NGC 1052-DF2 and -DF4 are two ultradiffuse galaxies that have been reported as deficient in dark matter and associated with the same galaxy group. Recent findings suggest that DF2 and DF4 are part of a large linear substructure of dwarf galaxies that could have been formed from a high-velocity head-on encounter of two gas-rich galaxies, known as a “bullet dwarf” collision. Based on new observations

Multiplanet systems face significant challenges to detection. For example, farther-orbiting planets have a reduced signal-to-noise ratio in radial velocity detection methods, and small mutual inclinations between planets can prevent them from all transiting. One mechanism for exciting mutual inclination between planets is secular resonance, where the nodal precession frequencies of the planets align

Gigahertz peaked spectrum (GPS) and compact steep spectrum (CSS) sources are compact radio galaxies (RGs), with jets extending up to 20 kpc and ages <103 yr. They are considered to evolve to Fanaroff–Riley RGs, but the real scenario to explain the compact sources remains unsolved. The young compact jets make GPS/CSS ideal for studying feedback in the nuclear region of active galactic nuclei because

Stellar clusters are critical constituents within galaxies: They are the result of highest-density star formation, and through their spatially and temporally correlated feedback, they regulate their host galaxy evolution. We present a novel numerical method to model star clusters as individual units of star formation using sink particles. In our method, star clusters grow via gas accretion and via

Spatially resolved emission-line kinematics are invaluable for investigating fundamental galaxy properties and have become increasingly accessible for galaxies at z ≳0.5 through sensitive near-infrared imaging spectroscopy and millimeter interferometry. Kinematic modeling is at the core of the analysis and interpretation of such data sets, which at high z present challenges due to the lower signal-to-noise

We present a method that calibrates a semianalytic model to the Renaissance Simulations, a suite of cosmological hydrodynamical simulations with high-redshift galaxy formation. This approach combines the strengths of semianalytic techniques and hydrodynamical simulations, enabling the extension to larger volumes and lower redshifts that are inaccessible to simulations due to computational expense.

Low-mass X-ray binaries with a neutron star as the primary object show a complex array of phenomenology during outbursts. The observed variability in X-ray emission primarily arises from changes in the innermost regions of the accretion disk, neutron star surface, and corona. In this work, we present the results of a comprehensive X-ray spectral and timing analysis of the neutron star transient MAXI

In the leading theory of lunar formation, known as the giant impact hypothesis, a collision between two planet-sized objects resulted in a young Earth surrounded by a circumplanetary debris disk from which the Moon later accreted. The range of giant impacts that could conceivably explain the Earth–Moon system is limited by the set of known physical and geochemical constraints. However, while several

Quasiperiodic eruptions (QPEs) are high-amplitude, soft X-ray bursts recurring every few hours, associated with supermassive black holes. Many interpretations for QPEs were proposed since their recent discovery in 2019, including extreme mass ratio inspirals and accretion disk instabilities. But, as of today, their nature still remains debated. We perform the first high-resolution X-ray spectral study

Charge exchange is a predominant process in inelastic collisions in astronomical plasmas, influencing the charge state balance and leading to X-ray emissions when solar wind ions interact with neutral gas in astrophysical environments. Accurate analysis of these dynamic properties to diagnose the solar wind composition and velocities, as well as the spatial distribution of the heliospheric neutral

Radio halos of edge-on galaxies are crucial for investigating cosmic ray propagation and magnetic field structures in galactic environments. We present VLA C-configuration S-band (2–4 GHz) observations of the spiral galaxy NGC 3556, a target from the Continuum Halos in Nearby Galaxies—an EVLA Survey. We estimate the thermal contribution to the radio emission from a combination of the Hα and mid-IR

Observations have revealed unique temperature profiles in hot Jupiter atmospheres. We propose that the energy transport by vertical mixing could lead to such thermal features. In our new scenario, strong absorbers, TiO, and VO are not necessary. Vertical mixing could be naturally excited by atmospheric circulation or internal gravity wave breaking. We perform radiative transfer calculations by taking

We explore how the definition of a void influences the conclusions drawn about the impact of the void environment on galactic properties using two void-finding algorithms in the Void Analysis Software Toolkit: Voronoi Voids (V2), a Python implementation of ZOnes Bordering On Voidness (ZOBOV); and VoidFinder, an algorithm that grows and merges spherical void regions. Using the Sloan Digital Sky Survey

