UchUchU

Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SRastro-ph.GA

The IACOB project XIX. Revisiting massive-star evolution with empirical TAMS constraints: updated models, overshoot calibration, and the population of blue supergiants

Luca Sciarini, Abel de Burgos, Sophie Rosu, Sylvia Ekström, Sergio Simón-Díaz, Cyril Georgy

Massive stars play a fundamental role in the evolution of the Universe. Yet, several physical processes governing their evolution remain poorly constrained. Notably, the main-sequence width is sensitive to the convective boundary mixing efficiency; it becomes necessary to account for binary interactions to explain some observed properties of massive-star populations. We constrain single-star models using recent observations of massive Galactic stars from the IACOB database. We use the latest pro…

Read →
astro-ph.EPastro-ph.IM

Critical Sizes of Satellite Constellations

Hugh G. Lewis

The precipitous growth of commercial space activity, largely from the development of satellite constellations, threatens to produce a runaway orbital debris population. National regulators are attempting to limit these risks through orbital debris mitigation requirements, but these fail to address the large scale and long lifetimes of satellite constellations. Instead, evaluations are based on the risks from single satellites, and the aggregate risks across constellations are neglected. This sit…

Read →
astro-ph.SR

On the use of field RR Lyrae as Galactic probes:. IX. Radial velocities

K. Baeza-Villagra, V. F. Braga, M. Fabrizio, G. Bono, V. D'Orazi, Z. Prudil, F. Berrilli, G. Böcek Topcu et al.

We present the largest and most homogeneous catalog of radial velocity (RV) measurements for field RR Lyrae (RRL) variables, based on both proprietary and publicly available spectroscopic data. The sample includes 17,563 RRLs pulsating in the fundamental mode (12,353 RRab), in the first overtone (5,011 RRc), and in double-mode (199 RRd). The RV curve (RVC) templates for metallic and Balmer lines were used to derive RV amplitudes and $V_γ$ velocities, defined as the RV of the stellar barycenter w…

Read →
astro-ph.GA

A Massive Galaxy at the Edge of Feedback-Free Efficiency

K. Aditya, Kartick C. Sarkar

The efficiency with which galaxies convert their available baryonic reservoir into stars sets a fundamental ceiling on stellar mass assembly in the early Universe and encodes the cumulative effect of stellar feedback. in this paper, we report the measurement of star-formation efficiency (SFE) of a photometrically and spectroscopically vetted reference sample at $z=9-10$, out of which 31 are spectroscopically confirmed. Among them, we highlight a spectroscopically confirmed galaxy, \texttt{UNCOVE…

Read →
astro-ph.SR

Asteroseismic models of the magnetic binary HD 156424

C. C. Lovekin, S. Davis, V. Khalack

HD 156424 is a hot magnetic star in the Sco OB4 association and has previously been identified as part of a binary system. Spectropolarimetric results show that the companion star is also strongly magnetic, and thus this is a rare example of a doubly magnetic hot binary. In this work, we aim to present a more detailed analysis of Transiting Exoplanet Survey Satellite data including phase variation. We find short-term phase variation consistent with an oblique magnetic rotator, as well as long-te…

Read →
astro-ph.IMastro-ph.EPastro-ph.SR

The Tartu Observatory Fiber-fed Echelle Spectrograph (TOFES) Data Reduction Pipeline

Sandipan P. D. Borthakur, Tõnis Eenmäe, Nikolai Piskunov, Luca Fossati, Mihkel Kama, Thomas Marquart, Anni Kasikov, Heleri Ramler et al.

