Frederic Schuller

Leibniz Institute for Astrophysics Potsdam · Solar Physics

Despite recent progress, the question of what regulates the star formation efficiency in galaxies remains one of the most debated problems in astrophysics. According to the dominant picture, star formation (SF) is regulated by turbulence and feedback, and the SFE is 1-2% per local free-fall time. In an alternate scenario, the SF rate in galactic di...

Context . The solar energetic particle analysis platform for the inner heliosphere (SERPENTINE) project, funded through the H2020-SPACE-2020 call of the European Union’s Horizon 2020 framework program, employs measurements of the new inner heliospheric spacecraft fleet to address several outstanding questions on the origin of solar energetic partic...

We investigate observational signatures of explosive chromospheric evaporation during a white-light flare (WLF) that occurred on 2022 August 27. Using the moment analysis, bisector techniques, and the Gaussian fitting method, redshifted velocities of less than 20 km s ⁻¹ are detected in low-temperature spectral lines of H α , C i, and Si iv at the...

Context. The Solar Orbiter mission completed its first remote-sensing observation windows in the spring of 2022. On 2 April 2022, an M-class flare followed by a filament eruption was seen both by the instruments on board the mission and from several observatories in Earth’s orbit, providing an unprecedented view of a flaring region with a large ran...

The Solar Orbiter mission completed its first remote-sensing observation windows in the spring of 2022. On 2/4/2022, an M-class flare followed by a filament eruption was seen both by the instruments on board the mission and from several observatories in Earth's orbit. The complexity of the observed features is compared with the predictions given by...

We investigate observational signatures of explosive chromospheric evaporation during a white-light flare (WLF) that occurred on 2022 August 27. Using the moment analysis, bisector techniques, and the Gaussian fitting method, red-shifted velocities of less than 20 km/s are detected in low-temperature spectral lines of Ha, C I and Si IV at the conju...

Context. A complex and long-lasting solar eruption on 17 April 2021 produced a widespread solar energetic particle (SEP) event that was observed by five longitudinally well-separated observers in the inner heliosphere that covered distances to the Sun from 0.42 to 1 au: BepiColombo, Parker Solar Probe, Solar Orbiter, STEREO A, and near-Earth spacec...

Context.We study the solar energetic particle (SEP) event observed on 9 October 2021 by multiple spacecraft, including Solar Orbiter. The event was associated with an M1.6 flare, a coronal mass ejection, and a shock wave. During the event, high-energy protons and electrons were recorded by multiple instruments located within a narrow longitudinal c...

Context. A solar eruption on 17 April 2021 produced a widespread Solar Energetic Particle (SEP) event that was observed by five longitudinally well-separated observers in the inner heliosphere at heliocentric distances of 0.42 to 1 au: BepiColombo, Parker Solar Probe, Solar Orbiter, STEREO A, and near-Earth spacecraft. The event produced relativist...

Aims. To provide a schematic mathematical description of the imaging concept of the Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter. The derived model is the fundamental starting point for both the interpretation of STIX data and the description of the data calibration process. Methods. We describe the STIX indirect imaging...

The Spectrometer/Telescope for Imaging X-rays (STIX) onboard Solar Orbiter observes solar X-ray emission in the range of 4 to 150 keV and produces spectra and images of solar flares over a wide range of flare magnitudes. During nominal operation, STIX continuously generates data. A constant data flow requires fully automated data processing pipelin...

We study the solar energetic particle (SEP) event observed on 9 October 2021, by multiple spacecraft including Solar Orbiter (SolO). The event was associated with an M1.6 flare, a coronal mass ejection (CME) and a shock wave. During the event, high-energy protons and electrons were recorded by multiple instruments located within a narrow longitudin...

We report on one of the first solar-eruptive events that was simultaneously observed by three of the remote-sensing instruments onboard Solar Orbiter during the cruise phase. The Extreme Ultraviolet Imager (EUI) observed an eruption on 22 April 2021. The corresponding CME was recorded by the coronagraph Metis. Finally, the Spectrometer/Telescope fo...

