Many intermediate-mass close binaries exhibit photometric cycles longer than their orbital periods, likely linked to variations in their accretion disks. Previous studies suggest that analyzing historical light curves provides key insights into disk evolution and may help track changes in mass transfer rates in such systems. Our research explores short- and long-term fluctuations in the eclipsing system ̌ar, focusing on the variability of its long cycle. We aim to clarify the role of the accretion disk in these modulations, especially those spanning hundreds of days, and to determine the system's evolutionary status to better understand its stellar components. We analyzed 32.3 years of photometric time series from the Optical Gravitational Lensing Experiment (OGLE) in the I and V bands, and from the MAssive Compact Halo Objects (MACHO) project in B_M and R_M bands. Using data from multiple epochs, we modeled the accretion disk across 20 equally spaced phases of the long cycle. To solve the inverse problem, we implemented an optimized simplex algorithm to determine the best parameters for the stars, their orbit, and the disk. The Modules for Experiments in Stellar Astrophysics ( ) code was employed to assess the system's evolutionary stage and predict its past and future development. MESA We find an orbital period of 6 and a long cycle of 229 Our orbital solutions reproduce the light curves, but the quasi-conservative mass transfer scenario yields rates that are too high for the orbital period stability. We find a consistency with the observed orbital-to-long-period ratio under the magnetic dynamo hypothesis. The normalized mass transfer rate follows the long cycle, reaching a maximum when brightness is minimum. At that phase, the disk's inner edge thickens, obscuring more of the gainer star. Disk variability mainly occurs in its vertical extension, with a standard deviation of 69% the mean value at the inner border, with minor changes in the outer radius and temperature of 7% and 5%, respectively.

The Mid-Infrared Instrument (MIRI) is the imager and spectrograph covering wavelengths from 4.9 to 27.9 μm on board the Space Telescope (JWST). James Webb The MIRI Medium-Resolution Spectrometer (MRS) consists of four integral field units (IFU) and two wheels with three rotation settings, producing four spectral channels and three spectral sub-channels. . The 12 resulting spectral data cubes have different fields of view, spatial coverages, and spectral resolutions. The wavelength range of each cube partially overlaps with the neighboring bands, and the overlap regions typically show flux mismatches that have to be corrected by spectral stitching methods. The aim of stitching methods is to produce a single data cube incorporating the data of the individual sub-channels, which requires matching the spatial resolution and the flux discrepancies. We present , a novel stitching algorithm that uses nonnegative matrix factorization to perform a matrix completion, where the available MRS data cubes are treated as 12 sub-matrices of a larger incomplete matrix. Haute Couture Prior to matrix completion, we also introduced a novel preprocessing method to homogenize the global intensities of the 12 cubes. Our preprocessing consists of jointly optimizing a set of global scale parameters that maximize the fit between the cubes where spectral overlap occurs. We applied our novel stitching method to JWST data obtained as part of the PDRs4All observing program of the Orion Bar and produced a uniform cube reconstructed with the best spatial resolution over the full range of wavelengths.

We constrained minimally extended cosmological models with the cosmic shear analysis of the final data release from the Kilo-Degree Survey (KiDS-Legacy) in combination with external probes. Due to the consistency of the KiDS-Legacy analysis with the cosmic microwave background (CMB), we could combine these datasets reliably for the first time. Additionally, we used CMB lensing, galaxy redshift-space distortions, and baryon acoustic oscillations. We assessed, in turn, the effects of spatial curvature, varying neutrino masses, and an evolving dark energy component on cosmological constraints from KiDS-Legacy alone and from KiDS-Legacy combined with external probes. We find KiDS-Legacy to be consistent with the fiducial flat Λ-cold dark matter (ΛCDM) analysis with c^2 ∑ m_νłeq 1.5,eV, w_0 = -1.0± 0.7, and w_a = +1.9 _ -2.0 while Ω_K = 0.08^ +0.16 _ -0.17 (1σ bounds) with an almost equal goodness of fit. The w_0w_aCDM model is not a significant improvement over ΛCDM when cosmic shear and CMB lensing are combined, yielding a Bayes factor B = 0.07. If all probes are combined, however, B increases to 2.73, corresponding to a 2.6σ suspiciousness tension. The constraint on S_8 = σ_8 is robust to opening up the parameter space for cosmic shear. Adding all external datasets to KiDS-Legacy, we find S_8 = 0.816 ± 0.006 in ΛCDM and S_8 = 0.837 ± 0.008 in w_0 w_aCDM for all probes combined. Ω_ /0.3 m