A high-resolution fourth-order Padé scheme is used to simulate locally isothermal 3D disk turbulence driven by the vertical shear instability (VSI) using 268.4 M points. In the early nonlinear period of axisymmetric VSI, angular momentum transport by vertical jets creates correlated N-shaped radial profiles of perturbation vertical and azimuthal velocity. This implies dominance of positive perturbation

Upon interaction, a pair of magnetic flux ropes can merge to form a new pair, each consisting of opposite helicity along their axis. Magnetic helicity along such new structures may annihilate and release the energy of the azimuthal magnetic field. In this study, we model the deformation dynamics of such structures within the solar wind at 1 au. The perturbation front of deformation propagates along

We report the discovery of three ultracompact binary white dwarf systems hosting accretion disks, with orbital periods of 7.95, 8.68, and 13.15 minutes. This significantly augments the population of mass-transferring binaries at the shortest periods, and provides the first evidence that accretors in ultracompacts can be dense enough to host accretion disks even below 10 minutes (where previously only

The search for accreted satellites in the Galactic disk is a challenging task, to which Gaia plays a crucial role in synergy with ground-based spectroscopic surveys. In 2021, P. Re Fiorentin et al. discovered five substructures with disk kinematics including Icarus. To gain more insight into the origin of Icarus as a remnant of a dwarf galaxy rather than a signature of secular processes of disk formation

We present images of the Vega planetary debris disk obtained at 15.5, 23, and 25.5 μm with the Mid-Infrared Instrument on JWST. The debris system is remarkably symmetric, smooth, and centered accurately on the star. There is a broad Kuiper-belt-analog ring at ∼80–170 au that coincides with the planetesimal belt detected with the Atacama Large Millimeter/submillimeter Array at 1.34 mm. The interior

The line-of-sight structure of the Galactic magnetic field (GMF) can be studied using Faraday rotation measure (RM) grids. We analyze how the choice of interpolation kernel can affect the accuracy and reliability of reconstructed RM maps. We test the following kernels: inverse distance weighting (IDW), natural neighbor interpolation (NNI), inverse multiquadric interpolation (IM), thin-plate spline

We present a detailed imaging analysis of 260 ks of subarcsecond resolution Chandra (ACIS-S) observations of the nearby Seyfert 2 galaxy NGC 5728. Our study focuses on the bright and diffuse soft X-ray emission within the galaxy's inner ∼1 kpc. By comparing the X-ray emission across different energy bands, we identify localized variations in the absorbing column and emission processes. We observe more

The circumgalactic medium (CGM) is responsive to kinetic disruptions generated by nearby astrophysical events. In this work, we study the saturation and dissipation of turbulent hydrodynamics within the CGM through an extensive array of 252 numerical simulations with proper cooling mechanisms and a large parameter space spanning average gas density, metallicity, and turbulence driving strength. A dichotomy

Fast radio bursts (FRBs) represent one of the most intriguing phenomena in modern astrophysics. However, their classification into repeaters and nonrepeaters is challenging. Here, we present the application of the graph theory minimum spanning tree (MST) methodology as an unsupervised classifier of repeater and nonrepeater FRBs. By constructing MSTs based on various combinations of variables, we identify

We present new radio images of the supernova remnant (SNR) CTA 1 at 1420 and 408 MHz, and in the 21 cm line of H i observed with the Dominion Radio Astrophysical Observatory Synthesis Telescope and at 1420 MHz observed with the Effelsberg 100 m telescope. We confirm previously described continuum features and elaborate further on filamentary features identified using the high-resolution (1′) maps from

We present a noteworthy transient AT 2021aeuk exhibiting three distinct optical flares between 2018 and 2023. It is hosted in a radio-loud narrow-line Seyfert 1 galaxy, with an optical image showing a minor tidal morphology and a red mid-infrared color (W1 − W2 = 1.1). Flares II and III exhibit rapid rises, and long-term decays (≳1000 days) with recurring after-peak bumps. The g − r color after subtracting

