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Recent breakthroughs in generative modeling have sparked interest in practical single-model attribution. Such methods predict whether a sample was generated by a specific generator or not, for instance, to prove intellectual property theft. However, previous works are either limited to the closed-world setting or require undesirable changes to the generative model. We address these shortcomings by, first, viewing single-model attribution through the lens of anomaly detection. Arising from this change of perspective, we propose FLIPAD, a new approach for single-model attribution in the open-world setting based on final-layer inversion and anomaly detection. We show that the utilized final-layer inversion can be reduced to a convex lasso optimization problem, making our approach theoretically sound and computationally efficient. The theoretical findings are accompanied by an experimental study demonstrating the effectiveness of our approach and its flexibility to various domains., Comment: Accepted at the Forty-first International Conference on Machine Learning [ICML2024]

Warm Jupiters are close-in giant planets with relatively large planet-star separations (i.e., $10< a/R_\star <100$). Given their weak tidal interactions with their host stars, measurements of stellar obliquity may be used to probe the initial obliquity distribution and dynamical history for close-in gas giants. Using spectroscopic observations, we confirm the planetary nature of TOI-1859b and determine the stellar obliquity of TOI-1859 to be $\lambda = 38.9^{+2.8}_{-2.7}\deg$ relative to its planetary companion using the Rossiter-McLaughlin effect. TOI-1859b is a 64-day warm Jupiter orbiting around a late-F dwarf and has an orbital eccentricity of $0.57^{+0.12}_{-0.16}$, inferred purely from transit light curves. The eccentric and misaligned orbit of TOI-1859b is likely an outcome of dynamical interactions, such as planet-planet scattering and planet-disk resonance crossing., Comment: 15 pages, 7 figures, 1 table; accepted to ApJL

The generalized Ces\`aro operators $C_t$, for $t\in [0,1]$, were first investigated in the 1980's. They act continuously in many classical Banach sequence spaces contained in $\mathbb{C}^{\mathbb{N}_0}$, such as $\ell^p$, $c_0$, $c$, $bv_0$, $bv$ and, as recently shown, \cite{CR4}, also in the discrete Ces\`aro spaces $ces(p)$ and their (isomorphic) dual spaces $d_p$. In most cases $C_t$ ($t\not=1$) is compact and its spectra and point spectrum, together with the corresponding eigenspaces, are known. We study these properties of $C_t$, as well as their linear dynamics and mean ergodicity, when they act in certain non-normable sequence spaces contained in $\mathbb{C}^{\mathbb{N}_0}$. Besides $\mathbb{C}^{\mathbb{N}_0}$ itself, the Fr\'echet spaces considered are $\ell(p+)$, $ces(p+)$ and $d(p+)$, for $1\leq p<\infty$, as well as the (LB)-spaces $\ell(p-)$, $ces(p-)$ and $d(p-)$, for $1

We report the detection and validation of two planets orbiting TOI-2095 (TIC 235678745). The host star is a 3700K M1V dwarf with a high proper motion. The star lies at a distance of 42 pc in a sparsely populated portion of the sky and is bright in the infrared (K=9). With data from 24 Sectors of observation during TESS's Cycles 2 and 4, TOI-2095 exhibits two sets of transits associated with super-Earth-sized planets. The planets have orbital periods of 17.7 days and 28.2 days and radii of 1.30 and 1.39 Earth radii, respectively. Archival data, preliminary follow-up observations, and vetting analyses support the planetary interpretation of the detected transit signals. The pair of planets have estimated equilibrium temperatures of approximately 400 K, with stellar insolations of 3.23 and 1.73 times that of Earth, placing them in the Venus zone. The planets also lie in a radius regime signaling the transition between rock-dominated and volatile-rich compositions. They are thus prime targets for follow-up mass measurements to better understand the properties of warm, transition radius planets. The relatively long orbital periods of these two planets provide crucial data that can help shed light on the processes that shape the composition of small planets orbiting M dwarfs., Comment: Submitted to AAS Journals

We report the discovery of a hot ($T_{\rm eq}$ $\approx$ 1055 K) planet in the small planet radius valley transiting the Sun-like star TOI-733, as part of the KESPRINT follow-up program of TESS planets carried out with the HARPS spectrograph. TESS photometry from sectors 9 and 36 yields an orbital period of $P_{\rm orb}$ = $4.884765 _{ - 2.4e-5 } ^ { + 1.9e-5 }$ days and a radius of $R_{\mathrm{p}}$ = $1.992 _{ - 0.090 } ^ { + 0.085 }$ $R_{\oplus}$. Multi-dimensional Gaussian process modelling of the radial velocity measurements from HARPS and activity indicators, gives a semi-amplitude of $K$ = $2.23 \pm 0.26 $ m s$^{-1}$, translating into a planet mass of $M_{\mathrm{p}}$ = $5.72 _{ - 0.68 } ^ { + 0.70 }$ $M_{\oplus}$. These parameters imply that the planet is of moderate density ($\rho_\mathrm{p}$ = $3.98 _{ - 0.66 } ^ { + 0.77 }$ g cm$^{-3}$) and place it in the transition region between rocky and volatile-rich planets with H/He-dominated envelopes on the mass-radius diagram. Combining these with stellar parameters and abundances, we calculate planet interior and atmosphere models, which in turn suggest that TOI-733 b has a volatile-enriched, most likely secondary outer envelope, and may represent a highly irradiated ocean world - one of only a few such planets around G-type stars that are well-characterised., Comment: Accepted for publication in A&A

Recent advances in generative artificial intelligence (AI) have captured worldwide attention. Tools such as Dalle-2 and ChatGPT suggest that tasks previously thought to be beyond the capabilities of AI may now augment the productivity of creative media in various new ways, including through the generation of synthetic video. This research paper explores the utility of using AI-generated synthetic video to create viable educational content for online educational settings. To date, there is limited research investigating the real-world educational value of AI-generated synthetic media. To address this gap, we examined the impact of using AI-generated synthetic video in an online learning platform on both learners content acquisition and learning experience. We took a mixed-method approach, randomly assigning adult learners (n=83) into one of two micro-learning conditions, collecting pre- and post-learning assessments, and surveying participants on their learning experience. The control condition included a traditionally produced instructor video, while the experimental condition included a synthetic video with a realistic AI-generated character. The results show that learners in both conditions demonstrated significant improvement from pre- to post-learning (p<.001), with no significant differences in gains between the two conditions (p=.80). In addition, no differences were observed in how learners perceived the traditional and synthetic videos. These findings suggest that AI-generated synthetic learning videos have the potential to be a viable substitute for videos produced via traditional methods in online educational settings, making high quality educational content more accessible across the globe., Comment: 12 pages, 1 table, 3 figures. International conference of Artificial Intelligence in Education (AIED 2023)

We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single transit events in the light curves generated from the full frame images of the Transiting Exoplanet Survey Satellite (TESS). Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of $M_P$= 0.30 $\pm$ 0.04 $M_J$ , a radius of $R_P$= 1.00 $\pm$ 0.02 $R_J$ , and a low eccentricity orbit (e=0.15 $\pm$ 0.05) with a period of P= 30.08364 $\pm$ 0.00005 d . TOI 2338b has a mass of $M_P$= 5.98 $\pm$ 0.20 $M_J$ , a radius of $R_P$= 1.00 $\pm$ 0.01 $R_J$ , and a highly eccentric orbit (e= 0.676 $\pm$ 0.002 ) with a period of P= 22.65398 $\pm$ 0.00002 d . Finally, TOI 2589b has a mass of $M_P$= 3.50 $\pm$ 0.10 $M_J$ , a radius of $R_P$= 1.08 $\pm$ 0.03 $R_J$ , and an eccentric orbit (e = 0.522 $\pm$ 0.006 ) with a period of P= 61.6277 $\pm$ 0.0002 d . TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star., Comment: 24 pages, 16 figures, accepted in AJ

