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1. GJ 3929: High-precision Photometric and Doppler Characterization of an Exo-Venus and Its Hot, Mini-Neptune-mass Companion

   https://doi.org/10.3847/1538-4357/ac8480  

   Beard, Corey ; Robertson, Paul ; Kanodia, Shubham ; Lubin, Jack ; Cañas, Caleb I. ; Gupta, Arvind F. ; Holcomb, Rae ; Jones, Sinclaire ; Libby-Roberts, Jessica E. ; Lin, Andrea S. J. ; et al ( August 2022 , The Astrophysical Journal)

   We detail the follow-up and characterization of a transiting exo-Venus identified by TESS, GJ 3929b (TOI-2013b), and its nontransiting companion planet, GJ 3929c (TOI-2013c). GJ 3929b is an Earth-sized exoplanet in its star’s Venus zone (P_b= 2.616272 ± 0.000005 days; S_b=${17.3}_{-0.7}^{+0.8}$S_⊕) orbiting a nearby M dwarf. GJ 3929c is most likely a nontransiting sub-Neptune. Using the new, ultraprecise NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak National Observatory, we are able to modify the mass constraints of planet b reported in previous works and consequently improve the significance of the mass measurement to almost 4σconfidence (M_b= 1.75 ± 0.45M_⊕). We further adjust the orbital period of planet c from its alias at 14.30 ± 0.03 days to the likely true period of 15.04 ± 0.03 days, and we adjust its minimum mass to$m\sin i$= 5.71 ± 0.92M_⊕. Using the diffuser-assisted ARCTIC imager on the ARC 3.5 m telescope at Apache Point Observatory, in addition to publicly available TESS and LCOGT photometry, we are able to constrain the radius of planet b toR_p= 1.09 ± 0.04R_⊕. GJ 3929b is a top candidate for transmission spectroscopy in its size regime (TSM = 14more »± 4), and future atmospheric studies of GJ 3929b stand to shed light on the nature of small planets orbiting M dwarfs.

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2. Stellar Companions to TESS Objects of Interest: A Test of Planet–Companion Alignment

   https://doi.org/10.3847/1538-3881/ac53a7  

   Behmard, Aida ; Dai, Fei ; Howard, Andrew W. ( March 2022 , The Astronomical Journal)

   We present a catalog of stellar companions to host stars of Transiting Exoplanet Survey Satellite Objects of Interest (TOIs) identified from a marginalized likelihood ratio test that incorporates astrometric data from the Gaia Early Data Release 3 catalog (EDR3). The likelihood ratio is computed using a probabilistic model that incorporates parallax and proper-motion covariances and marginalizes the distances and 3D velocities of stars in order to identify comoving stellar pairs. We find 172 comoving companions to 170 non-false-positive TOI hosts, consisting of 168 systems with two stars and 2 systems with three stars. Among the 170 TOI hosts, 54 harbor confirmed planets that span a wide range of system architectures. We conduct an investigation of the mutual inclinations between the stellar companion and planetary orbits using Gaia EDR3, which is possible because transiting exoplanets must orbit within the line of sight; thus, stellar companion kinematics can constrain mutual inclinations. While the statistical significance of the current sample is weak, we find that${73}_{-20}^{+14}\%$of systems with Kepler-like architectures (R_P≤ 4R_⊕anda< 1 au) appear to favor a nonisotropic orientation between the planetary and companion orbits with a typical mutual inclinationαof 35° ± 24°. In contrast,${65}_{-35}^{+20}$% ofmore »systems with close-in giants (P< 10 days andR_P> 4R_⊕) favor a perpendicular geometry (α= 89° ± 21°) between the planet and companion. Moreover, the close-in giants with large stellar obliquities (planet–host misalignment) are also those that favor significant planet–companion misalignment.

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3. NEID Reveals That the Young Warm Neptune TOI-2076 b Has a Low Obliquity

   https://doi.org/10.3847/2041-8213/acba18  

   Frazier, Robert C. ; Stefánsson, Gudmundur ; Mahadevan, Suvrath ; Yee, Samuel W. ; Cañas, Caleb I. ; Winn, Joshua N. ; Luhn, Jacob ; Dai, Fei ; Doyle, Lauren ; Cegla, Heather ; et al ( February 2023 , The Astrophysical Journal Letters)

