets b and c in the system can induce radio emission from 10 MHz – 3 GHz in the corona of the host star for the majority of their orbits, with peak flux densities of 10 mJy. Our predicted emission bears a striking similarity to that recently reported from GJ 1151 by Vedantham et al. (2020), which is indicative of being induced by a planet., {"references":["van der Holst, Bart et al. (2014). Alfvén Wave Solar Model (AWSoM): Coronal Heating.","Klein, Baptiste et al. (2021b). Investigating the young AU Mic system with SPIRou: large-scale stellar magnetic field and close-in planet mass.","Turnpenney, Sam et al. (2018). Exoplanet-induced Radio Emission from M Dwarfs.","Vedantham, Harish et al (2020). Coherent radio emission from a quiescent red dwarf indicative of star-planet interaction."]}

This poster presents new results derived from spectropolarimetric and photometric observations of the young weak line T Tauri star V410 Tau, collected respectively with the new near-infrared spectropolarimeter SPIRou at CFHT, and with the TESS space probe. For the first time, we combined high-resolution spectropolarimetry and high-precision photometry with Zeeman-Doppler Imaging, in order to reconstruct maps of the photospheric brightness and of the large-scale magnetic field at the surface of V410 Tau. Our results reveal a complex magnetic field, consistent with previous studies, and a high level of stellar activity. Our study also illustrates the benefits of near-infrared (vs optical) observations, to investigate the magnetic topologies of young stars and look for the potential presence of massive planets on close-in orbits through radial velocity measurements., {"references":["Brown S. F., Donati J. F., Rees D. E., Semel M., 1991, A&A, 250, 463","Donati J. F., Brown S. F., 1997, A&A, 326, 1135","Donati J.-F., Semel M., Carter B. D., Rees D. E., Collier Cameron A., 1997, MNRAS, 291","Donati J. F., et al., 2006, MNRAS, 370, 629","Haywood R. D., et al., 2014, MNRAS, 443, 2517","Semel M., 1989, A&A, 225, 456","Yu L., et al., 2019, MNRAS, 489, 5556"]}

Measuring the mean densities of close-in planets orbiting pre-main-sequence (PMS) stars is crucially needed by planet formation and evolution models. However, PMS stars exhibit intense magnetic activity inducing fluctuations in both photometric and RV curves that overshadow planet signatures. As a result, no close-in planet younger than 25 Myr has a well-constrained bulk density. In this study, we present a spectropolarimetric and velocimetric analysis of 27 near-infrared observations of the nearby active 22 Myr-old red dwarf AU Microscopii collected with SPIRou at the end of the year 2019. We jointly model the planet and stellar activity RV components, resulting in a 3.9σσ-detection of the recently-discovered close-in Neptune-sized planet AU Mic b, with an estimated mass of 17.1+4.7−4.5−4.5+4.7 M⊕⊕, implying a Neptune-like density for the planet. A consistent detection of the planet is independently obtained by simultaneously reconstructing the surface distribution of bright and dark inhomogeneities and estimating the planet parameters using Doppler imaging (DI). Using Zeeman-Doppler Imaging, we invert our time-series of intensity and circularly-polarized line profiles into distributions of brightness and large-scale magnetic field at the surface of the star and explore how these distributions are sheared by latitudinal differential rotation. Finally, we investigate the magnetic activity of AU Mic by computing various indicators and found that the disk-integrated magnetic flux density correlates best with the stellar activity RV signal, in line with recent solar observations., See the associated poster and punlication in MNRAS: https://ui.adsabs.harvard.edu/abs/2021MNRAS.502..188K/abstract

There have recently been detections of radio emission from low-mass stars, some of which are indicative of star-planet interactions. Motivated by these exciting new results, here we present stellar wind models for the active planet-hosting M dwarf AU Mic. Our models incorporate the large-scale photospheric magnetic field map of the star, reconstructed using the Zeeman-Doppler Imaging method. We use our models to assess if planet-induced radio emission could be generated in the corona of AU Mic, through a mechanism analogous to the sub-Alfvénic Jupiter-Io interaction. In the case that AU Mic has a mass-loss rate of < 590 times that of the Sun, we find that both planets b and c in the system can induce radio emission from 10 MHz – 3 GHz in the corona of the host star for the majority of their orbits, with peak flux densities of 10 mJy. Our predicted emission bears a striking similarity to that recently reported from GJ 1151 by Vedantham et al. (2020), which is indicative of being induced by a planet.

Measured spectral shifts due to intrinsic stellar variability (e.g., pulsations, granulation) and activity (e.g., spots, plages) are the largest source of error for extreme precision radial velocity (EPRV) exoplanet detection. Several methods are designed to disentangle stellar signals from true center-of-mass shifts due to planets. The EXPRES Stellar Signals Project (ESSP) presents a self-consistent comparison of 22 different methods tested on the same extreme-precision spectroscopic data from EXPRES. Methods derived new activity indicators, constructed models for mapping an indicator to the needed RV correction, or separated out shape- and shift-driven RV components. Since no ground truth is known when using real data, relative method performance is assessed using the total and nightly scatter of returned RVs and agreement between the results of different methods. Nearly all submitted methods return a lower RV RMS than classic linear decorrelation, but no method is yet consistently reducing the RV RMS to sub-meter-per-second levels. There is a concerning lack of agreement between the RVs returned by different methods. These results suggest that continued progress in this field necessitates increased interpretability of methods, high-cadence data to capture stellar signals at all timescales, and continued tests like the ESSP using consistent data sets with more advanced metrics for method performance. Future comparisons should make use of various well-characterized data sets -- such as solar data or data with known injected planetary and/or stellar signals -- to better understand method performance and whether planetary signals are preserved., 33 pages (+12 pages of Appendix), 10 figures, 8 tables, accepted for publication in AJ