Solar and Stellar Astrophysics
The Debris Disk Host $\beta$ Piscis Austrinus is a Rapidly Rotating Star Seen Nearly Pole-On
Colin Kane, Russel White, Jeremy Jones et al. (+6 more)
Previous studies of $\beta$ Piscis Austrinus (PsA) have speculated that the narrow and saddle-like shapes of some of its weak metallic lines are a consequence of it being a rapidly rotating
star viewed nearly pole-on. Here we use the fastrot-spec spectral synthesis code to model high-dispersion (R = 115,000) HARPS spectra of $\beta$ PsA in order to determine its inclination and photospheric properties, with additional constraints on the surface temperature set by measures of Fe II/Fe I line ratios. The analysis confirms that $\beta$ PsA is oriented nearly pole-on ($i = 4.75^{+0.75}_{-0.50}$$^o$) and experiences substantial
gravity darkening caused by its rapid rotation ($\Omega/\Omega_{crit}=0.93\pm0.17$). $\beta$ PsA has a polar temperature of $10300^{+200}_{-250}$ K that is 24% hotter than its equatorial temperature ($8275^{+317}_{-400}$ K). This results in its apparent luminosity being 48% larger than its actual luminosity of 26.2$^{+1.9}_{-2.4}$ L$_\odot$. When this methodology is applied to high-dispersion spectra of the
star Vega, the analysis determines a nearly pole-on orientation that is consistent with interferometric measurements, validating the technique. Based on comparisons with PARSEC evolutionary models of
stars rotating at similar velocities, $\beta$ PsA has a mass of $2.20\pm0.03$ M$_{\odot}$ and an age of $141^{+113}_{-49}$ Myr; this age is consistent with the age inferred for its G5V companion
star, CD-32 17127, based on lithium depletion models. The analysis demonstrates the potential for both identifying and determining the
stellar properties of rapidly rotating
stars viewed nearly pole-on via spectroscopy alone.
Read the full abstract ▾
All authors Colin Kane, Russel White, Jeremy Jones, Benjamin Montesinos, Sebastian Carrazco-Gaxiola, Tim Johns, Aman Kar, Wei-Chun Jao, Todd Henry
Astrophysics of Galaxies
The Merger-Driven Origin of the Vast Extended Stellar Disc Around the Andromeda Galaxy
C. Tsakonas, M. Arnaboldi, F. Hammer et al. (+4 more)
The closest
giant spiral, the Andromeda
galaxy (M31), shows compelling evidence for a recent, gas-rich major merger event. Pronounced substructures in its inner
halo and a kinematically hot
stellar disc, whose
star formation history shows a widespread
star formation episode 2.5 Gyr ago, are telltale evidence that may be directly linked to a major (mass ratio 1 to 4) merger event that took place 2-4 Gyr ago. Spectroscopy of resolved
giant stars in the remote outskirts of M31's disc revealed a vast extended structure that rotates with a circular velocity close to the HI gas. In addition, the spatial distribution and significant prograde rotation of two distinct, compact groups of globular clusters (GCs) in the disc outskirts are unusual for typical inner
halo GCs. We employ an available N-body hydrodynamical simulation of a major merger that reproduces the morphology of the inner
halo substructures, the age-velocity dispersion relation, and the
star formation history in the disc. We compare model particles with resolved tracers in the M31 disc. To examine the
evolution of the progenitor M31 disc – that appears to get stretched, distorted, and warped due to the gravitational perturbation inflicted by the major merger – we investigate the properties of the pre- versus post-merger discs of the simulated analog. The merger transforms the disc of the progenitor
galaxy, which becomes kinematically hot and asymmetric. In addition, the post-merger disc gets stretched by almost a factor of 2, and its extent spans distances greater than 40 kpc. The
stellar warp in populations older than 2 Gyr is characterized by a monotonic decrease of inclination with radius, with the outer
stellar distribution appearing less edge-on at larger
galactic radii. These results provide a comprehensive picture of the
evolution of the
giant disc of M31, the closest merger-inflicted massive
galaxy.
Read the full abstract ▾
All authors C. Tsakonas, M. Arnaboldi, F. Hammer, Y. Yang, O. Gerhard, A. Burkert, D. Hatzidimitriou
Solar and Stellar Astrophysics
Native-Opacity Sensitivity of a Fixed Delta Cephei MESA-RSP Pulsation Model
Zuhoor Elahi, Christopher Sirola and Wafa Gull
Radiative opacity is one of the central microphysical inputs controlling the thermal response of Cepheid envelopes and the driving or damping of radial pulsations. We present a controlled opacity-sensitivity experiment for a fixed delta Cephei nonlinear radial pulsation model computed with the MESA Radial
Stellar Pulsation module. The
stellar and pulsation parameters are held fixed at M = 5.0
solar masses , Teff = 6050 K, L = 2360
solar luminosities , X = 0.73, Z = 0.007, and RSP_alfam = 0.425, while the high-temperature opacity source is varied among native MESA opacity configurations: OPAL-A09, OP-A09, and OPLIB-AGSS09. The low-temperature opacity prefix, C/O-dependent opacity prefix, and all other RSP parameters are kept fixed so that the comparison isolates the effect of the adopted high-temperature opacity table. Verification integrations were performed at 20, 100, and 300 pulsation cycles, followed by photo-restarted continuations to 500 cycles. At 500 cycles, OPAL-A09 gives the closest period agreement, PRSP = 5.366986 d, only about 39 s longer than Pobs = 5.366531 d. OP-A09 gives the largest amplitude-growth diagnostics, with Delta Mag = 0.037307 and Delta R = 0.293677, corresponding to increases of 42.5% and 43.9% relative to OPAL-A09. OPLIB-AGSS09 gives a systematically longer period, P_RSP = 5.403926 d, with more modest amplitude-growth changes. The same ordering is reflected in the MESA history-column diagnostic rsp_GREKM, defined by the MESA defaults as the fractional growth of kinetic energy per pulsation period. These results show that native opacity choice measurably affects period matching, pulsation growth diagnostics, and nonlinear amplitude growth in this fixed {\delta} Cephei model. However, the tested opacity choices do not by themselves resolve the known observed-amplitude discrepancy.