We introduce the data reduction pipeline for the Tartu Observatory Fiber-fed Echelle Spectrograph (TOFES). TOFES is installed in the Coudé room and will be connected to the 1.5 m Tartu Observatory AZT-12 telescope through a four-channel instrument adapter to be mounted at the Cassegrain focus of the telescope. The spectrograph has an average spectral resolution of 30,000 and covers the 390 to 900 nm wavelength band in a single exposure. The data reduction pipeline, based on the PyReduce package,…

Read →
astro-ph.EP

Warm Sub-Saturns Orbiting Single Stars Are Spin-Orbit Aligned

Xian-Yu Wang, Songhu Wang

In this work, we show that warm sub-Saturns orbiting single stars are predominantly aligned, in contrast to hot sub-Saturns, which are frequently misaligned, with the two populations differing at the 3.2$σ$ level. Because both populations are observed around cool stars, they are free from the ambiguity introduced by the $T_{\rm eff}$-$λ$ dependence. Together with the established alignment of warm Jupiters, this demonstrates, among single-star systems, that spin-orbit misalignment arises specific…

Read →
astro-ph.EPastro-ph.IM

Towards Autodifferentiable Point Spread Function Modelling for the VLT/ERIS Vortex Coronagraph

P. Van de Walle Suarez, G. Orban De Xivry, O. Absil, M. J. Bonse, R. J. De Rosa, V. Christiaens

High-contrast imaging of exoplanets is limited by the presence of quasi-static speckles and existing post-processing methods remain above the theoretical noise limit. We investigate a novel framework that incorporates adaptive optics (AO) wavefront sensor telemetry into post-processing using a differentiable optical model of the ERIS vortex coronagraph. As a first proof of concept, we inject AO telemetry into an ERIS forward model and assess its ability to reproduce the on-sky point spread funct…

Read →
astro-ph.GA

The TOP-SCOPE Survey of Planck Galactic Cold Clumps: Molecular gas properties

Yuebin Yang, Jarken Esimbek, Tie Liu, Willem Baan, Xunchuan Liu, Kee-Tae Kim, Gang Wu, Xindi Tang et al.

We surveyed 2008 Planck Galactic Cold Clumps (PGCCs) in $^{12}\mathrm{CO}$ and $^{13}\mathrm{CO}$ $J=1$--0 lines using the Taeduk Radio Astronomy Observatory (TRAO) 14 m telescope's multi-beam receiver. We detected 2784 ($^{12}\mathrm{CO}$) and 2291 ($^{13}\mathrm{CO}$) velocity components, their closely correlated centroid velocities suggest that $^{12}$CO and $^{13}$CO generally trace kinematically associated gas. PGCCs have low excitation temperatures (mean $\sim$10 K), mean $^{13}\mathrm{CO}…

Read →
astro-ph.GA

ROLLIN': Rotating globular cluster simulations II. The complex morphology of globular clusters driven by multi-scale dynamics

Arn Marklund, Paolo Bianchini, Anna Lisa Varri, Katarina Kraljic, Giulia Pagnini

Globular clusters (GCs) are inherently non-spherical systems that in many cases show internal rotation. Typically, rotation is considered the main driver of GC morphology; however, the relationship between ellipticity and rotational support is not a simple one-to-one mapping, and other multi-scale dynamical processes may contribute. We investigate how morphology evolves in realistic models of rotating GCs, and how it correlates with key physical ingredients, including mass loss, stellar evolutio…

Read →
astro-ph.SR

Spectroscopic Analysis of the 2025 Eclipse of the Symbiotic Binary V1413 Aquilae

David Boyd, James Foster, Forrest Sims, David Cejudo, Robin Leadbeater, Pavol Dubovsky, Xavier Dupont, Keith Shank et al.

We report on a coordinated campaign by amateur astronomers using a combination of high and low resolution spectroscopy to observe the 2025 eclipse of the symbiotic binary V1413 Aql shortly after a probable Z And-type symbiotic outburst. We measured the eclipse time of minimum and computed an updated eclipse ephemeris. Our spectra were calibrated in absolute flux and multi-Gaussian fits were used to resolve and quantify components of the Hα emission line. We measured the radial velocity curve of…

Read →
astro-ph.HE

Gamma-ray emission from particle illumination and shock-cloud interaction in the W51 Complex

Alan Sunny, Martina Cardillo

In the current era of very-high-energy (VHE) and ultra-high-energy (UHE) $γ$-ray astronomy, understanding Galactic PeVatrons and their acceleration mechanisms remains a primary objective. Recent LHAASO observations of the W51 Complex make it an ideal laboratory for investigating the origin of UHE emission, particularly due to the presence of massive and dense molecular environment surrounding multiple potential particle accelerators. In this work, we study two hadronic scenarios for the W51 Comp…

Read →
astro-ph.EPastro-ph.IM

Twin Impact Lunar Telescope network: Lunar Impact Flash observations of the 2025 Geminids

Daniel Sheward, Marco Delbo, Chrysa Avdellidou, Philippe Lognonné, Jeremie Vaubaillon, Pierre-Yves Froissart, Christelle Saliby, Paul Girard et al.