Context. One of the main science questions of the Solar Orbiter and Parker Solar Probe missions deals with understanding how electrons in the lower solar corona are accelerated and how they subsequently access interplanetary space. Aims. We aim to investigate the electron acceleration and energy release sites as well as the manner in which accelera...

One of the main science questions of the Solar Orbiter and Parker Solar Probe missions deals with understanding how electrons in the lower solar corona are accelerated and how they subsequently access interplanetary space. We aim to investigate the electron acceleration and energy release sites as well as the manner in which accelerated electrons a...

Aiming at delivering a highly available service, the French national optical fiber link network is run mostly unmanned and automatically, with the help of a global supervision. However, at a year scale, missing data are seemingly unavoidable. Here, we present a first study of the uncertainty of coherent fiber links with missing data. We present the...

The Spectrometer/Telescope for Imaging X-rays (STIX) is one of six remote sensing instruments on-board Solar Orbiter. The telescope applies an indirect imaging technique that uses the measurement of 30 visibilities, i.e., angular Fourier components of the solar flare X-ray source. Hence, the imaging problem for STIX consists of the Fourier inversio...

The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter ob-served an eruption through both of its channels (17.4/30.4 nm) of its Full Sun Imager, on 22 April 2021. At the time, the spacecraft was at 0.87 au from the Sun,and 98◦ east of the Sun-Earth line. The eruption was slightly back-sided, emerging close to the southwest limb, starting at 04:...

The Structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium (SEDIGISM) survey has produced high (spatial and spectral) resolution ¹³ CO (2−1) maps of the Milky Way. It has allowed us to investigate the molecular interstellar medium in the inner Galaxy at an unprecedented level of detail and characterise it into molecular cloud...

The Structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium (SEDIGISM) survey has produced high (spatial and spectral) resolution $^{13}$CO (2-1) maps of the Milky Way. It has allowed us to investigate the molecular interstellar medium in the inner Galaxy at an unprecedented level of detail and characterise it into molecular c...

Recently, we reported the discovery of a kpc-scale CO structure in the inner Galaxy which we named the Gangotri wave. The structure is at least 2 kpc in extent and its vertical distribution is wave-like in morphology. The analysis of the velocity data suggests Gangotri wave being a spur of the Milky Way or a sub-branch of the Norma arm. Following t...

We present one of the very first extensive classifications of a large sample of molecular clouds based on their morphology. This is achieved using a recently published catalogue of 10663 clouds obtained from the first data release of the SEDIGISM survey. The clouds are classified into four different morphologies by visual inspection and using an au...

Context. The Spectrometer/Telescope for Imaging X-rays (STIX) is one of 6 remote sensing instruments on-board Solar Orbiter. It provides hard X-ray imaging spectroscopy of solar flares by sampling the Fourier transform of the incoming flux. Aims. To show that the visibility amplitude and phase calibration of 24 out of 30 STIX sub-collimators is wel...

The ALMA-IMF Large Program imaged a total noncontiguous area of 53pc2, covering 15 extreme, nearby protoclusters of the Milky Way. They were selected to span relevant early protocluster evolutionary stages. Our 1.3mm and 3mm observations provide continuum images that are homogeneously sensitive to point-like cores with masses of 0.2 and 0.6Msun, re...

Context. The formation processes of massive stars are still unclear but a picture is emerging involving accretion disks and molecular outflows in what appears to be a scaled-up version of low-mass star formation. A census of outflow activity towards massive star-forming clumps in various evolutionary stages has the potential to shed light on massiv...

We report the discovery of a velocity coherent, kiloparsec-scale molecular structure toward the Galactic center region with an angular extent of 30° and an aspect ratio of 60:1. The kinematic distance of the CO structure ranges between 4.4 and 6.5 kpc. Analysis of the velocity data and comparison with the existing spiral arm models support that a m...

Filaments are a ubiquitous morphological feature of the molecular interstellar medium and are identified as sites of star formation. In recent years, more than 100 large-scale filaments (with a length > 10 pc) have been observed in the inner Milky Way. As they appear linked to Galactic dynamics, studying those structures represents an opportunity t...