Investigating the angular momentum evolution of pre-main-sequence (PMS) stars provides important insight into the interactions between Sun-like stars and their protoplanetary disks, and the timescales that govern disk dissipation and planet formation. We present projected rotational velocities (v sin i values) of 254 T Tauri stars (TTSs) in the ∼3 Myr old open cluster NGC 2264, measured using high-dispersion

We present an analysis of the absorption-line system in the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph spectrum at a redshift of za = 3.1448 associated with the quasar SDSS J122040.23+092326.96, whose systematic redshift is ze = 3.1380 ± 0.0007, measured from the Hβ+[O iii] emission lines in our newly acquired NIR P200/TripleSpec data. This absorbing system, detected in numerous

In galactic centers, stars and binaries can be injected into low-angular-momentum orbits, resulting in close encounters with the central supermassive black hole (SMBH). Previous works have shown that under different conditions, such close encounters can lead to the breakup of the binary, disruptions of both stars, and collision between the stars. We use three-body scattering experiments to characterize

The Kelvin–Helmholtz instability (KHI) has been considered important in the energy transfer and momentum coupling between the solar wind and planetary magnetospheres. To explore this issue, we employ a two-dimensional magnetohydrodynamic simulation to study the nonlinear evolution of the KHI at Mercury’s magnetopause using the parameters derived from a global hybrid simulation of MESSENGER’s first

Secure methods for identifying the host galaxies of individual massive black hole (MBH) binaries and mergers detected by gravitational-wave experiments such as the Laser Interferometer Space Antenna and pulsar timing arrays are currently lacking, but will be critical to a variety of science goals. Recently, in Bardati et al., we used the Romulus25 cosmological simulation to show that MBH merger host

Switchbacks, defined as Alfvénic reversals in magnetic field polarity, can dissipate their magnetic energy with heliocentric distance. To further investigate this, two distinct solar wind parcels tracing back to a similar solar source region were examined during a radial alignment between Parker Solar Probe (@25.8RS) and Solar Orbiter (@152RS). The one caveat was that the two probes were located on

The role of internal and environmental factors in the star formation activity of galaxies is still a matter of debate, in particular at higher redshifts. Leveraging the most recent release of the COSMOS catalog, COSMOS2020, as well as density measurements from our previous study, we disentangle the impact of environment and stellar mass on the star formation rate (SFR) and specific SFR (sSFR) of a

The recent discovery of planetesimals orbiting white dwarfs has renewed interest in the final chapters of the evolution of planetary systems. Although observational and theoretical studies have examined the dynamical evolution of these systems, studies of their magnetic star–planet interactions, as powered by unipolar induction, have thus far only been assessed theoretically. This fifth paper of the

Electron cyclotron maser (ECM) emission is an important coherent emission mechanism for the direct amplification of electromagnetic waves by nonthermal electrons in a magnetized plasma. This paper will report on our recent study on ECM emission by fast electron beams with moderately relativistic energy. The results show that, similar to the spontaneous emission by the magnetic cyclotron motion of energetic

Several filament eruptions with pronounced writhing of the axis of the structure are analyzed. Initially, smooth arches of eruptive filaments are transformed into large-scale helical structures with at least one complete turn due to the development of kink instability. However, the initiation of the eruptions seems to be caused not by the kink instability but by catastrophic loss of equilibrium or

The nearby long gamma-ray burst (GRB) 190829A was observed using the Hubble Space Telescope/Wide Field Camera 3/infrared grisms about four weeks to 500 days after the burst. We find the spectral features of its associated supernova, SN 2019oyw, are redshifted by several thousand km s−1 compared to the redshift of the large spiral galaxy on which it is superposed. This velocity offset is seen in several

The magnetar SGR 1935+2154 is the only known Galactic source of fast radio bursts (FRBs). FRBs from SGR 1935+2154 were first detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB and the Survey for Transient Astronomical Radio Emission 2 in 2020 April, after the conclusion of the LIGO, Virgo, and KAGRA Collaborations’ O3 observing run. Here, we analyze four periods of gravitational

We present photometric and spectroscopic observations of SN 2023fyq, a Type Ibn supernova (SN) in the nearby galaxy NGC 4388 (D ≃ 18 Mpc). In addition, we trace the 3 yr long precursor emission at the position of SN 2023fyq using data from DLT40, ATLAS, Zwicky Transient Facility, ASAS-SN, Swift, and amateur astronomer Koichi Itagaki. The double-peaked postexplosion light curve reaches a luminosity