The finite Hilbert transform $T$ is a classical (singular) kernel operator which is continuous in every rearrangement invariant space $X$ over $(-1,1)$ having non-trivial Boyd indices. For $X=L^p$, $1

We report the discovery of TOI-4127 b, a transiting, Jupiter-sized exoplanet on a long-period ($P = 56.39879^{+0.00010}_{-0.00010}$ d), high-eccentricity orbit around a late F-type dwarf star. This warm Jupiter was first detected and identified as a promising candidate from a search for single-transit signals in TESS Sector 20 data, and later characterized as a planet following two subsequent transits (TESS Sectors 26 and 53) and follow-up ground-based RV observations with the NEID and SOPHIE spectrographs. We jointly fit the transit and RV data to constrain the physical ($R_p = 1.096^{+0.039}_{-0.032} R_J$, $M_p = 2.30^{+0.11}_{-0.11} M_J$) and orbital parameters of the exoplanet. Given its high orbital eccentricity ($e=0.7471^{+0.0078}_{-0.0086}$), TOI-4127 b is a compelling candidate for studies of warm Jupiter populations and of hot Jupiter formation pathways. We show that the present periastron separation of TOI-4127 b is too large for high-eccentricity tidal migration to circularize its orbit, and that TOI-4127 b is unlikely to be a hot Jupiter progenitor unless it is undergoing angular momentum exchange with an undetected outer companion. Although we find no evidence for an external companion, the available observational data are insufficient to rule out the presence of a perturber that can excite eccentricity oscillations and facilitate tidal migration.

We present the TESS light curve of GRB 230307A. We find two distinct components: a bright, prompt optical component at the time of the Fermi observation that peaked at TESS magnitude 14.49 (averaged over 200 seconds), followed by a gradual rise and fall over 0.5 days, likely associated with the afterglow, that peaked at 17.65 mag. The prompt component is observed in a single 200s Full Frame Image and was undetectable in the next TESS image ($T_{\rm mag} > 17.79$). Assuming that the onset of the optical transient was coincident with the gamma-ray emission, the prompt emission lasted less than 73.6 seconds, which implies the true peak was actually brighter than $T_{\rm mag} =$ 13.40. We also fit parametric models to the afterglow to characterize its shape. The TESS light curve can be retrieved at https://tess.mit.edu/public/tesstransients/light_curves/lc_grb230307A_cleaned.txt., Comment: Published as a Research Notes of the AAS

We report the discovery and characterisation of the transiting mini-Neptune HD~207496~b (TOI-1099) as part of a large programme that aims to characterise naked core planets. We obtained HARPS spectroscopic observations, one ground-based transit, and high-resolution imaging which we combined with the TESS photometry to confirm and characterise the TESS candidate and its host star. The host star is an active early K dwarf with a mass of $0.80 \pm 0.04\,$M$_\odot$, a radius of $0.769 \pm 0.026\,$R$_\odot$, and a G magnitude of 8. We found that the host star is young, $\sim 0.52\,$ Myr, allowing us to gain insight into planetary evolution. We derived a planetary mass of $6.1 \pm 1.6\,\mathrm{M}_E$,\, a planetary radius of $2.25 \pm 0.12\,\mathrm{R}_E$,\ and a planetary density of $\rho_p = 3.27_{-0.91}^{+0.97}\,\mathrm{g.cm^{-3}}$. From internal structure modelling of the planet, we conclude that the planet has either a water-rich envelope, a gas-rich envelope, or a mixture of both. We have performed evaporation modelling of the planet. If we assume the planet has a gas-rich envelope, we find that the planet has lost a significant fraction of its envelope and its radius has shrunk. Furthermore, we estimate it will lose all its remaining gaseous envelope in $\sim 0.52\,$ Gyr. Otherwise, the planet could have already lost all its primordial gas and is now a bare ocean planet. Further observations of its possible atmosphere and/or mass-loss rate would allow us to distinguish between these two hypotheses. Such observations would determine if the planet remains above the radius gap or if it will shrink and be below the gap., Comment: 20 pages, 18 figures, 4 tables, A&A accepted

We report the discovery of a super-Jovian 2:1 mean-motion resonance (MMR) pair around the G-type star TIC 279401253, whose dynamical architecture is a prospective benchmark for planet formation and orbital evolution analysis. The system was discovered thanks to a single transit event recorded by the Transiting Exoplanet Survey Satellite (TESS) mission, which pointed to a Jupiter-sized companion with poorly constrained orbital parameters. We began ground-based precise radial velocity (RV) monitoring with HARPS and FEROS within the Warm gIaNts with tEss (WINE) survey to constrain the transiting body's period, mass, and eccentricity. The RV measurements revealed not one but two massive planets with periods of 76.80$_{-0.06}^{+0.06}$ days and 155.3$_{-0.7}^{+0.7}$ days, respectively. A combined analysis of transit and RV data yields an inner transiting planet with a mass of 6.14$_{-0.42}^{+0.39}$ M$_{\rm Jup}$ and a radius of 1.00$_{-0.04}^{+0.04}$ R$_{\rm Jup}$, and an outer planet with a minimum mass of 8.02$_{-0.18}^{+0.18}$ M$_{\rm Jup}$, indicating a massive giant pair. A detailed dynamical analysis of the system reveals that the planets are locked in a strong first-order, eccentricity-type 2:1 MMR, which makes TIC 279401253 one of the rare examples of truly resonant architectures supporting disk-induced planet migration. The bright host star, $V \approx$ 11.9 mag, the relatively short orbital period ($P_{\rm b}$ = 76.80$_{-0.06}^{+0.06}$ d) and pronounced eccentricity (e =0.448$_{-0.029}^{+0.028}$) make the transiting planet a valuable target for atmospheric investigation with the James Webb Space Telescope (JWST) and ground-based extremely-large telescopes., Comment: Published in the ApJL

We present the discovery of TOI-3235 b, a short-period Jupiter orbiting an M-dwarf with a stellar mass close to the critical mass at which stars transition from partially to fully convective. TOI-3235 b was first identified as a candidate from TESS photometry, and confirmed with radial velocities from ESPRESSO, and ground-based photometry from HATSouth, MEarth-South, TRAPPIST-South, LCOGT, and ExTrA. We find that the planet has a mass of $\mathrm{0.665\pm0.025\,M_J}$ and a radius of $\mathrm{1.017\pm0.044\,R_J}$. It orbits close to its host star, with an orbital period of $\mathrm{2.5926\,d}$, but has an equilibrium temperature of $\mathrm{\approx 604 \, K}$, well below the expected threshold for radius inflation of hot Jupiters. The host star has a mass of $\mathrm{0.3939\pm0.0030\,M_\odot}$, a radius of $\mathrm{0.3697\pm0.0018\,R_\odot}$, an effective temperature of $\mathrm{3389 \, K}$, and a J-band magnitude of $\mathrm{11.706\pm0.025}$. Current planet formation models do not predict the existence of gas giants such as TOI-3235 b around such low-mass stars. With a high transmission spectroscopy metric, TOI-3235 b is one of the best-suited giants orbiting M-dwarfs for atmospheric characterization., Comment: 15 pages, 4 figures. Accepted for publication in APJL

The generalized Ces\`{a}ro operators $\mathcal{C}_t$, for $t\in[0,1)$, introduced in the 1980's by Rhaly, are natural analogues of the classical Ces\`{a}ro averaging operator $\mathcal{C}_1$ and act in various Banach sequence spaces $X\subseteq {\mathbb C}^{{\mathbb N}_0}$. In this paper we concentrate on a certain class of Banach lattices for the coordinate-wise order, which includes all separable, rearrangement invariant sequence spaces, various weighted $c_0$ and $\ell^p$ spaces and many others. In such Banach lattices $X$ the operators $\mathcal{C}_t$, for $t\in[0,1)$, are always compact (unlike $\mathcal{C}_1$) and a full description of their point, continuous and residual spectrum is given. Estimates for the operator norm of $\mathcal{C}_t$ are also presented.

