TOI-1695 b:A Water World Orbiting an Early-M Dwarf in the Planet Radius Valley

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 (Tmag = 11.0294 ± 0.0074, Ms = 0.513 ± 0.012 M⊙, Rs = 0.515 ± 0.015 R⊙, and Teff = 3690 ± 50 K): TOI-1695 b (P = 3.13 days and Rp = 1.90−0.14+0.16 R⊕ ). 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 ± 1.00 M⊕, 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.</p

RNA G‑Quadruplex Invasion and Translation Inhibition by Antisense γ‑Peptide Nucleic Acid Oligomers

We have examined the abilities of three complementary γ-peptide nucleic acid (γPNA) oligomers to invade an RNA G-quadruplex and potently inhibit translation of a luciferase reporter transcript containing the quadruplex-forming sequence (QFS) within its 5′-untranslated region. All three γPNA oligomers bind with low nanomolar affinities to an RNA oligonucleotide containing the QFS. However, while all probes inhibit translation with low to midnanomolar IC₅₀ values, the γPNA designed to hybridize to the first two G-tracts of the QFS and adjacent 5′-overhanging nucleotides was 5–6 times more potent than probes directed to either the 3′-end or internal regions of the target at 37 °C. This position-dependent effect was eliminated after the probes and target were preincubated at an elevated temperature prior to translation, demonstrating that kinetic effects exert significant control over quadruplex invasion and translation inhibition. We also found that antisense γPNAs exhibited similarly potent effects against luciferase reporter transcripts bearing QFS motifs having G₂, G₃, or G₄ tracts. Finally, our results indicate that γPNA oligomers exhibit selectivity and/or potency higher than those of other antisense molecules such as standard PNA and 2′-OMe RNA previously reported to target G-quadruplexes in RNA

Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Year, Highly Eccentric Orbit

Radial velocity (RV) surveys have discovered giant exoplanets on au-scale orbits with a broad distribution of eccentricities. Those with the most eccentric orbits are valuable laboratories for testing theories of high eccentricity migration. However, few such exoplanets transit their host stars thus removing the ability to apply constraints on formation from their bulk internal compositions. We report the discovery of Kepler-1704 b, a transiting 4.15 $M_{\rm J}$ giant planet on a 988.88 day orbit with the extreme eccentricity of $0.921^{+0.010}_{-0.015}$. Our decade-long RV baseline from the Keck I telescope allows us to measure the orbit and bulk heavy element composition of Kepler-1704 b and place limits on the existence of undiscovered companions. Kepler-1704 b is a failed hot Jupiter that was likely excited to high eccentricity by scattering events that possibly began during its gas accretion phase. Its final periastron distance was too large to allow for tidal circularization, so now it orbits it host from distances spanning 0.16 - 3.9 au. The maximum difference in planetary equilibrium temperature resulting from this elongated orbit is over 700 K. A simulation of the thermal phase curve of Kepler-1704 b during periastron passage demonstrates that it is a remarkable target for atmospheric characterization from the James Webb Space Telescope, which could potentially also measure the planet's rotational period as the hot spot from periastron rotates in and out of view. Continued characterization of the Kepler-1704 system promises to refine theories explaining the formation of hot Jupiters and cool giant planets like those in the solar system

Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Year, Highly Eccentric Orbit

Radial velocity (RV) surveys have discovered giant exoplanets on au-scale orbits with a broad distribution of eccentricities. Those with the most eccentric orbits are valuable laboratories for testing theories of high eccentricity migration. However, few such exoplanets transit their host stars thus removing the ability to apply constraints on formation from their bulk internal compositions. We report the discovery of Kepler-1704 b, a transiting 4.15 $M_{\rm J}$ giant planet on a 988.88 day orbit with the extreme eccentricity of $0.921^{+0.010}_{-0.015}$. Our decade-long RV baseline from the Keck I telescope allows us to measure the orbit and bulk heavy element composition of Kepler-1704 b and place limits on the existence of undiscovered companions. Kepler-1704 b is a failed hot Jupiter that was likely excited to high eccentricity by scattering events that possibly began during its gas accretion phase. Its final periastron distance was too large to allow for tidal circularization, so now it orbits it host from distances spanning 0.16 - 3.9 au. The maximum difference in planetary equilibrium temperature resulting from this elongated orbit is over 700 K. A simulation of the thermal phase curve of Kepler-1704 b during periastron passage demonstrates that it is a remarkable target for atmospheric characterization from the James Webb Space Telescope, which could potentially also measure the planet's rotational period as the hot spot from periastron rotates in and out of view. Continued characterization of the Kepler-1704 system promises to refine theories explaining the formation of hot Jupiters and cool giant planets like those in the solar system