Read the full abstract ▾
Astrophysics of Galaxies
The Road to Identifying the Earliest Radio-Powerful AGN with the SKA
Jose Afonso, Stergios Amarantidis, Stas Shabala et al. (+20 more)
The Epoch of Reionization (EoR) is one of the most pivotal frontiers in modern astrophysics, marking the emergence of the first
galaxies,
stars, and supermassive black holes (SMBHs). Despite insights from the Atacama Large Millimetre/submillimetre Array and the James Webb Space
Telescope, we still struggle to explain how $\sim10^{9}$ M$_\odot$ SMBHs powering luminous active
galactic nuclei (AGN) already exist by $z\sim7$. The recent discovery of powerful
radio emission from some of these early AGN is notable, offering new constraints on early black-hole
accretion and, with the Square Kilometre Array Observatory (SKAO), the prospect of directly probing neutral hydrogen through 21-cm absorption studies. Yet progress remains slow: only a few
radio-powerful AGN are known at $z>6$, far fewer than theoretical predictions suggest, raising questions about whether this reflects intrinsic properties or selection biases and incomplete spectral information. In this chapter we synthesise predictions from state-of-the-art hydrodynamical and semi-analytic simulations with observational constraints from SKAO pathfinder facilities. These models suggest the existence of a substantial, still-undetected population of
radio-powerful AGN in the EoR, but show that present surveys are limited by selection biases and incomplete
radio spectral information. We discuss a physically motivated strategy for identifying high-
redshift radio AGN, based on broadband
radio spectral energy distributions, spectral
curvature, dynamical jet
evolution, and
radio-only
redshift estimation, offering a transformative alternative to traditional empirical approaches. Finally, we justify how the sensitivity and spectral coverage of the SKAO will allow fine-frequency sampling across the 50 MHz - 15 GHz range, revolutionising our ability to identify the earliest
radio-powerful AGN and probe the earliest SMBHs.
Read the full abstract ▾
All authors Jose Afonso, Stergios Amarantidis, Stas Shabala, Ross J. Turner, Luca Ighina, Mojtaba Raouf, Nuno Covas, Pedro Martins, Nick Seymour, Alessandro Caccianiga, Alexander Hedge, Jess W. Broderick, Davi Barbosa, Isabella Prandoni, Sabyasachi Pal, Bruno Arsioli, Luis Barroso, Rodrigo Carvajal, João Tiago, Andrew Hopkins, Manuela Magliocchetti, Israel Matute, Ciro Pappalardo
Astrophysics of Galaxies
Assessing Ultra-Cool Dwarf Contamination in Photometrically Selected High-Redshift Galaxy Samples
Onnalin Innala, Nicha Leethochawalit, Takahiro Morishita et al. (+1 more)
Ultra-cool
dwarf stars (UCDs) are a common source of contamination in high-
redshift galaxy searches because both populations have red colors and these early-forming
galaxies can have sizes that are difficult to resolve even with space
telescopes. We develop Foreground Contamination Evaluator of Nearby
dwarf stars in high-Z photometrically selected Objects (FC-ENZO), a code that predicts magnitude-dependent UCD contamination for a given survey setup and
galaxy selection method. FC-ENZO combines UCD number-density models, synthetic spectral libraries, and photometric selection criteria to estimate contaminant populations. We find that the predicted contamination is sensitive to the adopted UCD spectral model,
stellar metallicity, and
Galactic distribution models, with the
Galactic distribution model producing variations of up to several factors. The Elf Owl models predict higher contamination than the Bobcat models, primarily because of their broader coverage of T and Y
dwarf spectra. The dominant contaminants are late L to early Y-type UCDs, which are most commonly misclassified as
galaxies at $z \sim 8$. For surveys with similar areas, broad-band observations from different space
telescopes produce comparable numbers of contaminants at a given
redshift, but contaminants are concentrated near the survey limiting magnitude, resulting in higher bright-end contamination fractions for shallower surveys. Adding medium-band filters can reduce the UCD contamination rate at $z\sim8$ by a factor of a few. At $z\gtrsim30$, F356W dropout selections can suffer substantial contamination from Y
dwarfs. FC-ENZO provides a practical tool for survey design and for identifying fields suitable for spectroscopic follow-up.
Read the full abstract ▾
All authors Onnalin Innala, Nicha Leethochawalit, Takahiro Morishita, Michele Trenti
Astrophysics of Galaxies
Tracing grain growth in the forming prestellar core L1506C with 3D modeling of Herschel, IRAM, and CFHT observations
E. Zhu, I. Ristorcelli, K. Demyk et al. (+5 more)
In the early phases of
star formation, properties of prestellar cores are commonly inferred from observations of thermal
dust emission and thus depend on
dust properties, which must be carefully characterized. Our target, L1506C, is part of the filament L1506 in the Taurus molecular cloud. The spectral energy distributions over the whole spectral range (from 160 {\mu}m to 2 mm), built from Herschel PACS and SPIRE and IRAM-NIKA2 data, have been fitted with a modified blackbody. These data were also modelled using the 3D radiative transfer code SOC and the latest THEMIS 2
dust model using extinction observations from WIRCam at CFHT and from Spitzer as additional constraints. The MBB modeling reveals that L1506C is fragmented into two low density cores with masses smaller than their Jeans masses. The
dust color temperature and the emissivity spectral index show clear anti-correlation and change in grain properties. Grains more evolved than the diffuse interstellar medium are needed to model the densest part showing that grain growth already occurs at very early stage of
star formation, even before the onset of gravitational collapse.
Read the full abstract ▾
All authors E. Zhu, I. Ristorcelli, K. Demyk, M. Juvela, N. Ysard, D. Paradis, H. Roussel, W. Kiviaho
Astrophysics of Galaxies
Indicatives of Early Stages of Star Formation in the Universe
Irina Acharova and Margarita Sharina
The paper analyzes formation conditions for globular clusters (GCs) in circumgalactic clouds. The similarity between the
metallicity distributions of GCs in the nearby Universe and of circumgalactic clouds is substantiated in detail over a wide range of
redshifts: from \mbox{0.2} to \mbox{5.9}. The distributions of the number of circumgalactic clouds and GCs both contain a sequence of four local maxima at the
metallicity values: \mbox{$[\rm{X/H}]\simeq -2.6, -2.0, -1.4,-0.5$}. The sequential enrichment of a circumgalactic cloud with a mass of $10^{8}\,M_{\odot}$ is calculated starting the extremely low
metallicity \mbox{$ [\rm{X/H}] <-2.3$}, then following through the stages of \mbox{$-2.3 \le [\rm{X/H}]<-1.7$} and \mbox{$-1.7 \le [\rm{X/H}] < -0.9$} to the high
metallicity \mbox{$[\rm{X/H}] \ge -0.9$}, where the boundaries of these ranges coincide with the local minima of the number of objects in the distributions. It is shown that for the reproduction of such distributions, it is sufficient that at each stage of enrichment of a part of a cloud in metals, one or more GCs with a total mass of \mbox{$3 \times 10^{6}\,M_{\odot}$} are formed. It is shown that the maximum mass of
stars capable of leading to
supernova explosions increases with the increase of
metallicity. Possible values of this mass are calculated for the
metallicities corresponding to the maxima in the distributions of clouds and GCs.
