arXiv subjects

Juan F. Pagés Navarrete

Publications and source records attributed to Juan F. Pagés Navarrete.

2 recordsLinked to original sources

arXiv2026

Characterization of the Compact Multi-planet System TOI-789: Validation of Three Terrestrial Planets, Dynamical Characterization, and Detection of a Fourth Temperate Candidate

We present the validation and dynamical characterization of TOI-789 (TIC 300710077), a compact multi-planet system around an M3 dwarf at 43 pc. Using ~7 yr of TESS photometry (42 sectors), public ground-based follow-up (LCOGT, MEarth), and high-resolution imaging (Gemini/Zorro, SOAR), we statistically validate three terrestrial planets with TRICERATOPS: TOI-789 b (Rp = 1.18 Rearth, P = 5.45 d), c (1.15 Rearth, 8.04 d), and d (1.40 Rearth, 12.97 d), with false-positive and nearby-false-positive probabilities below the validation thresholds once resolved neighbours are excluded using the on-target ground-based photometry. Through an iterative Transit Least Squares search we identify a fourth, previously uncatalogued planet candidate (P = 19.74 d, Rp ~ 0.88 Rearth), the outermost and most temperate member (S = 1.71 Searth, Teq ~ 292 K); its low signal-to-noise ratio precludes formal validation, so we report it as a candidate pending confirmation. A dynamical analysis (SPOCK and N-body integrations) indicates a dynamically cold, near-resonant system, stable only for low eccentricities (e < 0.05), eccentricity rather than mass limiting stability; including the fourth candidate tightens this further. The four objects span the Earth-Venus transition across the Venus zone, two validated planets falling in the temperate regime under the equilibrium-temperature criterion, making the system a potential comparative-planetology laboratory anchored on confirmed planets. The low TSM (~3-5) and moderate host brightness place atmospheric characterization beyond reach. TOI-789 exemplifies the numerically dominant population of compact terrestrial-planet systems around M dwarfs whose characterization is limited by host brightness, for which dynamical characterization offers a complementary route.

astro-ph.EP↗

arXiv2026

Beyond gas dwarfs and water worlds: hybrid envelopes among the M-dwarf sub-Neptunes characterised with JWST

Sub-Neptunes orbiting M dwarfs are commonly interpreted either as rocky cores beneath primordial H/He envelopes (gas dwarfs) or as volatile-rich bodies formed beyond the water-ice line (water worlds). Because the two are degenerate in mass and radius once envelope evolution is treated self-consistently, the atmospheric mean molecular weight $μ$ is the more direct discriminant. We compile the eight M-dwarf sub-Neptunes with published JWST transmission spectra and a constraint on $μ$, grade each constraint by the quality of the underlying evidence, and combine it with the restricted Jeans parameter and with energy-limited escape integrated over the system lifetime, using XUV histories from M-dwarf activity-age relations. Planets are classified by what their present composition implies about their origin. At the $μ= 3.8$ amu threshold adopted in the gas-dwarf literature, four planets fit neither end-member: their envelopes ($3.8 < μ\le 18$ amu) are too heavy for primordial H/He, yet neither their composition nor their escape history requires a volatile-rich origin. Two of these assignments rest on molecular detections (LP 791-18 c and TOI-270 d) and two on bounded or conditional metallicities. One planet, LHS 1140 b, requires a volatile-rich origin; one, TOI-776 c, is tentatively a gas dwarf; two remain ambiguous. We propose the term hybrid worlds for the intermediate class, whose envelopes can be produced by magma-ocean equilibration, supercritical miscibility, preferential hydrogen loss or accretion interior to the ice line. The count depends on the adopted threshold (three planets at 5 amu, one at 10 amu), but no threshold leaves both end-member classes physically consistent. The sample is set by JWST target selection, so these fractions are not occurrence rates; a homogeneous survey testing whether $μ$ is bimodal would test the proposed class directly.

astro-ph.EP↗