Schmidt Sciences
This paper presents Internal Coherence Maximization (ICM), an unsupervised algorithm for fine-tuning language models by having them generate and refine their own labels based on internal consistency and mutual predictability. The research demonstrates that this method can match or surpass human supervision on various tasks, including the successful training of a production-scale Claude 3.5 Haiku assistant that performs competitively against its human-supervised counterpart.
Rapidly improving AI capabilities and autonomy hold significant promise of transformation, but are also driving vigorous debate on how to ensure that AI is safe, i.e., trustworthy, reliable, and secure. Building a trusted ecosystem is therefore essential -- it helps people embrace AI with confidence and gives maximal space for innovation while avoiding backlash. The "2025 Singapore Conference on AI (SCAI): International Scientific Exchange on AI Safety" aimed to support research in this space by bringing together AI scientists across geographies to identify and synthesise research priorities in AI safety. This resulting report builds on the International AI Safety Report chaired by Yoshua Bengio and backed by 33 governments. By adopting a defence-in-depth model, this report organises AI safety research domains into three types: challenges with creating trustworthy AI systems (Development), challenges with evaluating their risks (Assessment), and challenges with monitoring and intervening after deployment (Control).
We present results from a systematic search for transiting short-period Giant Exoplanets around M-dwarf Stars (GEMS; P < 10 days, Rp8 RR_p \gtrsim 8~R_\oplus) within a distance-limited 100\,pc sample of 149,316 M-dwarfs using TESS-Gaia Light Curve (TGLC) data. This search led to the discovery of one new candidate GEM, following spectroscopic vetting of 12 additional candidates to eliminate astrophysical false positives and refine our occurrence rate estimates. We describe the development and application of the \texttt{TESS-miner} package and associated vetting procedures used in this analysis. To assess detection completeness, we conducted \sim 72 million injection-recovery tests across \sim 26,000 stars with an average of \sim3 sectors of data per star, subdivided into early-type (M0--M2.5), mid-type (M2.5--M4), and late-type (M4 or later) M-dwarfs. Our pipeline demonstrates high sensitivity across all M-dwarf subtypes within the injection bounds. We estimate the occurrence rates of short-period GEMS as a function of stellar mass, and combine our measured occurrence rates with those derived for FGK stars and fit an exponential trend with stellar mass, consistent with core-accretion theory predictions. We find GEMS occurrence rates of 0.067%±0.047%0.067\% \pm 0.047\% for early-type M-dwarfs, 0.139%±0.069%0.139\% \pm 0.069\% for mid-type, and 0.032%±0.032%0.032\% \pm 0.032\% for late-type M-dwarfs, with a mean rate of 0.0650.027+0.025%0.065^{+0.025}_{-0.027}\% across the full M-dwarf sample. We note that while our search spanned 1.0~\mathrm{days} < P < 10.0 days, these occurrence rates were calculated using planets orbiting with 1.0~\mathrm{days} < P < 5.0 days. This work lays the foundation for future occurrence rate investigations for GEMS.
We confirm the planetary nature of (1) TOI-5916 b and (2) TOI-6158 b, two Exoplanets Transiting M-dwarf Stars (GEMS), both discovered by the Transiting Exoplanet Survey Satellite (TESS). Both systems were confirmed with ground-based photometry (Red Buttes Observatory and Swope, respectively) and radial velocity data from the Habitable-zone Planet Finder. Their radii are R1=11.80.51+0.52 RR_{1}=11.8^{+0.52}_{-0.51}\text{ }R_{\oplus} and R2=10.41.11+2.70 RR_{2}=10.4^{+2.70}_{-1.11}\text{ }R_{\oplus} and masses are M1=219±28 MM_{1}=219\pm28\text{ }M_{\oplus} and M2=13518+19 MM_{2}=135^{+19}_{-18}\text{ }M_{\oplus}. Both planets have Saturn-like densities (ρ1=0.730.13+0.14g cm3\rho_{1} = 0.73^{+0.14}_{-0.13}\,\text{g cm}^{-3}, ρ2=0.660.23+0.41g cm3\rho_{2} = 0.66^{+0.41}_{-0.23}\,\text{g cm}^{-3}), which appears to be a growing trend among GEMS systems and, more generally, warm Jupiters. In confirming both of these exoplanets, we add to the growing evidence for a population of Saturn-density planets among the GEMS systems. We also find evidence for a preliminary trend in which GEMS exhibit systematically closer orbits compared to FGK giants.