Read the full abstract ▾
Solar and Stellar Astrophysics
Analyses on Christoph Clavius' Reports of Total Solar Eclipses in 1560 and 1567: Key References for the Centennial Variations of the Earth's Rotation Speed and the Solar Radius
Hisashi Hayakawa, Mitsuru Sôma, Jean-Pierre Rozelot et al. (+4 more)
Variations in
solar radius (hereafter R_Sun) is a key reference for
solar magnetic activity in time. The sunlight amount may have varied with R_Sun and had an effect on the Earth's
climate in the past. Eclipse observations offer a unique opportunity to measure the absolute R_Sun value before modern direct observations. The scientific community has discussed a possible long-term R_Sun variability from 1715 onward. Prior to their coverage, Clavius' eclipse reports had been subjected to qualitative debates regarding the local eclipse visibility and a possible secular R_Sun trend. This study leverages the recent dramatic developments of lunar topography data and ephemeris data to provide an effective resolution of this debate. Clavius' eclipse reports described an explicit totality in 1560 at Coimbra and a "slender circle" around the eclipsing Moon in 1567 at Rome. Our study revised the {\Delta}T constraints of -492 s =< {\Delta}T =< 200 s in 1560 and 140 s =< {\Delta}T =< 151 s in 1567 to satisfy Clavius' descriptions, considering the lunar limb profile and assuming Auwers' canonical R_Sun. This study constrains the R_Sun margin of 1567, utilising three scenarios to interpret Clavius' account. The local totality requires an upper R_Sun limit of 1567 as R_Sun =< 696200 km in absolute size (959.92" in angular size), indicating no linear secular R_Sun shrinkage but possible R_Sun oscillations on a centennial timescale. Conversely, the annularity scenario is considered unlikely because it requires an R_Sun decrease of 7.5" within 3 centuries, even beyond the capacity of extreme shrinking-Sun hypotheses.
Read the full abstract ▾
All authors Hisashi Hayakawa, Mitsuru Sôma, Jean-Pierre Rozelot, Koji Murata, Alexei A. Pevtsov, Stanislav Gunár, Lucie M. Green
Astrophysics of Galaxies
The VLA-COSMOS 3 GHz Large Project: Polarised source counts and catalogue
S. Ranchod, S. A. Mao, R. P. Deane et al. (+5 more)
The exploration of the faint polarised
radio source population is essential for interpreting the nature and
evolution of
magnetic fields in
galaxies. While recent studies have provided insight into source counts for the $\mu$Jy polarised source population at 1.4 GHz, higher frequency surveys may be more sensitive to new populations that are depolarised at lower frequencies (i.e. due to internal or external depolarisation effects). We present the deepest polarised source counts at 3 GHz to date, at an angular resolution of $1.5''$. With these relatively higher frequency observations, we aim to probe the faint polarised
star-forming
galaxy (SFG) population. Furthermore, through spectral modelling, we aim to provide further insight into the frequency
evolution of polarised source counts. We processed the polarisation data of the VLA-COSMOS 3 GHz Large Project, one of the deepest high-resolution
radio continuum surveys. We produced Stokes Q and U mosaicked channel maps. After selecting known sources in total intensity, we performed 3D rotation measure synthesis and searched for polarised emission using an empirically determined threshold. With a sensitivity of 2.6 $\mu$Jy/beam in Faraday depth, we detect 65 polarised sources (51 deg$^{-2}$) above our threshold. We find that our cumulative and Euclidean-normalised source counts at 3 GHz are consistent with those in the literature at 1.4 GHz, which we attribute to the combined effect of spectral index and depolarisation in the detected sources. We detect no SFGs in our sample and derive a 2$\sigma$ upper limit on the density of polarised SFGs of $<2.0~\mathrm{deg}^{-2}$. This implies that significantly deeper observations will be required to readily detect this population in the SKA-era.
Read the full abstract ▾
All authors S. Ranchod, S. A. Mao, R. P. Deane, V. Smolčić, J. D. Wagenveld, M. Bondi, K. Mooley, E. Schinnerer
High Energy Astrophysical Phenomena
SN 2020bij and a Possible Slow-Rise High-Velocity Subclass of Type IIP Supernovae
Sondos Mohsen-Tanev, Iair Arcavi, Shahar Bracha et al. (+17 more)
Mapping how the explosion properties of Type II
supernovae (SNe II) relate to the properties of their progenitors can provide strong constraints for understanding the final evolutionary stages of massive
stars. Type IIP SNe, linked to the explosions of single red super-
giant (RSG)
stars, have recently been found to require some form of interaction with circumstellar material (CSM) to reproduce the rapid rise to the plateau often seen in their light curves. In this work, we present observations and analysis of the Type IIP SN 2020bij, characterized by a slow rise to its plateau as well as high expansion velocities. We identify four other SNe IIP from the literature (ASASSN-14kg, SN 2018fif, SN 2021yja and SN 2023axu) with similarly slowly rising light curves and find that they also show high expansion velocities. Using both analytical and numerical models, all five events can be explained with weak to no CSM interaction. We therefore propose that these events constitute a new subclass of Type IIP SNe which could be associated with relatively confined CSM. Early and dense photometric coverage of future SNe IIP together with early spectroscopic observations will further map this subclass and its physical properties. Understanding such rare events could be key to constraining the diversity of late-stage mass-loss in RSGs.