We investigate convolution operators in the sequence spaces $d_p$, for $1\le p<\infty$. These spaces, for $p>1$, arise as dual spaces of the \ces sequence spaces $ces_p$ thoroughly investigated by G.~Bennett. A detailed study is also made of the algebra of those sequences which convolve $d_p$ into $d_p$. It turns out that such multiplier spaces exhibit features which are very different to the classical multiplier spaces of $\ell^p$.

TOI-2525 is a K-type star with an estimated mass of M = 0.849$_{-0.033}^{+0.024}$ M$_\odot$ and radius of R = 0.785$_{-0.007}^{+0.007}$ R$_\odot$ observed by the TESS mission in 22 sectors (within sectors 1 and 39). The TESS light curves yield significant transit events of two companions, which show strong transit timing variations (TTVs) with a semi-amplitude of a $\sim$6 hours. We performed TTV dynamical, and photo-dynamical light curve analysis of the TESS data, combined with radial velocity (RV) measurements from FEROS and PFS, and we confirmed the planetary nature of these companions. The TOI-2525 system consists of a transiting pair of planets comparable to Neptune and Jupiter with estimated dynamical masses of $m_{\rm b}$ = 0.088$_{-0.004}^{+0.005}$ M$_{\rm Jup.}$, and $m_{\rm c}$ = 0.709$_{-0.033}^{+0.034}$ M$_{\rm Jup.}$, radius of $r_b$ = 0.88$_{-0.02}^{+0.02}$ R$_{\rm Jup.}$ and $r_c$ = 0.98$_{-0.02}^{+0.02}$ R$_{\rm Jup.}$, and with orbital periods of $P_{\rm b}$ = 23.288$_{-0.002}^{+0.001}$ days and $P_{\rm c}$ = 49.260$_{-0.001}^{+0.001}$ days for the inner and the outer planet, respectively. The period ratio is close to the 2:1 period commensurability, but the dynamical simulations of the system suggest that it is outside the mean motion resonance (MMR) dynamical configuration. TOI-2525 b is among the lowest density Neptune-mass planets known to date, with an estimated median density of $\rho_{\rm b}$ = 0.174$_{-0.015}^{+0.016}$ g\,cm$^{-3}$. The TOI-2525 system is very similar to the other K-dwarf systems discovered by TESS, TOI-2202 and TOI-216, which are composed of almost identical K-dwarf primary and two warm giant planets near the 2:1 MMR., Comment: Accepted for publication in AJ

In 2017, the LIGO and Virgo gravitational wave (GW) detectors, in conjunction with electromagnetic (EM) astronomers, observed the first GW multi-messenger astrophysical event, the binary neutron star (BNS) merger GW170817. This marked the beginning of a new era in multi-messenger astrophysics. To discover further GW multi-messenger events, we explore the synergies between the Transiting Exoplanet Survey Satellite (TESS) and GW observations triggered by the LIGO-Virgo-KAGRA Collaboration (LVK) detector network. TESS's extremely wide field of view of ~2300 deg^2 means that it could overlap with large swaths of GW localizations, which can often span hundreds of deg^2 or more. In this work, we use a recently developed transient detection pipeline to search TESS data collected during the LVK's third observing run, O3, for any EM counterparts. We find no obvious counterparts brighter than about 17th magnitude in the TESS bandpass. Additionally, we present end-to-end simulations of BNS mergers, including their detection in GWs and simulations of light curves, to identify TESS's kilonova discovery potential for the LVK's next observing run (O4). In the most optimistic case, TESS will observe up to one GW-found BNS merger counterpart per year. However, TESS may also find up to five kilonovae which did not trigger the LVK network, emphasizing that EM-triggered GW searches may play a key role in future kilonova detections. We also discuss how TESS can help place limits on EM emission from binary black hole mergers, and rapidly exclude large sky areas for poorly localized GW events., Comment: 16 pages, 7 figures, 2 tables. Submitted to AAS Journals

The planetary system around the naked-eye star $\nu^2$ Lupi (HD 136352; TOI-2011) is composed of three exoplanets with masses of 4.7, 11.2, and 8.6 Earth masses. The TESS and CHEOPS missions revealed that all three planets are transiting and have radii straddling the radius gap separating volatile-rich and volatile-poor super-earths. Only a partial transit of planet d had been covered so we re-observed an inferior conjunction of the long-period 8.6 Earth-mass exoplanet $\nu^2$ Lup d with the CHEOPS space telescope. We confirmed its transiting nature by covering its whole 9.1 h transit for the first time. We refined the planet transit ephemeris to P = 107.1361 (+0.0019/-0.0022) days and Tc = 2,459,009.7759 (+0.0101/-0.0096) BJD_TDB, improving by ~40 times on the previously reported transit timing uncertainty. This refined ephemeris will enable further follow-up of this outstanding long-period transiting planet to search for atmospheric signatures or explore the planet's Hill sphere in search for an exomoon. In fact, the CHEOPS observations also cover the transit of a large fraction of the planet's Hill sphere, which is as large as the Earth's, opening the tantalising possibility of catching transiting exomoons. We conducted a search for exomoon signals in this single-epoch light curve but found no conclusive photometric signature of additional transiting bodies larger than Mars. Yet, only a sustained follow-up of $\nu^2$ Lup d transits will warrant a comprehensive search for a moon around this outstanding exoplanet., Comment: 16 pages, 9 figures. Accepted for publication in Astronomy & Astrophysics

We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite TESS as TOI-588 b. HIP 33609 b is a large (R$_{b}$ = 1.580$_{-0.070}^{+0.074}$ R$_{J}$) brown dwarf on a highly eccentric (e = 0.560$_{-0.031}^{+0.029}$) orbit with a 39-day period. The host star is a bright (V = 7.3 mag), T$_{eff}$ = 10,400$_{-660}^{+800}$ K star with a mass of M$_{*}$ = 2.383$_{-0.095}^{+0.10}$ M$_{\odot}$ and radius of R$_{*}$ = 1.863$_{-0.082}^{+0.087}$ R$_{\odot}$, making it the hottest transiting brown dwarf host star discovered to date. We obtained radial velocity measurements from the CHIRON spectrograph confirming the companion's mass of M$_{b}$ = 68.0$_{-7.1}^{+7.4}$ M$_{J}$ as well as the host star's rotation rate ($vsini_{*} = 55.6 \pm 1.8$ km/s). We also present the discovery of a new comoving group of stars, designated as MELANGE-6, and determine that HIP 33609 is a member. We use a combination of rotation periods and isochrone models fit to the cluster members to estimate an age of 150 $\pm$ 25 Myr. With a measured mass, radius, and age, HIP 33609 b becomes a benchmark for substellar evolutionary models., Comment: 16 pages, 5 figures, 4 tables, Submitted to AAS Journals