Mid-infrared spectroscopy of protoplanetary disks provides a chemical inventory of gas within a few au, where planets are readily detected around older stars. With the JWST Disk Infrared Spectral Chemistry Survey (JDISCS), we explore demographic trends among 31 disks observed with MIRI (MRS) and with previous ALMA millimeter continuum imaging at high angular resolution (5-10 au). With these S/N \sim200-450 spectra, we report emission from H2_2O, OH, CO, C2_2H2_2, HCN, CO2_2, [Ne II], [Ne III], and [Ar II]. Emission from H2_2O, OH and CO is nearly ubiquitous for low-mass stars, and detection rates of all molecules are higher than for similar disks observed with Spitzer-IRS. Slab model fits to the molecular emission lines demonstrate that emission from C2_2H2_2, HCN, and possibly CO2_2 is optically thin; thus since column densities and emitting radii are degenerate, observations are actually sensitive to the total molecular mass. C2_2H2_2 and HCN emission also typically originate in a hotter region (920130+70920^{+70}_{-130}, 820130+70820^{+70}_{-130} K, respectively) than CO2_2 (600160+200600^{+200}_{-160} K). The HCN to cold H2_2O luminosity ratios are generally smaller in smooth disks, consistent with more efficient water delivery via icy pebbles in the absence of large dust substructures. The molecular emission line luminosities are also correlated with mass accretion rates and infrared spectral indices, similar to trends reported from Spitzer-IRS surveys. This work demonstrates the power of combining multi-wavelength observations to explore inner disk chemistry as a function of outer disk and stellar properties, which will continue to grow as the sample of observed Class II systems expands in the coming JWST observation cycles.
This study from the University of Pennsylvania and Penn State University introduces Order-by-Order (OBO) and Joint Keplerian (JK) modeling paradigms to leverage multi-wavelength information in exoplanet radial velocity data. These methods improved the precision of exoplanet minimum mass uncertainties by factors of 1.5 to 6.8, providing better constraints than traditional Variance-Weighted Mean approaches.
Hundreds of exoplanets between 1-1.8 times the size of the Earth have been discovered on close in orbits. However, these planets show such a diversity in densities that some appear to be made entirely of iron, while others appear to host gaseous envelopes. To test this diversity in composition, we update the masses of 5 rocky exoplanets (HD 93963 A b, Kepler-10 b, Kepler-100 b, Kepler-407 b, and TOI-1444 b) and present the confirmation of a new planet (TOI-1011) using 187 high precision RVs from Gemini/MAROON-X and Keck/KPF. Our updated planet masses suggest compositions closer to that of the Earth than previous literature values for all planets in our sample. In particular, we report that two previously identified ``super-Mercuries'' (Kepler-100 b and HD 93963 A b) have lower masses that suggest less iron-rich compositions. We then compare the ratio of iron to rock-building species to the abundance ratios of those elements in their host stars. These updated planet compositions do not suggest a steep relationship between planet and host star compositions, contradictory to previous results, and suggest that planets and host stars have similar abundance ratios.
The NEID Earth Twin Survey (NETS) has been delivering a rich set of precise radial velocity (RV) measurements for 41 bright, nearby main sequence stars. Here, we describe the status of the survey after three years on sky and we present the full set of RV measurements and accompanying stellar activity indicators. We discuss intermediate survey diagnostics, including calibration of the known RV zero point offset introduced following the Contreras fire in 2022 and the identification of an undiagnosed and previously unknown zero point offset in 2021. An analysis of our data set using RVSearch demonstrates that for these target stars, NEID is independently sensitive to nearly all known planets with periods shorter than the NETS observing baseline. We also highlight a number of newly detected RV signals, which present exciting opportunities for future investigations.
