As KNA/RNAS Chair I wish to open the conference, during a 10min presentation in which I also shall recall the WWII episode of the Society. After the 10min I will hand over to the LOC Chair.
HARPS3 is a high resolution (R~115,000) stabilized Doppler spectrograph covering a wavelength range from 380-690nm with polarimetric capabilities that is coming online on the roboticized 2.5m Isaac Newton Telescope (INT) at La Palma in Fall 2025. HARPS3 is designed to enable ~10cm/s radial velocity (RV) precision on nearby bright solar-type stars to enable the detection of Earth Twins. The...
I will present the status of WEAVE, the new wide-field spectroscopic survey facility for the William Herschel Telescope at the ING, and some early science results. WEAVE has been operational in its Large Integral-Field Unit (LIFU) mode since late 2022 and is presently commissioning its MultiObject Spectroscopy (MOS) and mini-IFU (mIFU) modes. I will present the instrument performance in the...
One of the remaining unsolved questions is the one of globular cluster formation, as there is still no definite consensus on whether the clusters have formed within the Milky Way galaxy (in situ) or have been accreted. Current estimates suggest that between 25-65% of all Milky Way GCs were accreted, however the exact number is still uncertain. Since GCs are significantly old (up to 12 Gyr),...
In June 2023, International Pulsar Timing Array (IPTA) collaborations in Europe, America, India and Australia simultaneously announced the first compelling evidence of the low-frequency (nHz) gravitational wave background. This was a milestone in gravitational wave astronomy. These results were further strengthened by detailed comparative analysis at the IPTA level. The main source of noise in...
Massive stars are chemical factories, they are progenitors of supernovae, neutron stars and black holes, and they play a crucial role in the formation and evolution of their local environment as well as their entire host galaxies. Given their prevalence in close binary systems, at the end of their lives they may produce double-compact objects, which are potential gravitational-wave sources....
Gravitational waves (GW) are providing a new way to study the properties of compact objects. In this context, understanding what determines the final fate of stars, the role of binary interactions, and which signatures to expect in GW observations is becoming increasingly important. The formation of black holes (BHs) or neutron stars (NS) is not a simple function of the initial mass of a...
How the chemistry in the universe evolves from diffuse interstellar medium to a life-harboring environment on our Earth? Complex organic molecules (COMs), typically defined as carbon-bearing molecules with at least six atoms, have gained their popularity over the past several decades due to their importance of linking atoms and simple molecules with prebiotic species. COMs are suggested to be...
In the past decade, hundreds of exoplanets have been discovered in extremely short orbits below 10 days. Unlike in the Solar System, planets in these systems orbit their host stars close enough to disturb the stellar magnetic field lines. The interaction can enhance the star's magnetic activity, such as its chromospheric and radio emission, or flaring. So far, the search for magnetic...
The Event Horizon Telescope (EHT) has imaged the black hole shadows of the supermassive black hole at the center of the galaxy M87 (M87) and at the center of the Milky Way (Sgr A), using the technique of very long baseline interferometry (VLBI) at 230 GHz. In the future, black hole imaging will transition to movie making with ground-based upgrades and extensions of the EHT array. However,...
While the political attention to it is waning, the scientific facts have not changed. Human-induced climate change is already causing damage and misery, and unless the world acts quickly and decisively, this will increase in the decades to come. The scientific information on climate change is assessed and brought to climate policymakers globally by a special organization: the IPCC. In this...
The chemical composition of tidally locked gas giant atmospheres is the result of an intricate balance between the temperature, the wind dynamics, and the incident radiation coming from the host star. As such, the planet can show distinct atmospheric signatures dependent on the phase during which it is observed. Now, with the unprecedented sensitivity of the James Webb Space Telescope, we can...
The origins of fast X-ray transients (FXTs), which are bursts of soft X-ray photons (~0.3-10 keV), have so far been amongst the most elusive of transients. Their origins in binary neutron star mergers which lead to the formation of a millisecond pulsars whose rapid spin down power the bursts; tidal disruption events (TDE) involving white dwarfs disrupted by intermediate-mass black holes; shock...
Active galactic nuclei (AGNs) play a crucial role in the coevolution of supermassive black holes (SMBHs) and their host galaxies from high redshift to the present. They influence their host galaxies through powerful winds and jets that generate massive outflows, and these feedback processes can either quench star formation by heating and expelling gas or trigger it by compressing the...