Filaments are a ubiquitous morphological feature of the molecular interstellar medium and are identified as sites of star formation. In recent years, more than 100 large-scale filaments (with a length $>10$\,pc) have been observed in the inner Milky Way. As they appear linked to Galactic dynamics, studying those structures represents an opportunity...

We report the discovery of a velocity coherent, kpc-scale molecular structure towards the Galactic center region with an angular extent of 30deg and an aspect ratio of 60:1. The kinematic distance of the CO structure ranges between 4.4 to 6.5 kpc. Analysis of the velocity data and comparison with the existing spiral arm models support that a major...

The morphology of the Milky Way is still a matter of debate. In order to shed light on uncertainties surrounding the structure of the Galaxy, in this paper, we study the imprint of spiral arms on the distribution and properties of its molecular gas. To do so, we take full advantage of the SEDIGISM (Structure, Excitation, and Dynamics of the Inner G...

The morphology of the Milky Way is still a matter of debate. In order to shed light on uncertainties surrounding the structure of the Galaxy, in this paper, we study the imprint of spiral arms on the distribution and properties of its molecular gas. To do so, we take full advantage of the SEDIGISM survey that observed a large area of the inner Gala...

We report observations of a relatively long period of 3He-rich solar energetic particles (SEPs) measured by Solar Orbiter. The period consists of several well-resolved ion injections. The high-resolution STEREO-A imaging observations reveal that the injections coincide with EUV jets/brightenings near the east limb, not far from the nominal magnetic...

The Spectrometer/Telescope for Imaging X-rays (STIX) is the HXR instrument onboard Solar Orbiter designed to observe solar flares over a broad range of flare sizes, between 4-150 keV. We report the first STIX observations of microflares recorded during the instrument commissioning phase in order to investigate the STIX performance at its detection...

Context. The Orion molecular cloud is the closest region of high-mass star formation. It is an ideal target for investigating the detailed structure of massive star-forming filaments at high resolution and the relevance of the filament paradigm for the earliest stages of intermediate- to high-mass star formation. Aims. Within the Orion A molecular...

(abridged) Within the Orion A molecular cloud, the integral-shaped filament (ISF) is a prominent, degree-long structure of dense gas and dust, with clear signs of recent and on-going high-mass star formation. We used the ArTeMiS bolometer camera at APEX to map a 0.6x0.2 deg^2 region covering OMC-1, OMC-2, OMC-3 at 350 and 450 micron. We combined th...

The high-resolution temperature and H_2 column density maps t constructed from the combined ArTeMiS + Herschel data are made available. The resolution of the temperature map is limited by that of the Herschel-SPIRE 250um data (18.2arcsec). The column density map has a resolution of 8arcsec. \\\\(2 data files).

By combining two surveys covering a large fraction of the molecular material in the Galactic disk we investigate the role the spiral arms play in the star formation process. We have matched clumps identified by ATLASGAL with their parental GMCs as identified by SEDIGISM, and use these giant molecular cloud (GMC) masses, the bolometric luminosities,...

The SEDIGISM (Structure, Excitation and Dynamics of the Inner Galactic Interstellar Medium) survey used the APEX telescope to map 84 deg^2 of the Galactic plane between l = -60 deg and l = +31 deg in several molecular transitions, including 13CO(2-1) and C18O(2-1), thus probing the moderately dense (~10^3 cm^-3) component of the interstellar medium...

We use the 13CO(2-1) emission from the SEDIGISM high-resolution spectral-line survey of the inner Galaxy, to extract the molecular cloud population with a large dynamic range in spatial scales, using the SCIMES algorithm. This work compiles a cloud catalogue with a total of 10663 molecular clouds, 10300 of which we were able to assign distances and...

Sgr E is a massive star formation complex found toward the Galactic center that consists of numerous discrete, compact H ii regions. It is located at the intersection between the central molecular zone (CMZ) and the far dust lane of the Galactic bar, similar to “hot spots” seen in external galaxies. Compared with other Galactic star formation compl...