The radius valley carries implications for how the atmospheres of small planets form and evolve, but this feature is visible only with highly precise characterizations of many small planets. We present the characterization of nine planets and one planet candidate with both NASA TESS and ESA CHEOPS observations, which adds to the overall population of planets bordering the radius valley. While four of our planets - TOI 118 b, TOI 455 b, TOI 560 b, and TOI 562 b - have already been published, we vet and validate transit signals as planetary using follow-up observations for five new TESS planets, including TOI 198 b, TOI 244 b, TOI 262 b, TOI 444 b, and TOI 470 b. While a three times increase in primary mirror size should mean that one CHEOPS transit yields an equivalent model uncertainty in transit depth as about nine TESS transits in the case that the star is equally as bright in both bands, we find that our CHEOPS transits typically yield uncertainties equivalent to between two and 12 TESS transits, averaging 5.9 equivalent transits. Therefore, we find that while our fits to CHEOPS transits provide overall lower uncertainties on transit depth and better precision relative to fits to TESS transits, our uncertainties for these fits do not always match expected predictions given photon-limited noise. We find no correlations between number of equivalent transits and any physical parameters, indicating that this behavior is not strictly systematic, but rather might be due to other factors such as in-transit gaps during CHEOPS visits or nonhomogeneous detrending of CHEOPS light curves., Comment: Published in AJ; changed to reflect our vetting of TOI 262 b

We report the discovery of TOI-700 e, a 0.95 R$_\oplus$ planet residing in the Optimistic Habitable Zone (HZ) of its host star. This discovery was enabled by multiple years of monitoring from NASA's Transiting Exoplanet Survey Satellite (TESS) mission. The host star, TOI-700 (TIC 150428135), is a nearby (31.1 pc), inactive, M2.5 dwarf ($V_{mag} = 13.15$). TOI-700 is already known to host three planets, including the small, HZ planet, TOI-700 d. The new planet has an orbital period of 27.8 days and, based on its radius (0.95 R$_\oplus$), it is likely rocky. TOI-700 was observed for 21 sectors over Years 1 and 3 of the TESS mission, including 10 sectors at 20-second cadence in Year 3. Using this full set of TESS data and additional follow-up observations, we identify, validate, and characterize TOI-700 e. This discovery adds another world to the short list of small, HZ planets transiting nearby and bright host stars. Such systems, where the stars are bright enough that follow-up observations are possible to constrain planet masses and atmospheres using current and future facilities, are incredibly valuable. The presence of multiple small, HZ planets makes this system even more enticing for follow-up observations., Comment: 16 pages, 4 figures, 2 tables, accepted for publication in ApJL

The TESS mission produces a large amount of time series data, only a small fraction of which contain detectable exoplanetary transit signals. Deep learning techniques such as neural networks have proved effective at differentiating promising astrophysical eclipsing candidates from other phenomena such as stellar variability and systematic instrumental effects in an efficient, unbiased and sustainable manner. This paper presents a high quality dataset containing light curves from the Primary Mission and 1st Extended Mission full frame images and periodic signals detected via Box Least Squares (Kov\'acs et al. 2002; Hartman 2012). The dataset was curated using a thorough manual review process then used to train a neural network called Astronet-Triage-v2. On our test set, for transiting/eclipsing events we achieve a 99.6% recall (true positives over all data with positive labels) at a precision of 75.7% (true positives over all predicted positives). Since 90% of our training data is from the Primary Mission, we also test our ability to generalize on held-out 1st Extended Mission data. Here, we find an area under the precision-recall curve of 0.965, a 4% improvement over Astronet-Triage (Yu et al. 2019). On the TESS Object of Interest (TOI) Catalog through April 2022, a shortlist of planets and planet candidates, Astronet-Triage-v2 is able to recover 3577 out of 4140 TOIs, while Astronet-Triage only recovers 3349 targets at an equal level of precision. In other words, upgrading to Astronet-Triage-v2 helps save at least 200 planet candidates from being lost. The new model is currently used for planet candidate triage in the Quick-Look Pipeline (Huang et al. 2020a,b; Kunimoto et al. 2021)., Comment: accepted for publication in AJ. code can be found at: https://github.com/mdanatg/Astronet-Triage and data can be found at: https://zenodo.org/record/7411579

With data from the Transiting Exoplanet Survey Satellite (TESS), we showcase improvements to the MIT Quick-Look Pipeline (QLP) through the discovery and validation of a multi-planet system around M-dwarf TOI 4342 ($T_{mag}=11.032$, $M_* = 0.63 M_\odot$, $R_* = 0.60 R_\odot$, $T_{eff} = 3900$ K, $d = 61.54$ pc). With updates to QLP, including a new multi-planet search, as well as faster cadence data from TESS' First Extended Mission, we discovered two sub-Neptunes ($R_b = 2.266_{-0.038}^{+0.038} R_\oplus$ and $R_c = 2.415_{-0.040}^{+0.043} R_\oplus$; $P_b$ = 5.538 days and $P_c$ = 10.689 days) and validated them with ground-based photometry, spectra, and speckle imaging. Both planets notably have high transmission spectroscopy metrics (TSMs) of 36 and 32, making TOI 4342 one of the best systems for comparative atmospheric studies. This system demonstrates how improvements to QLP, along with faster cadence Full-Frame Images (FFIs), can lead to the discovery of new multi-planet systems., Comment: accepted for publication in AJ

The finite Hilbert transform T is a singular integral operator which maps the Zygmund space $LlogL:=LlogL(-1,1)$ continuously into $L^1:=L^1(-1,1)$. By extending the Parseval and Poincar\'e-Bertrand formulae to this setting, it is possible to establish an inversion result needed for solving the airfoil equation $T(f)=g$ whenever the data function $g$ lies in the range of $T$ within $L^1$ (shown to contain $LlogL$). Until now this was only known for $g$ belonging to the union of all $L^p$ spaces with $p>1$. It is established (due to a result of Stein) that $T$ cannot be extended to any domain space beyond $LlogL$ whilst still taking its values in $L^1$, i.e., $T:LlogL\to L^1$ is optimally defined., Comment: This is the final version, to be published in Annali della Scuola Normale Superiore di Pisa, Classe di Scienze

NASA's Transiting Exoplanet Survey Satellite (TESS) mission, has been uncovering a growing number of exoplanets orbiting nearby, bright stars. Most exoplanets that have been discovered by TESS orbit narrow-line, slow-rotating stars, facilitating the confirmation and mass determination of these worlds. We present the discovery of a hot Jupiter orbiting a rapidly rotating ($v\sin{(i)}= 35.1\pm1.0$km/s) early F3V-dwarf, HD115447 (TOI-778). The transit signal taken from Sectors 10 and 37 of TESS's initial detection of the exoplanet is combined with follow-up ground-based photometry and velocity measurements taken from Minerva-Australis, TRES, CORALIE and CHIRON to confirm and characterise TOI-778b. A joint analysis of the light curves and the radial velocity measurements yield a mass, radius, and orbital period for TOI-778b of $2.76^{+0.24}_{-0.23}$Mjup, $1.370\pm0.043$Rjup and $\sim4.63$ days, respectively. The planet orbits a bright ($V = 9.1$mag) F3-dwarf with $M=1.40\pm0.05$Msun, $R=1.70\pm0.05$Rsun, and $\log g=4.05\pm0.17$. We observed a spectroscopic transit of TOI-778b, which allowed us to derive a sky-projected spin-orbit angle of $18^{\circ}\pm11^{\circ}$, consistent with an aligned planetary system. This discovery demonstrates the capability of smaller aperture telescopes such as Minerva-Australis to detect the radial velocity signals produced by planets orbiting broad-line, rapidly rotating stars., Comment: 18 pages, 9 figures, and 4 tables. Submitted to the Astronomical Journal

