The production of Neptune-like planets with orbital periods of 3–6 days is challenging for conventional models of high-eccentricity migration. We present the discovery and characterization of TOI-2195 A b, an inflated hot Neptune (P = 4.16 days, m_p= 1.46M_ Nep, R_p = 0.79R_ J) orbiting an early K-type star with a wide binary companion at ∼ 600 au. Detection of the Rossiter-McLaughlin effect at ∼2.6σ confidence with Magellan/PFS reveals the planet is likely on a near-polar orbit with a sky-projected stellar obliquity λ= 109^+35_-53 ^∘. We perform coupled dynamical and structural modeling that reproduces the observed characteristics of the system. We show that the planet may have originated as a cold, Jovian planet that was excited to high eccentricities via the stellar Eccentric Kozai-Lidov (EKL) mechanism, where it lost up to ∼90% of its mass via Roche lobe overflow during close periastron passages, enabling rapid tidal migration and radius inflation due to tidal heating. TOI-2195 A b provides a test for planetary migration theories, and our simulations suggest that puffy hot Neptunes originated as more massive Jovians that underwent mass loss during high-eccentricity migration.

The radii of small exoplanets form two populations, super-Earths and sub-Neptunes, separated by a gap known as the radius valley. This feature could be produced by the removal of atmospheres by stellar or internal heating or by the lack of an initial envelope. We used transit photometry and radial velocity measurements to detect and characterize four exoplanets orbiting LHS 1903, a red dwarf star in the Milky Way's thick disk. These four planets have orbital periods ranging from 2.2 to 29.3 days and span the radius valley within a single planetary system. The derived densities indicate that LHS 1903 b is rocky, whereas LHS 1903 c and LHS 1903 d have extended atmospheres. The most distant planet from the host star, LHS 1903 e, has no gaseous envelope, indicating that it formed from gas-depleted material.

Interest in discovering the cosmic Dark Ages signal is higher than ever, with the Astro2020 Decadal Survey naming it as the cosmological discovery area of the decade. In response to this call to action, the Lunar Surface Electromagnetics Experiment (LuSEE-Night) was designed with the Dark Ages in mind (Bale, et al., “LuSEE ‘Night’: The Lunar Surface Electromagnetics Experiment”, URSI GASS, Jan. 2023). As a low frequency radio telescope, LuSEE-Night is best utilized outside the ionosphere in an area with very low radio frequency interference (RFI), and the far side of the Moon fits this requirement very well. Our work seeks to maximize the prospect of detecting this low frequency 21 cm signal from the Dark Ages by using high fidelity simulations as a tool to better understand and account for instrument and environmental systematics. We can also use these simulated data to develop more robust methods of extracting low intensity signals from far brighter backgrounds.

Studying planetary interactions in exoplanet systems informs theories of planet formation and evolution, providing essential context for understanding our own solar system. We combine spectroscopy, transit photometry, transit timing variations, and astrometry to characterize the TOI-201 system. The cotransiting system consists of a super-Earth, warm Jupiter, and massive companion at 5.8-, 53-, and 2900-day orbital periods, respectively. We perform dynamical simulations to study the past and future of the system. von-Zeipel-Kozai-Lidov oscillations emerge as the most plausible scenario to explain the outer companion's high orbital eccentricity, with planet-planet scattering a possible but less likely contender. Because of nonzero mutual inclinations between the planets, the system is visibly evolving on very short timescales, with the current cotransiting configuration ending in 200 years.

Radio wave Observations on the Lunar Surface of the photo-Electron Sheath (ROLSES-1) instrument on board Intuitive Machines’ Odysseus lunar lander represents NASA’s first radio telescope on the Moon, and the first United States spacecraft landing on the lunar surface in five decades. Despite a host of challenges, ROLSES-1 managed to collect a small amount of data over fractions of 1 day during cruise phase and 2 days on the lunar surface with four monopole Stacer antennas that were in a nonideal deployment. All antennas recorded shortwave radio transmissions breaking through the Earth’s ionosphere—or terrestrial technosignatures—from spectral and raw waveform data. These technosignatures appear to be modulated by density fluctuations in the Earth’s ionosphere and could be used as markers when searching for extraterrestrial intelligence from habitable exoplanets. After data reduction and marshalling a host of statistical and sampling techniques, 5 minutes of raw waveforms from the least noisy antenna were used to generate covariances constraining both the antenna parameters and the amplitude of the low-frequency isotropic Galactic spectrum. ROLSES-2 and LuSEE-Night, both lunar radio telescopes launching later in the decade, will have significant upgrades from ROLSES-1 and will be set to take unprecedented measurements of the low-frequency sky, lunar surface, and constrain the cosmological 21 cm signal. ROLSES-1 represents a trailblazer for lunar radio telescopes, and many of the statistical tools and data reduction techniques presented in this work will be useful for upcoming lunar radio telescope missions.