The SEDIGISM (Structure, Excitation and Dynamics of the Inner Galactic Interstellar Medium) survey used the APEX telescope to map 84 deg2 of the Galactic plane between ℓ = −60○ and ℓ = +31○ in several molecular transitions, including 13CO (2 – 1) and C18O (2 – 1), thus probing the moderately dense (∼103 cm−3) component of the interstellar medium. W...

By combining two surveys covering a large fraction of the molecular material in the Galactic disk we investigate the role the spiral arms play in the star formation process. We have matched clumps identified by ATLASGAL with their parental GMCs as identified by SEDIGISM, and use these giant molecular cloud (GMC) masses, the bolometric luminosities,...

We use the 13CO (2-1) emission from the SEDIGISM (Structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium) high-resolution spectral-line survey of the inner Galaxy, to extract the molecular cloud population with a large dynamic range in spatial scales, using the Spectral Clustering for Interstellar Molecular Emission Segmentat...

The mass growth of protostars is a central element to the determination of fundamental stellar population properties such as the initial mass function. Constraining the accretion history of individual protostars is therefore an important aspect of star formation research. The goal of the study presented here is to determine whether high-mass (proto...

Sgr E is a massive star formation complex found toward the Galactic center that consists of numerous discrete, compact HII regions. It is located at the intersection between the Central Molecular Zone (CMZ) and the far dust lane of the Galactic bar, similar to "hot spots" seen in external galaxies. Compared with other Galactic star formation comple...

The Spectrometer/Telescope for Imaging X-rays (STIX) is a remote sensing instrument on Solar Orbiter that observes the hard X-ray bremsstrahlung emission of solar flares. This paper describes the STIX Aspect System (SAS), a subunit that measures the pointing of STIX relative to the Sun with a precision of ±4″, which is required to accurately locali...

Context. The edges of ionized (H II ) regions are important sites for the formation of (high-mass) stars. Indeed, at least 30% of the Galactic high-mass-star formation is observed there. The radiative and compressive impact of the H II region could induce star formation at the border following different mechanisms such as the collect and collapse o...

The mass growth of protostars is a central element to the determination of fundamental stellar population properties such as the initial mass function. Constraining the accretion history of individual protostars is therefore an important aspect of star formation research. The goal of the study presented here is to determine whether high-mass (proto...

The edges of ionized (HII) regions are important sites for the formation of (high-mass) stars. Indeed, at least 30% of the galactic high mass star formation is observed there. The radiative and compressive impact of the HII region could induce the star formation at the border following different mechanisms such as the Collect & Collapse (C&C) or th...

Context. The role of ionization feedback on high-mass (>8 M⊙) star formation is still highly debated. Questions remain concerning the presence of nearby H II regions changes the properties of early high-mass star formation and whether H II regions promote or inhibit the formation of high-mass stars. Aims. To characterize the role of H II regions on...

Context. Massive stars and their associated ionized (H II ) regions could play a key role in the formation and evolution of filaments that host star formation. However, the properties of filaments that interact with H II regions are still poorly known. Aims. To investigate the impact of H II regions on the formation of filaments, we imaged the Gala...

Massive stars and their associated ionized (HII) regions could play a key role in the formation and evolution of filaments that host star formation. However, the properties of filaments that interact with H regions are still poorly known. To investigate the impact of HII regions on the formation of filaments, we imaged the Galactic HII region RCW 1...

The role of ionization feedback on high-mass (>8 Msun) star formation (HMSF) is still highly debated. Questions remain concerning the presence of nearby HII regions changes the properties of early HMSF and whether HII regions promote or inhibit the formation of high-mass stars. To characterize the role of HII regions on the HMSF, we study the prope...

Context. The role of ionization feedback on high-mass (>8 M⊙ ) star formation is still highly debated. Questions remain concerning the presence of nearby H II regions changes the properties of early high-mass star formation and whether H II regions promote or inhibit the formation of high-mass stars. Aims. To characterize the role of H II regions o...

This table presents the properties of each of 203 compact ArTeMiS sources identified in the images analysed in the paper. These sources have been identified across 5 fields: SDC326, SDC328, SDC340, SDC343, SDC345. \\\\(1 data file).

Velocity and Distance of HiGAL sources. \\\\(2 data files).