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1. TESS Reveals HD 118203 b to be a Transiting Planet

   https://doi.org/10.3847/1538-3881/ab84f2  

   Pepper, Joshua ; Kane, Stephen R. ; Rodriguez, Joseph E. ; Hinkel, Natalie R. ; Eastman, Jason D. ; Daylan, Tansu ; Mocnik, Teo ; Dalba, Paul A. ; Gaudi, B. Scott ; Fetherolf, Tara ; et al ( June 2020 , The Astronomical Journal)
2. Improved Orbital Constraints and Hα Photometric Monitoring of the Directly Imaged Protoplanet Analog HD 142527 B

   https://doi.org/10.3847/1538-3881/ac73f4  

   Balmer, William O. ; Follette, Katherine B. ; Close, Laird M. ; Males, Jared R. ; De Rosa, Robert J. ; Adams Redai, Jéa I. ; Watson, Alex ; Weinberger, Alycia J. ; Morzinski, Katie M. ; Morales, Julio ; et al ( July 2022 , The Astronomical Journal)

   Companions embedded in the cavities of transitional circumstellar disks have been observed to exhibit excess luminosity at Hα, an indication that they are actively accreting. We report 5 yr (2013–2018) of monitoring of the position and Hαexcess luminosity of the embedded, accreting low-mass stellar companion HD 142527 B from the MagAO/VisAO instrument. We usepyklip, a Python implementation of the Karhunen–Loeve Image Processing algorithm, to detect the companion. Usingpyklipforward modeling, we constrain the relative astrometry to 1–2 mas precision and achieve sufficient photometric precision (±0.2 mag, 3% error) to detect changes in the Hαcontrast of the companion over time. In order to accurately determine the relative astrometry of the companion, we conduct an astrometric calibration of the MagAO/VisAO camera against 20 yr of Keck/NIRC2 images of the Trapezium cluster. We demonstrate agreement of our VisAO astrometry with other published positions for HD 142527 B, and useorbitize!to generate a posterior distribution of orbits fit to the relative astrometry of HD 142527 B. Our data suggest that the companion is close to periastron passage, on an orbit significantly misaligned with respect to both the wide circumbinary disk and the recently observed inner disk encircling HD 142527 A. We translate observed Hαcontrasts formore »HD 142527 B into mass accretion rate estimates on the order of 4–9 × 10⁻¹⁰M_⊙yr⁻¹. Photometric variation in the Hαexcess of the companion suggests that the accretion rate onto the companion is variable. This work represents a significant step toward observing accretion-driven variability onto protoplanets, such as PDS 70 b&c.

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3. Dynamical Mass of the Young Substellar Companion HD 984 B

   https://doi.org/10.3847/1538-3881/ac35e8  

   Franson, Kyle ; Bowler, Brendan P. ; Brandt, Timothy D. ; Dupuy, Trent J. ; Tran, Quang H. ; Brandt, G. Mirek ; Li, Yiting ; Kraus, Adam L. ( January 2022 , The Astronomical Journal)

   Model-independent masses of substellar companions are critical tools to validate models of planet and brown dwarf cooling, test their input physics, and determine the formation and evolution of these objects. In this work, we measure the dynamical mass and orbit of the young substellar companion HD 984 B. We obtained new high-contrast imaging of the HD 984 system with Keck/NIRC2 that expands the baseline of relative astrometry from 3 to 8 yr. We also present new radial velocities of the host star with the Habitable-Zone Planet Finder spectrograph at the Hobby-Eberly Telescope. Furthermore, HD 984 exhibits a significant proper motion difference between Hipparcos and Gaia EDR3. Our joint orbit fit of the relative astrometry, proper motions, and radial velocities yields a dynamical mass of 61 ± 4M_Jupfor HD 984 B, placing the companion firmly in the brown dwarf regime. The new fit also reveals a higher eccentricity for the companion (e= 0.76 ± 0.05) compared to previous orbit fits. Given the broad age constraint for HD 984, this mass is consistent with predictions from evolutionary models. HD 984 B’s dynamical mass places it among a small but growing list of giant planet and brown dwarf companions with direct massmore »measurements.

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4. Independent Validation of the Temperate Super-Earth HD 79211 b using HARPS-N

   https://doi.org/10.3847/1538-3881/ac9ccd  

   DiTomasso, Victoria ; Nava, Chantanelle ; López-Morales, Mercedes ; Bieryla, Allyson ; Cloutier, Ryan ; Malavolta, Luca ; Mortier, Annelies ; Buchhave, Lars A. ; Stassun, Keivan G. ; Sozzetti, Alessandro ; et al ( January 2023 , The Astronomical Journal)

   We present high-precision radial velocities (RVs) from the HARPS-N spectrograph for HD 79210 and HD 79211, two M0V members of a gravitationally bound binary system. We detect a planet candidate with a period of${24.421}_{-0.017}^{+0.016}$days around HD 79211 in these HARPS-N RVs, validating the planet candidate originally identified in CARMENES RV data alone. Using HARPS-N, CARMENES, and RVs spanning a total of 25 yr, we further refine the planet candidate parameters toP= 24.422 ± 0.014 days,K= 3.19 ± 0.27 m s⁻¹,Msini= 10.6 ± 1.2M_⊕, anda= 0.142 ± 0.005 au. We do not find any additional planet candidate signals in the data of HD 79211, nor do we find any planet candidate signals in HD 79210. This system adds to the number of exoplanets detected in binaries with M-dwarf members and serves as a case study for planet formation in stellar binaries.
5. Obliquity Constraints on the Planetary-mass Companion HD 106906 b

   https://doi.org/10.3847/1538-3881/ac1bb1  

   Bryan, Marta L. ; Chiang, Eugene ; Morley, Caroline V. ; Mace, Gregory N. ; Bowler, Brendan P. ( October 2021 , The Astronomical Journal)