High-resolution spectroscopy (HRS) is a powerful tool for studying the atmospheres of planetary-mass objects, including brown dwarfs and exoplanets. By analysing the fine details in near-infrared spectra, we can detect absorption features from key molecules and their isotopic variants, revealing the chemical composition of these sub-stellar objects. Such measurements offer clues about their...
XRISM, launched in September 2023, offers unprecedented capability in resolving the Fe K band. We use a deep 430 ks observation with XRISM/Resolve to investigate the AGN environment of NGC 3783 and model the structure through Fe Kα emission lines. I will present our latest results on both the narrow Fe Kα line and the relativistic broad iron line.
Our preliminary findings suggest that the...
It remains an unanswered question what dictates the amount of dust in the interstellar medium. Asymptotic giant branch stars and supernovae produce dust in their cold atmospheres, but dust gets destroyed during star-formation and supernova shockwaves. The timescales for these effects combined with the observed dust masses in galaxies implies that dust also grows in the interstellar...
Population III stars were the first generation of stars that formed in the Universe out of primordial gas. Thanks to JWST, we are now in an era where observing campaigns to discover Pop III stars has become a possibility. Over the last 3 years, several proposals on Pop III stars (from star cluster to galaxy scales) have been successful in getting time on JWST, however no convincing detections...
The recent very-high-energy (VHE; >100GeV) spectra of the afterglow emission of three gamma-ray bursts (GRBs) shake the current understanding of the underlying physics of a relativistic shock, formed at the impact surface from a plasma outflow crashing at almost the speed of light into its surrounding. I will show the limitations of established modeling and discuss new scenarios including...
Understanding the stellar mass build-up and evolution of the surprisingly massive galaxies in the Epoch of Reionization (EoR) requires insight into their molecular gas reservoirs, which fuel star formation. I will present new deep VLA observations of REBELS-25 (z = 7.31), a massive star-forming galaxy and the highest-redshift dynamically cold disk (V_rot,max/σ ≃ 11) confirmed to date. Using...
Fast X-ray transients (FXTs) are extragalactic flashes of X-rays, lasting from seconds to hours, whose nature remains largely unknown. Several progenitor mechanisms have been proposed to explain their origin, for instance, neutron star mergers, tidal disruption events involving a white dwarf and an intermediate-mass black hole, supernova shock break-out, and gamma-ray burst cocoon-like/jet...
HD 135344 is a visual binary system that is best known for the protoplanetary disk around the secondary star. Various substructures, such as a cavity and spiral arms, point to ongoing planet formation, but putative planets have remained hidden. The circumstellar environment of the A-type primary star, on the other hand, has evolved faster as inferred from the absence of accretion and...
This talk introduces ShadowSWIFT, a novel moving-mesh hydrodynamical code for large-scale cosmological and galaxy simulations, developed within the SWIFT collaboration. SWIFT is a highly optimised and scalable software that allows hydrodynamical solvers to use multiple subgrid routines. ShadowSWIFT is currently compatible with the EAGLE and GEAR subgrid routines, and is expected to release...
Recent direct imaging surveys like YSES and BEAST have revealed a population of young, super-Jupiter exoplanets at extreme distances from their host stars (>100 AU). These discoveries challenge planet formation theory which struggles to explain how such massive planets are formed so far away from their stars. Proposed mechanisms include in-situ formation through cloud fragmentation or disk...
Wide field surveys searching for transiting exoplanets also record and discover both known stellar variability and previously unknown phenomena. Deep and complex eclipses of otherwise unremarkable stars reveal eclipsing companions that have complex substructures. The ASAS-SN survey has now produced over a dozen complex eclipses that last from weeks to years, and we present our analyses of...
Construction of low frequency component (50 - 350 MHz) of the Square Kilometre Array has started in Australia. With an immensely dense core of almost 60 thousand antennas within a square kilometer, the telescope provides a unique opportunity to study cosmic rays in the energy range between 10$^{15}$ and 10$^{18}$ eV. High resolution observations and new analysis strategies will provide more...
