ESA's MADRID-Area Exoplanet Science Meeting (MAESM) 2025

Programme (9 October 2025, ESAC B101 room and Webex)

Abstracts

Worldwide synergies in target lists for exoearth hunting (José Caballero,  CAB (CSIC-INTA)) [Slides] [Video]

Dozens of European astronomers, in collaboration with international colleagues, work on target lists for exoplanet hunting: from defining input catalogues to carefully characterising stellar parameters, through curation of data bases and cross-match with other archives. The target lists for CHEOPS (GTO), PLATO (LOPS2, LOPN1) and ARIEL from space, but also HARMONI (Planets and discs) at the ELT or HARPS-3 (THE) at the Isaac Newton Telescope from the ground, are representative examples. 
Thanks to my previous experience with the input catalogue for CARMENES, which has discovered dozens of exoplanets in the solar neighbourhood, including some of the planets with the greatest Earth-similarity index, I am deeply involved in the target list working groups of the Large Interferometer For Exoplanets (LIFE, a proposal for ESA's Voyage 2050 that fits the 'temperate exoplanet' theme) and Habitable Worlds Observatory (HWO, the next NASA Great Observatory to which ESA may contribute). 
Since LIFE and HWO will observe very similar, complementary targets, we are starting conversations between European and US astronomers to share ideas and resources on LIFE and HWO target input catalogues for maximising synergies and minimising overlaps. Tianlin, the Chinese exolife-searching space mission, may also join this initiative. The first example of this collaboration is a forthcoming joint LIFE+HWO proposal for SPHERE/VLT that also includes key HARMONI members. 'From space the Earth has no frontiers'.

The TROY project: exotrojan candidates hidden in the KEPLER data (Carmen Haukes,  CAB (CSIC-INTA)) [Slides] [Video]

New computational capabilities allow now to squeeze existing data to explore other parameter spaces of the exoplanet population. Despite the extensive amount of Kepler data available, systematic searches for co-orbital exoplanets (exotrojans) remain unexplored. In this work, as part of the TROY project, we present a new detection method based on the dynamical properties of these systems. We have developed a dedicated algorithm that enhances the identification of co-orbital configurations by orbital dynamics rather than traditional transit detection techniques. This approach not only offers a new paradigm for the detection of exotrojans but also maximizes the scientific potential of large datasets such as Kepler’s, with future applications for missions like PLATO. We will present the first results obtained with this method, highlighting its potential to uncover previously undetected co-orbital exoplanets (paper in preparation).

Looking closer at PDS 70: a third protoplanet? (Olga Balsalobre-Ruza,  CAB (CSIC-INTA))

The young PDS 70 system (~5 Myr) is home to the first two directly imaged protoplanets, PDS 70 b & c. It remains a benchmark target for probing planet formation processes, driving extensive observational campaigns across the spectra. A decade of near-infrared follow-up has led to the tentative identification of a third, inner companion (PDS 70 d), whose blue, flat spectrum challenges its planetary classification. In this talk, we will present new VLT/SPHERE observations exploiting state-of-the-art strategies to boost contrast at close separations from the star. We will share results on the morphology and dynamics of the candidate, along with the identification of additional, unexpected features. These findings open the door to alternative scenarios that are currently under active investigation.

RV characterization and detection limits of circumbinary planets: Kepler-38 and Kepler-1647 (Onė Mikulskytė, ESA - ESAC) [Slides] [Video]

Circumbinary planets (CBPs), planets orbiting binary star systems, offer unique insights into planet formation. However, they are challenging to detect using traditional methods. While photometric surveys such as Kepler and TESS have led to the discovery of around a dozen transiting CBPs, the majority of these systems lack precise mass measurements due to limitations of transit-based methods. Radial velocity (RV) observations provide a direct way to measure planetary masses and detect non-transiting CBPs.

Two circumbinary planets with some of the largest uncertainties on planet mass from the known catalogue are Kepler-38b - an <122 Earth Mass planet orbiting an 18.8d binary, and Kepler-1647b - an 483±206 Earth Mass planet orbiting an 11.3d binary. Kepler-1647b is notable for its unusually wide 1108-day orbit beyond the stability limit. In this talk I will present an analysis of CARMENES RV data of these extremely faint targets (V~13.5) to establish detection limits for additional planets, and update mass constraints using a full photodynamical fit.