Read the full abstract ▾
All authors Sondos Mohsen-Tanev, Iair Arcavi, Shahar Bracha, K. Azalee Bostroem, Griffin Hosseinzadeh, Jesper Sollerman, Claudia P. Gutiérrez, Priscila J. Pessi, Joseph Anderson, Mariusz Gromadzki, Avishay Gal-Yam, Daichi Hiramatsu, Jamison Burke, Koichi Itagaki, Ting-Wan Chen, D. Andrew Howell, Curtis McCully, Megan Newsome, Estefania Padilla Gonzalez, Craig Pellegrino
Instrumentation and Methods for Astrophysics
Design and development of a near-IR integral field spectrograph for the HWO Coronagraph Instrument
Stephen P. Todd, Dan Dicken, Raziye Artan et al. (+5 more)
The primary mission of the Habitable Worlds Observatory (HWO) is to identify and characterise potentially habitable worlds. Spectra across a wide wavelength range are needed to cover multiple spectral features per molecule of interest. An integral field spectrometer (IFS), fed by a coronograph system, can be used to measure spectra from any
planets within the nulled field of the coronograph, while also characterizing the residual speckles as a function of wavelength, enabling the contrast ratio to be further enhanced. We present design trades for an infrared IFS (0.8 to 1.7 {\mu}m) for the HWO Coronagraph Instrument, including assessment of the relative merits of lenslet and image slicer based architectures. Key requirements include full sampling of the speckle field at all wavelengths, maximized optical throughput, and control of spectral cross talk and stray light. We identify technology developments needed to advance the instrument design to the required technology readiness level.
Read the full abstract ▾
All authors Stephen P. Todd, Dan Dicken, Raziye Artan, Beth A. Biller, Cassandra Mercury, Katherine Morris, Vinooja Thurairethinam, Feng Zhao
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Sideband Structure of Axion Electrodynamics
Run-Min Yao, Xiao-Jun Bi, Peng-Fei Yin et al. (+1 more)
We develop a Floquet–Bloch sideband formulation of the linearized Maxwell–
axion system in a coherent periodic
axion background. Linearizing around prescribed
magnetic and
axion fields, we show that the pump generates a sideband ladder of
photon and
axion branches. Near an isolated folded degeneracy, this ladder reduces to a two-mode crossing whose
algebra is fixed by the
symplectic signatures of the colliding modes. In temporal fixed-momentum
evolution, same-Krein-sign collisions give stable avoided crossings, whereas opposite-sign collisions give parametric instabilities, unifying the
axion-
photon difference channel with the Mathieu and Masaki-Aoki-Soda resonances. In stationary fixed-frequency transfer, the corresponding flux signatures distinguish bounded forward conversion from forward-backward stop bands and distributed reflection. Ray projection of a temporal pump gives a related but local WKB description of driven forward mixing, with an effective wavenumber distinct from the true
axion momentum. External-field diagrams reproduce the sideband selection rules, and full temporal monodromy calculations verify the instability
topology and finite-coupling shifts.
Read the full abstract ▾
All authors Run-Min Yao, Xiao-Jun Bi, Peng-Fei Yin, Qing-Guo Huang
High Energy Astrophysical Phenomena
Timing and spectral analysis of the 2025 outburst of 4U 1630$-$47 with NICER
Haifan Zhu, Mariano Méndez, Xiao Chen et al. (+1 more)
We analyzed NICER observations of the 2025 outburst of the black hole X-ray binary 4U~1630$-$47 to investigate the spectral–timing properties of its transient low-frequency quasi-periodic oscillations (QPOs) and millihertz-scale quasi-regular modulation (QRM). During the rising phase of the outburst, the QPO centroid frequency increased from $\sim 0.24$ Hz to $\sim 3.43$ Hz. Wavelet-based state separation shows that the with-QPO intervals are associated with a higher inner disk temperature and a lower diskbb normalization than the without-QPO intervals, while the
photon index ($\Gamma$) shows weaker changes within the uncertainties. Near the outburst peak, the source displayed a weak QRM at $\sim 0.07$ Hz with a fractional rms amplitude of $\sim 4.7\%$, lower than that of the heartbeat state observed in 2023. Phase-resolved
Hilbert–Huang analysis shows that the inner disk temperature is positively correlated with the X-ray flux, the diskbb normalization is anticorrelated, and $\Gamma$ varies only weakly. Overall, the short-timescale spectral–timing variability is expressed most clearly through the disk-related parameters. The transient QPOs are therefore consistent with short-timescale disk-related variability during the rising phase, whereas the millihertz-scale QRM may represent a weaker heartbeat-like variability mode appearing near the outburst peak.
Read the full abstract ▾
All authors Haifan Zhu, Mariano Méndez, Xiao Chen, Wei Wang
Instrumentation and Methods for Astrophysics
HARMONI at ELT: line spread functions in a diffraction limited spectrometer
Stephen P. Todd, Éamonn J. Harvey, Anna MacIver et al. (+8 more)
HARMONI is the first light, adaptive optics assisted, near-IR integral field spectrograph for the ELT. It covers a spectral range from 800~nm to 2450~nm with resolving powers from 3000 to 7000 and spatial sampling of 25~mas and 6~mas. It can operate in two adaptive optics modes - SCAO (including a high contrast capability) and MCAO. The project is resuming its final design phase after a rescope design phase in 2025. Diffraction of the pupil becomes significant in a spectrograph where the slit width is comparable to the diffraction limited PSF. When the spatial coherence due to the narrow slit is considered, the resulting line spread function can be narrower than the
geometric width of the input slit, with a non-linear dependence on the size of the pupil aperture after the slit. We outline the impact of these diffraction and spatial filtering effects on the line spread function of HARMONI and identify parameters that should be considered when designing a diffraction limited spectrograph.
Read the full abstract ▾
All authors Stephen P. Todd, Éamonn J. Harvey, Anna MacIver, William Taylor, Eduard Muslimov, Kjetil Dohlen, Matthias Tecza, Magali Loupias, Paula Bañares-Palacios, Mark Swinbank, Ryan Griffiths
Solar and Stellar Astrophysics
Discovery of sulfur oxides in the ejecta of a B[e] supergiant
C. Bordiu, J. Ricardo Rizzo, D. Navarro-Almaida et al. (+12 more)
B[e] supergiants represent a rare class of luminous, evolved massive
stars surrounded by dusty circumstellar disks. Since their intense UV fields were long thought to sterilize their surroundings, molecular detections beyond carbon monoxide have remained elusive, leaving their chemical reservoirs largely unexplored. Whether these environments can sustain a complex molecular chemistry is a fundamental question with significant astrochemical implications. Here we report the detection of chemically rich molecular gas surrounding the B[e] supergiant HD~87643, using ALMA observations. Our data reveal the presence of the sulfur
oxides SO and SO$_2$ and other sulfur-bearing species, marking the first detection of these molecules in an early-type evolved massive
star. We find a high fractional abundance of SO$_2$ relative to H$_2$, which our chemical modelling can reproduce in timescales as short as $\sim$10$^4$ yr in an oxygen-rich environment. These results indicate that the detected molecules trace a short-lived, rapidly evolving phase of out-of-
equilibrium chemistry. Furthermore, we measure an anomalously low $^{32}$SO/$^{33}$SO, that we attribute to mass-independent fractionation driven by intense photochemistry. This mechanism mirrors processes proposed to explain the $^{33}$S excesses in the atmosphere of the Archaean Earth. Our findings suggest that B[e] supergiants could serve as unique laboratories for studying sulfur chemistry under extreme radiation conditions, opening potential avenues to investigate the fractionation processes that shaped the isotopic signatures found in the early geological record.