Recent multiwavelength observations of gamma-ray burst afterglows observed in the TeV energy range challenge the simplest synchrotron self-Compton (SSC) interpretation of this emission and are consistent with a single power-law component spanning over 8 orders of magnitude in energy. To interpret this generic behavior in the single-zone approximation without adding further free parameters, we perform

The distribution of delay times between the formation of binary black hole (BBH) progenitors and their gravitational-wave (GW) merger provides important clues about their unknown formation histories. When inferring the delay time distribution, it is typically assumed that BBH progenitor formation traces the star formation rate (SFR). In this work, we consider the rate of long gamma-ray bursts (LGRBs)

Combining Chandra, Atacama Large Millimeter/submillimeter Array, EVLA, and Hubble Space Telescope archival data and newly acquired data from the Apache Point Observatory/Dual Imaging Spectrograph, we detect a double-lobed 17 kpc X-ray emission with plumes oriented approximately perpendicular and parallel to the galactic plane of the massive lenticular galaxy NGC 5084 at 0.3–2.0 keV. We detect a highly

Extreme coronal-line emitters (ECLEs) are objects showing transient high-ionization lines in the centers of galaxies. They have been attributed to echoes of high-energy flares of ionizing radiation, such as those produced by tidal disruption events (TDEs), but have only recently been observed within hundreds of days after an optical transient was detected. AT 2022upj is a nuclear UV–optical flare at

We present observations and analysis of an X1.8 noneruptive solar flare on 2012 October 23, which is characterized by an extremely large late-phase peak seen in the warm coronal extreme-ultraviolet (EUV) emissions (∼3 MK), with the peak intensity over 1.4 times that of the main flare peak. The flare is driven by a failed eruption of a magnetic flux rope, whose strong squeeze force acting on the overlying

Models predict that the well-studied mass–radius relation of white dwarf stars depends on the temperature of the star, with hotter white dwarfs having larger masses at a given radius than cooler stars. In this paper, we use a catalog of 26,041 DA white dwarfs observed in Sloan Digital Sky Survey Data Releases 1–19. We measure the radial velocity, effective temperature, surface gravity, and radius for

The eruption of prominences can have a significant influence on the solar–terrestrial environment. However, accurately predicting these eruptions remains a challenge. We apply automated detection methods for extreme ultraviolet (EUV) prominences observed by the twin spacecraft from the Solar Terrestrial Relations Observatory (STEREO) mission and the Solar Dynamics Observatory near Earth. We study an

The Milky Way (MW) is a barred spiral galaxy shaped by tidal interactions with its satellites. The Large Magellanic Cloud (LMC) and the Sagittarius dwarf galaxy (Sgr) are the dominant influences at the present day. This paper presents a suite of four 109 particle N-body simulations, illustrating the response of the stellar disk of the MW to the close approach of the LMC and the merger of Sgr into the

We present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of a starburst galaxy at cosmic noon hosting a radio-loud active galactic nucleus: PKS 0529-549 at z = 2.57. To investigate the conditions of its cold interstellar medium, we use ALMA observations that spatially resolve the [C i] fine-structure lines, [C i] (2–1) and [C i] (1–0), CO rotational lines, CO (7–6) and CO (4–3)

We present JWST NIRSpec prism spectroscopy of lensed galaxies at z ≳ 9 found behind the massive galaxy cluster Abell 2744 in the UNCOVER Cycle 1 Treasury Program. We confirm the redshift via emission lines and/or the Lyα break for 10 galaxies at z = 8.50–13.08 down to MV = −17.3. We achieve a 100% confirmation rate for z > 9 candidates reported in H. Atek et al. Using six sources with multiple line

The imaging of Sagittarius A* (Sgr A*) and the supermassive black hole at the center of Messier 87 (M87*) by the Event Horizon Telescope constrains the location and nature of emission from these objects. Coupled with flux limits from the near-infrared through the ultraviolet, the attendant size constraints provide strong evidence for the absence of an accretion-powered photosphere, and therefore for