We report the discovery of a sub-Neptune and a Neptune-like planet (R (b)=2.48(-0.10)(+0.14) R (circle plus), R (c)=4.03(-0.15)(+0.23 )R (circle plus)) orbiting the F-type star TOI-4495. The planets have orbital periods of 2.567 and 5.185 days, lying close to a 2:1 mean-motion resonance (MMR). Our photodynamical analysis of the TESS light curves constrains the planetary masses to M (b) = 7.7 +/- 1.4 M (circle plus)and M (c) = 23.2 +/- 4.7 M (circle plus). The measured masses and radii indicate the presence of volatile-rich gaseous envelopes on both planets. The Rossiter-McLaughlin effect and the Doppler shadow of TOI-4495 c reveal a well-aligned orbit with a projected stellar obliquity of lambda=-2.3(-7.8)(+8.3)degrees . Combined with the low mutual inclination constrained by the photodynamical analysis (Delta I < 8.7 degrees), the planetary orbits are likely coplanar and aligned with the host star's spin axis. We show that the planets are near, but not in, the 2:1 MMR, with a circulating resonant angle. We also find substantial free eccentricity for the inner planet, TOI-4495 b ( e(b)=0.078(-0.013)(+0.02) ). Given the observed proximity to the 2:1 resonance and the more massive outer planet, TOI-4495 b and c are particularly susceptible to resonant overstability, which in turn can explain the observed eccentricity by converting resonantly excited eccentricity into free eccentricity. However, additional mechanisms (e.g., planetesimal scattering) may be required to further excite the eccentricity by similar to 4%. To prevent tidal damping from reducing the eccentricity below the observed level over the star's lifetime (1.9 Gyr), the reduced tidal quality factor of TOI-4495 b must be Q 'greater than or similar to 10(5) , consistent with the presence of a thick envelope on the planet.

LuSEE-Night is a pathfinder radio telescope on the lunar far side employing four 3-m monopole antennas arranged as two horizontal cross pseudo-dipoles on a rotational stage and sensitive to the radio sky in the 1-50 MHz frequency band. LuSEE-Night measures the corresponding 16 correlation products as a function of frequency. While each antenna combination measures radiation coming from a large area of the sky, their aggregate information as a function of phase in the lunar cycle and rotational stage position can be deconvolved into a low-resolution map of the sky. We study this deconvolution using linear map-making based on the Wiener filter algorithm. We illustrate how systematic effects can be effectively marginalised over as contributions to the noise covariance and demonstrate this technique on beam knowledge uncertainty and gain fluctuations. With reasonable assumptions about instrument performance, we show that LuSEE-Night should be able to map the sub-50 MHz sky at a ~5-degree resolution.

The Lunar Surface Electromagnetics Experiment (LuSEE-Night) is a joint NASA-DOE-ESA low-frequency radio telescope that will reach the lunar far side in 2027. The unknown dielectric properties of the subsurface at the LuSEE-Night landing site impose the most significant limitation for precision instrument calibration, as reflections from the lunar subsurface can change the primary beam at the 10-20

Exoplanets with and without a magnetic field are predicted to form, behave, and evolve very differently. Therefore, there is great need to directly constrain these fields to holistically understand the properties of exoplanets including their potential habitability. This goal aligns with the Astro2020 Decadal Survey recommendations. Observing planetary auroral radio emissions is among the most promising detection methods, but decades of searching have yet to yield a conclusive detection, though promising hints are now emerging from ground-based radio telescopes. However, these ground-based efforts are fundamentally limited by Earth's ionosphere, which blocks the low-frequency signals (<10 MHz) expected from terrestrial and Neptune-like exoplanets. In this white paper, we outline a strategy to overcome this barrier by utilizing the unique environment of the Moon. We discuss how the upcoming LuSEE-Night and ROLSES pathfinder missions will study our Solar System's planets as exoplanet analogs and place the first meaningful upper limits on exoplanetary radio flux below 10 MHz. Furthermore, we explore the revolutionary potential of the proposed future lunar arrays FarView and FARSIDE. For example, FarView will be sensitive enough to study the magnetic fields of a diverse set of exoplanets (super-Earths to gas giants) and an order of magnitude more Jupiter-like planets than ground-based telescopes, providing crucial tests for dynamo theory. Most significantly, FARSIDE will be able to detect the magnetospheres of nearby terrestrial exoplanets, offering a powerful synergy with atmospheric characterization efforts by JWST and HWO to fully assess their potential habitability. By opening this unexplored low-frequency window, radio astronomy from the Moon is poised to transform the field of exoplanet magnetospheric science. [Abridged]