Read the full abstract ▾
All authors C. Bordiu, J. Ricardo Rizzo, D. Navarro-Almaida, A. Fuente, F. Bufano, G. Umana, S. Loru, A. C. Ruggeri, C. Buemi, F. Cavallaro, L. Cerrigone, A. Ingallinera, P. Leto, S. Riggi, C. Trigilio
Astrophysics of Galaxies
Resolved HI and Environmental Dynamics
M. Ramatsoku, P. Serra, N. Deg et al. (+8 more)
Spatially resolved, deep HI observations from SKA precursors and pathfinders such as MeerKAT, FAST, and ASKAP have demonstrated their ability to reveal the complex interactions between
galaxies and their environments. These include, but are not limited to, recent observations of the Virgo cluster showing that the hydrodynamical effects of ram pressure stripping can operate effectively at unexpectedly large cluster-centric distances. In the Fornax cluster, the discovery of long HI tails with mixed
tidal-ram-pressure origins indicates the interplay between gravitational and hydrodynamical mechanisms. Similar HI features in nearby filaments and
galaxy groups, where ram pressure is expected to be weak, highlight the influence of hydrodynamical processes even in low-density environments. Multi-resolution studies have further revealed signs of cold gas
accretion and HI replenishment driven by
tidal interactions. While highly informative, these studies remain limited to small, specific regions of the sky. With SKA-mid AA4, it will become possible to carry out deep, spatially resolved HI imaging over hundreds of square degrees, covering environments from isolated
galaxies to filaments. By reaching column-density sensitivities between $1.0 \times 10^{18}$ and $\sim 1.0 \times 10^{19}~\mathrm{cm^{-2}}$ at physical resolutions of $\sim$10 and $\sim$1 - 2 kpc, respectively, and by enabling sensitive, contiguous observations of wide areas within short integrations, SKA-mid AA4 will allow the construction of large, statistically representative samples of
galaxies and detailed studies of environmental mechanisms operating across the full range of these less-studied environments at resolved scales.
Read the full abstract ▾
All authors M. Ramatsoku, P. Serra, N. Deg, R. Ianjamasimanana, A. Sorgho, G. De Lucia, K. Spekkens, L. Verdes-Montenegro, H. Yoon, B. Namumba, M. Meyer
Cosmology and Nongalactic Astrophysics
Spherically Symmetric Fluid Simulations of Black Hole Accretion in Self-Interacting Dark Matter Halos
Zhe Meng, Tan Chen, Bocheng Zhu et al. (+4 more)
We investigate black hole
accretion in self-interacting dark matter (SIDM)
halos using a self-gravitating fluid model with thermal conduction. We develop a robust one-dimensional spherically symmetric hydrodynamic code based on an operator-splitting finite-volume method. Simulating both Singular Isothermal Sphere (SIS) and Navarro-Frenk-White (NFW) profiles, we find that black hole growth is regulated by the competition between
gravity-driven inflow and SIDM heat transport. Our results demonstrate that an SIS-like environment facilitates rapid
accretion, allowing a $100\,\mathrm{M_{\odot}}$ seed to grow to $10^4\,\mathrm{M_{\odot}}$ within $2\,\mathrm{Myr}$. Furthermore, we show that larger initial black hole masses, steeper density profiles, and higher scattering cross sections significantly enhance the
accretion rate. This study provides a comprehensive fluid-dynamical picture of black hole growth in SIDM
halos.
Read the full abstract ▾
All authors Zhe Meng, Tan Chen, Bocheng Zhu, Fan Zhou, Bin Hu, Liang Gao, Rong-Gen Cai
High Energy Astrophysical Phenomena · Cross-listed from physics.hist-ph
Black Boxes in Black Hole Imaging
Juliusz Doboszewski and Jamee Elder
We investigate the epistemic opacity of computer simulations and machine learning methods in the context of black hole imaging. We argue that there are forms of opacity-including opacity resulting from the use of machine learning-which do not need to affect the reliability of an inference when it is seen as a part of a broader inferential framework. We propose conditions under which that can plausibly be the case, and discuss how opaque methods can be useful in the context of the (next generation) Event Horizon
Telescope. However, we also argue that at least one problematic form of opacity is currently present in black hole imaging: GRMHD models of Sagittarius A* are opaque. This form of opacity signals the limitations of current understanding of the models of this source, and constrains the potential uses of ML models in future observations.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Development of a cosmic ray detector using CMOS sensors embedded in smartphones and Raspberry Pi devices
Wakiko Takano, Shigeharu Udo, Atsushi Shiomi et al. (+1 more)
Cosmic rays are ubiquitous; however, their direct observation traditionally demands specialized, high-cost hardware and significant technical expertise, presenting a high barrier for non-specialist environments such as schools and community settings. We present SORAMAME, a smartphone and tablet application that lowers this barrier by repurposing built-in CMOS image sensors as particle detectors. The system enables real-time recording and visualization of particle-like events without additional hardware, integrating on-device extraction - calibration, noise filtering, and track-candidate detection - with cloud-based data management. By simplifying the detection process, SORAMAME facilitates widespread adoption across diverse user groups, fostering an environment where educational outreach can transition into large-scale data collection. This scalability is particularly significant given the unprecedented number of internet-connected consumer devices equipped with silicon CMOS image sensors. Despite the inherent constraints of consumer-grade sensors, our in-flight validation and Raspberry Pi-based measurements successfully captured altitude and latitude-dependent variations in particle flux consistent with geomagnetic shielding. These results suggest that lowering barriers to participation in observation not only serves educational purposes but also has the potential to contribute to future scientific breakthroughs through the development of global citizen science.
