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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.EP

Rotation, spectral type, and albedo of the potentially hazardous asteroid (153814) 2001 WN$_{\text 5}$ Prior to the 2028 June close approach

Jin Beniyama, Alexey V. Sergeyev, Konstantinos Odysseas Xenos, Benoit Carry, Petr Pravec, Petr Fatka, Peter Kušnírák, Larry Denneau et al.

The potentially hazardous asteroid (153814) 2001 WN$_5$ will pass inside the lunar distance on June 26, 2028, offering a rare opportunity to characterize a kilometer-scale near-Earth asteroid at high angular resolution. We aim to constrain the rotation state, shape, visible colors, geometric albedo, and taxonomy of 2001 WN$_5$ before its 2028 close approach. We combined new photometry from the 1.54 m Danish Telescope (DK154) with archival and survey observations from the Transiting Exoplanet Sur…

astro-ph.IM

Foundation Models for Astrophysics

Xiaosheng Zhao, Yuan-Sen Ting

Foundation models are high-capacity networks pretrained once on broad data and then reused across many tasks. This chapter introduces them through the idea of a transferable representation, the internal description a network forms during training, which, rather than the fitted task, is what carries over to new problems. We develop the idea from first principles for an astronomical reader, starting from why a representation matters and what makes one useful, and then surveying the architectures,…

astro-ph.GAastro-ph.SR

Radial abundance gradients of 18 elements in Galactic open clusters from infrared MWM spectra A detailed analysis of 655 giants in 133 clusters

S. Bijavara Seshashayana, H. Jönsson, V. D'Orazi, K. Cunha, P. Frinchaboy, J. M. Otto

Open clusters are powerful tools for studying the Milky Way. While large spectroscopic surveys now provide spectra for many cluster members, automated pipelines and heterogeneous membership selections can introduce systematics and inflate apparent cluster scatter. Therefore, a homogeneous re-analysis with careful membership control and an explicit treatment of departures from Local Thermodynamic Equilibrium is valuable for establishing robust abundance gradients. The aim is to derive precise Gal…

astro-ph.SR

You're Gonna Need a Bigger Core: Calibrating Massive Star Models against Galactic OB-type Stars

Thibault Lechien, Selma E. de Mink, Stephen Justham, Abel de Burgos, Ruggero Valli, Sergio Simón-Díaz

The evolution of massive stars above 8 M$_\odot$ depends critically on the amount of mixing above the convective core during the main sequence. However, current models typically extrapolate results from lower-mass stars, where constraints from asteroseismology and eclipsing binary systems are more readily available. A new opportunity to study the evolution of massive stars and their distribution in the Hertzsprung--Russell diagram arises by combining the IACOB spectroscopic sample of over 900 Ga…

astro-ph.EPphysics.space-ph

The Length of Martian Crater Rays and Their Relation to Lunar Cold Spots

Trevor P. Erwin, Brandon C. Johnson, David Minton, Alexandria V. Johnson

Impact-generated crater rays are well-documented on the Moon, with most appearing as high-albedo streaks extending radially from a crater's center. On Mars, however, crater rays are significantly rarer and discernible only through thermal imaging due to their lower thermal inertia compared to surrounding terrain. This study presents the first comparative analysis between the lengths of Martian and lunar crater rays, including lunar albedo rays and cold spots, which are ray-like thermal anomalies…

nucl-thastro-ph.HE

The $g$-mode frequencies in cold neutron stars and nuclear saturation parameters

Hajime Sotani, Hajime Togashi

Oscillation frequencies excited in neutron stars are crucial for extracting their interior properties. In addition to the fundamental and pressure modes, the gravity ($g$-) modes can be excited even in zero-temperature stellar models due to the composition gradient. In this study, we systematically study the $g$-mode frequencies, focusing on the nucleonic equation of state. Then, we can derive an empirical relation for the 1st $g$-mode frequencies as a function of the stellar compactness and the…

astro-ph.SR

A catalogue of high angular resolution and contrast polarimetric maps of 45 nearby AGB stars with SPHERE/ZIMPOL

Nekolgne Aymard Badolo, Eric Lagadec, Mamadou N'Diaye, Sie Zacharie Kam, Iain McDonald, Alexis Matter, Jean Koulidiati, Lyu Abe et al.

