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- ItemNo further evidence for a transiting inner companion to the hot Jupiter HATS-50b(Berlin : Wiley-VCH Verl., 2019) Mallonn, MatthiasMost hot Jupiter exoplanets do not have a nearby planetary companion in their planetary system. One remarkable exception is the system of WASP-47 with an inner and outer nearby companion to a hot Jupiter, providing detailed constraints on its formation history. In this work, we follow up on a tentative photometric signal of a transiting inner companion to the hot Jupiter HATS-50 b. If confirmed, it would be the third case of a hot Jupiter with an inner companion. Sixty three hours of new ground-based photometry were employed to rule out this signal to about 96% confidence. The injection of artificial transit signals showed the data to be of sufficient quality to reveal the potential photometric feature at high significance. However, no transit signal was found. The discrete pattern of observing blocks leaves a slight chance that the transit was missed.
- 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.