Earthshine observations as a benchmark for rocky exoplanet characterization (Giulia Roccetti, ESA - ESAC) [Slides] [Video]

Future ground- and space-based facilities will enable the characterization of non-transiting rocky exoplanets through reflected light. To prepare for these observations, we study Earth as an exoplanet via Earthshine, which is the sunlight reflected from Earth onto the darker portion of the visible Moon, allowing observations at different phase angles. Previous models failed to reproduce Earth’s polarization spectra, revealing the need for more realistic surface and cloud treatments. We developed wavelength-dependent surface albedo maps that capture spatial and temporal variability, as well as a cloud generator that accurately models the 3D structure and radiative response of clouds. Using the full-3D Monte Carlo radiative transfer code MYSTIC, we reproduce a decade-long Earthshine polarization catalog in both intensity and polarization, establishing a benchmark Earth model. This model provides the foundation for generating spectra of rocky exoplanets across a wide parameter space using climate model outputs. Such a catalog guides reflected light observing strategies and enables investigation of the added value of polarization for probing surface features (such as ocean glint) and cloud properties (such as the primary rainbow), ultimately supporting robust habitability assessments and informing the design of future telescopes.

On the use of Gaia astrometry to identify planets and companions around Young Stars  (Miguel Vioque,  ESO) [Slides] [Video]

I will show how Gaia astrometry can be used to identify planets and companions around young stars. I will illustrate the power of this technique with several science cases, ranging from newly identified protoplanets within protoplanetary disks to a reassessment of multiplicity in populations of circumbinary and transition disks. Our results highlight the importance of giant protoplanets in shaping protoplanetary disks and the resulting planetary systems formed during the star-formation process. If time permits, I will also present our findings based on Gaia XP spectra, which provide new insights into disk evolution and, consequently, planet formation through measurements of accretion rates. I will conclude by looking ahead to the upcoming Gaia DR4 and the revolution it will bring for multiplicity studies and the detection of forming planets, once all individual epochs are released.

Unveiling Planetary Systems around Intermediate Mass Evolved Stars Using NIRPS (Elisa Delgado Mena,  CAB (CSIC-INTA)) [Slides] [Video]

The number of detected planets orbiting intermediate-mass stars is still low and several studies point to a sharp decrease in the planet occurrence around stars more massive than ∼2 Msun. To fill this gap in the planetary zoo we carried a radial-velocity (RV) survey of young open clusters K giants, the evolved counterparts of those intermediate-mass stars. A major challenge to detect such planets is the large jitter present in these cool giants. On top of that, we have detected intriguing RV signals which mimic long-period planets (P>650 days) and are stable for periods as long as 15 years. However, their origin is not clear yet. We present the first results of a survey done with HARPS+NIRPS. The combination of high precision optical and NIR RV points will serve to disentangle the stellar activity from the true planets and better understand the demographics of planets at large stellar masses.

Follow-up of exocomet host candidates (Paula Muñoz Cutanda,  OAN - IGN) [Slides] [Video]

Exocomets are small bodies that evaporate when they approach their host star. They are detected through variability of non-photospheric features with spectroscopy and/or asymmetric transits in time-series photometry. In the past four decades ∼30 systems have shown such variations. However, some publications have pointed out mechanisms that might mimic exocometary features, and therefore, careful monitoring is needed to confirm the origin of the observed variability. In this context, we revisited the exocomet nature of the non-photospheric variable features observed in three stars (HD 36546, HD 42111 and HD 85905) in new high-resolution spectra, obtained using new FIES/NOT and HERMES/Mercator. Strong variability was found for HD 85905, consistent with a potential link to exocometary activity but leaving room for other scenarios, such as binarity, that must be explored.

Investigating the lack of exomoons: Catalogues and dynamical constraints (Alicia Pérez Rodrigo,  UCM) [Slides] [Video]

Moons are ubiquitous in the Solar System, yet despite the discovery of more than 5,600 exoplanets no exomoon has been unambiguously confirmed. We investigate the reasons for this persistent non-detection by compiling a homogeneous catalogue of 24 reported exomoon candidates, including stellar, planetary, and putative lunar parameters. For each system we apply Hill, Roche, and Laplace stability criteria, and estimate detectability limits for current and forthcoming instruments. We further extend our analysis to 6,038 confirmed exoplanets, testing them against the same dynamical and mission-specific observational filters. Our results show that half of the reported candidates are dynamically unstable or produce signals below Kepler sensitivity, with only a subset (8 out of 13 with sufficient data) consistent with long-term survival. Applying observational filters highlights 23 promising targets for the PLATO mission, although most Solar-System-like moons remain below current thresholds. We conclude that the lack of exomoon detections likely results from a combination of inefficient formation of massive moons, early loss during planetary migration, and limited instrumental sensitivity, and suggest that future searches focus on long-period, massive planets around quiet stars to maximize discovery space.