We present the largest catalogue of asymptotic giant branch (AGB) stars, 45 targets in total, observed in polarized light at high angular resolution (~ 20 milliarcsec). The main goal of the study is to detect and characterize dust shells in the close environment of nearby AGB stars. This work also aims to systematically classify the AGB star circumstellar morphologies obtained with the SPHERE instrument installed at the Very Large Telescope (VLT), thanks to its Zurich Imaging Polarimeter (ZIMPOL…

astro-ph.SRphysics.space-ph

Statistical insights on the decorrelation lengths of solar wind parameters at L1 point under varying conditions

Yogesh, Aparupa Apsara Baruah, Dibyendu Chakrabarty, Kalyan Bhuyan, Aakash Gupta, Gregory G. Howes

Understanding the spatial coherence of solar wind plasma and magnetic field properties is essential for interpreting multi-spacecraft observations and for characterizing the large-scale structure of heliospheric transients. In this study, we quantify the spatial correlation of six key solar wind parameters - interplanetary magnetic field components, bulk flow speed, proton number density, and the alpha-to-proton abundance ratio - using simultaneous measurements from the ACE and Wind spacecraft a…

astro-ph.HE

Magnetic rigidity reveals the PeVatron acceleration region in SS433

Jie Liao, Wancheng Xu, Lang Cui, Pak-Hin Thomas Tam, Xi Yan, Linuo Yang, Ruo-yu Liu, Liang Chen et al.

PeVatrons are cosmic accelerators capable of driving particles to petaelectronvolt (PeV) energies. Recently, microquasar jets have emerged as compelling Galactic PeVatron candidates. This is especially the case for SS 433 as its $>100$ TeV gamma-ray emission is spatially coincident with an atomic cloud. However, the exact region where PeV protons are accelerated and injected within these jets remains unresolved. Here we report, using archival, multi-frequency VLBA observations, the magnetic fiel…

astro-ph.GA

XRISM Resolves the Circum-nuclear Environment of NGC 4945

Peter G. Boorman, Poshak Gandhi, Yoshihiro Ueda, Bert Vander Meulen, Kanta Fujiwara, Aoi Nakano, Johannes Buchner, Claudio Ricci et al.

Compton-thick Active Galactic Nuclei (AGN) represent one of the most elusive phases of massive black hole growth, yet are expected to contribute substantially to the Cosmic X-ray Background and the integrated growth of massive black holes. NGC 4945 is the closest Compton-thick AGN and amongst the brightest AGN in the hard X-ray sky, making it an important benchmark for more distant Compton-thick AGN. We present the first high-resolution X-ray spectral analysis of NGC 4945 using XRISM/Resolve. Th…

astro-ph.IM

Spatial Mapping and Capacitor Trimming Developments to Improve Usable Pixel Yield in PRIMA FIRESS Kilo-Pixel Arrays

Chris Albert, Jonathon Hunacek, Hien Nguyen, Ritoban Basu Thakur, Andrew Beyer, Charles, Bradford, Peter Day et al.

The Probe far-Infrared Mission for Astrophysics (PRIMA) will use 8 kilo-pixel kinetic inductance detector (KID) arrays in its spectrometer module. We present an improved resonant frequency to spatial position mapping system designed to preserve each array's mapping after transferring it from the mapping apparatus to the flight housing. Such a mapping is necessary for astronomical observations, and additionally allows us to laser trim the capacitive elements of KIDs to optimize resonance separati…

astro-ph.HE

Production of High Energy Neutrinos in the Coronae of Ultraluminous X-ray Sources

Norita Kawanaka, Shigeo S. Kimura

We investigate the possibility of high-energy neutrino production in coronae associated with ultraluminous X-ray sources (ULXs) as super-Eddington accreting black holes. Adopting the disk-wind-fed corona model, we calculate stochastic proton acceleration and the resulting neutrino emission from the ULX corona. We first examine whether the corona can be regarded as a collisionless plasma, which is a prerequisite for efficient non-thermal particle acceleration. We find that the collisionless condi…

astro-ph.SR

Towards understanding stellar variability at the sub m/s level: granulation-induced variability across the optical spectrum

Cis Lagae, Ginger Frame, Heather M. Cegla, Veronika Witzke, René Holzreuter, Sergiy Shelyag, Christopher Watson, Alexander Shapiro et al.