Read the full abstract ▾
All authors Wakiko Takano, Shigeharu Udo, Atsushi Shiomi, Kinya Hibino
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
$\Lambda$ hyperons in core-collapse supernovae: Equilibration and neutrino opacities
Ruben Zatini, Jorge Martin Camalich, Pasquale Dario Serpico et al. (+1 more)
Strange
hadrons are commonly included in dense-matter equation-of-state models by imposing chemical
equilibrium, but the weak-interaction timescales required to establish it in core-collapse
supernovae have not been systematically assessed. In this paper we compute the $\Lambda$-hyperon production rates in the hot, dense, and isospin-asymmetric conditions characteristic of post-collapse proto-
neutron stars. We find that local $\Lambda$ chemical equilibration is driven by nonleptonic strangeness-changing reactions, especially $NN\leftrightarrow N\Lambda$ scattering, on timescales of order $10^{-11}$-$10^{-10}$ s, many orders of magnitude shorter than macroscopic proto-
neutron-
star evolution timescales. Using an effective-field-theory framework constrained by hypernuclear weak-decay data, we find that short-range contact interactions dominate the nonleptonic rates, beyond a pure one-
meson-exchange description. Semileptonic channels are too slow to set the
equilibrium $\Lambda$ abundance, but they open additional absorption channels for low-energy
muon neutrinos and antineutrinos, such as $\nu_\mu+\Lambda\to\mu^-+p$ and $p+\mu^-+\bar\nu_\mu\to\Lambda$. At low energies, these $\Lambda$-induced
neutrino opacities exceed the corresponding nucleonic contributions for
muon (anti)
neutrinos, possibly influencing the
evolution of the
muon lepton number during proto-
neutron-
star deleptonization. These results support local chemical
equilibrium for $\Lambda$ hyperons under the conditions studied and provide new weak-interaction input for
flavor-dependent
neutrino transport, muonization, and proto-
neutron-
star evolution.
Read the full abstract ▾
All authors Ruben Zatini, Jorge Martin Camalich, Pasquale Dario Serpico, Tobias Fischer
Solar and Stellar Astrophysics
Revision of the Detached Eclipsing System IR Cas from TESS Observations, Ground-Based Photometry and Spectroscopy
Matúš Kamenec, Pavol Gajdoš, Martin Vaňko et al. (+3 more)
We present a new photometric and spectroscopic analysis of detached eclipsing binary IR Cas based on TESS observations, supplementary ground-based photometry in Sloan $g^\prime$, $r^\prime$, and $i^\prime$ filters, and newly obtained radial velocity measurements. The updated orbital and physical parameters of the system were derived using combined light-curve and radial-velocity modeling. The resulting solution indicates that both components are main-sequence
stars with masses of approximately $1.32$ M$_{\odot}$ and $1.05$ M$_{\odot}$. We investigated in detail the fact, that the TESS light curves exhibit asymmetries near the maxima, which were reproduced by introducing a cool spot that moves on the surface of the secondary component. Long-term analysis of times of minima revealed quasi-periodic variations in the O$-$C diagram that can be interpreted as a light-time effect due to a possible third body with an orbital period of about 38 years. The positions of both components in the mass-radius diagram agree well with empirical relations for detached main-sequence binaries and do not indicate substantial deviations from standard
stellar evolution. Overall, IR Cas appears to be an evolutionarily representative detached eclipsing system with moderate indications of
stellar activity.
Read the full abstract ▾
All authors Matúš Kamenec, Pavol Gajdoš, Martin Vaňko, Reddy Charan Reddy Munagala, Marek Skarka, Štefan Parimucha
Instrumentation and Methods for Astrophysics
Quantum-optimal coronagraphy with spatial mode sorting for direct exoplanet observations
Yinzi Xin, Sebastiaan Haffert, Yoo Jung Kim et al. (+1 more)
Conventional coronagraphs struggle to reach the theoretical limit of
exoplanet detection at close separations to the
star, particularly when the
telescope has a complex aperture or when the
star is partially resolved. Coronagraphy or nulling using spatial mode-sorting can reach the theoretical limit, but the optimal solution has so far only been calculated for an idealized unresolved
star, whose signal lies entirely in the piston mode of the
telescope. This work aims to enable the calculation of optimal nulling modes for realistic observational scenarios as a function of the size of the
star and
planet parameters, with the goal of improving coronagraphic performance at ~lambda/D working angles given partially resolved
stars and complex
telescope apertures. We perform numerical calculations using tools from
quantum information theory and explore the behavior of optimal mode-sorting measurements. The optimal measurement for measuring a
planet parameter is calculable from the density
matrix describing the state of the system. The spatial mode that maximizes the classical signal-to-noise ratio is approximately
quantum optimal to leading order in the
stellar leakage and the
planet flux ratio. We present optimal modes for measuring
planets with known signals, and we characterize the tradeoffs inherent to coronagraphs targeting more than one
planet location. Example coronagraph designs are presented for three cases of scientific interest: 1) the optimal extension of the fiber nuller architecture for detecting and spectrally characterizing
planets across an arbitrary field-of-view using high-resolution spectroscopy, 2) following up
planets detected by the visible coronagraph of the Habitable Worlds Observatory at more challenging infrared wavelengths, and 3) detecting and localizing
planets at close working angles with the Planetary Camera and Spectrograph on the Extremely Large
Telescope.
Read the full abstract ▾
All authors Yinzi Xin, Sebastiaan Haffert, Yoo Jung Kim, Jonathan Lin
High Energy Astrophysical Phenomena
Testing Gravity with Binary Pulsars in the SKA Era
V. Venkatraman Krishnan, L. Shao, V. Balakrishnan et al. (+21 more)
Binary (and trinary)
radio pulsars are natural laboratories in space for understanding
gravity in the strong field regime, with many unique and precise tests carried out so far, including the most precise tests of the strong equivalence principle and of the radiative properties of
gravity. The Square Kilometre Array (SKA)
telescope, with its high sensitivity in the Southern Hemisphere, will vastly improve the timing precision of recycled
pulsars, allowing for a deeper search of potential deviations from general relativity (GR) in currently known systems. A
Galactic census of
pulsars will, in addition, will yield the discovery of dozens of relativistic
pulsar systems, including potentially
pulsar – black hole binaries, which can be used to test the
cosmic censorship hypothesis and the “no-hair”
theorem. Aspects of gravitation to be explored include tests of strong equivalence principles, gravitational dipole radiation, extra field components of gravitation, gravitomagnetism, and spacetime
symmetries. In this chapter, we describe the kinds of
gravity tests possible with binary
pulsar and outline the features and abilities that SKA must possess to best contribute to this science.