GJ 357 b - A rocky world - hotter than expected (Merlin Zgraggen,  ESA - ESAC, University of Bern) [Slides] [Video]

The Hot Rocks Survey (PIs: Hannah Diamond-Lowe and João Mendonca) aims to test the thermal emission of 9 short-period rocky exoplanets around small stars using JWST MIRI/Imaging. One of them - GJ 357 b - shows an unexpected occultation depth (to be published soon). Atmospheric models - even bare rock and no-redistribution blackbody models - cannot explain its dayside temperature at more than 3σ. This occultation follows the recent results on TOI-1468 b, which also struggled to explain high occultation depths, by an even larger margin.
The observation on 11 May 2024 coincided with one of the strongest solar storms ever recorded. Earth and JWST were both affected, with aurorae visible at low latitudes. As a result, the rate of detector jumps on MIRI was an order of magnitude higher compared to other survey targets.
Since literature values of the system parameters did not constrain the fits sufficiently, a global fit of the GJ 357 system was performed to constrain orbital parameters (TESS, NIRSpec and MIRI/Imaging).
This talk will present the resulting data-analysis challenges, compare reduction and light-curve fitting approaches, and discuss possible solar and atmospheric scenarios for the hot rocky planet GJ 357 b (≈2 M⊕, 3.9-day orbit, M-dwarf host with Teff ≈ 3550 K). In addition, I will address the broader context of the Hot Rocks Survey, comparing GJ 357 b to other planets in the program and place it in context.

A Catalogue of Stellar Encounters with the Beta Pictoris System (Jose Luis Gragera Más,  CAB (CSIC-INTA)) [Slides] [Video]

β Pictoris is an A-type star with a rich planetary system: two giant planets, a massive debris disk, and even evidence of exocomets seen in its spectrum. One possible source of this dynamical activity is stellar flybys, which can perturb distant comets and send them into the inner system.

In this work, we searched for past and future stellar encounters that may have influenced β Pic’s comet population. Using Gaia DR3 data, combined with spectroscopic radial velocities, we traced the orbits of nearly 100,000 stars within 80 pc of β Pic backward and forward in time, and identified 49 stars—several of them binaries—that passed within 2 pc of the system over the last 1.5 Myr and into the next 2 Myr. While no single flyby appears strong enough to explain the prominent disc structures observed today, they may still affect the long-term evolution of a potential Oort Cloud around β Pic. This catalogue represents the most complete reconstruction of the system’s encounter history to date and provides a solid foundation for future dynamical simulations.

Towards a meaningful characterization of rocky exoplanets (Leonardos Gkouvelis,  LMU Munich) [Slides] [Video]

Recent advances in space- and ground-based facilities now allow the  atmospheric characterization of a selected sample of rocky exoplanets.  These planets offer key insights into formation and evolution, but  their interpretation requires models that couple atmospheric processes  with both the planetary interior and the surrounding space  environment. I will present a theoretical framework that treats both  the lower and upper atmospheric boundaries of rocky exoplanets. Using  LP 791-18 d as a case study, we link interior redox state and volcanic  outgassing to atmospheric composition and stability, finding that only  highly oxidized interiors can sustain atmospheres over geological  timescales. I then extend the modeling to airless rocky exoplanets,  introducing a new treatment of the opposition surge—a sharp  reflectance enhancement at small phase angles. Finally, I will discuss  how targeted photometric colors, accounting for the effects of hazes  and clouds, can help resolve observational degeneracies between thick  atmospheres and bare rock surfaces.