We report the discovery and characterization of a nearby (~ 85 pc), older (27 +/- 3 Myr), distributed stellar population near Lower-Centaurus-Crux (LCC), initially identified by searching for stars co-moving with a candidate transiting planet from TESS (HD 109833; TOI 1097). We determine the association membership using Gaia kinematics, color-magnitude information, and rotation periods of candidate members. We measure it's age using isochrones, gyrochronology, and Li depletion. While the association is near known populations of LCC, we find that it is older than any previously found LCC sub-group (10-16 Myr), and distinct in both position and velocity. In addition to the candidate planets around HD 109833 the association contains four directly-imaged planetary-mass companions around 3 stars, YSES-1, YSES-2, and HD 95086, all of which were previously assigned membership in the younger LCC. Using the Notch pipeline, we identify a second candidate transiting planet around HD 109833. We use a suite of ground-based follow-up observations to validate the two transit signals as planetary in nature. HD 109833 b and c join the small but growing population of <100 Myr transiting planets from TESS. HD 109833 has a rotation period and Li abundance indicative of a young age (< 100 Myr), but a position and velocity on the outskirts of the new population, lower Li levels than similar members, and a CMD position below model predictions for 27 Myr. So, we cannot reject the possibility that HD 109833 is a young field star coincidentally nearby the population., Comment: 23 pages, 15 figures, Accepted for publication in AJ

We report the discovery and confirmation of the planetary system TOI-1288. This late G dwarf harbours two planets: TOI-1288 b and TOI-1288 c. We combine TESS space-borne and ground-based transit photometry with HARPS-N and HIRES high-precision Doppler measurements, which we use to constrain the masses of both planets in the system and the radius of planet b. TOI-1288~b has a period of $2.699835^{+0.000004}_{-0.000003}$ d, a radius of $5.24 \pm 0.09$ R$_\oplus$, and a mass of $42 \pm 3$ M$_\oplus$, making this planet a hot transiting super-Neptune situated right in the Neptunian desert. This desert refers to a paucity of Neptune-sized planets on short period orbits. Our 2.4-year-long Doppler monitoring of TOI-1288 revealed the presence of a Saturn-mass planet on a moderately eccentric orbit ($0.13^{+0.07}_{-0.09}$) with a minimum mass of $84 \pm 7$ M$_\oplus$ and a period of $443^{+11}_{-13}$ d. The 5 sectors worth of TESS data do not cover our expected mid-transit time for TOI-1288 c, and we do not detect a transit for this planet in these sectors., Comment: 16 pages, 17 figures, under review MNRAS

Characterizing the bulk compositions of transiting exoplanets within the M dwarf radius valley offers a unique means to establish whether the radius valley emerges from an atmospheric mass loss process or is imprinted by planet formation itself. We present the confirmation of such a planet orbiting an early M dwarf ($T_{\rm mag} = 11.0294 \pm 0.0074, M_s = 0.513 \pm 0.012\ M_\odot, R_s = 0.515 \pm 0.015\ R_\odot, T_{\rm eff} =3690\pm 50 K$): TOI-1695 b ($P = 3.13$ days, $R_p = 1.90^{+0.16}_{-0.14}\ R_\oplus$). TOI-1695 b's radius and orbital period situate the planet between model predictions from thermally-driven mass loss versus gas depleted formation, offering an important test case for radius valley emergence models around early M dwarfs. We confirm the planetary nature of TOI-1695 b based on five sectors of TESS data and a suite of follow-up observations including 49 precise radial velocity measurements taken with the HARPS-N spectrograph. We measure a planetary mass of $6.36 \pm 1.00\ M_\oplus$, which reveals that TOI-1695 b is inconsistent with a purely terrestrial composition of iron and magnesium silicate, and instead is likely a water-rich planet. Our finding that TOI-1695 b is not terrestrial is inconsistent with the planetary system being sculpted by thermally driven mass loss. We present a statistical analysis of seven well-characterized planets within the M dwarf radius valley demonstrating that a thermally-driven mass loss scenario is unlikely to explain this population., Comment: 22 pages, 11 figures. Accepted in AJ

Tidal orbital decay is suspected to occur especially for hot Jupiters, with the only observationally confirmed case of this being WASP-12 b. By examining this effect, information on the properties of the host star can be obtained using the so-called stellar modified tidal quality factor $Q_*'$, which describes the efficiency with which kinetic energy of the planet is dissipated within the star. This can help to get information about the interior of the star. In this study, we aim to improve constraints on the tidal decay of the KELT-9, KELT-16 and WASP-4 systems, to find evidence for or against the presence of this particular effect. With this, we want to constrain each star's respective $Q_*'$ value. In addition to that, we also aim to test the existence of the transit timing variations (TTVs) in the HD 97658 system, which previously favoured a quadratic trend with increasing orbital period. Making use of newly acquired photometric observations from CHEOPS and TESS, combined with archival transit and occultation data, we use Markov chain Monte Carlo (MCMC) algorithms to fit three models, a constant period model, an orbital decay model, and an apsidal precession model, to the data. We find that the KELT-9 system is best described by an apsidal precession model for now, with an orbital decay trend at over 2 $\sigma$ being a possible solution as well. A Keplerian orbit model with a constant orbital period fits the transit timings of KELT-16 b the best due to the scatter and scale of their error bars. The WASP-4 system is represented the best by an orbital decay model at a 5 $\sigma$ significance, although apsidal precession cannot be ruled out with the present data. For HD 97658 b, using recently acquired transit observations, we find no conclusive evidence for a previously suspected strong quadratic trend in the data., Comment: 19 pages, 11 figures, 9 tables, accepted for publication in A&A

We present High-Level Science Products (HLSPs) containing light curves from MIT's Quick-Look Pipeline (QLP) from the second year of TESS' first Extended Mission (Sectors 40 - 55; 2021 July - 2022 September). In total, 12.2 million per-sector light curves for 5.7 million unique stars were extracted from 10-minute cadence Full-Frame Images (FFIs) and are made available to the community. As in previous deliveries, QLP HLSPs include both raw and detrended flux time series for all observed stars brighter than TESS magnitude T = 13.5 mag. Starting in Sector 41, QLP also produces light curves for select fainter M dwarfs. QLP has provided the community with one of the largest sources of FFI-extracted light curves to date since the start of the TESS mission., Comment: 3 pages, 1 figure

We used TESS light curves and HARPS-N spectrograph radial velocity measurements to establish the physical properties of the transiting exoplanet candidate found around the star HD 20329 (TOI-4524). We performed a joint fit of the light curves and radial velocity time series to measure the mass, radius, and orbital parameters of the candidate. We confirm and characterize HD 20329b, an ultra-short-period (USP) planet transiting a solar-type star. The host star (HD 20329, $V = 8.74$ mag, $J = 7.5$ mag) is characterized by its G5 spectral type with $\mathrm{M}_\star= 0.90 \pm 0.05$ M$_\odot$, $\mathrm{R}_\star = 1.13 \pm 0.02$ R$_\odot$, and $\mathrm{T}_{\mathrm{eff}} = 5596 \pm 50$ K; it is located at a distance $d= 63.68 \pm 0.29$ pc. By jointly fitting the available TESS transit light curves and follow-up radial velocity measurements, we find an orbital period of $0.9261 \pm (0.5\times 10^{-4})$ days, a planetary radius of $1.72 \pm 0.07$ $\mathrm{R}_\oplus$, and a mass of $7.42 \pm 1.09$ $\mathrm{M}_\oplus$, implying a mean density of $\rho_\mathrm{p} = 8.06 \pm 1.53$ g cm$^{-3}$. HD 20329b joins the $\sim$30 currently known USP planets with radius and Doppler mass measurements., Comment: Accepted for publication in A&A, 26 pages