Transiting giant exoplanets around M-dwarf stars (GEMS) are rare, owing to the low-mass host stars. However, the all-sky coverage of TESS has enabled the detection of an increasingly large number of them to enable statistical surveys like the \textit{Searching for GEMS} survey. As part of this endeavour, we describe the observations of six transiting giant planets, which includes precise mass measurements for two GEMS (K2-419Ab, TOI-6034b) and statistical validation for four systems, which includes validation and mass upper limits for three of them (TOI-5218b, TOI-5616b, TOI-5634Ab), while the fourth one -- TOI-5414b is classified as a `likely planet'. Our observations include radial velocities from the Habitable-zone Planet Finder on the Hobby-Eberly Telescope, and MAROON-X on Gemini-North, along with photometry and high-contrast imaging from multiple ground-based facilities. In addition to TESS photometry, K2-419Ab was also observed and statistically validated as part of the K2 mission in Campaigns 5 and 18, which provides precise orbital and planetary constraints despite the faint host star and long orbital period of 20.4\sim 20.4 days. With an equilibrium temperature of only 380 K, K2-419Ab is one of the coolest known well-characterized transiting planets. TOI-6034 has a late F-type companion about 40\arcsec~away, making it the first GEMS host star to have an earlier main-sequence binary companion. These confirmations add to the existing small sample of confirmed transiting GEMS.
We report the masses, sizes, and orbital properties of 86 planets orbiting 55 stars observed by NASA's K2 Mission with follow-up Doppler measurements by the HIRES spectrometer at the W. M. Keck Observatory and the Automated Planet Finder at Lick Observatory. Eighty-one of the planets were discovered from their transits in the K2 photometry, while five were found based on subsequent Doppler measurements of transiting planet host stars. The sizes of the transiting planets range from Earth-size to larger than Jupiter (1-3 REarth is typical), while the orbital periods range from less than a day to a few months. For 32 of the planets, the Doppler signal was detected with significance greater than 5-sigma (51 were detected with >3-sigma significance). An important characteristic of this catalog is the use of uniform analysis procedures to determine stellar and planetary properties. This includes the transit search and fitting procedures applied to the K2 photometry, the Doppler fitting techniques applied to the radial velocities, and the spectral modeling to determine bulk stellar parameters. Such a uniform treatment will make the catalog useful for statistical studies of the masses, densities, and system architectures of exoplanetary systems. This work also serves as a data release for all previously unpublished RVs and associated stellar activity indicators obtained by our team for these systems, along with derived stellar and planet parameters.
We discuss the emerging advances and opportunities at the intersection of machine learning (ML) and climate physics, highlighting the use of ML techniques, including supervised, unsupervised, and equation discovery, to accelerate climate knowledge discoveries and simulations. We delineate two distinct yet complementary aspects: (1) ML for climate physics and (2) ML for climate simulations. While physics-free ML-based models, such as ML-based weather forecasting, have demonstrated success when data is abundant and stationary, the physics knowledge and interpretability of ML models become crucial in the small-data/non-stationary regime to ensure generalizability. Given the absence of observations, the long-term future climate falls into the small-data regime. Therefore, ML for climate physics holds a critical role in addressing the challenges of ML for climate simulations. We emphasize the need for collaboration among climate physics, ML theory, and numerical analysis to achieve reliable ML-based models for climate applications.