The influence of the inner disc on the properties of Herbig stars (Gwendolyn Meeus, UAM) [Slides] [Video]

The discs around young intermediate-mass stars (Herbigs) is the location where planets form. These protoplanetary discs have been studied extensively, and can be classified into 2 groups, depending on their geometry: flared with a gap (group I) or flat (group II) . Within group I, we can still distinguish between objects with an inner dust disc and those without. In this talk, I will present a study of the properties of Herbig stars, and the influence the presence of an inner disc has on those properties. In particular, we look at the accretion rate and the stellar metallicity.

Chemo-dynamic clues to the birthplaces of exoplanetary systems (Juan José García Delgado, UCM, UAH) [Slides] [Video]

As stars orbit the Galaxy, their trajectories are perturbed by gravitational interactions with the Milky Way’s major structures, such as the bar, spiral arms, and giant molecular clouds. While the dynamical influence of these structures on stellar motion is relatively well understood, their effects on planetary systems remain unexplored. We present a homogeneous sample of stars hosting confirmed exoplanets, built by crossmatching the Extrasolar Planets Encyclopaedia with Gaia DR3. Distances were estimated using a Bayesian approach, orbits were integrated over 10 Gyr, and birth radii were inferred from Galactic chemical evolution models combined with a generalised additive model. Our sample is slightly skewed to more metal-rich values, when compared to the Sun (<[Fe/H]>=0.05) and intermediate ages (<t>=4.0Gyr). Preliminary results indicate that most stars in our sample belong to the thin disc, with a few thick disc interlopers. Those belonging from the thin disc seem to have predominantly migrated outward from their birthplaces, with a minority showing inward migration toward the solar vicinity. Systems are further categorised by the types of planets they host (rocky, gaseous or mixed) highlighting possible correlations between stellar motion and planetary system architecture.

JWST and cross-correlation techniques: An isotopologue-sensitive technique for exoplanet atmospheric studies (Emma Esparza-Borges, IAC) [Slides] [Video]

The application of cross-correlation techniques to JWST transmission spectra has opened an alternate pathway to study exoplanet atmospheres with JWST observations. JWST observed for the first time the hot-Jupiter WASP-39b on July 2022 as part of the JWST Transiting Exoplanet Community Early Release Science (JTEC ERS) Program. Since then, several atomic and molecular species (e.g K, H2O, CO2, SO2) have been detected in its transmission spectrum. In the initial analysis, CO was detected using the NIRSpec PRISM transit observation. However, this detection could not be confidently confirmed in the initial analysis of the higher resolution observations with NIRSpec G395H. We developed a cross-correlation technique that leaded to the detection of CO in JWST NIRSpec G395H transmission spectrum, including novel hints of detection of CO isotopologues, which could provide some advantages compared to traditional techniques. Here we present the concept of applying cross-correlation techniques to JWST data, explaining the advantages and potential applications of this technique in the context of JWST, which might be of interest not only for exoplanet atmospheres but also for other fields involving JWST observations. Additionally, besides the initial CO detection in WASP-39b, we will show our latest results on more molecules.

Characterization of three exoplanet candidates to be part of the Neptune Desert (Ysrael Ortigoza, UCM) [Slides] [Video]

This work report on the characterization results obtained for three exoplanet candidates to be part of the Neptune Desert, a parametric space region dearth of planets that could host planets with radii between 3 and 10 earth-radius and orbital period less than 5 days. The reason for this dearth of planets could be related to their birth mechanism and evolution. The exoplanet candidates studied here, TOI-355.01, TOI-855.01 and TOI-906.01, were previously observed in the past by the TESS space telescope and, nowadays, a follow-up observation of them is being carried out by the CHEOPS space telescope. In order to get the planet radii and their orbital periods, the transit produced by these planets must be measured from their light curve data, not only characterizing these planets in this way, but also claiming their nature as an exoplanet and as a planet to be part of the Neptune Desert. Also, an improvement value for the planet radii, and other parameters related to them, are reported here, taking into account measurements published previously.

Exoplanets in triple star systems (Carlos Cifuentes,  CAB (CSIC-INTA))

Stellar multiplicity significantly shapes planetary system architectures. While binary systems have been widely studied, hierarchical triple systems remain largely unexplored. Their complex gravitational dynamics challenge planet formation models, influencing migration, orbital eccentricities, and long-term stability. Only about 40 exoplanet systems have been found in triple-star systems, mostly poorly mapped long-period gas giants. This talk presents an observational effort to study short-period planetary companions in hierarchical triples. We aim to constrain planetary architectures and uncover how stellar companions shape planetary properties.