Frédéric P. A. Vogt

We present new Multi Unit Spectroscopic Explorer (MUSE) Narrow Field Mode with adaptive optics observations of the optical torus surrounding a central compact object candidate within the oxygen-rich supernova remnant 1E 0102.2–7219 located in the Small Magellanic Cloud. These data provide nearly an order-of-magnitude improvement in spatial resolution over previous MUSE Wide Field Mode observations. The improved spatial resolution resolved the previously identified torus into a cavity-like structure with a sharply defined inner edge and diffuse, outer filamentary substructure. The emission shows continuous velocity connectivity, broad intrinsic line widths, and cospatial contributions from neutral and partially ionized species, including O i , Ne i , [O i ], [O ii ], and [O iii ]. Spatially resolved line-ratio maps indicate that the emission arises from a multiphase, nonequilibrium medium rather than a single homogeneous component. Comparison with photoionization and shock models shows that no single-component model within the explored parameter space can simultaneously reproduce both the strong neutral and high-ionization diagnostics, indicating that multiple physical conditions must coexist. We favor an interpretation in which shocks propagating through density inhomogeneities in the ejecta shape the observed morphology and excitation, while also considering alternative mechanisms linked to the central source, binary evolution, or interaction with an embedded object within the remnant.

Total and altitude-dependent cloud cover are important characteristics of the present weather and used in nowcasting, numerical weather prediction and climate applications as well as for scientific studies. While cloud cover is still widely observed by humans, MeteoSwiss is in the process to automate the procedure using a variety of sensors. In this effort, the estimation of the cloud amount per cloud layer appeared to be particularly challenging as algorithms based exclusively on ceilometers could not satisfy all quality requirements. The main shortcomings are limitations in the representativity and the long integration time of 15 minutes, which prevents the delivery of timely and accurate values for the present weather.In this context, we investigate how a well-calibrated hemispheric infrared camera combined with the ceilometer cloud base measurements can improve the cloud information. In the different investigated synergetic algorithms the ceilometer is the predominant source of cloud height information whereas the infrared camera provides information on the cloud amount. The more basic algorithm uses a threshold on the infrared brightness temperatures to distinguish cloudy from clear-sky pixels. A more elaborate algorithm matches cloud-base hits of the ceilometers with infrared camera pixels to produce cloud cover estimates for each cloud layer. This approach does not require a clear sky reference and is to a large extent insensitive to calibration inaccuracies. It further allows us to exploit the infrared image at high airmasses, i.e. far down towards the horizon, what in turn further improves spatial representativity. In this work, we evaluate both algorithms with respect to human observations and the reference algorithm based on ceilometers only.

The distance to the Vela Junior supernova remnant (RX J0852.0–4622 or G266.2–1.2) has long remained uncertain, limiting our understanding of its physical properties. Using Very Large Telescope/Multi Unit Spectroscopic Explorer integral field spectroscopy, we uncover chemical and kinematic connections between the nebula surrounding its central compact object (CXOU J085201.4–461753) and the nearby Herbig–Haro outflow of Ve 7–27 (Wray 16–30), indicating a shared nitrogen-rich, Fe-peak-enhanced environment. This link ties stellar birth and death, with the young star Ve 7–27 embedded in material expelled by Vela Junior’s massive progenitor, and the remnant’s blast wave is expanding through the same medium. Adopting the Gaia-based distance to Ve 7–27, we revise Vela Junior’s distance to 1.41 ± 0.14 kpc. At this distance, the remnant’s physical radius is 23.3 ± 2.3 pc, and X-ray proper motions of the northwestern rim correspond to shock speeds of (2.8 ± 0.7) × 10 ³ to (5.6 ± 1.5) × 10 ³ km s ⁻¹ . These imply an age of ∼1.6–3.3 kyr and a very low ambient density, indicating that Vela Junior is expanding within a highly rarefied wind-blown cavity carved by a massive progenitor—consistent with the nondetection of strong thermal X-ray emission. This distance update also resolves long-standing inconsistencies, with major implications for its energy budget, particle acceleration efficiency, and compact object evolution.

Type Ia supernovae play a fundamental role as cosmological probes of dark energy and produce more than half of the iron in our Galaxy. Despite their central importance, a comprehensive understanding of their progenitor systems and triggering mechanism is still a long-standing fundamental problem. Here we present high-resolution integral field spectroscopic observations of the young supernova remnant SNR 0509-67.5 in the Large Magellanic Cloud. We uncover a double-shell morphology of highly ionized calcium [Ca XV] and a single shell of sulphur [S XII], observed in the reverse shocked ejecta. Our analysis reveals that the outer calcium shell originates from the helium detonation at the base of the outer envelope, while the inner shell is associated with the carbon–oxygen core detonation. This morphological distribution of intermediate-mass elements agrees qualitatively with the predicted signature of the double detonation of a sub-Chandrasekhar-mass white dwarf from a hydrodynamical explosion simulation. Our observations reveal two distinct, spatially separated peaks in surface brightness of [Ca XV] from the supernova remnant phase, providing substantial evidence that sub-Chandrasekhar-mass explosions through the double-detonation mechanism could occur in nature. They also highlight the importance of remnant tomography in understanding explosion mechanisms from the remnant phase.