Meteoroid impacts on the Moon, observed from Earth as flashes typically lasting a few tens of milliseconds, have been monitored for three decades for determining meteoroids' size and mass frequency distribution in the cm to dm range. Studies link these observed impact events to fresh craters advancing our understanding of energy partitioning during an impact. Currently we are transitioning to a new era where lunar impact flashes (LIFs) can be used to supplement upcoming lunar seismology to study…

Read →
astro-ph.SRastro-ph.EPastro-ph.IM

The Fe I 4377 Å Line as a Solar Faculae Indicator: Insights from Spectral Ratio Analysis

Katlyn L. Hobbs, Christopher A. Watson, Jean C. Costes, Yvonne Unruh, Dana Clarice Yaptangco, Krishnamurthy Sowmya, Mitchell E. Young, Ernst J. W. de Mooij et al.

Faculae are a dominant source of stellar activity noise in radial velocity measurements, yet their low contrast and broad surface distribution make them difficult to track in disc-integrated observations. We apply Spectral Ratio Analysis (SRA) to HARPS-N Sun-as-a-star observations to isolate and characterize the spectral imprint of facular regions over rotational timescales. The resulting SRA spectra show coherent, line-dependent variability sensitive to surface magnetic activity, with the Fe I…

Read →
astro-ph.HEastro-ph.GA

Rates of tidal disruption events from constrained cosmological simulations of the local Universe: population properties and implications for transient surveys

Julian S. Sommer, Ildar Khabibullin, Klaus Dolag, Luca Sala, Benjamin Seidel, Jenny G. Sorce, Alice Damiano

(abridged) Motivated by upcoming surveys like LSST, we estimate tidal disruption event (TDE) rates using the constrained cosmological Simulation of the LOcal Web (SLOW) to test the limitations of traditional 2D analytical extrapolations within a fully 3D framework. We aim to provide reliable TDE budgets extracted from the simulated zoom-in volumes of the digital counterparts of the Coma, Hercules, Shapley, Virgo, and Perseus supercluster environments, and the Fornax galaxy cluster. From the zoom…

Read →
astro-ph.IM

Charge migration characterization in the METIS H2RG detectors

Danny Gasman, Benoît Serra, Roy van Boekel, Ioannis Argyriou, Daniel Dicken, Vianak Naranjo, Peter Bizenberger

The Mid-infrared ELT Imager and Spectrograph (METIS) is one of the first-light instruments of the Extremely Large Telescope (ELT). For the L and M band, the instrument makes use of Teledyne's H2RG detectors, known to be affected by charge migration, also known as the brighter-fatter effect (BFE). In the H2RG detectors this manifests as photo-electrons moving from a central bright pixel to neighboring pixels as the depletion region of the central pixel shrinks with accumulated charge. Due to its…

Read →
astro-ph.GA

CatBoost versus Spectral Energy Distribution-Fitting: Estimating Galaxy Properties under Controlled Photometric Incompleteness

Vahid Asadi, Hosein Haghi, Akram Hasani Zonoozi

Estimating galaxy physical parameters from photometric data is fundamentally challenged by missing measurements that are endemic to astronomical surveys. Using a mock catalog from the Horizon-AGN hydrodynamical simulation that provides the true physical parameters, we evaluate CatBoost, a gradient-boosting algorithm that natively handles missing data, under a deliberately adversarial scenario: we train it on 12 photometric bands with increasing levels of injected missingness (10%, 20%, 30% missi…

Read →
astro-ph.IMphysics.ins-det

Persistence characteristics of H4RG-15 detectors for ESO instruments

Elizabeth M. George, Domingo Alvarez Mendez, Nagaraja Naidu Bezawada, Derek J. Ives, Mark Neeser, Benoit Serra