The NASA/DOE LuSEE Night experiment (Bale et al. (2023), arXiv:2301.10345) will be deployed on the lunar farside in early 2026 to make full-Stokes spectral measurements of the radio sky below 50 MHz using a simple crossed-dipole antenna system. LuSEE Night will be a pathfinder for future farside observatories, demonstrating many of the (quite ambitious) technologies required to make synoptic, radio quiet measurements throughout the lunar night. Additionally, a second experiment LuSEE Lite will make direct measurements of the DC electric field on the lunar surface which is thought to be a controlling factor for the electrostatic dust levitation which gave rise to the lunar ‘horizon glow’ observed by the Apollo astronauts.

We present the discovery of TOI-7041 b (TIC 201175570 b), a hot Saturn transiting a red giant star with measurable stellar oscillations. We observe solar-like oscillations in TOI-7041 with a frequency of maximum power of nu max=218.50 +/- 2.23 mu Hz and a large frequency separation of Delta nu = 16.5282 +/- 0.0186 mu Hz. Our asteroseismic analysis indicates that TOI-7041 has a mass of 1.07 +/- 0.05(stat) +/- 0.02(sys) M-circle dot and a radius of 4.10 +/- 0.06(stat) +/- 0.05(sys) R-circle dot, making it one of the largest stars around which a transiting planet has been discovered with the Transiting Exoplanet Survey Satellite (TESS), and the mission's first oscillating red giant with a transiting planet. TOI-7041 b has an orbital period of 9.691 +/- 0.006 days and a low eccentricity of e = 0.04 +/- 0.04. We measure a planet radius of 1.02 +/- 0.03 R-Jup with TESS photometry, and a planet mass of 0.36 +/- 0.16 M-Jup (114 +/- 51 M-circle plus) with ground-based radial velocity measurements. TOI-7041 b appears less inflated than similar systems receiving equivalent incident flux, and its circular orbit indicates that it is not undergoing tidal heating due to circularization. The asteroseismic analysis of the host star provides some of the tightest constraints on the stellar properties of a TESS planet host and enables precise characterization of the hot Saturn. This system joins a small number of TESS-discovered exoplanets orbiting stars that exhibit clear stellar oscillations and indicates that extended TESS observations of evolved stars will similarly provide a path to improved exoplanet characterization.

The Lunar Surface Electromagnetics Explorer at Night (LuSEE-Night) experiment will reach the lunar farside in 2026 to observe the sky in frequencies between 0.1 and 50 MHz. The radio sky below 20 MHz is largely unexplored, since the ionosphere blocks ground-based observations. LuSEE-Night will observe these new skies from a site remarkably isolated from terrestrial radio interference.

TOI-2015 is a known exoplanetary system around an M4 dwarf star, consisting of a transiting sub-Neptune planet in a 3.35-day orbital period, TOI-2015b, accompanied by a non-transiting companion, TOI-2015c. High-precision RV measurements were taken with the MAROON-X spectrograph, and high-precision photometric data were collected several networks. We re-characterize the target star by combining optical spectr, Bayesian Model Averaging (BMA) and Spectral Energy Distribution (SED) analysis. The TOI-2015 host star is a K=10.3mag M4-type dwarf with a sub-solar metallicity of [Fe/H]=-0.31+/-0.16, and a Teff=3200K. Our photodynamical analysis of the system strongly favors the 5:3 mean motion resonance and in this scenario the planet b has an orbital period of 3.34days, a mass of Mp=9.02+/-0.34Me, a radius of Rp=3.309+/-0.012Re, resulting in a density of rhop= 1.40+/-0.06g/cm3, indicative of a Neptune like composition. Its transits exhibit large (>1hr) timing variations indicative of an outer perturber in the system. We performed a global analysis of the high-resolution RV measurements, the photometric data, and the TTVs, and inferred that TOI-2015 hosts a second planet, TOI-2015c, in a non-transiting configuration. TOI-2015c has an orbital period of Pc=5.583days and a mass of Mp=8.91+0.38-0.40Me. The dynamical configuration of TOI-2015b and TOI-2015c can be used to constrain the system's planetary formation and migration history. Based on the mass-radius composition models, TOI-2015b is a water-rich or rocky planet with a hydrogen-helium envelope. Moreover, TOI-2015b has a high transmission spectroscopic metric (TSM=149), making it a favorable target for future transmission spectroscopic observations with JWST to constrain the atmospheric composition of the planet. Such observations would also help to break the degeneracies in theoretical models of the planet's interior structure.