We carry out this study on the solar energetic particle (SEP) event that occurred on 2023 August 5 over the ascending phase of the current solar cycle 25. It is found that the SEP event might have been initiated by the M1.6 flare, while the SEP peak was caused by the coronal shock manifested in DH-type II radio burst over the propagation phase of a halo coronal mass ejection (CME; ∼1000 km s−1), thus

Brown dwarfs with measured dynamical masses and spectra from direct imaging are benchmarks that anchor substellar atmosphere cooling and evolution models. We present Subaru SCExAO/CHARIS infrared spectroscopy of HIP 93398 B, a brown dwarf companion recently discovered by Y. Li et al. (2023), as part of an informed survey using the Hipparcos–Gaia Catalog of Accelerations. This object was previously

A number of works have considered the role of turbulence in energy release and transport in solar flares, and in particular, on the transport of energy by thermal conduction. Here, we point out that for physical consistency, the effects of turbulence on the electrical conductivity, and hence on the ohmic heating by the return current that neutralizes the current in injected electron beams, must also

We report the discovery of a close binary J0606+2132 (Gaia DR3 3423365496448406272) with Pobs = 2.77 days containing a possible massive white dwarf (WD) or a neutron star (NS) using LAMOST spectroscopic data. By a joint fitting of the radial velocity from LAMOST and the light curve from TESS, we derived a circular Keplerian orbit with an inclination of i = 81.°31 , which is consistent with that derived

We analyze accretion-rate time series for equal-mass binaries in coplanar gaseous disks spanning a continuous range of orbital eccentricities up to 0.8 for both prograde and retrograde systems. The dominant variability timescales match those of previous investigations; the binary orbital period is dominant for prograde binaries with e ≳ 0.1, with a 5 × longer “lump” period taking over for e ≲ 0.1.

Through a detailed timing analysis of Fermi-LAT data, the rotational behavior of the γ-ray pulsar PSR J1522−5735 was tracked from 2008 August (MJD 54692) to 2024 January (MJD 60320). During this 15.4 yr period, two overrecovery glitches and four antiglitches were identified, marking a rare occurrence in rotation-powered pulsars (RPPs). The magnitudes of these (net) spin-down glitches were determined

We report a δ Scuti star, KIC 10407873, exhibiting significant amplitude modulation. Fourier analysis of Kepler long-cadence data (i.e., Q0-Q17, spanning 1471 days) reveals two distinct features: harmonic series of frequencies in the low-frequency region and the frequencies of the split triplet lines in the high-frequency region. Using the Hilbert transform method, we separated the amplitude modulation

Turbulent transport characteristics of the particles within two Crab-like pulsar wind nebulae (PWNe), 3C58 and G54.1+0.3, are investigated in the framework of a time-dependent turbulent diffusion model. The model takes the gyroresonant interactions between the particles and turbulent waves into account, which enables us to self-consistently determine the energy and spatial coefficients of particles

W Serpentis is an eclipsing binary system and the prototype of the Serpentid class of variable stars. These are interacting binaries experiencing intense mass transfer and mass loss. However, the identities and properties of both stars in W Ser remain a mystery. Here, we present an observational analysis of high-quality, visible-band spectroscopy made with the Apache Point Observatory 3.5 m telescope

Fast-mode magnetohydrodynamic waves in the solar corona are often known to be produced by solar flares and eruptive prominences. Here, we simulate the effect of the interaction of an external perturbation on a magnetic null in the solar corona, which results in the formation of a current sheet (CS). Once the CS undergoes a sufficient extension in its length and squeezing of its width, it may become

We resolve the multiple images of the binary-lens microlensing event ASASSN-22av using the GRAVITY instrument of the Very Large Telescope Interferometer (VLTI). The light curves show weak binary-lens perturbations, complicating the analysis, but the joint modeling with the VLTI data breaks several degeneracies, arriving at a strongly favored solution. Thanks to precise measurements of the angular Einstein

We investigate the Lyα and Lyman continuum (LyC) properties of the Sunburst Arc, a z = 2.37 gravitationally lensed galaxy with a multiply imaged, compact region leaking LyC and a triple-peaked Lyα profile indicating direct Lyα escape. Non-LyC-leaking regions show a redshifted Lyα peak, a redshifted and central Lyα peak, or a triple-peaked Lyα profile. We measure the properties of the Lyα profile from