As a part of the ESO Instrumentation Program, we already ordered 23 H4RG-15 (2.5 um cut-off) detectors for the instruments MOONS, MICADO, and HARMONI, with more of these detectors planned for future instruments on the ELT as well as possibly other ESO telescopes. As part of our comprehensive detector testing program, we characterize detector persistence at different temperatures between 40 and 85 K, allowing the best-informed choice of operating temperature for the science focal planes. We repor…

Read →
astro-ph.IMastro-ph.COastro-ph.GA

Visual analytics for cosmological simulation results

Paul Vauterin, Maarten Baes

Context: Modern cosmological simulations rely on sophisticated assumptions and generate rich, highly complex datasets. Interpreting their results in order to extract new scientific insights remains challenging. Existing visualisation tools offer powerful capabilities but often come with a relatively high barrier for entry, and are not designed with a focus on knowledge discovery through real-time, intuitive visual analytics. This stands in contrast to other research domains, such as bioinformati…

Read →
astro-ph.COastro-ph.GA

Planck Constraints on Turbulence in the Coma Cluster

Baptiste Sigal, Etienne Pointecouteau, Nicolas Clerc, Simon Dupourqué, Alexeï Molin, François Mernier, Rémi Adam, Tanguy Dusserre et al.

Turbulence within the intracluster medium (ICM) influences galaxy cluster thermodynamics and virialisation, contributing to non-thermal pressure support and impacting hydrostatic mass estimates. Characterising this turbulence through thermodynamic fluctuations remains observationally challenging due to the non-linear relationships between observables such as density and pressure, and the underlying velocity field. This study aims to constrain the properties of ICM turbulence by performing a comp…

Read →
astro-ph.GA

Recovering pattern speeds of simulated face-on barred galaxies via Schwarzschild modelling

Iliya S. Tikhonenko, Jens Thomas, Roberto P. Saglia

Stellar bars are a major driving force in the secular evolution of their host galaxies. To better understand the connections between the 3D bar density structure, its orbital composition, stellar populations, and underlying dark matter distribution, it is desirable to construct detailed dynamical models of barred galaxies. However, only a few external barred galaxies have been studied in this way so far. We present a new Schwarzschild orbit superposition code for triaxial potentials with figure…

Read →
astro-ph.IMastro-ph.GAastro-ph.SR

The critical role of HST UV spectroscopy in constraining red supergiant binary systems

Daniel Jadlovský, Andreas Sander, Lee Patrick, Jiří Krtička, Gemma González-Torà, Matheus Bernini-Peron

The Hubble Space Telescope (HST) has advanced our knowledge of stellar evolution thanks to its unique high-spectral resolution and high-sensitivity capabilities in the UV region, especially for hot massive stars. Within the field of red supergiants (RSGs), it has led to several major insights as well, such as, for example, characterizing the embedded hot companion in the VV Cephei system, the detection of surface mass ejection from Betelgeuse, and unveiling the rich population of RSG+B binaries…

Read →
hep-phastro-ph.IMgr-qchep-ex

Halbach Magnetic Weber Bars

Valerie Domcke, Itay M. Bloch

Magnetic Weber Bars have been proposed to search for gravitational waves in the kHz to GHz regime by exploiting the mechanical deformation of a large magnet induced by a gravitational wave. Here we propose to increase the effectiveness of such devices by considering magnetic field configurations with strong gradients, albeit lower field strengths, such as Halbach arrays. We focus on one of the most challenging but most realistic signals, with short duration and low coherence, exploiting the ring…

Read →
astro-ph.EP

Gas Phase Ion Species Released During Grain Collisions: Implications For Protoplanetary Disks

Patrick Hock, Gerhard Wurm

Grain charging and gas ionization are important processes in protoplanetary disks. Both occur in mutual collisions between grains, as charge is exchanged between grain surfaces but also released into the surrounding gas as ions. The charge carrier for tribocharging, the origin of the gaseous ions, and their composition are currently unknown. However, it is important to know to validate the significance of these processes under disk conditions. In this work, we approach these questions by detecti…