Masses, revised radii, and a third planet candidate in the “Inverted” planetary system around TOI-1266

Funding: RC acknowledges support from the Natural Sciences and Engineering Council of Canada (NSERC) and the Banting Postdoctoral Fellowship Program administered by the Government of Canada. MP acknowledges the financial support from the Agenzia Spaziale Italiana-Istituto Nazionale di Astrofisica (ASI-INAF) Addendum no. 2018-24-HH.1-2022 ‘Partecipazione italiana al Gaia DPAC – Operazioni e attività analisi dati’. FR is funded by the University of Exeter’s College of Engineering, Maths and Physical Sciences, UK.Is the population of close-in planets orbiting M dwarfs sculpted by thermally driven escape or is it a direct outcome of the planet formation process? A number of recent empirical results strongly suggest the latter. However, the unique architecture of the TOI-1266 system presents a challenge to models of planet formation and atmospheric escape given its seemingly ‘inverted’ architecture of a large sub-Neptune (Pb = 10.9 d, Rp,b = 2.62 ± 0.11 R⊕) orbiting interior to that of the system’s smaller planet (Pc = 18.8 d, Rp,c = 2.13 ± 0.12 R⊕). Here, we present revised planetary radii based on new TESS and diffuser-assisted ground-based transit observations, and characterize both planetary masses using a set of 145 radial velocity measurements from HARPS-N (Mp,b = 4.23 ± 0.69 M⊕, Mp,c = 2.88 ± 0.80 M⊕). Our analysis also reveals a third planet candidate (Pd = 32.3 d, Mp,d sin i = 4.59+0.96-0.94, M⊕), which if real, would form a chain of near 5:3 period ratios, although the system is likely not in a mean motion resonance. Our results indicate that TOI-1266 b and c are among the lowest density sub-Neptunes around M dwarfs and likely exhibit distinct bulk compositions of a gas-enveloped terrestrial (Xenv,b = 5.5 ± 0.7 per cent) and a water-rich world (WMFc = 59 ± 14 per cent), which is supported by hydrodynamic escape models. If distinct bulk compositions are confirmed through atmospheric characterization, the system’s unique architecture would represent an interesting test case of inside-out sub-Neptune formation at pebble traps.Publisher PDFPeer reviewe

New Mass and Radius Constraints on the LHS 1140 Planets -- LHS 1140 b is Either a Temperate Mini-Neptune or a Water World

LHS 1140 b and c are two small temperate exoplanets transiting a nearby M4.5 dwarf. The planetary system was observed with multiple facilities since its discovery in 2017, including MEarth, $Spitzer$, HARPS, ESPRESSO, HST, and TESS, placing strong constraints on the physical parameters of the planets and star. Here, we reanalyse the publicly available ESPRESSO observations of LHS 1140 with the novel line-by-line framework designed to fully exploit the radial velocity content of a stellar spectrum while being resilient to outlier measurements. This analysis reduces radial velocity uncertainties by 60% compared with published values derived from the cross-correlation function method. This improvement, combined with updated stellar parameters, consolidates our knowledge on the mass of LHS 1140 b (5.60$\pm$0.19 M$_{\oplus}$) and LHS 1140 c (1.91$\pm$0.06 M$_{\oplus}$) with unprecedented precision (3%). A joint analysis of transit data obtained with $Spitzer$, HST, and TESS allows us to refine the planetary radius for b (1.730$\pm$0.025 R$_{\oplus}$) and c (1.272$\pm$0.026 R$_{\oplus}$). Stellar abundance measurements of refractory elements (Fe, Mg and Si) obtained with NIRPS are used to constrain the internal structure of LHS 1140 b. This habitable zone planet is unlikely to be a rocky super-Earth, but rather a mini-Neptune with a $\sim$0.1% H/He-rich mass envelope or a water world with a water-mass fraction between 9 and 19% depending on the atmospheric composition and relative abundance of Fe and Mg. Although LHS 1140 c remains consistent with a rocky planet, we detect a 4$σ$ discrepancy in the transit depths measured by $Spitzer$ and TESS. Finally, we find no evidence of the candidate LHS 1140 d and attribute this 80-day signal to stellar activity