The fate of planets around rapidly evolving stars is not well understood. Previous studies have suggested that relative to the main sequence population, planets transiting evolved stars ($P$ $<$ 100 d) tend to have more eccentric orbits. Here we present the discovery of TOI-4582 b, a 0.94 $\pm$ 0.12 R$_\mathrm{J}$, 0.53 $\pm$ 0.05 M$_\mathrm{J}$ planet orbiting an intermediate-mass subgiant star every 31.034 days. We find that this planet is also on a significantly eccentric orbit ($e$ = 0.51 $\pm$ 0.05). We then compare the population of planets found transiting evolved (log$g$ $<$ 3.8) stars to the population of planets transiting main sequence stars. We find that the rate at which median orbital eccentricity grows with period is significantly higher for evolved star systems than for otherwise similar main sequence systems, particularly for systems with only one planet detected. In general, we observe that mean planet eccentricity $$ = $a$ + $b$log$_{10}$($P$) for the evolved population with a single transiting planet where $a$ = (-0.18 $\pm$ 0.08) and $b$ = (0.38 $\pm$ 0.06), significantly distinct from the main sequence planetary system population. This trend is seen even after controlling for stellar mass and metallicity. These systems do not appear to represent a steady evolution pathway from eccentric, long-period planetary orbits to circular, short period orbits, as orbital model comparisons suggest inspiral timescales are uncorrelated with orbital separation or eccentricity. Characterization of additional evolved planetary systems will distinguish effects of stellar evolution from those of stellar mass and composition., Comment: 21 pages, 11 figures, favorably reviewed by AAS Journals

NASA's Transiting Exoplanet Survey Satellite (TESS) mission promises to improve our understanding of hot Jupiters by providing an all-sky, magnitude-limited sample of transiting hot Jupiters suitable for population studies. Assembling such a sample requires confirming hundreds of planet candidates with additional follow-up observations. Here, we present twenty hot Jupiters that were detected using TESS data and confirmed to be planets through photometric, spectroscopic, and imaging observations coordinated by the TESS Follow-up Observing Program (TFOP). These twenty planets have orbital periods shorter than 7 days and orbit relatively bright FGK stars ($10.9 < G < 13.0$). Most of the planets are comparable in mass to Jupiter, although there are four planets with masses less than that of Saturn. TOI-3976 b, the longest period planet in our sample ($P = 6.6$ days), may be on a moderately eccentric orbit ($e = 0.18\pm0.06$), while observations of the other targets are consistent with them being on circular orbits. We measured the projected stellar obliquity of TOI-1937A b, a hot Jupiter on a 22.4 hour orbit with the Rossiter-McLaughlin effect, finding the planet's orbit to be well-aligned with the stellar spin axis ($|\lambda| = 4.0\pm3.5^\circ$). We also investigated the possibility that TOI-1937 is a member of the NGC 2516 open cluster, but ultimately found the evidence for cluster membership to be ambiguous. These objects are part of a larger effort to build a complete sample of hot Jupiters to be used for future demographic and detailed characterization work., Comment: 67 pages, 11 tables, 13 figures, 2 figure sets. Resubmitted to ApJS after revisions

Populating the exoplanet mass-radius diagram in order to identify the underlying relationship that governs planet composition is driving an interdisciplinary effort within the exoplanet community. The discovery of hot super-Earths - a high temperature, short-period subset of the super-Earth planet population - has presented many unresolved questions concerning the formation, evolution, and composition of rocky planets. We report the discovery of a transiting, ultra-short period hot super-Earth orbiting TOI-1075 (TIC 351601843), a nearby ($d$ = 61.4 pc) late K-/early M-dwarf star, using data from the Transiting Exoplanet Survey Satellite (TESS). The newly discovered planet has a radius of $1.791^{+0.116}_{-0.081}$ $R_{\oplus}$, and an orbital period of 0.605 days (14.5 hours). We precisely measure the planet mass to be $9.95^{+1.36}_{-1.30}$ $M_{\oplus}$ using radial velocity measurements obtained with the Planet Finder Spectrograph (PFS), mounted on the Magellan II telescope. Our radial velocity data also show a long-term trend, suggesting an additional planet in the system. While TOI-1075 b is expected to have a substantial H/He atmosphere given its size relative to the radius gap, its high density ($9.32^{+2.05}_{-1.85}$ $\rm{g/cm^3}$) is likely inconsistent with this possibility. We explore TOI-1075 b's location relative to the M-dwarf radius valley, evaluate the planet's prospects for atmospheric characterization, and discuss potential planet formation mechanisms. Studying the TOI-1075 system in the broader context of ultra-short period planetary systems is necessary for testing planet formation and evolution theories, density enhancing mechanisms, and for future atmospheric and surface characterization studies via emission spectroscopy with JWST., Comment: 24 pages, 9 figures, 6 tables. Accepted for publication in The Astronomical Journal

In the course of the past few years, diffusion models (DMs) have reached an unprecedented level of visual quality. However, relatively little attention has been paid to the detection of DM-generated images, which is critical to prevent adverse impacts on our society. In contrast, generative adversarial networks (GANs), have been extensively studied from a forensic perspective. In this work, we therefore take the natural next step to evaluate whether previous methods can be used to detect images generated by DMs. Our experiments yield two key findings: (1) state-of-the-art GAN detectors are unable to reliably distinguish real from DM-generated images, but (2) re-training them on DM-generated images allows for almost perfect detection, which remarkably even generalizes to GANs. Together with a feature space analysis, our results lead to the hypothesis that DMs produce fewer detectable artifacts and are thus more difficult to detect compared to GANs. One possible reason for this is the absence of grid-like frequency artifacts in DM-generated images, which are a known weakness of GANs. However, we make the interesting observation that diffusion models tend to underestimate high frequencies, which we attribute to the learning objective., Comment: Accepted at VISAPP 2024. This is the extended version with additional experiments and supplemental material. Code and data: https://github.com/jonasricker/diffusion-model-deepfake-detection

We report the discovery of three transiting low-mass companions to aged stars: a brown dwarf (TOI-2336b) and two objects near the hydrogen burning mass limit (TOI-1608b and TOI-2521b). These three systems were first identified using data from the Transiting Exoplanet Survey Satellite (TESS). TOI-2336b has a radius of $1.05\pm 0.04\ R_J$, a mass of $69.9\pm 2.3\ M_J$ and an orbital period of 7.71 days. TOI-1608b has a radius of $1.21\pm 0.06\ R_J$, a mass of $90.7\pm 3.7\ M_J$ and an orbital period of 2.47 days. TOI-2521b has a radius of $1.01\pm 0.04\ R_J$, a mass of $77.5\pm 3.3\ M_J$ and an orbital period of 5.56 days. We found all these low-mass companions are inflated. We fitted a relation between radius, mass and incident flux using the sample of known transiting brown dwarfs and low-mass M dwarfs. We found a positive correlation between the flux and the radius for brown dwarfs and for low-mass stars that is weaker than the correlation observed for giant planets. We also found that TOI-1608 and TOI-2521 are very likely to be spin-orbit synchronized, leading to the unusually rapid rotation of the primary stars considering their evolutionary stages. Our estimates indicate that both systems have much shorter spin-orbit synchronization timescales compared to their ages. These systems provide valuable insights into the evolution of stellar systems with brown dwarf and low-mass stellar companions influenced by tidal effects., Comment: 23 pages, 15 figures; Published in MNRAS