We report the delivery to the Mikulski Archive for Space Telescopes (MAST) of tables containing Root Mean Square (RMS) Combined Differential Photometric Precision (CDPP) values for all TESS 2-min cadence targets with Science Processing Operations Center (SPOC) light curves in Sectors 1-90. Each comma-separated values (CSV) file contains CDPP values for all 2-min light curves in the given sector. The tables include robust RMS CDPP values for the 15 trial transit pulse durations searched in the SPOC 2-min processing pipeline, ranging from 0.5-15.0 hr. For each pulse duration, CDPP is computed in the transit search for a trial transit centered on every cadence. The RMS value of the CDPP time series is a metric that may be employed to estimate signal-to-noise ratio for transits with the given duration and a specified depth. We will continue to deliver the RMS CDPP tables to MAST for each observing sector.

Context. GJ 581 is a nearby M dwarf known to host a packed multiple planet system composed of two super-Earths and a Neptune-mass planet. We present new orbital analyses of the GJ 581 system, utilizing recent radial velocity (RV) data obtained from the CARMENES spectrograph combined with newly reprocessed archival data from the HARPS and HIRES spectrographs. Aims. Our aim was to analyze the post-discovery spectroscopic data of GJ581, which were obtained with CARMENES. In addition, we used publicly available HIRES and HARPS spectroscopic data to seek evidence of the known and disputed exoplanets in this system. We aimed to investigate the stellar activity of GJ 581 and update the planetary system's orbital parameters using state-of-the-art numerical models and techniques. Methods. We performed a periodogram analysis of the available precise CARMENES, HIRES, and HARPS RVs and of stellar activity indicators. We conducted detailed orbital analyses by testing various orbital configurations consistent with the RV data. We studied the posterior probability distribution of the parameters fit to the data and we explored the long-term stability and overall orbital dynamics of the GJ 581 system. Results. We refined the orbital parameters of the GJ 581 system using the most precise and complete set of Doppler data available. Consistent with the existing literature, our analysis confirms that the system is unequivocally composed of only three planets detectable in the present data, dismissing the putative planet GJ 581 d as an artifact of stellar activity. Our N-body fit reveals that the system's inclination is i = 47.0(-13.0)(+14.6) deg, which implies that the planets could be up to 30% more massive than their previously reported minimum masses. Furthermore, we report that the GJ 581 system exhibits long-term stability, as indicated by the posterior probability distribution, characterized by secular dynamical interactions without the involvement of mean motion resonances.

Neural network (NN) emulators of the global 21 cm signal need an emulation error much less than the observational noise in order to be used to perform unbiased Bayesian parameter inference. To this end, we introduce 21cmLSTM-a long short-term memory (LSTM) NN emulator of the global 21 cm signal that leverages the intrinsic correlation between frequency channels to achieve exceptional accuracy compared to previous emulators, which are all feedforward, fully connected NNs. LSTM NNs are a type of recurrent NN designed to capture long-term dependencies in sequential data. When trained and tested on the same simulated set of global 21 cm signals as the best previous emulators, 21cmLSTM has an average relative rms error of 0.22%-equivalently 0.39 mK-and comparably fast evaluation time. We perform seven-dimensional Bayesian parameter estimation analyses using 21cmLSTM to fit global 21 cm signal mock data with different adopted observational noise levels, sigma 21. The posterior 1 sigma rms error is approximate to three times less than sigma 21 for each fit and consistently decreases for tighter noise levels, showing that 21cmLSTM can sufficiently exploit even very optimistic measurements of the global 21 cm signal. We have made the emulator, code, and data sets publicly available so that 21cmLSTM can be independently tested and used to retrain and constrain other 21 cm models.