Detecting the radial velocity signal of Earth-mass exoplanets requires the characterisation and removal of granulation-induced radial velocity variability from spectroscopic observations. By coupling three-dimensional (3D) hydrodynamic (HD) simulations to a radiative transfer code, we can isolate and study the effect of granulation on stellar lines. In this study we isolated the impact of granulation on spectral line shapes and shifts for the largest and most diverse synthetic spectral line samp…

astro-ph.EP

Accretion across scales: streamers, surface-layer transport, and rapid replenishment in young protoplanetary discs

Christian Granzow Holm, Michiel Lambrechts, Michael Kuffmeier, Anders Johansen, Troels Haugbølle, Åke Nordlund

Protoplanetary discs evolve around newly-formed stars through an interplay of infall from surrounding turbulent cloud material, accretion towards the young star, and outflow driven mass-loss. It has been challenging to determine if discs are fed predominantly through infall along the disc midplane, or along the poles, and if accretion occurs in a steady or burst-like fashion. Here, we present a suite of 3D ideal magnetohydrodynamical simulations of protoplanetary disc formation and evolution in…

astro-ph.COastro-ph.HE

A refined method for measuring cosmological distances using variability and proper motions in AGN with VLBI-detected counter-jets

Jeffrey A. Hodgson, Anthony Carr, David Parkinson, Matteo Statti, Jaehyeon Myeong, Benjamin L'Huillier, Arman Shafieloo, Ioannis Liodakis et al.

In a previous paper, we described a `standard speed-gun' (SSG) distance that uses the speed of light to standardize a ruler under the assumption that the radio variability seen in blazars is causally limited. The apparent size is then measured with Very Long Baseline Interferometry in order to derive the angular diameter distance. A key limitation of this method is that it requires knowledge of the relativistic Doppler factor. Previously, we estimated the distance to the bright radio source, 3C…

astro-ph.SRastro-ph.IMphysics.plasm-phphysics.space-ph

Performance of radio-based detection to operational monitoring M5+ class solar flares

Julia van Ravenswaaij, Ines Wilms, Ivan Ricardo, Michaela Brchnelova

Early detection of major solar flares is critical for defense operations due to their potential to disturb radar and radio systems. Typically, soft X-ray flux is used to monitor and classify solar flares, but since this flux has to be measured in space, it means that its availability itself is dependent on space weather conditions. For this reason, in this paper, we investigated the feasibility of using ground radio observations to monitor major (M5+ class) solar flares. We made use of datasets…

astro-ph.IM

The Wetterstein Millimeter Telescope: A New German Facility for Astronomy and Geodesy

Alexander Neidhardt, Matthias Kadler, A. K. -Baczko, Guido Dietl, Urs Hugentobler, Matthias Schartner, Tobias Ullmann, Till Rehm et al.

The Wetterstein Millimeter Telescope (WMT) is a planned broadband (1.2-120 GHz) radio telescope to be established near the Environmental Research Station Schneefernerhaus (UFS) on Germany's highest mountain, the Zugspitze. Developed by a consortium of German research institutes and partners, the WMT is conceived as a multidisciplinary research infrastructure supporting radio astronomy, geodetic VLBI, satellite communications, space situational awareness, and technology development. The telescope…

astro-ph.EP

A JWST Study of Stardust. I. Infrared Spectroscopy of Comet 81P/Wild 2 and Overall Composition

Nathan X. Roth, Stefanie N. Milam, Diane H. Wooden, Charles E. Woodward, Dominique Bockelee-Morvan, Michael S. P. Kelley, Steven B. Charnley, Simon J. Clemett et al.