The Transiting Exoplanet Survey Satellite mission identified a deep and asymmetric transit-like signal with a periodicity of 4.5 days orbiting the M4 dwarf star TOI-3884. The signal has been confirmed by follow-up observations collected by the ExTrA facility and Las Cumbres Observatory Global Telescope, which reveal that the transit is chromatic. The light curves are well modelled by a host star having a large polar spot transited by a 6-R$_{\oplus}$ planet. We validate the planet with seeing-limited photometry, high-resolution imaging, and radial velocities. TOI-3884 b, with a radius of $6.00 \pm 0.18$ R$_{\oplus}$, is the first sub-Saturn planet transiting a mid-M dwarf. Owing to the host star's brightness and small size, it has one of the largest transmission spectroscopy metrics for this planet size and becomes a top target for atmospheric characterisation with the James Webb Space Telescope and ground-based telescopes., Comment: 13 pages, 13 figures, accepted for publication in A&A Letters

The current architecture of a given multi-planetary system is a key fingerprint of its past formation and dynamical evolution history. Long-term follow-up observations are key to complete their picture. In this paper we focus on the confirmation and characterization of the components of the TOI-969 planetary system, where TESS detected a Neptune-size planet candidate in a very close-in orbit around a late K-dwarf star. We use a set of precise radial velocity observations from HARPS, PFS and CORALIE instruments covering more than two years in combination with the TESS photometric light curve and other ground-based follow-up observations to confirm and characterize the components of this planetary system. We find that TOI-969 b is a transiting close-in ($P_b\sim 1.82$ days) mini-Neptune planet ($m_b=9.1^{+1.1}_{-1.0}$ M$_{\oplus}$, $R_b=2.765^{+0.088}_{-0.097}$ R$_{\oplus}$), thus placing it on the {lower boundary} of the hot-Neptune desert ($T_{\rm eq,b}=941\pm31$ K). The analysis of its internal structure shows that TOI-969 b is a volatile-rich planet, suggesting it underwent an inward migration. The radial velocity model also favors the presence of a second massive body in the system, TOI-969 c, with a long period of $P_c=1700^{+290}_{-280}$ days and a minimum mass of $m_{c}\sin{i_c}=11.3^{+1.1}_{-0.9}$ M$_{\rm Jup}$, and with a highly-eccentric orbit of $e_c=0.628^{+0.043}_{-0.036}$. The TOI-969 planetary system is one of the few around K-dwarfs known to have this extended configuration going from a very close-in planet to a wide-separation gaseous giant. TOI-969 b has a transmission spectroscopy metric of 93, and it orbits a moderately bright ($G=11.3$ mag) star, thus becoming an excellent target for atmospheric studies. The architecture of this planetary system can also provide valuable information about migration and formation of planetary systems., Comment: Accepted for publication in A&A. 25 pages, 15 figures, 12 tables

The HD108236 system was first announced with the detection of four small planets based on TESS data. Shortly after, the transit of an additional planet with a period of 29.54d was serendipitously detected by CHEOPS. In this way, HD108236 (V=9.2) became one of the brightest stars known to host five small transiting planets (R$_p$<3R$_{\oplus}$). We characterize the planetary system by using all the data available from CHEOPS and TESS space missions. We use the flexible pointing capabilities of CHEOPS to follow up the transits of all the planets in the system, including the fifth transiting body. After updating the host star parameters by using the results from Gaia eDR3, we analyzed 16 and 43 transits observed by CHEOPS and TESS, respectively, to derive the planets physical and orbital parameters. We carried out a timing analysis of the transits of each of the planets of HD108236 to search for the presence of transit timing variations. We derived improved values for the radius and mass of the host star (R$_{\star}$=0.876$\pm$0.007 R$_{\odot}$ and M$_{\star}$=0.867$_{-0.046}^{+0.047}$ M$_{\odot}$). We confirm the presence of the fifth transiting planet f in a 29.54d orbit. Thus, the system consists of five planets of R$_b$=1.587$\pm$0.028, R$_c$=2.122$\pm$0.025, R$_d$=2.629$\pm$0.031, R$_e$=3.008$\pm$0.032, and R$_f$=1.89$\pm$0.04 [R$_{\oplus}$]. We refine the transit ephemeris for each planet and find no significant transit timing variations for planets c, d, and e. For planets b and f, instead, we measure significant deviations on their transit times (up to 22 and 28 min, respectively) with a non-negligible dispersion of 9.6 and 12.6 min in their time residuals. We confirm the presence of planet f and find no significant evidence for a potential transiting planet in a 10.9d orbital period, as previously suggested. Full abstract in the PDF file., Comment: 18 Figures and 25 pages. Accepted for publication in A&A

Convergent disk migration has long been suspected to be responsible for forming planetary systems with a chain of mean-motion resonances (MMR). Dynamical evolution over time could disrupt the delicate resonant configuration. We present TOI-1136, a 700-Myr-old G star hosting at least 6 transiting planets between $\sim$2 and 5 $R_\oplus$. The orbital period ratios deviate from exact commensurability by only $10^{-4}$, smaller than the $\sim$\,$10^{-2}$ deviations seen in typical Kepler near-resonant systems. A transit-timing analysis measured the masses of the planets (3-8$M_\oplus$) and demonstrated that the planets in TOI-1136 are in true resonances with librating resonant angles. Based on a Rossiter-McLaughlin measurement of planet d, the star's rotation appears to be aligned with the planetary orbital planes. The well-aligned planetary system and the lack of detected binary companion together suggest that TOI-1136's resonant chain formed in an isolated, quiescent disk with no stellar fly-by, disk warp, or significant axial asymmetry. With period ratios near 3:2, 2:1, 3:2, 7:5, and 3:2, TOI-1136 is the first known resonant chain involving a second-order MMR (7:5) between two first-order MMR. The formation of the delicate 7:5 resonance places strong constraints on the system's migration history. Short-scale (starting from $\sim$0.1 AU) Type-I migration with an inner disk edge is most consistent with the formation of TOI-1136. A low disk surface density ($\Sigma_{\rm 1AU}\lesssim10^3$g~cm$^{-2}$; lower than the minimum-mass solar nebula) and the resultant slower migration rate likely facilitated the formation of the 7:5 second-order MMR. TOI-1136's deep resonance suggests that it has not undergone much resonant repulsion during its 700-Myr lifetime. One can rule out rapid tidal dissipation within a rocky planet b or obliquity tides within the largest planets d and f., Comment: 48 pages, 23 figures, 8 tables. Accepted to AAS journals. Comments welcome!

We present an estimate of the occurrence rate of hot Jupiters ($7\ R_{\oplus}\leq R_{p}\leq 2\ R_{J}$, $0.8 \leq P_{b}\leq 10$ days) around early-type M dwarfs based on stars observed by TESS during its Primary Mission. We adopt stellar parameters from the TESS Input Catalog, and construct a sample of 60,819 M dwarfs with $10.5 \leq T_{\rm mag}\leq 13.5$, effective temperature $2900 \leq T_{\rm eff}\leq 4000\ K$ and stellar mass $0.45\leq M_{\ast}\leq 0.65\ M_{\odot}$. We conduct a uninformed transit search using a detection pipeline based on the box least square search and characterize the searching completeness through an injection and recovery experiment. We combine a series of vetting steps including light centroid measurement, odd/even and secondary eclipse analysis, rotation and transit period synchronization tests as well as inspecting the ground-based photometric, spectroscopic and imaging observations. Finally, we find a total of nine planet candidates, all of which are known TESS objects of interest. We obtain an occurrence rate of $0.27\pm0.09\%$ for hot Jupiters around early-type M dwarfs that satisfy our selection criteria. Compared with previous studies, the occurrence rate of hot Jupiters around early-type M dwarfs is smaller than all measurements for FGK stars, although they are consistent within 1--2$\sigma$. Combining results from transit, radial velocity and microlensing surveys, we find that hot Jupiters around early-type M dwarfs possibly show a steeper decrease in occurrence rate per logarithmic semi-major axis bin (${{\rm d}N}/{\rm d}\log_{10} a$) when compared with FGK stars., Comment: 34 pages, 18 figures, accepted for publication in AJ