ABSTRACT We report the discovery of the most eccentric transiting brown dwarf in the brown dwarf desert, TOI-2490b. The brown dwarf desert is the lack of brown dwarfs around main-sequence stars within $\sim 3$ au and is thought to be caused by differences in formation mechanisms between a star and planet. To date, only $\sim 40$ transiting brown dwarfs have been confirmed. TOI-2490b is a $73.6\pm 2.4$ $M_{\rm J}$, $1.00\pm 0.02$ $R_{\rm J}$ brown dwarf orbiting a $1.004_{-0.022}^{+0.031}$ ${\rm M}_{\odot }$, $1.105_{-0.012}^{+0.012}$ ${\rm R}_{\odot }$ sun-like star on a 60.33 d orbit with an eccentricity of $0.77989\pm 0.00049$. The discovery was detected within Transiting Exoplanet Survey Satellite sectors 5 (30 min cadence) and 32 (2 min and 20 s cadence). It was then confirmed with 31 radial velocity measurements with FEROS by the WINE collaboration and photometric observations with the Next Generation Transit Survey. Stellar modelling of the host star estimates an age of $\sim 8$ Gyr, which is supported by estimations from kinematics likely placing the object within the thin disc. However, this is not consistent with model brown dwarf isochrones for the system age suggesting an inflated radius. Only one other transiting brown dwarf with an eccentricity higher than 0.6 is currently known in the brown dwarf desert. Demographic studies of brown dwarfs have suggested such high eccentricity is indicative of stellar formation mechanisms.

The stellar obliquity distribution of warm-Jupiter systems is crucial for constraining the dynamical history of Jovian exoplanets, as the warm Jupiters' tidal detachment likely preserves their primordial obliquity. However, the sample size of warm-Jupiter systems with measured stellar obliquities has historically been limited compared to that of hot Jupiters, particularly in hot-star systems. In this work, we present newly obtained sky-projected stellar obliquity measurements for the warm-Jupiter systems TOI-559, TOI-2025, TOI-2031, TOI-2485, TOI-2524, and TOI-3972, derived from the Rossiter-McLaughlin effect, and show that all six systems display alignment with a median measurement uncertainty of 13 degrees. Combining these new measurements with the set of previously reported stellar obliquity measurements, our analysis reveals that single-star warm-Jupiter systems tend to be aligned, even around hot stellar hosts. This alignment exhibits a 3.4 sigma deviation from the T eff-lambda dependency observed in hot-Jupiter systems, where planets around cool stars tend to be aligned, while those orbiting hot stars show considerable misalignment. The current distribution of spin-orbit measurements for Jovian exoplanets indicates that misalignments are neither universal nor primordial phenomena affecting all types of planets. The absence of misalignments in single-star warm-Jupiter systems further implies that many hot Jupiters, by contrast, have experienced a dynamically violent history.

In 21 cm experimental cosmology, accurate characterization of a radio telescope's antenna beam response is essential to measure the 21 cm signal. Computational electromagnetic (CEM) simulations estimate the antenna beam pattern and frequency response by subjecting the EM model to different dependencies, or beam hyperparameters, such as soil dielectric constant or orientation with the environment. However, it is computationally expensive to search all possible parameter spaces to optimize the antenna design or accurately represent the beam to the level required for use as a systematic model in 21 cm cosmology. We therefore present the Model for Emulating Directivities and Electric fields of Antennas (MEDEA), an emulator that rapidly and accurately generates far-field radiation patterns over a large hyperparameter space. MEDEA takes a subset of beams simulated by CEM software, spatially decomposes them into coefficients on a complete, linear basis, and then interpolates them to form new beams at arbitrary hyperparameters. We test MEDEA on an analytical dipole and two numerical beams motivated by upcoming lunar lander missions, and then employ MEDEA as a model to fit mock radio spectrometer data to extract covariances on the input beam hyperparameters. We find that the interpolated beams have rms relative errors of at most 10-2 using 20 input beams or less, and that fits to mock data are able to recover the input beam hyperparameters when the model and mock are derived from the same set of beams. When a systematic bias is introduced into the mock data, extracted beam hyperparameters exhibit bias, as expected. We propose several extensions to MEDEA to potentially account for such bias.

Neural network (NN) emulators of the global 21 cm signal need emulation error much less than the observational noise in order to be used to perform unbiased Bayesian parameter inference. To this end, we introduce – a long short-term memory (LSTM) NN emulator of the global 21 cm signal that leverages the intrinsic correlation between frequency channels to achieve exceptional accuracy compared to previous emulators, which are all feedforward, fully connected NNs. LSTM NNs are a type of recurrent NN designed to capture long-term dependencies in sequential data. When trained and tested on the same simulated set of global 21 cm signals as the best previous emulators, has average relative rms error of 0.22 0.39 mK – and comparably fast evaluation time. We perform seven-dimensional Bayesian parameter estimation analyses using to fit global 21 cm signal mock data with different adopted observational noise levels, σ_21. The posterior 1σ rms error is ≈3× less than σ_21 for each fit and consistently decreases for tighter noise levels, showing that can sufficiently exploit even very optimistic measurements of the global 21 cm signal. We made the emulator, code, and data sets publicly available so that can be independently tested and used to retrain and constrain other 21 cm models.