Over 300 different molecular species have been identified in space, with approximately 90% of these discoveries made through radio astronomy, utilizing the rotational spectra at radio wavelengths. However, radio astronomy faces inherent sensitivity limitations, especially when detecting large, symmetrical molecules like C₆₀. For such molecules, we rely on their vibrational (infrared, IR) and/or electronic (near-IR/visible) spectral signatures for identification. Interestingly, only three large molecules—C₆₀, C₆₀⁺, and C₇₀—have been detected using IR and near-IR spectral features. A significant knowledge gap remains, as the next largest molecules identified in space contain only 11 carbon atoms (e.g., HC₁₁N, C₁₀H₇CN). In this context, I will present the experimental toolbox I have developed to address this gap, focusing on large carbon-rich molecular ions and using the diffuse interstellar bands as a proxy.
Cologne, Host Stephan Schlemmer

In recent years, surveys have discovered many sub-planet-sized objects in the Solar System’s outer reaches, beyond Neptune’s orbit. These trans-Neptunian objects (TNOs) hold vital clues to understanding the Solar System’s formation. Unlike the planets, these TNOs mostly orbit the Sun on inclined, eccentric orbits. While the innermost TNOs may have been ejected onto these orbits while interacting with the planets, the most distant are too far away. The explanation for their current orbits is likely an external force.  Here, I’ll show that a specific close flyby of another star can explain the TNOs dynamical properties of the known TNOs on a quantitative level. I will also illustrate how such a flyby can provide an explanation for the irregular moons of the giant planets and the Trojan asteroids that share the orbits of the planets.

In our Cologne laboratories we are interested in the role that molecules play in the astrophysics context. High-resolution spectroscopy is the main focus of this work which is a trademark of our institute for decades. In this presentation I will highlight three ingredients of our work which make molecular astrophysics strong. First, the CDMS database is the most prominent link to astrophysics.
Second, the development of new laboratory techniques allows us to study new molecules desired by astrophysics. Third, experimental spectra of several molecules challenge current spectroscopy models which we try to extend or revise.
Based on examples from our current research I will address possible future directions.

QUIJOTE and SANCHO are two observational projects at the Yebes 40m radiotelescope, which target the cold and dense core TMC-1. QUIJOTE is an ultra deep spectral line survey in the Q band (31-50 GHz), with current sensitivities between 0.08-0.2 mK at the observed frequencies. Since 2020, QUIJOTE has allowed the discovery of more than 60 new molecules in space, together with the detection of many isotopologues of known abundant species. Among the new discoveries, it is remarkable the detection of several large hydrocarbons and cyclic molecules, unexpected in such a cold cloud. However, the QUIJOTE data is incomplete, since we lack information on the spatial distribution of these molecules, which can help to constrain their chemical origin. SANCHO covers the same frequencies as QUIJOTE over an area of 4’x4′ around the cyanopolyynne peak of TMC-1, with sensitivities of 2-4 mK across the band. Thus, like the characters imagined by Miguel de Cervantes, SANCHO is QUIJOTE’s loyal companion in pursuit of understanding the molecular complexity of the TMC-1 cloud. In this talk, I will present the latest and most significant results of these two projects. The impact of QUIJOTE and SANCHO’s results have been possible thanks to the full instantaneous coverage and the high sensitivity of the 40m Q band receiver. I will also show the characteristics of the Yebes 40m telescope and the upcoming upgrades, which might be available in the next call for proposals of the Yebes Observatory in December.

Figure credits: Background image: Taurus Molecular Cloud, Grand Mesa Observaroty, Terry Hancock and Tom Masteron.
(Cologne, Host: Wonju Kim)

As many unsubstituted polycyclic aromatic hydrocarbons (PAHs) and smaller aromatic rings do not possess a permanent electric dipole moment, the search for and detection of substituted PAHs in the interstellar medium has dominated recent literature. Substitutions with cyano-groups are great targets as they often imbue a large molecular dipole moment. Detected molecules include single aromatic rings like benzonitrile, but more recently the PAH systems of cyano-naphthalene and cyano-pyrenes have been detected in TMC-1.  Our benchmarking and rotational spectroscopy group has been interested in the fundamental binding of molecular hydrogen to model surfaces that mimic the real interactions of H_2. As hydrogen very likely to encounter ice-grains containing cyano-PAHs in the ISM, we have been adapting our spectroscopic targets towards aromatic systems already detected in the ISM. 

In this talk, we will explore the formation of molecular hydrogen complexes with aromatic rings using rotational spectroscopy.  A primary focus of the talk will be on benzonitrile-H₂. We discuss the binding of not only molecular hydrogen, but also the minor isotopologues HD and D₂, and heavier substitutions of benzonitrile.  Also observed are the differences in binding preference in our experiment, where the favorability of binding to ortho-H₂ is favored over para-H₂and also depends on the relative concentration of hydrogen in the experiment.  
Cologne, Host: Stephan Schlemmer

The amount, size, and complexity of astronomical data-sets is growing rapidly in the last decades. Now, with new technologies and dedicated survey telescopes, the databases are even growing faster. Besides dealing with poly-structed and complex data, sparse data has become a field of growing scientific interest. By applying technologies from the fields of computer sciences, mathematics, and statistics, astronomical data can be accessed and analysed more efficiently.

A specific field of research in astroinformatics is the estimation of the redshift of extra-galactic sources, a measure of their distance, by just using sparse photometric observations. Observing the full spectroscopic information that would be necessary to directly measure the redshift, would be too time-consuming. Therefore, building accurate statistical models is a mandatory step, especially when it comes to reflecting the uncertainty of the estimates. Statistics and especially weather forecasting has introduced and utilized proper scoring rules and especially the continuous ranked probability score to characterize the calibration as well as the sharpness of predicted probability density functions.

After presenting how this work led from well calibrated redshift estimates to an improvement in statistical post-processing of weather forecast simulations, an example of interdisciplinarity in data-science, we continue with unsupervised machine learning techniques. We start with the challenge of classifying morphologies of radio-galaxies, talk about star-formation history in LMC, discuss the difficulties in representing time-series, and end with a discussion on novel explorative science platforms for e.g. spectral data. In this part of the talk, we show-case how machine learning can be used as a machinery of discovery to access large data-sets. Several examples are presented to provide examples for the individual researchers in the audience.
Cologne, Host Isabelle Breloy