We present new analysis of the CWW 89 system as part of the Orbital Architectures of Transiting Massive Exoplanets And Low-mass stars (OATMEAL) survey. The CWW 89 system is a member of the 2.8 Gyr old Ruprecht 147 (NGC 6774) cluster and features two stars, CWW 89A (EPIC 219388192) and CWW 89B, with the primary hosting a transiting brown dwarf. We use in-transit, highly precise radial velocity measurements with the Keck Planet Finder (KPF) to characterize the Rossiter-McLaughlin (RM) effect and measure the projected spin-orbit obliquity λ=1.4±2.5|\lambda|=1.4\pm2.5^\circ and the full 3D spin-orbit obliquity of the brown dwarf to be ψ=15.110.9+15.0\psi=15.1^{+15.0^\circ}_{-10.9}. This value of λ\lambda implies that the brown dwarf's orbit is prograde and well-aligned with the equator of the host star, continuing the trend of transiting brown dwarfs showing a preference for alignment (λ0\lambda \approx 0^\circ) regardless of the stellar effective temperature. We find that this contrast with the transiting giant planet population, whose spin-orbit alignments depend on host TeffT_{\rm eff}, shows an increasingly clear distinction in the formation and orbital migration mechanisms between transiting giant planets and transiting brown dwarfs like CWW 89Ab. For this system in particular, we find it plausible that the brown dwarf may have undergone coplanar high-eccentricity migration influence by CWW 89B.
The rates and properties of tidal disruption events (TDEs) provide valuable insights into their host galaxy central stellar densities and the demographics of their central supermassive black holes (SMBHs). TDEs have been observed only at low redshifts (z1z \lesssim 1), due to the difficulty in conducting deep time-domain surveys. In this work, we present the discovery of a high-redshift TDE candidate, HZTDE-1, in the COSMOS-Web survey with JWST's NIRCam, using a novel selection technique based on color and morphology. We first outline a methodology for identifying high-z TDEs in deep infrared imaging surveys, leveraging their unique spectral energy distributions (SEDs) and morphologies of these transients. We apply this technique to COSMOS-Web in filters F115W, F150W, F277W, and F444W, and identify HZTDE-1, a transient point source relative to archival UltraVISTA infrared observations. If we assume it is a TDE, we estimate its photometric redshift to be z=5.021.11+1.32z=5.02^{+1.32}_{-1.11}. HZTDE-1 cannot be explained by reasonable supernova or AGN models. However, we cannot rule out a superluminous supernova at z3z\gtrsim3. If confirmed with follow-up observations, HZTDE-1 would represent the highest-redshift TDE discovery to date, and would suggest an enhancement of the TDE rate in the high-redshift universe. Our method, which can be applied to future deep surveys with JWST and Roman, offers a pathway to identify TDEs at z>4z>4 and probe black hole demographics at early cosmic times.
We confirm the planetary nature of (1) TOI-5916 b and (2) TOI-6158 b, two Exoplanets Transiting M-dwarf Stars (GEMS), both discovered by the Transiting Exoplanet Survey Satellite (TESS). Both systems were confirmed with ground-based photometry (Red Buttes Observatory and Swope, respectively) and radial velocity data from the Habitable-zone Planet Finder. Their radii are R1=11.80.51+0.52 RR_{1}=11.8^{+0.52}_{-0.51}\text{ }R_{\oplus} and R2=10.41.11+2.70 RR_{2}=10.4^{+2.70}_{-1.11}\text{ }R_{\oplus} and masses are M1=219±28 MM_{1}=219\pm28\text{ }M_{\oplus} and M2=13518+19 MM_{2}=135^{+19}_{-18}\text{ }M_{\oplus}. Both planets have Saturn-like densities (ρ1=0.730.13+0.14g cm3\rho_{1} = 0.73^{+0.14}_{-0.13}\,\text{g cm}^{-3}, ρ2=0.660.23+0.41g cm3\rho_{2} = 0.66^{+0.41}_{-0.23}\,\text{g cm}^{-3}), which appears to be a growing trend among GEMS systems and, more generally, warm Jupiters. In confirming both of these exoplanets, we add to the growing evidence for a population of Saturn-density planets among the GEMS systems. We also find evidence for a preliminary trend in which GEMS exhibit systematically closer orbits compared to FGK giants.
Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity data are needed for definitive confirmation. Here we present radial velocity follow-up observations of 28 M and K stars with candidate astrometric substellar companions, which led to the confirmation of two systems, Gaia-4b and Gaia-5b, and the refutation of 21 systems as stellar binaries. Gaia-4b is a massive planet (M=11.8±0.7MJM = 11.8 \pm 0.7 \:\mathrm{M_J}) in a P=571.3±1.4dayP = 571.3 \pm 1.4\:\mathrm{day} orbit with a projected semi-major axis a0=0.312±0.040masa_0=0.312 \pm 0.040\:\mathrm{mas} orbiting a 0.644±0.02M0.644 \pm 0.02 \:\mathrm{M_\odot} star. Gaia-5b is a brown dwarf (M=20.9±0.5MJM = 20.9 \pm 0.5\:\mathrm{M_J}) in a P=358.58±0.19daysP = 358.58 \pm 0.19\:\mathrm{days} eccentric e=0.6412±0.0027e=0.6412 \pm 0.0027 orbit with a projected angular semi-major axis of a0=0.947±0.038masa_0 = 0.947 \pm 0.038\:\mathrm{mas} around a 0.34±0.03M0.34 \pm 0.03 \mathrm{M_\odot} star. Gaia-4b is one of the first exoplanets discovered via the astrometric technique, and is one of the most massive planets known to orbit a low-mass star.
Recent observations with the LOw Frequency ARray (LOFAR) have revealed 19 nearby M dwarfs showing bright circularly polarised radio emission. One of the possible sources of such emission is through magnetic star-planet interactions (MSPI) with unseen close-in planets. We present initial results from a spectroscopic survey with the Habitable-zone Planet Finder (HPF) and NEID spectrographs designed to characterize this sample and further investigate the origin of the radio emission. We provide four new insights into the sample. I) We uniformly characterize the stellar properties, constraining their effective temperatures, surface gravities, metallicities, projected rotational velocities, rotation periods, stellar radii, and stellar inclinations where possible. Further, from a homogenous analysis of the HPF spectra, we infer their chromospheric activity and spectroscopic multiplicity states. From this, we identify GJ 625, GJ 1151, and LHS 2395 as single, quiescent stars amenable to precise RV follow-up, making them strong MSPI candidates. II) We show that the distribution of stellar inclinations are compatible with an isotropic distribution, providing no evidence for a preference to pole-on configurations. III) We refine the radial velocity solution for GJ 625 b, the only currently known close-in planet in the sample, reducing the uncertainty in its orbital period by a factor of three, to facilitate future phase-dependent radio analysis. IV) Finally, we identify GJ 3861 as a spectroscopic binary with an orbital period of P=14.8411810.00010+0.00011P=14.841181_{-0.00010}^{+0.00011} d, making it the only confirmed binary with a relatively short orbit in the sample, where we surmise the radio emission is likely related to magnetospheric interactions between the two stars. These results advance our understanding of radio-emitting M dwarfs and establish an observational foundation for identifying MSPI.
We report on the discovery of a transiting giant planet around the 3500 K M3-dwarf star TOI-6383A located 172 pc from Earth. It was detected by the Transiting Exoplanet Survey Satellite (TESS) and confirmed by a combination of ground-based follow-up photometry and precise radial velocity measurements. This planet has an orbital period of \sim1.791 days, mass of 1.040±\pm0.094 MJM_J and a radius of 1d.0080.033+0.036 RJ^{+0.036}_{-0.033} ~R_J, resulting in a mean bulk density of 1.260.17+0.18^{+0.18}_{-0.17} g cm3^{-3}. TOI-6383A has an M-dwarf companion star, TOI-6383B, which has a stellar effective temperature TeffT_{eff} \sim 3100 K and a projected orbital separation of 3100 AU. TOI-6383A is a low-mass dwarf star hosting a giant planet and is an intriguing object for planetary evolution studies due to its high planet-to-star mass ratio. This discovery is part of the \textit{Searching for Giant Exoplanets around M-dwarf Stars (GEMS)} Survey, intending to provide robust and accurate estimates of the occurrence of GEMS and the statistics on their physical and orbital parameters. This paper presents an interesting addition to the small number of confirmed GEMS, particularly notable since its formation necessitates massive, ust-rich protoplanetary discs and high accretion efficiency (>> 10\%).