In this talk, I will introduce the Resolved Cluster Evolution Sunyaev-Zeldovich Survey (ReCESS): a 200-hour-plus observing campaign aimed at resolving the intracluster medium (ICM) through the thermal Sunyaev-Zeldovich (tSZ) effect in 25 ACT-selected galaxy clusters within a redshift range of 1.2 < z <2.0 using MUSTANG-2 on the GBT and ALMA. I will present the first results on the average...
The equatorial jets observed on the Jovian planets—Jupiter, Saturn, Uranus, and Neptune—exhibit extreme zonal flow patterns, manifesting as either strongly prograde or strongly retrograde (Ingersoll, 1990). Existing theories have often treated gas giants and ice giants separately, primarily focusing on the shallower atmospheric layers of the ice giants (e.g., Schneider and Liu, 2009; Liu and...
The Radio Detector (RD) at the Pierre Auger Observatory is a new large-scale instrument designed to measure the highest-energy cosmic rays. It consists of 1660 radio antennas spread across 3000 km², detecting the radio emission from extensive air showers in the 30–80 MHz range. By combining these measurements with data from water-Cherenkov detectors, we can determine both the energy and...
Many close-in exoplanets are expected to orbit inside the Alfvén surface of the stellar wind, the region where the stellar wind is dominated by the stellar magnetic field. In this scenario, the planet acts as an obstacle to the stellar wind flow, leading to an electromagnetic coupling between the star and the planet. The energy fluxes arising from this interaction can power enhanced emission...
Mass and angular momentum regulate most of their formation and evolution of galaxies, including their morphological, kinematic, and star-forming properties.
In this talk, I will present our recent results characterising the angular momentum of the molecular gas in nearby disc galaxies. Exploiting data from the PHANGS-ALMA survey, we have performed the first statistical study of the...
Context. Type III solar radio bursts are among the most common radio emissions from the Sun, produced by energetic electron beams propagating through the solar corona and interplanetary space. These bursts are characterized by their rapid frequency drift, and through them, we can further study solar activity. Since the launch of ESA’s Solar Orbiter mission in 2020, the Radio and Plasma...
We present two new radio continuum images obtained with Apertif at 1.4 GHz. The images, produced with a direction-dependent
calibration pipeline, cover 136 square degrees of the Lockman Hole and 24 square degrees of the ELAIS-N fields, with an average
resolution of 17×12′′ and residual noise of 33 μJy/beam. With the improved depth of the images we found in total 63692 radio
sources, many of...
The Radar Echo Telescope for Cosmic Rays (RET-CR) is a prototype experiment for the future neutrino detector, the Radar Echo Telescope for Neutrinos (RET-N). It is deployed at Summit Station in Greenland, with an entire data-taking run conducted in the summer of 2024.
RET-CR explores the possibility of the long-term goal for RET-N, hence advancing neutrino astronomy with new detection...
The Solar and Heliospheric Observatory (SOHO) Extreme-ultraviolet Imaging Telescope (EIT) has been taking images of the Solar disk and corona in four narrow EUV bandpasses (171, 195, 284, and 304 angstroms) at a minimum cadence of once per day since early 1996. The time series of fully-calibrated EIT images now spans approximately 28 years, from early 1996 to the early 2024, covering solar...
Cataclysmic variables, accreting white dwarfs in binaries, can zoom into and out of view of our telescopes in a matter of days or weeks, first brightening then fading, only to repeat this later the same year. This timescale of variability is a sign of the dwarf nova, a class of cataclysmic variable. The dwarf nova outburst is a change in the accretion disc of these systems, which not only...
Direct imaging is a technique that allows us to spatially resolve the planet from its host star. Due to the big difference in flux between star and planet, a very high contrast must be reached to observe the planet that would be otherwise hidden in the glare of the star.
Coronagraphs are optical systems that work as angular filters, suppressing the on-axis star light and letting the...
Pulsar Timing Array (PTA) projects hold the promise of becoming sensitive Gravitational-Wave (GW) detectors in the nanoHertz frequency band. Multiple international PTA collaborations are actively timing an array of pulsars with their respective radio observatories, and each collaboration carries out GW searches in their own data. In principle, a combined search over all available PTA data is...
Unlucky stars that venture too close to a supermassive black hole (BH) get ripped apart by gravitational tidal forces. These tidal disruption events (TDEs) offer a rare probe of otherwise quiescent BHs.
