arXiv subjects

Biel Escolà-Rodrigo

Publications and source records attributed to Biel Escolà-Rodrigo.

3 recordsLinked to original sources

arXiv2026

Comprehensive Statistical Validation of TOI-7701.01: A Sub-Saturn Companion at the Giant Planet Boundary

We present the formal statistical validation of TOI-7701.01 (TIC 122522333), a sub-Saturn transiting companion candidate orbiting a bright F-type subgiant host star ($V=11.09$). Initially detected via an automated machine-learning transit survey by Salinas et al. (2025), the planetary nature of this signal remained unclear. We implement an independent vetting and statistical pipeline leveraging multi-sector space kinematics and the \texttt{triceratops} Bayesian framework to compute false positive scenarios. A key methodological finding is the structural convergence of the companion's physical scale; despite utilizing un-detrended Simple Aperture Photometry (SAP) with a raw depth of $2417$ ppm to preserve field dilution metrics, the \texttt{triceratops} MCMC engine naturally converges on a physical radius of $7.86\,R_\oplus$ under the dominant Target Planet scenario ($\mathcal{P}_{\rm TP} = 78.1\%$). This independent statistical derivation matches the geometric radius of $8.07\,R_\oplus$ inferred directly from the instrumentally corrected Pre-Search Data Conditioning (PDCSAP) data. By aggregating our multi-iteration ensemble to suppress MCMC stochasticity, we derive a robust global False Positive Probability ($\mathrm{FPP} = 0.00191$) and a Nearby False Positive Probability ($\mathrm{NFPP} < 10^{-6}$), firmly validating the companion well below the rigorous $1.5\%$ threshold established for this Bayesian framework. While the derived $7.8\text{--}8.1\,R_\oplus$ radius places the object at the boundary between giant planets and low-mass brown dwarfs, such a radius is highly atypical for a brown dwarf, pointing to a planetary nature. We report TOI-7701.01 as a validated companion and encourage prompt radial velocity characterization.

astro-ph.EP↗

arXiv2026

Statistical Validation and Photometric Characterization of the Hot Jupiter Candidate TOI 7475.01

We present the statistical validation and full photometric characterization of the exoplanet candidate TOI 7475.01 (TIC 376866659), detected by the TESS mission. Using a custom pipeline combining natural flux preservation with robust BLS detection, we identified a transit signal with a period of $3.2538$ days and a depth of $\sim 4600$ ppm. To rule out false positives, we performed centroid analysis, spatial contamination checks using Gaia DR3, and a statistical validation using TRICERATOPS. Our results show a Signal-to-Noise Ratio (SNR) of 294.13 and a False Positive Probability (FPP) of $\approx 0$. Based on the clean spatial environment, stable centroids, and high statistical probability, we validate TOI 7475.01 as a planetary companion. We subsequently performed a Bayesian transit fit using juliet with Dynesty nested sampling, and derived physical parameters via Monte Carlo error propagation. We find a planetary radius of $R_p = 1.18^{+0.39}_{-0.40}\ R_\mathrm{Jup}$ and an equilibrium temperature of $T_\mathrm{eq} = 1455^{+77}_{-56}$ K, consistent with a hot Jupiter classification. The planet mass is estimated at $M_p \approx 2.2\ M_\mathrm{Jup}$ (MAP) via the Chen&Kipping mass-radius relation; radial velocity follow-up is required for a precise measurement. The impact parameter remains unconstrained ($b = 0.46 \pm 0.34$), a limitation of single-band TESS photometry that future CHEOPS observations could resolve.

astro-ph.EP↗

arXiv2026

Vetting and False Positive Analysis of TOI 864.01: Evidence for a Likely Hierarchical Eclipsing Binary Masked by Dilution

We present a detailed vetting analysis of the TESS candidate TOI 864.01, initially identified as a potential ultra-short-period (P ~ 0.52 d) Earth-sized planet orbiting an M-dwarf. Using 12 sectors of TESS photometry spanning a multi-year baseline, we recover a robust periodic transit-like signal. While the recovered transit depth is attenuated by detrending (~ 158 ppm), the SPOC pipeline reports an undiluted depth of ~ 640 ppm. Stellar characterization based on Gaia DR3 astrometry yields a nominally single-star solution (RUWE = 1.18), highlighting the limitations of astrometric vetting for tight companions. We performed a statistical validation analysis using TRICERATOPS, aggregating data from all 12 available sectors. The analysis yields a False Positive Probability (FPP) of 0.25 and a Nearby False Positive Probability (NFPP) of < 10^-4. While these metrics ostensibly classify the target as a viable planetary candidate based on Gaia-resolved sources, they fail to account for sub-pixel companions. Crucially, archival high-resolution imaging from the TESS Follow-up Observing Program (TFOP SG1) reveals a stellar companion at a separation of 0.04", unresolved by both Gaia and TESS. When this companion is considered, the signal is best interpreted as a Hierarchical Eclipsing Binary (HEB) on the companion. Bayesian model comparison yields an inconclusive result (Delta ln Z ~ 0.25), consistent with the degeneracy introduced by unresolved blending. Ground-based follow-up photometry further supports significant dilution, with a measured transit depth (~ 0.37 ppt) shallower than predicted (~ 0.64 ppt) and a timing offset of 6.3 minutes. Taken together, we classify TOI 864.01 as a probable False Positive and recommend its retirement from planetary candidate lists.

astro-ph.EP↗