The evolution of one member of a stellar binary into a white dwarf has been proposed as a mechanism that triggers the formation of close-in gas giant planets. The star's asymmetric mass loss during the AGB stage gives it a "kick" that can initiate Eccentric Lidov-Kozai oscillations, potentially causing a planet around the secondary star to migrate inwards and perturbing the eccentricity and inclination of its orbit. Here we present a measurement of the stellar obliquity of TOI-1259Ab, a gas giant in a close-in orbit around a K star with a white dwarf companion about 1650 au away. By using the NEID spectrograph to detect the Rossiter-McLaughlin effect during the planetary transit, we find the sky-projected obliquity to be λ=622+21\lambda = 6^{+21}_{-22}\,^\circ. When combined with estimates of the stellar rotation period, radius, and projected rotation velocity, we find the true 3D obliquity to be ψ=2412+14\psi = 24^{+14}_{-12}\,^\circ (\psi < 48^\circ at 95% confidence), revealing that the orbit of TOI-1259Ab is well aligned with the star's equatorial plane. Because the planet's orbit is too wide for tidal realignment to be expected, TOI-1259Ab might have formed quiescently in this well-aligned configuration. Alternatively, as we show with dynamical simulations, Eccentric Lidov-Kozai oscillations triggered by the evolution of the binary companion are expected to lead to a low obliquity with a probability of about \sim14%.
Detections of Earth-analog planets in radial velocity observations are limited by stellar astrophysical variability occurring on a variety of timescales. Current state-of-the-art methods to disentangle potential planet signals from intrinsic stellar signals assume that stellar signals introduce asymmetries to the line profiles that can therefore be separated from the pure translational Doppler shifts of planets. Here, we examine this assumption using a time series of resolved stellar p-mode oscillations in HD 142091 (κ\kappa CrB), as observed on a single night with the NEID spectrograph at 2-minute cadence and with 25 cm/s precision. As an evolved subgiant star, this target has p-mode oscillations that are larger in amplitude (4-8 m/s) and occur on longer timescales (80 min.) than those of typical Sun-like stars of RV surveys, magnifying their corresponding effects on the stellar spectral profile. We show that for HD 142091, p-mode oscillations manifest primarily as pure Doppler shifts in the average line profile -- measured by the cross-correlation function (CCF) -- with "shape-driven" CCF variations as a higher-order effect. Specifically, we find that the amplitude of the shift varies across the CCF bisector, with 10% larger oscillation amplitudes closer to the core of the CCF, and 25% smaller oscillation amplitudes for bisector velocities derived near the wings; we attribute this trend to larger oscillation velocities higher in the stellar atmosphere. Using a line-by-line analysis, we verify that a similar trend is seen as a function of average line depth, with deeper lines showing larger oscillation amplitudes. Finally, we find no evidence that p-mode oscillations have a chromatic dependence across the NEID bandpass beyond that due to intrinsic line depth differences across the spectrum.
Stellar activity contamination of radial velocity (RV) data is one of the top challenges plaguing the field of extreme precision RV (EPRV) science. Previous work has shown that photometry can be very effective at removing such signals from RV data, especially stellar activity caused by rotating star spots and this http URL exact utility of photometry for removing RV activity contamination, and the best way to apply it, is not well known. We present a combination photometric and RV study of eight Kepler/K2 FGK stars with known stellar variability. We use NEID RVs acquired simultaneously with TESS photometry, and we perform injection recovery tests to quantify the efficacy of recent TESS photometry versus archival Kepler/K2 photometry for removing stellar variability from RVs. We additionally experiment with different TESS sectors when training our models in order to quantify the real benefit of simultaneously acquired RVs and photometry. We conclude that Kepler photometry typically performs better than TESS at removing noise from RV data when it is available, likely due to longer baseline and precision. In contrast, for targets with available K2 photometry, especially those most active, and with high precision (σNEID\sigma_{NEID} < 1 m s1^{-1}) NEID RVs, TESS may be the more informative dataset. However, contrary to expectations, we have found that training on simultaneous photometry does not always achieve the best results.
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