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• 27.11.2026 - Ivelin Georgiev (MPA)
• 20.11.2026 - Louis Mueller (University of Vienna) & Tanja Rindler-Daller (University of Vienna)
• 13.11.2026 - Ryan Leaman (University of Vienna) & Alvaro Hacar (University of Vienna)
• 06.11.2026 - Shaunak Padhyegurjar (University of Vienna)
• 30.10.2026 - Leon Noble (Indian Institute of Technology Indore) & Alina Boecker (University of Vienna)
• 23.10.2026 - Institute Assembly
• 16.10.2026 - Luca Fossati (University of Graz) & Benjamin Collins (Universidad de Chile)

  WALTzER and POLLUX: Two Approaches to Exploring the Universe from the UV to the IR

  Luca Fossati (University of Graz)

  I will present the science cases and payload concepts of two conceptually related, though fundamentally different, space instruments with major Austrian contributions: WALTzER and Pollux.

  WALTzER (Wide-band Atmospheric Laboratory for Transiting Exoplanet Research) is a recently submitted ESA F3 mission concept dedicated primarily to the characterisation of exoplanet atmospheres, while also opening new opportunities for Solar System and Galactic astrophysics. The payload uses a single 35-cm telescope feeding a near-ultraviolet spectrograph, a visible spectrograph, and a near-infrared photometer, providing simultaneous near-ultraviolet to near-infrared coverage.

  Pollux is a high-resolution spectrograph, with optional spectropolarimetric capability, working simultaneously from 100 nm to 1.75 microns proposed for the Habitable Worlds Observatory by a European consortium. Pollux will provide an exceptionally broad and detailed view of stars, planets, and their environments. Pollux will also probe the cosmic ecosystem and the baryon cycle across time: from the formation of stars and planets out of gas and dust, through the evolution of galaxies, to the feedback processes that return matter and energy to the interstellar and intergalactic media, including those driven by active galactic nuclei.
  Together, WALTzER and Pollux illustrate how complementary approaches to broad spectroscopic coverage can address science ranging from the atmospheres of nearby planets to the evolution of matter and energy across the Universe.

   

  Tipping the scales in Blue Jay: Dust energy balance overpredicts IR luminosity in galaxies at z ~ 2.

  Benjamin Collins (Universidad de Chile)

  The spectral energy distribution (SED) of a galaxy encodes vital information about its chemical composition, stellar populations, and dust content. To model the infrared emission, many modern SED-fitting codes rely on dust energy balance, which assumes that all energy absorbed by dust in the UV-optical is equal to the energy emitted in the infrared regime. However, few studies have been carried out to test the validity of this assumption at high redshift, where direct infrared observations are sparse. In this work, we perform aperture photometry in 111 galaxies from the Blue Jay survey (1.7 < z < 3.5) using public JWST/MIRI observations from the PRIMER, COSMOS-Web and COSMOS-3D surveys. By comparing measurements from MIRI to Prospector SED models derived using HST and NIRCam photometry, we find that mid-infrared fluxes are systematically overpredicted by about 10% at 7.7µm up to a factor of ~3 at 21µm. The discrepancy increases with inferred dust attenuation, indicating that dust energy balance suffers from line-of-sight effects in systems with complex dust geometries.

  Adding NIRSpec spectroscopy to the fits breaks parameter degeneracies and reduces the overpredictions by a factor of ~2. When fitting the measured MIRI photometry with the HST and NIRCam data, the resulting best-fit model spectra of dusty galaxies (Av  >1) show significantly lower infrared luminosities (-30%) compared to spectra obtained without MIRI, strongly suggesting that the total energy budget drives the overpredictions. Our study highlights the limitations of dust energy balance at high redshift and underlines the importance of direct observations for accurately recovering the ISM and dust properties of Cosmic Noon galaxies.
• 09.10.2026 - Ronan Kerr (University of Toronto) & Meet Vyas (University of Vienna)

  Reconstructing Local Galactic Star-Forming Processes with Young Stellar Populations

  Ronan Kerr (University of Toronto)

  Young stellar populations provide a fossil record of star formation spanning tens of Myr. With high quality positions, velocities, and ages available through the Gaia and other large surveys, it is now possible to reconstruct the sites of past star formation and the track the evolution of dense gas, outlining the physical processes guiding the evolution of local star-forming structures. With this stellar record, we have corroborated the recent discovery of cluster families: expanding groups of clusters and associations that originate in a single molecular cloud and drive expanding bubbles. We have also constructed empirical models for nearby bubble structures, replicating the extent of the Local Bubble while predicting the location of the Mirzam Tunnel as the product of a collision with the Cinyras complex. New preliminary results show the signature of a galactic spur structure that dominated nearby star formation between 25 and 40 Myr ago, along with several convergence signatures that appear to trace the ubiquitous initiation of star formation through bubble collisions. In this talk, I provide a cross-section of these emerging structures and signatures traced by young stars, and discuss their potential impact on our understanding of star formation. 

  
  Envisioning the Vera C. Rubin Observatory LSST Target of Opportunity (ToO) program: Gravitational Wave Counterparts 

  Meet Vyas (University of Vienna)

  With the start of the Legacy Survey of Space and Time (LSST) through the Vera C. Rubin Observatory, we now have a uniquely powerful facility for finding the optical counterparts of gravitational wave (GW) events. Through the recommendation of the Science Cadence Optimization Committee (SCOC), the Target of Opportunity (ToO) program was introduced to allow Rubin to respond to external alerts. In this talk, I will present our work from the Rubin ToO report (Andreoni et al. 2024), focusing on binary neutron star (BNS) and neutron star–black hole (NS–BH) mergers. Observations of these kilonovae, which act as electromagnetic counterparts to the GW triggers, powered by the radioactive decay of freshly synthesized r-process elements, can reveal the origin of heavy elements, constrain the neutron star equation of state, and provide an independent measurement of the Hubble constant. 
  I will explain why Rubin is the only facility able to cover LIGO-Virgo-KAGRA (LVK) skymaps of 100–500 deg² while also reaching the depths needed to detect kilonovae at 350–700 Mpc. I will then present the projected event rates for the LVK O5 observing run, the criteria for triggering Rubin on a GW alert, and the observing strategies we propose for well-localized "gold" and larger "silver" events, including the required telescope time. Finally, I will show the kilonova light curve simulations we used to validate these strategies.