TDEs are usually detected in the optical and ultraviolet (UV), where light curves show an early-time peak, often followed by a late-time plateau. Recent modelling shows that these plateaus...
Astronomical instrumentation projects are often very international, with team members coming from different cultural backgrounds, being proficient in multiple different languages, working across different time zones, and frequently having a different (professional) understanding of the same – often English – working language.
In this talk, I would like to share my personal and professional...
We see considerable political pressure against "DEI" (Or EDI, Equity, Diversity and Inclusion). We still have more freedom of speech on this than our colleagues in the USA (where I previously lived and worked for 20 years);
We need to address the question of how we can explain to guys like Donald why EDI matters, what it is and what it isn't. Much of the time we are "preaching to the...
The European Regional Office of Astronomy for Development (E-ROAD), part of the International Astronomical Union’s global OAD network, harnesses astronomy to drive societal progress and contribute to the United Nations Sustainable Development Goals (SDGs). Based at Leiden University, E-ROAD focuses on quality education (SDG 4), gender equality (SDG 5), economic growth (SDG 8), and reducing...
Ground-based observations of spacecraft signals have been used to study space weather. However, single spacecraft measurements observed from the Earth have limitations in studying the structure and evolution of solar plasma as they are unable to differentiate spatial and temporal variations. To overcome this limitation and improve our understanding of interplanetary scintillation, we...
After more than 30 years of talking, the construction of the Square Kilometre Array (SKA) is now well underway. In this talk, I will give a update on construction, discuss how anyone can get involved in the SKA now, and what this stage of project development means for the Dutch astronomy community. In particular, I will focus on the establishment of our own regional centre, and its expected...
DG CVn (GJ3789) is a famous, nearby (18pc) binary consisting of two young M4.0Ve red dwarf stars. It has been the source of the most luminous gamma flare event ever detected by Swift, and produces large flares in the optical and radio as well. Due to a maximum projected separation of only 0.2", it has been difficult to resolve optically, even for the Gaia mission.
One of the binary...
In the last few years, a new class of mysterious periodic radio transients has been discovered, with periods far exceeding those seen on pulsars. These long-period transients (LPTs) produce bright, often strongly polarised emission in pulses that last less than a minute and repeat on a timescale of minutes to hours. The origins of LPTs are largely unknown still, with proposed progenitor...
The interplay between gas accretion, feedback, and galactic dynamics plays a crucial role in shaping galaxy evolution. The MHONGOOSE survey, with its unprecedented HI sensitivity and high spatial resolution, provides a transformative opportunity to study these complex processes in nearby galaxies. By probing gas at extremely low column densities in the outskirts of galaxies, MHONGOOSE enables...
Fast Radio Bursts (FRBs) are millisecond-duration radio transients that serve as unique probes of extragalactic matter. We report on the discovery and localization of two FRBs piercing the Andromeda Galaxy (M31) by the realfast fast transient detection system at the Very Large Array. Their unique sightlines allow constraints on M31’s electron density distribution. We localized FRB 20230930A...
The cosmic star-forming activity peaked at redshifts z=1-4 in the so-called "Cosmic Noon". This vigorous star production is driven by massive galaxies with star-formation rates 100-1000x higher than the Milky Way. However, it has long been unclear what causes these immense star formation: were early galaxies forming stars very efficiently, or are they simply more gas-rich than present-day...
The streaming instability is an efficient method for overcoming the barriers to planet formation in protoplanetary discs. The streaming instability has been extensively modelled by hydrodynamic simulations of gas and a single dust size. However, more recent studies considering a more realistic case of a particle size distribution show that this will significantly decrease the growth rate of...
Very Low Mass Stars (VLMSs) are the most abundant stars in our galaxy. The occurrence rate of Earth-like planets orbiting VLMS is higher than for higher-mass stars. Their planet-forming disks evolve fast, which makes them ideal laboratories to study Earth-like planet formation in the evolved disk. The faintness of VLMSs and the small sizes of their disks make their observations challenging....
Most Sun-like stars host planets. Once these stars run out of fuel in the core, they will go through a short red giant phase and end their life as a white dwarf. It is unknown what happens the planetary systems around these stars: does the red giant engulf them, ejected, or are entirely new planets born?
In my talk, I will present the results of a systematic search of Zwicky Transient...
