arXiv subjects

A. Bello-Arufe

Publications and source records attributed to A. Bello-Arufe.

3 recordsLinked to original sources

arXiv2026

Biosignature detectability on transiting habitable worlds with ELT/ANDES

The search for life beyond the Solar System is at a turning point, transitioning from theoretical predictions to observations enabled by next-generation observatories. The Extremely Large Telescope (ELT) will host the ArmazoNes high Dispersion Echelle Spectrograph (ANDES), optimized for visible-to-near-infrared high-resolution spectroscopy. We present a simulation--detection pipeline and evaluate the detectability of CO$_2$, H$_2$O, and the biosignature gases O$_2$ and CH$_4$ in high-resolution transmission spectroscopy of transiting habitable-zone rocky planets with ANDES. Assuming cloud-free, modern Earth-like atmospheres, we model transmission spectra using noise estimates from the ANDES Exposure Time Calculator, based on the latest preliminary instrument design in seeing-limited mode. We introduce a novel Bayesian cross-correlation function (CCF) framework that incorporates molecule-specific kernels and a new autoregressive model to account for correlations in the CCF. We apply our framework to 18 known potentially habitable transiting exoplanets and estimate the number of transits required for a decisive detection ($\log_{10} B \ge 2.0$). We find that H$_2$O is the most accessible species, with potential detections in 10-19 transits for the TRAPPIST-1 planets and 30 transits for LHS 1140 b. CO$_2$, CH$_4$, and O$_2$ are more difficult to detect, requiring approximately 1.5, 3, and 4 times as many transits as H$_2$O. These estimates are lower limits that assume favorable observing conditions, perfect detrending, and the absence of systematics, yet still imply large observing campaigns. Alternative approaches, such as reflected-light high-dispersion coronagraphy of nearby nontransiting planets, may offer a promising complementary route for biosignature searches.

astro-ph.EP↗

arXiv2024

JWST reveals a rapid and strong day side variability of 55 Cancri e

The nature of the close-in rocky planet 55 Cnc e is puzzling despite having been observed extensively. Its optical and infrared occultation depths show temporal variability, in addition to a phase curve variability observed in the optical. We wish to explore the possibility that the variability originates from the planet being in a 3:2 spin-orbit resonance, thus showing different sides during occultations. We proposed and were awarded Cycle 1 time at the James Webb Space Telescope (JWST) to test this hypothesis. JWST/NIRCam observed five occultations (secondary eclipses), of which four were observed within a week, of the planet simultaneously at 2.1 and 4.5 μm. While the former gives band-integrated photometry, the latter provides a spectrum between 3.9-5.0 μm. We find that the occultation depths in both bandpasses are highly variable and change between a non-detection (-5 +/- 6 ppm and 7 +/- 9 ppm) to 96 +/- 8 ppm and 119 (+34) (-19) ppm at 2.1 μm and 4.5 μm, respectively. Interestingly, the variations in both bandpasses are not correlated and do not support the 3:2 spin-orbit resonance explanation. The measured brightness temperature at 4.5 μm varies between 873-2256 K and is lower than the expected dayside temperature of bare rock with no heat re-distribution (2500 K) which is indicative of an atmosphere. Our atmospheric retrieval analysis of occultation depth spectra at 4.5 μm finds that different visits statistically favour various atmospheric scenarios including a thin outgassed CO/CO2 atmosphere and a silicate rock vapour atmosphere. Some visits even support a flat line model. The observed variability could be explained by stochastic outgassing of CO/CO2, which is also hinted by retrievals. Alternatively, the variability, observed at both 2.1 and 4.5 μm, could be the result of a circumstellar patchy dust torus generated by volcanism on the planet.

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arXiv2021

The obliquity and atmosphere of the ultra-hot Jupiter TOI-1431b (MASCARA-5b): A misaligned orbit and no signs of atomic ormolecular absorptions

Ultra-hot Jupiters are defined as giant planets with equilibrium temperatures larger than 2000 K. Most of them are found orbiting bright A-F type stars, making them extremely suitable objects to study their atmospheres using high-resolution spectroscopy. Recent studies show a variety of atoms and molecules detected in the atmospheres of this type of planets. Here we present our analysis of the newly discovered ultra-hot Jupiter TOI-1431b/MASCARA-5b, using two transit observations with the HARPS-N spectrograph and one transit observation with the EXPRES spectrograph. Analysis of the Rossiter-McLaughlin effect shows that the planet is in a polar orbit, with a projected obliquity $ λ= -155^{+20}_{-10}$ degrees. Combining the nights and applying both cross-correlation methods and transmission spectroscopy, we find no evidences of CaI, FeI, FeII, MgI, NaI, VI, TiO, VO or H$α$ in the atmosphere of the planet. Our most likely explanation for the lack of atmospheric features is the large surface gravity of the planet.

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