We report observations of comet 81P/Wild 2, target of the Stardust sample return mission, on UT 2023 March 20 and 24 at a heliocentric distance ($r_H$) of 1.85 au using the NIRSpec and MIRI integral field unit spectrographs on board the James Webb Space Telescope (JWST). This study is the first compositional comparison between JWST remote-sensing spectroscopy of a solar system object against terrestrial analysis of its returned samples. We securely detected molecular emission from H$_2$O, CH$_4$…

astro-ph.EPastro-ph.GAastro-ph.SR

Ammonium salt formation and abundance in protoplanetary disks

Maxime Ruaud, Jean-Christophe Loison, Uma Gorti

Ammonium salts may represent an important reservoir of volatile species in Solar system primitive bodies, but the question of how and when these salts can form during the star formation process remains unknown. In this paper, we use thermo-chemical models to study the formation of ammonium salts during the protoplanetary disk stage. We show that ammonium salts form efficiently in the inner disk midplane (i.e. $r \lesssim 50 $ au), inside the comet forming region. In this region, our model predic…

astro-ph.EP

Dynamo generation reveals redox conditions during formation of differentiated planetesimals

Hannah R. Sanderson, James F. J. Bryson, Claire I. O. Nichols

In the early Solar System, an isotopic dichotomy existed between non-carbonaceous (NC) and carbonaceous (CC) planetesimals. Depending on the formation location of these planetesimals relative to condensation lines in the protoplanetary disk, NC and CC differentiated planetesimals could have had distinct redox states and water contents. However, the extent of these differences and the resulting accretion environments of NC and CC planetesimals are debated. Here, we use thermal evolution and dynam…

astro-ph.IM

Pollux UV & FUV polarimeters: first lab results

Adrien Girardot, Ninon Demelier, Coralie Neiner, Jean-Michel Reess, Juan Ignacio Larruquert, Paloma Lopez-Reyes, Anejandro Garcia Canas, Nuria Gutierrez Luna et al.

Pollux is a high-resolution spectropolarimeter proposed by a European consortium for the Habitable Worlds Observatory (HWO). Its design covers a broad spectral range from the far-ultraviolet (FUV) to the near-infrared (97-1\,750 nm), with polarimetric channels relying on \ch{MgF2} birefringent optics in the mid- and near-UV (MUV-NUV), and on an innovative all-reflective polarimeter in the FUV, where no birefringent material is available. To validate these polarimeters, whose required polarimetri…

astro-ph.HE

Accretion-induced spin-up: Implications for mass constraints of AMXPs

Xiaoyu Lai

We investigate the influence of the global structure of accreting millisecond X-ray pulsars (AMXPs) on accretion-induced spin-up, using three equations of state (EoS) models representing neutron stars, quark stars, and strangeon stars. By applying the classical accretion torque formalism, and deriving the accretion rate and magnetic field from observations of three AMXPs --- XTE J1751-305, SAX J1808.4-3658, and IGR J00291+5934 --- we derive mass contours in the plane of luminosity versus spin-up…

astro-ph.HE

The progenitors and circumstellar environments of stripped-envelope interacting supernovae from BPASS

B. Warwick, J. Lyman, D. L. Coppejans, C. M. Byrne, J. J. Eldridge, M. Pursiainen, E. R. Stanway

Understanding the progenitors of stripped-envelope interacting supernovae (SEISNe) is crucial for probing the final stages of massive star evolution. Despite this, their rarity means the nature of their progenitors remains poorly constrained. We investigate the progenitors of SEISNe, using the Binary Population and Spectral Synthesis stellar evolution models. The 30,153 stellar models that result in hydrogen-poor core-collapse supernovae (SN) includes both binary and single stars, spanning 13 me…

astro-ph.HE

Searching for core-collapse supernovae in binaries with ZTF

Sylvia J. Zhu, Jakob Nordin, Emma de Oña-Wilhelmi, Andrea Ercolino

Context. Stripped envelope supernovae occur in massive stars that have lost their outer layers before exploding, possibly from binary interactions. Recently, SN 2022jli was detected with significant periodic oscillations in its lightcurve, likely due to accretion from a binary companion onto the newborn compact object. Aims. While evidence for periodic oscillations has been found in a few bright and noteworthy supernovae, the population properties are best understood with systematic searches of…

astro-ph.SR

A new methodology for inferring the plasma conditions in solar flare energetic electron source regions from in situ electron energy spectra