Transiting exoplanets orbiting young nearby stars are ideal laboratories for testing theories of planet formation and evolution. However, to date only a handful of stars with age <1 Gyr have been found to host transiting exoplanets. Here we present the discovery and validation of a sub-Neptune around HD 18599, a young (300 Myr), nearby (d=40 pc) K star. We validate the transiting planet candidate as a bona fide planet using data from the TESS, Spitzer, and Gaia missions, ground-based photometry from IRSF, LCO, PEST, and NGTS, speckle imaging from Gemini, and spectroscopy from CHIRON, NRES, FEROS, and Minerva-Australis. The planet has an orbital period of 4.13 d, and a radius of 2.7Rearth. The RV data yields a 3-sigma mass upper limit of 30.5Mearth which is explained by either a massive companion or the large observed jitter typical for a young star. The brightness of the host star (V~9 mag) makes it conducive to detailed characterization via Doppler mass measurement which will provide a rare view into the interior structure of young planets., Comment: submitted to MNRAS

We present 2D hydrodynamical simulations of the transition of a proto-planetary nebula to a planetary nebula for central stars in binary systems that have undergone a common envelope event. After 1,000 yr of magnetically driven dynamics (proto-planetary nebula phase), a line-driven stellar wind is introduced into the computational domain and the expansion of the nebula is simulated for another 10,000 yr, including the effects of stellar photoionization. In this study we consider central stars with main sequence (final) masses of 1 (0.569) and 2.5 (0.677) \Mo, together with a 0.6 \Mo ma in sequence companion. Extremely bipolar, narrow-waisted proto-planetary nebulae result in bipolar planetary nebulae, while the rest of the shapes mainly evolve into elliptical planetary nebulae. The initial magnetic field's effects on the collimated structures, such as jets, tend to disappear in most of the cases, leaving behind the remnants of those features in only a few cases. Equatorial zones fragmented mainly by photoionization ( 1 \Mo progenitors), result in ``necklace'' structures made of cometary clumps aligned with the radiation field. On the other hand, fragmentation by photoionization and shocked wind ( 2.5 \Mo progenitors) give rise to the formation of multiple clumps in the latitudinal direction, which remain within the lobes, close to the center, which are immersed and surrounded by hot shocked gas, not necessarily aligned with the radiation field. These results reveal that the fragmentation process has a dependence on the stellar mass progenitor. This fragmentation is made possible by the distribution of gas in the previous post-common envelope proto-planetary nebula as sculpted by the action of the jets., Comment: 12 pages, 7 figures, accepted by MNRAS

Hot jupiters (P < 10 d, M > 60 $\mathrm{M}_\oplus$) are almost always found alone around their stars, but four out of hundreds known have inner companion planets. These rare companions allow us to constrain the hot jupiter's formation history by ruling out high-eccentricity tidal migration. Less is known about inner companions to hot Saturn-mass planets. We report here the discovery of the TOI-2000 system, which features a hot Saturn-mass planet with a smaller inner companion. The mini-neptune TOI-2000 b ($2.70 \pm 0.15 \,\mathrm{R}_\oplus$, $11.0 \pm 2.4 \,\mathrm{M}_\oplus$) is in a 3.10-day orbit, and the hot saturn TOI-2000 c ($8.14^{+0.31}_{-0.30} \,\mathrm{R}_\oplus$, $81.7^{+4.7}_{-4.6} \,\mathrm{M}_\oplus$) is in a 9.13-day orbit. Both planets transit their host star TOI-2000 (TIC 371188886, V = 10.98, TESS magnitude = 10.36), a metal-rich ([Fe/H] = $0.439^{+0.041}_{-0.043}$) G dwarf 174 pc away. TESS observed the two planets in sectors 9-11 and 36-38, and we followed up with ground-based photometry, spectroscopy, and speckle imaging. Radial velocities from CHIRON, FEROS, and HARPS allowed us to confirm both planets by direct mass measurement. In addition, we demonstrate constraining planetary and stellar parameters with MIST stellar evolutionary tracks through Hamiltonian Monte Carlo under the PyMC framework, achieving higher sampling efficiency and shorter run time compared to traditional Markov chain Monte Carlo. Having the brightest host star in the V band among similar systems, TOI-2000 b and c are superb candidates for atmospheric characterization by the JWST, which can potentially distinguish whether they formed together or TOI-2000 c swept along material during migration to form TOI-2000 b., Comment: v3 adds RV frequency analysis; 25 pages, 11 figures, 14 tables; revision submitted to MNRAS; machine-readable tables available as ancillary files; posterior samples available from Zenodo at https://doi.org/10.5281/zenodo.7683293 and source code at https://doi.org/10.5281/zenodo.7988268

We present a validation of the long-period ($91.68278^{+0.00032}_{-0.00041}$ days) transiting sub-Neptune planet TOI-1221 b (TIC 349095149.01) around a Sun-like (m$_{\rm V}$=10.5) star. This is one of the few known exoplanets with period >50 days, and belongs to the even smaller subset of which have bright enough hosts for detailed spectroscopic follow-up. We combine TESS light curves and ground-based time-series photometry from PEST (0.3~m) and LCOGT (1.0~m) to analyze the transit signals and rule out nearby stars as potential false positive sources. High-contrast imaging from SOAR and Gemini/Zorro rule out nearby stellar contaminants. Reconnaissance spectroscopy from CHIRON sets a planetary scale upper mass limit on the transiting object (1.1 and 3.5 M$_{\rm Jup}$ at 1$\sigma$ and 3$\sigma$, respectively) and shows no sign of a spectroscopic binary companion. We determine a planetary radius of $R_{\rm p} = 2.91^{+0.13}_{-0.12} R_{\oplus}$, placing it in the sub-Neptune regime. With a stellar insolation of $S = 6.06^{+0.85}_{-0.77}\ S_{\oplus}$, we calculate a moderate equilibrium temperature of $T_{\rm eq} =$ 440 K, assuming no albedo and perfect heat redistribution. We find a false positive probability from TRICERATOPS of FPP $ = 0.0014 \pm 0.0003$ as well as other qualitative and quantitative evidence to support the statistical validation of TOI-1221 b. We find significant evidence (>$5\sigma$) of oscillatory transit timing variations, likely indicative of an additional non-transiting planet., Comment: 17 pages, 9 figures, 4 tables

We present the Distant Giants Survey, a three-year radial velocity (RV) campaign to measure P(DG|CS), the conditional occurrence of distant giant planets (DG; M_p ~ 0.3 - 13 M_J, P > 1 year) in systems hosting a close-in small planet (CS; R_p < 10 R_E). For the past two years, we have monitored 47 Sun-like stars hosting small transiting planets detected by TESS. We present the selection criteria used to assemble our sample and report the discovery of two distant giant planets, TOI-1669 b and TOI-1694 c. For TOI-1669 b we find that Msin i = 0.573 +/- 0.074 M_J, P = 502 +/- 16 days, and e < 0.27, while for TOI-1694 c, Msin i = 1.05 +/- 0.05 M_J, P = 389.2 +/- 3.9 days, and e = 0.18 +/- 0.05. We also confirmed the 3.8-day transiting planet TOI-1694 b by measuring a true mass of M = 26.1 +/- 2.2 M_E. We also confirmed the 3.8-day transiting planet TOI-1694 b by measuring a true mass of M = 26.1 +/- 2.2 M_E. At the end of the Distant Giants Survey, we will incorporate TOI-1669 b and TOI-1694 c into our calculation of P(DG|CS), a crucial statistic for understanding the relationship between outer giants and small inner companions.