Read the full abstract ▾
All authors V. Venkatraman Krishnan, L. Shao, V. Balakrishnan, A. Carleo, M. Colom i Bernadich, A. Corongiu, A. Deller, P. C. C. Freire, M. Geyer, E. Hackmann, H. Hu, Z. Hu, M. Kramer, J. Kunz, K. Liu, M. E. Lower, X. Miao, D. Perrodin, D. S. Pillay, A. Possenti, S. Ransom, I. Stairs, B. Stappers, The SKA Pulsar Science Working Group
Earth and Planetary Astrophysics
NGTS-39 b: A 58 d transiting warm Jupiter in an eccentric orbit
Ioannis Apergis, Daniel Bayliss, Solène Ulmer-Moll et al. (+53 more)
We report the discovery and characterisation of NGTS-39 b (TIC 453147896 b), a warm Jupiter transiting a Sun-like
star on a 58.2 day, eccentric (e = 0.386 +/- 0.019) orbit. NGTS-39 b was first identified from a TESS single-transit event, and subsequently confirmed with NGTS photometry and radial-velocity measurements from CORALIE and HARPS. The host
star is a bright (Tmag = 11.02) F9
dwarf with an effective temperature of Teff = 6053 +67/-30 K. NGTS-39 b is a Jupiter-sized gas
giant with a radius of 1.088 +/- 0.012 RJ and a mass of 1.467 +/- 0.081 MJ. Its
equilibrium temperature is 519 +6/-5 K, placing it between short-period hot Jupiters and cold, Jupiter-like
giants. The high orbital eccentricity and intermediate
equilibrium temperature of NGTS-39 b make it a valuable test case for formation and migration models, particularly in the poorly sampled regime of long-period gas
giants. The RV data show a linear trend of gamma dot = -17.75 m s^-1 yr^-1, which indicates the presence of an outer companion. The discovery of NGTS-39 b contributes to the small but growing population of transiting warm Jupiters with P > 50 days orbiting bright
stars.
Read the full abstract ▾
All authors Ioannis Apergis, Daniel Bayliss, Solène Ulmer-Moll, Samuel Gill, Toby Rodel, Matthew Battley, Paul Benni, Allyson Bieryla, James A. Blake, Andrea Bonfanti, François Bouchy, Edward M. Bryant, Matthew R. Burleigh, Samuel J. Carlier, Sarah L. Casewell, Hritam Chakraborty, Alastair B. Claringbold, Karen A. Collins, Benjamin D. R. Davies, Xavier Dumusque, Troy A. Edkins, Fintan Eeles-Nolle, Jo Ann Egger, Jorge Fernández Fernández, Marcelo Aron Fetzner Keniger, Pedro Figueira, Michael R. Goad, George Harvey, Faith Hawthorn, Melissa J. Hobson, Mathilde Houelle, Giovanni Isopi, Timour Jestin, Alicia Kendall, Monika Lendl, Daniel Lewis, Isobel Lockley, Franco Mallia, James McCormac, Morgan A. Mitchell, Lucile Mignon, Hugh Osborn, Angelica Psaridi, Alex Romanec, Suman Saha, Amber Sedgley, Sérgio Sousa, Neil Thomas, Stéphane Udry, Christopher Watson, Richard G. West, Thomas G. Wilson, Peter J. Wheatley, Jamie T. Williams, Aldo Zapparata, Krzysztof Sz. Zieliński
High Energy Astrophysical Phenomena · Cross-listed from physics.space-ph
Energetic particle-mediated interplanetary shocks observed by Solar Orbiter
D. Trotta, D. Lario, B. Reville et al. (+10 more)
Context: In collisionless shocks, energetic particles can carry sufficient pressure to modify the upstream
plasma and the shock structure itself, a regime often invoked in theories of
cosmic-ray acceleration but rarely observed in the heliosphere. Aims: We find and characterize {interplanetary} IP shocks where energetic particles dynamically dominate the upstream pressure. Methods: We analyze IP shocks observed by
Solar Orbiter inside 1 au and compute the energetic particle pressure $P_{EP}$ from
proton measurements above 10\,keV, comparing it with the upstream thermal $P_{Th}$ and
magnetic $P_{B}$ pressures. Results: We identify four shocks for which $P_{EP} \geq P_{Th} + P_B $. These events correspond to strong and fast shocks in the high-Mach-number tail of the
Solar Orbiter shock population. In several cases the $P_{EP}$ increase coincides with a decreasing upstream bulk flow speed in the shock frame, and the resulting particle-mediated foreshocks extend up to $\sim10^5$ {ion inertial lengths} $d_i$. The extent of such energetic particle dominated region depends on shock geometry. Conclusions: These observations provide evidence that accelerated particles can dynamically modify interplanetary shocks. They highlight the importance of the coupling between energetic particles, upstream fluctuations, and shock structure for understanding particle acceleration at collisionless shocks.
Read the full abstract ▾
All authors D. Trotta, D. Lario, B. Reville, S. Raptis, O. Pezzi, H. Hietala, P. Mostafavi, J. Giacalone, R. F. Wimmer-Schweingruber, P. Kuehl, A. Kollhoff, D. Turner, D. Burgess
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Boson Stars in Teleparallel Gravity with a Nonminimally Coupled Field: The Violation of Energy Conditions and Gravitational Waveforms from EMRIs
Long-Xing Huang, Ke Yang and Yong-Qiang Wang
In this work, we investigate
boson star models within the framework of teleparallel
gravity with non-minimal coupling, and obtain static, spherically symmetric solutions for both the ground state and excited states. The results indicate that the energy density of the excited-state solutions can become negative. For these solutions, the four commonly used energy conditions are no longer satisfied. In contrast, for all the ground-state solutions we have studied, the energy density remains positive and all four energy conditions are consistently satisfied. Moreover, considering the importance of astrophysical observations, the gravitational-wave signals from Extreme-Mass-Ratio Inspirals (EMRIs) composed of these
boson stars are investigated. Our results reveal that the frequency-domain characteristic strain of these waveforms falls within the detectability range of LISA, which can provide potential evidence for distinguishing compact astrophysical objects.