We present integral-field spectroscopic observations of the Circinus galaxy performed with the MUSE narrow field mode on the VLT. The spatial resolution of ∼ 0.1 within the field-of-view of 7.5 × 7.5 enabled us to zoom into the ionized gas kinematics within the central ∼ 100 pc of the AGN. The analysis revealed that the systemic component resembles the ionization cone structure seen in larger scales, while the outflowing component shows a "tuning-fork" morphology: a collimated structure originating near the AGN location and extending in the north-western direction before it splits into two arms at around 30 pc from the AGN. We speculate that the origin of the collimated outflow might be due to the radio jet and ISM interactions on parsec scales, while a presense of a dust clump at the tip of the collimated part of the outflow might explain its fragmentation. The estimated total instantaneous and time-average mass outflow rates suggests that the observed outflow is not expected to regulate star formation within the ∼ 100 pc. BPT diagram revealed that the dominant source of ionization is the AGN. In addition, we will present also the morphology and kinematics of the coronal gas traced by the high-ionization forbidden lines.

Ceilometers are used routinely at aerodromes worldwide to derive the height and sky coverage fraction of cloud layers. This information, possibly combined with direct observations by human observers, contributes to the production of meteorological aerodrome reports (METARs). Here, we present ampycloud, a new algorithm, and its associated Python package for automatic processing of ceilometer data with the aim of determining the sky coverage fraction and base height of cloud layers above aerodromes. The ampycloud algorithm was developed at the Swiss Federal Office of Meteorology and Climatology (MeteoSwiss) as part of the AMAROC (AutoMETAR/AutoReport rOund the Clock) program to help in the fully automatic production of METARs at Swiss civil aerodromes. ampycloud is designed to work with no direct human supervision. The algorithm consists of three distinct, sequential steps that rely on agglomerative clustering methods and Gaussian mixture models to identify distinct cloud layers from individual cloud base hits reported by ceilometers. The robustness of the ampycloud algorithm stems from the first processing step, which is simple and reliable. It constrains the two subsequent processing steps that are more sensitive but also better suited to handling complex cloud distributions. The software implementation of the ampycloud algorithm takes the form of an eponymous, pip-installable Python package developed on GitHub and made publicly accessible.

Ceilometers are used routinely at aerodromes world-wide to measure the height and sky coverage fraction of cloud layers. This information, possibly combined with direct observations by human observers, contributes to the production of Meteorological Aerodrome Reports (METARs). Here, we present ampycloud, a new algorithm and associated Python package for automatic processing of ceilometer measurements, with the aim to characterize cloud layers above aerodromes. The ampycloud algorithm has been developed at the Swiss Federal Office of Meteorology and Climatology (MeteoSwiss) as part of the AMAROC (AutoMETAR/AutoReport rOund the Clock) program, to fully automate the creation of METARs at Swiss civil aerodromes. ampycloud is designed to work with no (direct) human supervision. The algorithm consists of three distinct, sequential steps that rely on agglomerative clustering methods and Gaussian mixture models to identify distinct cloud layers. The robustness of the ampycloud algorithm stems from the first processing step, simple and reliable. It constrains the two subsequent processing steps that are more sensitive, but also better suited to handle complex cloud distributions. The software implementation of the ampycloud algorithm takes the form of an eponym, pip-installable Python package developed on Github. The code is made accessible to the general community as an open-source software under the terms of the 3-Clause BSD license.

Near the center of the Puppis A supernova remnant a series of nested, optically emitting rings of high-velocity ejecta (known as “the Swirl”) were identified several decades ago by Winkler et al. To date, no follow-up observations of these rings have been published, and their physical origin has remained a mystery. We present results of integral field spectroscopy of the Swirl using the Wide Field Integral Spectrograph on the 2.3 m telescope at Siding Spring Observatory in Australia. The outermost ring exhibits a nitrogen-rich spectrum blueshifted to 1350 km s⁻¹, with smaller blueshifted rings within the first exhibiting mostly oxygen-rich spectra moving at 1000 and 750 km s⁻¹. The structures are connected by material of intermediate velocity and variable composition, including sulfur-rich material. The Swirl is turbulent and shock-excited, and contains as much as 0.5 M _⊙ of metal-rich material. The chemical composition and exclusively blueshifted radial velocities of the Swirl are consistent with progressively deeper nucleosynthetic layers in a massive progenitor star. We suggest the possibility that the Swirl marks a “funnel” carved into the supernova ejecta by a close, massive binary companion at the moment of explosion.

We present new and archival Australia Telescope Compact Array and Atacama Large Millimeter/submillimeter Array data of the Small Magellanic Cloud supernova remnant 1E 0102.2–7219 at 2100, 5500, 9000, and 108 000 MHz; as well as H i data provided by the Australian Square Kilometre Array Pathfinder. The remnant shows a ring-like morphology with a mean radius of 6.2 pc. The 5500 MHz image reveals a bridge-like structure, seen for the first time in a radio image. This structure is also visible in both optical and X-ray images. In the 9000 MHz image, we detect a central feature that has a flux density of 4.3 mJy but rule out a pulsar wind nebula origin, due to the lack of significant polarization towards the central feature with an upper limit of 4 per cent. The mean fractional polarization for 1E 0102.2–7219 is 7 ± 1 and 12 ± 2 per cent for 5500 and 9000 MHz, respectively. The spectral index for the entire remnant is −0.61 ± 0.01. We estimate the line-of-sight magnetic field strength in the direction of 1E 0102.2–7219 of ∼44 µG with an equipartition field of $65\pm 5\, \mu$G. This latter model uses the minimum energy of the sum of the magnetic field and cosmic ray electrons only. We detect an H i cloud towards this remnant at the velocity range of ∼160–180 km s−1 and a cavity-like structure at the velocity of 163.7–167.6 km s−1. We do not detect CO emission towards 1E 0102.2–7219.