Most Active Galactic Nuclei (AGNs) are thought to contain a molecular and dusty torus that surrounds the accretion disk and obscures the AGN. The high angular resolution of the Atacama Large Millimetre/submillimetre Array (ALMA) allows us to resolve these tori for the first time, opening up the road to answering some long-held questions. One such question is the dynamics of tori and their...
Oxygen and carbon are key ingredients for the formation of planets. While planet-forming regions around T Tauri stars are typically oxygen-rich, planet-forming regions around very low-mass star (VLMS) are known to exhibit highly carbon-rich environments. Infrared spectroscopy provides a powerful tool to detect and quantify these essential building blocks in protoplanetary disks. In this talk,...
Post-asymptotic giant branch (post-AGB) stars have recently lost their envelopes and are contracting to higher effective temperatures, while maintaining constant luminosity, to become white dwarfs. About half of the optically bright post-AGB stars are found to exhibit near-infrared excesses in their spectral energy distributions, interpreted as hot dusty discs around the objects, and are...
Before the launch of Gaia, eccentricity in wide evolved binaries (with periods of ~10²–10⁴ days) was considered an oddity, as only a few small samples were known. These observations have revealed that many of these systems are eccentric, with the range of observed eccentricities increasing with orbital period. Notably, the maximum observed eccentricities also rise as the orbital period grows....
The Advanced Telescope for High-Energy Astrophysics (Athena) has successfully completed a redefinition phase – both of the technical implementation, and mission driving science objectives – becoming ‘NewAthena’. With mission adoption by ESA foreseen in early 2027, the activities of the NewAthena Science Community are expected to ramp up in the very near term. I will give an update on the...
Since 2020, Microsoft’s emissions have risen by more than 30%, and Google’s by almost 50%. The reason, according to both companies, is the insatiable energy demand of generative AI. As a result, both companies are now openly wavering on their previous corporate emissions targets and making it clear that AI growth will take priority over achieving any climate goals.
To put it another way:...
The NOVA Submillimeter (submm) Group was established at the Kapteyn Astronomical Institute in 1998 as part of the Netherlands Research School for Astronomy (NOVA) instrumentation effort. Its primary goal was to develop technology for the ALMA project. This focus shaped the group's research and development direction, particularly in the field of low-noise heterodyne receivers for submillimeter...
The impetus for wide-field searches for counterparts of explosive transients including binary neutron-star mergers, supernovae, and tidal disruption events has never been higher. The ongoing operations with the LIGO-Virgo network of gravitational wave detectors in the 4th observing period continues to offer challenges for optical observers, primarily due to the poor (~100 deg$^2$) localisation...
The Habitable Worlds Observatory (HWO) is the next flagship of NASA, planned to be launched in the 2040s. With a wavelength coverage from the ultraviolet to the near-infrared and a suite of multi-purpose instruments, this observatory will be a successor to the Hubble Space Telescope. It will be the first space telescope designed specifically to directly characterize Earth-sized exoplanets...
Gaia is revolutionising our understanding of the Milky Way and can be used for research in many different areas of astronomy, ranging from solar system science to quasars. One field where the Gaia astrometry excels is the study of so-called runaway stars. Runaway stars move away from their birth region with a high peculiar velocity. The high-mass runaway stars can efficiently and effectively...
Constraining the Epoch of Reionization remains one of the pivotal tasks of modern cosmology, and next-generation telescopes are opening up the path to the first precision constraints on the timing of reionization derived from the Lyman-$\alpha$ damping wing signature imprinted on the spectra of high-redshift quasars by the foreground neutral intergalactic medium (IGM). In the coming years,...
Understanding the processes that drive the quenching of star formation in galaxies is crucial for unveiling the mechanisms that shape galaxy evolution. Quenching transforms actively star-forming galaxies into passive systems on very short timescales of a few hundred Myr, influencing the overall structure, morphology, and chemical composition of galaxies across cosmic time. Investigating...
Fast radio bursts (FRBs) – millisecond-duration, luminous radio transients – remain one of the biggest mysteries in modern astrophysics. While thousands have been detected, their sources and emission mechanisms are still widely debated. Precise localization is crucial for understanding the environments of FRBs, and very long baseline interferometry (VLBI) provides an unparalleled tool for...