Read the full abstract ▾
Solar and Stellar Astrophysics
Research Progress on Solar Small-Scale Dynamo
Wen-Jie Jiang, Lei Ni, Chun-Lan Jin et al. (+2 more)
The small-scale
solar dynamo theory, as the core mechanism explaining the origin of the persistent, disperse weak
magnetic field in the quiet Sun regions, has made significant progress over the past three decades in the fields of observation, theory, and simulation. Breakthrough observations from high-resolution space-based and ground-based
telescopes have revealed that the quiet Sun is ubiquitously populated by highly dynamic, mixed-polarity and possibly predominantly horizontal
magnetic structures with complex
topology. These observations confirm that their total
magnetic flux is substantial, with a high and widely distributed
magnetic flux emergence rate, strongly suggesting a local dynamo effect independent of the
solar cycle and driven by intense
turbulence and convection. Theoretical studies indicate that even in the challenging low
magnetic Prandtl number ( Pm << 1) environment of the
solar photosphere and convection zone, turbulent motions can self-excitedly convert kinetic energy into
magnetic energy through the stretching, folding, and twisting of
magnetic field lines. MHD simulations have successfully reproduced observed features, demonstrating that a pure small-scale dynamo can operate efficiently and sustain
magnetic fields even in an open, stratified
solar environment incorporating realistic physical processes. Current research strongly suggests that small-scale
magnetic fields constitute the majority of the
magnetic energy in the quiet Sun and also influence coronal heating,
solar wind acceleration, and radiation distribution. This article conducts a literature review centered on observations, theoretical models, and numerical simulations of the small-scale dynamo, organizing and discussing the relevant research history and progress. Finally, it summarizes the content and provides an outlook on future research from multiple perspectives.
Read the full abstract ▾
All authors Wen-Jie Jiang, Lei Ni, Chun-Lan Jin, Zhi Xu, Mei Zhang
Instrumentation and Methods for Astrophysics
Pulsar Backend for 21 CentiMeter Array: Implementation of Data Acquisition and Initial Results
Yukai Zhou, Junhua Gu, Mengyao Xue et al. (+8 more)
We implemented a data acquisition system for 21 CentiMeter Array (21CMA), enabling baseband observations targeting
pulsars and fast
radio bursts. Based on the
Radio Frequency System-on-Chip (RFSoC) platform, the new backend is capable of instantaneously covering the effective bandwidth from 50 to 350 MHz, with multi-board synchronization achieved at the timescale of the sampling clock. We observed PSR B0329+54 with a single station to verify the signal path integrity; then solved phase relations of multiple station pairs using bright persistent
radio sources like Cas A and Cyg A; using these phase solutions, a multiple-station coherently beamformed observation of PSR B0329+54 was carried out, showing a signal-to-noise ratio of 699.09 for a 2.5-hour observation with eight stations, opening up a possibility of tied-array low-frequency
pulsar observations on 21CMA.
Read the full abstract ▾
All authors Yukai Zhou, Junhua Gu, Mengyao Xue, Faxin Shen, Jian Li, Qiuyang Fu, Cijie Zhang, Youling Yue, Weiwei Zhu, Kejia Lee, Renxin Xu
Instrumentation and Methods for Astrophysics
Current status of the High-Resolution Multi-Object Spectrograph (MOS-HR) for the Wide-field Spectroscopic Telescope
Andrea Tozzi, Anna Brucalassi, Matteo Munari et al. (+10 more)
The Wide-field Spectroscopic
Telescope (WST) is a planned 12-meter class dedicated spectroscopic facility for massive spectroscopic surveys. This paper presents the current status of Work Package 4.5, the High Resolution Multi-Object Spectrograph (HR-MOS) module. We describe the international team organization and optical design resulting from extensive trade-off studies, presenting its
evolution driven by scientific requirements and technical constraints. Design parameters derived from science cases and astronomical community requirements are detailed. Given the critical importance of mass and volume budgets, we present envelope dimensions and mass estimates for HR-MOS. The spectrograph constructive parameters are defined, including optical fiber specifications, multiplex capability, and modular architecture. Finally, we present the structural analysis addressing mechanical stability and performance requirements for this high-resolution multi-object spectrograph.
Read the full abstract ▾
All authors Andrea Tozzi, Anna Brucalassi, Matteo Munari, Simone D'Auria, Andrea Bianco, Giorgio Pariani, Ciro Del Vecchio, Paolo Picchi, Roland Bacon, Bernard Delabre, David Lee, Sofia Randich, Will Saunders
Solar and Stellar Astrophysics
Asteroseismic Analysis of the Merger Product Red Giant in the $\gamma$ Persei System
Rozália Z. Ádám, László Molnár, Róbert Szabó et al. (+7 more)
Context. $\gamma$ Persei is a long-period eclipsing binary system ($P\approx 14.6$ years) containing a red
giant primary, and it is well known for its multi-faceted classification as a visual and spectroscopic binary. Its brightness and binary nature together make it a valuable target for both photometric and spectroscopic studies, particularly in the context of asteroseismology and
stellar evolution, as the primary
star likely formed through a
stellar merger. Aims. We aim to determine the seismic parameters $\nu_{\rm max}$, $\Delta \nu$, and the oscillation amplitudes of the primary component, an evolved
giant, to estimate its seismic mass $-$ which we can compare to its estimated dynamic mass. Methods. We use Transiting
Exoplanet Survey Satellite (TESS) data obtained during Sectors 58, 85, and 86 and to complement the space-based observations, we incorporate high-resolution RV measurements acquired by the
Stellar Observations Network Group (SONG) during two distinct epochs; 2017 and 2024. Results. We successfully detect
solar-like oscillations in $\gamma$ Per and infer a seismic mass of $3.25\pm0.13$ M$_\odot$, which is slightly below the dynamical mass. We find the photometric oscillation amplitudes to be significantly lower than predicted from scaling relations, but in line with other high-mass red
giants. We also find that radial velocity amplitudes along the Hertzsprung-Russell diagram cannot be fitted uniformly with current scaling relations.
Read the full abstract ▾
All authors Rozália Z. Ádám, László Molnár, Róbert Szabó, Csilla Kalup, Frank Grundahl, Daniel Huber, Mads Skakke Fredslund, Pere L. Pallé, Dóra Tarczay-Nehéz, Jonatan Rudrasingam