Samuel Carter, Natasha L. S. Jeffrey, Robert T. Wicks, Georgios Nicolaou

The conditions within solar flares that lead to efficient electron acceleration are not well constrained. It is not clear whether the populations accelerated out into the heliosphere and inward into the chromosphere originate in the same regions. By analysing the energy distributions of heliospheric populations, modelling suggests that it should be possible to see evidence of their originating region(s), including the presence of hot, dense flare plasma. By creating and utilising a novel in situ…

astro-ph.SR

A multi-epoch spectral and photometric study to understand the nature of the interesting Be star candidate HD 249179

Suman Bhattacharyya, Blesson Mathew, S Muneer, Sreeja S Kartha, Prakruthi Prasad

HD 249179, a B5 star with unclear classification as either a classical Be star or a high-mass X-ray binary (HMXB) system, is investigated using the first multi-epoch spectral and photometric analysis over 5.5 years (2017-2023). Optical spectroscopy from LAMOST, BeSS, and the Himalayan Chandra Telescope show large H-alpha variability (-17.6 to -3.2 angstrom, in six days, returning to -31.3 angstrom, in 2022) and the presence of Paschen and O I lines, confirming active circumstellar disc dynamics.…

astro-ph.GA

Environmental dependence of galaxy properties in the DESI DR1 Bright Galaxy Survey: Star formation, morphology, and AGN activity at z < 0.55

Duho Kim

We present the environmental dependence of galaxy properties using $\sim$1.4 million BGS_BRIGHT galaxies in groups and clusters ($\log(M_h/M_\odot) \geq 12.5$) from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 at $0.05 3$ in all four BPT lines), the combined AGN fraction increases monotonically with stellar mass. At fixed stellar mass, the Seyfert fraction shows no significant environmental trend (consistent with flat; field-to-cluster differences $\lesssim 3σ$ in the only well…

astro-ph.GA

Investigation of Calcium Dust in the Interstellar Medium

Ya-Yu Chu, Sascha Zeegers, Hsien Shang, Chi-Liang Chen, Mau-Tsu Tang, Ming-Jye Wang, Yun-Liang Soo, Elisa Costantini et al.

Calcium is a highly depleted element in the interstellar medium (ISM), however its composition in the solid phase remains elusive. The detection of Ca-bearing dust has been limited due to its lack of distinct spectral features in the cold phase of the diffuse ISM. X-rays provide a direct method for exploring the absorption and scattering properties of interstellar dust. In this study, we utilize high-resolution X-ray absorption spectroscopy to characterize Ca-bearing dust analogs at the Ca K-edg…

astro-ph.HE

Abnormal Nitrogen Abundance in the X-ray Spectrum of Quasi-periodically Erupting Source AT2019wzc

Tao Wu, Xinwen Shu, Luming Sun, Ning Jiang, Jiazheng Zhu, Wenjie Zhang

Quasi-periodic eruptions (QPEs) are rapid, recurring soft X-ray bursts, whose nature is still in dispute. A compelling case of QPEs has emerged in the slowly evolving optical transient AT2019wzc, possibly associated with the tidal disruption of a post-main-sequence star by a supermassive black hole. Further evidence of a tidal disruption event (TDE) is crucial to understand the nature of AT2019wzc and establish the link between TDE and QPEs. Here we report the detection of a narrow, blueshifted…

astro-ph.SR

The location and propagation of fine structures in type II solar radio bursts

S. Normo, K. Bhandari, A. Nadiger, D. E. Morosan

Solar eruptions such as coronal mass ejections can drive collisionless shocks that are good particle accelerators. Electrons accelerated by these shocks can be observed remotely via the electromagnetic emission they generate at low radio frequencies. The radio signatures of shock-accelerated electrons at the Sun are type II radio bursts that can be used to track the propagation of the shock wave in the solar corona and beyond. However, type II radio bursts can have complex morphologies in dynami…