   TOI-2076 b is a sub-Neptune-sized planet (R= 2.39 ± 0.10R_⊕) that transits a young (204 ± 50 MYr) bright (V= 9.2) K-dwarf hosting a system of three transiting planets. Using spectroscopic observations obtained with the NEID spectrograph on the WIYN 3.5 m Telescope, we model the Rossiter–McLaughlin effect of TOI-2076 b, and derive a sky-projected obliquity of$\lambda =-3_{-15}^{+16°}$. Using the size of the star (R= 0.775 ± 0.015R_⊙), and the stellar rotation period (P_rot= 7.27 ± 0.23 days), we estimate an obliquity of$\psi ={18}_{-9}^{+10°}$(ψ< 34° at 95% confidence), demonstrating that TOI-2076 b is in a well-aligned orbit. Simultaneous diffuser-assisted photometry from the 3.5 m telescope at Apache Point Observatory rules out flares during the transit. TOI-2076 b joins a small but growing sample of young planets in compact multi-planet systems with well-aligned orbits, and is the fourth planet with an age ≲300 Myr in a multi-transiting system with an obliquity measurement. The low obliquity of TOI-2076 b and the presence of transit timing variations in the system suggest the TOI-2076 system likely formed via convergent disk migration in an initially well-aligned disk.
4. The Warm Neptune GJ 3470b Has a Polar Orbit

   https://doi.org/10.3847/2041-8213/ac6e3c  

   Stefànsson, Guđmundur ; Mahadevan, Suvrath ; Petrovich, Cristobal ; Winn, Joshua N. ; Kanodia, Shubham ; Millholland, Sarah C. ; Maney, Marissa ; Cañas, Caleb I. ; Wisniewski, John ; Robertson, Paul ; et al ( May 2022 , The Astrophysical Journal Letters)

   The warm Neptune GJ 3470b transits a nearby (d= 29 pc) bright slowly rotating M1.5-dwarf star. Using spectroscopic observations during two transits with the newly commissioned NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak Observatory, we model the classical Rossiter–McLaughlin effect, yielding a sky-projected obliquity of$\lambda ={98}_{-12}^{+15◦}$and a$v\sin i={0.85}_{-0.33}^{+0.27}\mathrm{km}{\mathrm{s}}^{-1}$. Leveraging information about the rotation period and size of the host star, our analysis yields a true obliquity of$\psi ={95}_{-8}^{+9◦}$, revealing that GJ 3470b is on a polar orbit. Using radial velocities from HIRES, HARPS, and the Habitable-zone Planet Finder, we show that the data are compatible with a long-term radial velocity (RV) slope of$\dot{\gamma }=-0.0022\pm 0.0011\mathrm{m}{\mathrm{s}}^{-1}{\mathrm{day}}^{-1}$over a baseline of 12.9 yr. If the RV slope is due to acceleration from another companion in the system, we show that such a companion is capable of explaining the polar and mildly eccentric orbit of GJ 3470b using two different secular excitation models. The existence of an outer companion can be further constrained with additional RV observations, Gaia astrometry, and future high-contrast imaging observations. Lastly, we show that tidal heating frommore »GJ 3470b’s mild eccentricity has most likely inflated the radius of GJ 3470b by a factor of ∼1.5–1.7, which could help account for its evaporating atmosphere.

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5. A Tendency Toward Alignment in Single-star Warm-Jupiter Systems

   https://doi.org/10.3847/1538-3881/ac8153  

   Rice, Malena ; Wang, Songhu ; Wang, Xian-Yu ; Stefánsson, Guđmundur ; Isaacson, Howard ; Howard, Andrew W. ; Logsdon, Sarah E. ; Schweiker, Heidi ; Dai, Fei ; Brinkman, Casey ; et al ( August 2022 , The Astronomical Journal)

   The distribution of spin–orbit angles for systems with wide-separation, tidally detached exoplanets offers a unique constraint on the prevalence of dynamically violent planetary evolution histories. Tidally detached planets provide a relatively unbiased view of the primordial stellar obliquity distribution, as they cannot tidally realign within the system lifetime. We present the third result from our Stellar Obliquities in Long-period Exoplanet Systems (SOLES) survey: a measurement of the Rossiter–McLaughlin effect across two transits of the tidally detached warm Jupiter TOI-1478 b with the WIYN/NEID and Keck/HIRES spectrographs, revealing a sky-projected spin–orbit angle$\lambda ={6.2}_{-5.5}^{+5.9}°$. Combining this new measurement with the full set of archival obliquity measurements, including two previous constraints from the SOLES survey, we demonstrate that, in single-star systems, tidally detached warm Jupiters are preferentially more aligned than closer-orbiting hot Jupiters. This finding has two key implications: (1) planets in single-star systems tend to form within aligned protoplanetary disks, and (2) warm Jupiters form more quiescently than hot Jupiters, which, in single-star systems, are likely perturbed into a misaligned state through planet–planet interactions in the post-disk-dispersal phase. We also find that lower-mass Saturns span a wide range of spin–orbit angles, suggesting a prevalence of planet–planet scattering and/or secularmore »mechanisms in these systems.

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