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- ItemExoClock project: an open platform for monitoring the ephemerides of Ariel targets with contributions from the public(Dordrecht [u.a.] : Springer Science + Business Media B.V, 2021) Kokori, Anastasia; Tsiaras, Angelos; Edwards, Billy; Rocchetto, Marco; Tinetti, Giovanna; Wünsche, Anaël; Paschalis, Nikolaos; Agnihotri, Vikrant Kumar; Bachschmidt, Matthieu; Bretton, Marc; Caines, Hamish; Caló, Mauro; Casali, Roland; Crow, Martin; Dawes, Simon; Deldem, Marc; Deligeorgopoulos, Dimitrios; Dymock, Roger; Evans, Phil; Falco, Carmelo; Ferratfiat, Stephane; Fowler, Martin; Futcher, Stephen; Guerra, Pere; Hurter, Francois; Jones, Adrian; Kang, Wonseok; Kim, Taewoo; Lee, Richard; Lopresti, Claudio; Marino, Antonio; Mallonn, Matthias; Mortari, Fabio; Morvan, Mario; Mugnai, Lorenzo V.; Nastasi, Alessandro; Perroud, Valère; Pereira, Cédric; Phillips, Mark; Pintr, Pavel; Raetz, Manfred; Regembal, Francois; Savage, John; Sedita, Danilo; Sioulas, Nick; Strikis, Iakovos; Thurston, Geoffrey; Tomacelli, Andrea; Tomatis, AlbertoThe Ariel mission will observe spectroscopically around 1000 exoplanets to further characterise their atmospheres. For the mission to be as efficient as possible, a good knowledge of the planets’ ephemerides is needed before its launch in 2028. While ephemerides for some planets are being refined on a per-case basis, an organised effort to collectively verify or update them when necessary does not exist. In this study, we introduce the ExoClock project, an open, integrated and interactive platform with the purpose of producing a confirmed list of ephemerides for the planets that will be observed by Ariel. The project has been developed in a manner to make the best use of all available resources: observations reported in the literature, observations from space instruments and, mainly, observations from ground-based telescopes, including both professional and amateur observatories. To facilitate inexperienced observers and at the same time achieve homogeneity in the results, we created data collection and validation protocols, educational material and easy to use interfaces, open to everyone. ExoClock was launched in September 2019 and now counts over 140 participants from more than 15 countries around the world. In this release, we report the results of observations obtained until the 15h of April 2020 for 120 Ariel candidate targets. In total, 632 observations were used to either verify or update the ephemerides of 84 planets. Additionally, we developed the Exoplanet Characterisation Catalogue (ECC), a catalogue built in a consistent way to assist the ephemeris refinement process. So far, the collaborative open framework of the ExoClock project has proven to be highly efficient in coordinating scientific efforts involving diverse audiences. Therefore, we believe that it is a paradigm that can be applied in the future for other research purposes, too.
- ItemAn Aligned Orbit for the Young Planet V1298 Tau b(London : Institute of Physics Publ., 2022) Johnson, Marshall C.; David, Trevor J.; Petigura, Erik A.; Isaacson, Howard T.; Van Zandt, Judah; Ilyin, Ilya; Strassmeier, Klaus; Mallonn, Matthias; Zhou, George; Mann, Andrew W.; Livingston, John H.; Luger, Rodrigo; Dai, Fei; Weiss, Lauren M.; Močnik, Teo; Giacalone, Steven; Hill, Michelle L.; Rice, Malena; Blunt, Sarah; Rubenzahl, Ryan; Dalba, Paul A.; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.; Foreman-Mackey, DanielThe alignment of planetary orbits with respect to the stellar rotation preserves information on their dynamical histories. Measuring this angle for young planets helps illuminate the mechanisms that create misaligned orbits for older planets, as different processes could operate over timescales ranging from a few megayears to a gigayear. We present spectroscopic transit observations of the young exoplanet V1298 Tau b; we update the age of V1298 Tau to be 28 ± 4 Myr based on Gaia EDR3 measurements. We observed a partial transit with Keck/HIRES and LBT/PEPSI, and detected the radial velocity anomaly due to the Rossiter-McLaughlin effect. V1298 Tau b has a prograde, well-aligned orbit, with λ=4-10+7 deg. By combining the spectroscopically measured v sin i∗ and the photometrically measured rotation period of the host star we also find that the orbit is aligned in 3D, ψ=8-7+4 deg. Finally, we combine our obliquity constraints with a previous measurement for the interior planet V1298 Tau c to constrain the mutual inclination between the two planets to be i mut = 0° ± 19°. This measurements adds to the growing number of well-aligned planets at young ages, hinting that misalignments may be generated over timescales of longer than tens of megayears. The number of measurements, however, is still small, and this population may not be representative of the older planets that have been observed to date. We also present the derivation of the relationship between i mut, λ, and i for the two planets.
- ItemKELT-9 as an Eclipsing Double-lined Spectroscopic Binary: A Unique and Self-consistent Solution to the System(London : Institute of Physics Publ., 2022) Pai Asnodkar, Anusha; Wang, Ji; Gaudi, B. Scott; Cauley, P. Wilson; Eastman, Jason D.; Ilyin, Ilya; Strassmeier, Klaus; Beatty, ThomasTransiting hot Jupiters present a unique opportunity to measure absolute planetary masses due to the magnitude of their radial velocity signals and known orbital inclination. Measuring planet mass is critical to understanding atmospheric dynamics and escape under extreme stellar irradiation. Here we present the ultrahot Jupiter system KELT-9 as a double-lined spectroscopic binary. This allows us to directly and empirically constrain the mass of the star and its planetary companion without reference to any theoretical stellar evolutionary models or empirical stellar scaling relations. Using data from the PEPSI, HARPS-N, and TRES spectrographs across multiple epochs, we apply least-squares deconvolution to measure out-of-transit stellar radial velocities. With the PEPSI and HARPS-N data sets, we measure in-transit planet radial velocities using transmission spectroscopy. By fitting the circular orbital solution that captures these Keplerian motions, we recover a planetary dynamical mass of 2.17 ± 0.56 M J and stellar dynamical mass of 2.11 ± 0.78 M o˙, both of which agree with the discovery paper. Furthermore, we argue that this system, as well as systems like it, are highly overconstrained, providing multiple independent avenues for empirically cross-validating model-independent solutions to the system parameters. We also discuss the implications of this revised mass for studies of atmospheric escape.