Read →
gr-qcastro-ph.EPastro-ph.SR

Deviation of trajectories in nonrelativistic and relativistic cases and Shirokov effect

Yu. V. Pavlov, V. P. Vandeev

We compare the deviations of circular orbits in the nonrelativistic and relativistic cases. General solutions of the deviation equations are obtained. We find the potentials for the nonrelativistic case and the metric components in general relativity for which trajectories close to circular ones are closed curves. Explicit expressions for the pericenter shift of an orbit close to a circular one in a static spherically symmetric spacetime are obtained. Estimates of the cosmological constant effec…

Read →
astro-ph.IMphysics.opticsquant-ph

Information limits of photonic lantern wavefront sensing: a Fisher- and quantum-Fisher-information framework and its relation to Fourier-filtering sensitivity limits

Kalaga Madhav

The photonic lantern is an all-photonic wavefront sensor native to single-mode-fibre-fed instruments, but its performance is almost always quoted through a specific reconstruction algorithm, obscuring how much wavefront information the device itself encodes. We develop, from first principles, the Fisher-information and Cramer-Rao theory of the photonic-lantern wavefront sensor, benchmark it against the quantum Cramer-Rao bound via an explicit multi-parameter quantum-Fisher-information calculatio…

Read →
astro-ph.IM

Maximising the mid-infrared high-contrast performance of ELT/METIS despite water vapour seeing

Olivier Absil, Gilles Orban de Xivry, Prashant Pathak, Abhirami S. Raghu, Benjamin Courtney-Barrer, Roy van Boekel, Thomas Bertram, Markus Feldt et al.

The Mid-infrared ELT Imager and Spectrograph (METIS) will be equipped with a SCAO system delivering Strehl ratios above 90% at L band (3.5 - 4.1 um) and close to 99% at N band (8 - 13 um) on bright stars. Yet, the actual wavefront quality seen by the METIS coronagraphic modules used for high-contrast imaging will be significantly affected by water vapour seeing, which add a strong chromatic component to dry air seeing in the mid-infrared. We analysed two years of VLTI/GRAVITY fringe tracker arch…

Read →
astro-ph.SR

Spectroscopy of flares on AU Mic

P. Odert, M. Leitzinger, P. Kabáth, R. Greimel, J. Lipták, R. Karjalainen, P. Heinzel, J. Wollmann et al.

Photometric space missions like Kepler and TESS have revealed unprecedented statistics of stellar flares, including the frequent detection of highly energetic superflares. Spectroscopic characterization of flares and especially superflares, however, is still not as commonly available. In contrast to broad-band photometry, spectroscopic data can give more insights into the physical parameters of flares, as well as allowing to identify possibly accompanying CMEs. In this context, we monitored the…

Read →
astro-ph.SR

Spectroscopic investigation of the southern late-K/early-M dwarf binary CC Eri

M. Leitzinger, P. Odert, R. Greimel, P. Kabáth, J. Lipták, R. Karjalainen, P. Heinzel, J. Wollmann et al.

In the recent past investigations of stellar Coronal Mass Ejections (CMEs) and flares/superflares gained special attention because of their relevance for planetary habitability and stellar evolution. With respect to that, we present an observing campaign at the ESO152 telescope on LaSilla operated by the PLATOSpec consortium of the late-K/early-M dwarf binary CC Eri. The ESO152 telescope is currently equipped with an Echelle spectrograph which enables the investigation of a broad spectral range,…

Read →
astro-ph.GA

The Radial Acceleration Relation in Galaxies and Clusters from a Two-Component, Virial-Motivated Framework

Christine C. Dantas, Andre L. B. Ribeiro, Hugo V. Capelato

We present a comparative analysis of acceleration data for gravitational systems drawn from multiple observational sources, including: (i) early-type galaxies (ETGs) (Lelli et al. 2017); (ii) Brightest Cluster Galaxies (BCGs) and galaxy clusters (Tian et al. 2020, 2024); and (iii) weak gravitational lensing of isolated galaxies (Brouwer et al. 2021; Mistele et al. 2024). These data are interpreted within a framework motivated by the Two-component Virial Theorem (2VT), which defines a global bary…

Read →