Over 20 exocometary belts host detectable circumstellar gas, mostly in the form of CO. Two competing theories for its origin have emerged, positing that the gas is either primordial or secondary. Primordial gas survives from the belt's parent protoplanetary disc and is therefore H_2-rich. Secondary gas is outgassed in situ by exocomets and is relatively H_2-poor. Discriminating between these scenarios has not been possible for belts that host unexpectedly large quantities of CO. We aim to break this gas origin dichotomy through direct measurement of H_2 column densities in two edge-on, CO-rich exocometary belts around ∼15 Myr-old A-type stars, constraining the frac CO H _2 ratio and CO gas lifetimes. Observing edge-on belts enables rovibrational absorption spectroscopy against the stellar background. We present near-IR CRIRES+ spectra of HD 110058 and HD 131488, which provide the first direct probe of H_2 gas in CO-rich exocometary belts. We targeted the H_2 (v=1-0 S(0)) line at 2223.3 nm and the 12 CO v=2̊ightarrow0 rovibrational lines in the range 2333.8-2335.5 nm and derived constraints on column densities along the line of sight to the stars. We detect 12 CO strongly, but not H_2$, in the CRIRES+ spectra. This allows us to place 3σ lower limits on the frac CO H _2 ratios of $> 1.35 $ and $> 3.09 $ for HD 110058 and HD 131488, respectively. These constraints demonstrate that, at least for HD 110058, the exocometary gas is compositionally distinct and significantly H_2-poor compared to the <10^-4 frac 10^ -3 10^ -5 CO H _2 ratios typical of protoplanetary discs. For HD 131488, we further compared the CO photodissociation timescale to the age of the system through simple shielding arguments, and find that we cannot formally rule out a primordial origin; however, we suggest that a more realistic model of CO survival likely supports a secondary origin for this system as well. Overall, a high $ ratio for HD 110058 indicates that the gas in this CO-rich belt is most likely not primordial in composition, supporting the presence of exocometary gas. CO H _2

We present a comprehensive multifrequency VLBI analysis of the Fanaroff-Riley II (FRII) high-excitation radio galaxy 3C 452. Our aim is to resolve and analyze, for the first time, its twin-jet structure on sub-parsec scales. Our dataset comprises high-sensitivity array (HSA) observations at 4.9, 8.4, 15.4, 23.6, and 43.2 GHz. Through fitting methods performed in both the visibility and the image plane, we were able to trace the jet expansion from scales of a few thousand to nearly 10^5 Schwarzschild radii (R_ S) for both the approaching and receding jets. Additionally, we derived the core brightness temperatures and Doppler factors to constrain the orientation and intrinsic speed of the jet. Our study provides the first detailed description of the twin-jet system in 3C 452 on VLBI scales, confirming it as a rare FRII source with jets detected down to millimeter wavelengths. We resolved both the jet and counter-jet down to scales of a few thousand R_ R_ revealing a symmetric parabolically expanding structure with power-law indices of k≈ 0.66 (jet) and k≈ 0.47 (counter-jet). Jet-to-counter-jet intensity ratios remain nearly constant on larger scales but rise sharply within the inner 1–1.5 mas, as revealed by the higher-frequency data, consistent with increasing jet speed. We observed low core brightness temperatures values, which are indicative of Doppler de-boosting (δ ∼ 0.03–0.83) due to the large viewing (þeta ≈ 70^̧irc) and/or a magnetically dominated jet base. A spectral index analysis revealed a strongly inverted core spectrum (α > 2) with additional absorption at the highest frequencies, followed by a sharp steepening (α∼-2.5) to optically thin values in the innermost jet. Finally, a comparison between broad- and narrow-line high-excitation radio galaxies showed that jets in narrow-line sources, such as 3C 452 and Cygnus A, complete collimation at łesssim 10^ 5 S , whereas broad-line sources exhibit shape transitions at 10^6–10^ 7 R_ S , suggesting that orientation plays an important role in the observed collimation scales.

Stellar substructures within tidal debris preserve information about their progenitor galaxies' properties, offering insights into hierarchical mass assembly. We examine a compact stellar system (CSS) around the nearby spiral galaxy NGC 7531, including the shell-like tidal debris around it. Our goals are to determine the nature of the CSS, reconstruct the accretion history, and understand how the large, diffuse shell-like structure formed. We present photometric measurements of the shell-like debris and CSS using DESI Legacy Imaging Survey (LS) data. We obtained Keck/LRIS spectroscopic data for the CSS to confirm its association with NGC 7531 and to derive its star formation history (SFH). Deep (∼27.9 mag/arcsec 2 ) amateur telescope images enabled us to make a complete characterisation of the tidal debris structure. We confirm that the CSS is associated with NGC 7531. We rename it NGC 7531-UCD1, since its stellar mass (3.7_ -0.7 ^ +1.0 10^6 mathrm M _⊙), half-light radius (R_ h = 0.13 ± 0.05 arcsec), and SFH place it as an ultra-compact dwarf galaxy (UCD). We find that NGC 7531-UCD1 experienced a star formation burst ∼ 1 Gyr ago. NGC 7531-UCD1 was likely a nuclear star cluster (NSC) that was tidally stripped into a UCD- this is further supported by the presence of tidal tails. We quantify the shell-like debris' mass as M_ 3--11 10^8 M_⊙, implying a merger mass ratio of ∼ 300:1 to 10:1. Our amateur telescope images confirm new pieces of tidal debris, previously unclear in the DESI LS images. N-body simulations reproduce the tidal features, and require a near radial orbit of the progenitor dwarf galaxy with two pericentric passages. The first pericentre passage coincides with the measured star formation enhancement ∼ 1 Gyr ago. Our findings agree with theoretical predictions about the NSC to UCD formation pathway via tidal stripping, and further confirm the presence of these objects outside of our Milky Way.

Over the past decade, runaway stars believed to originate either as surviving donors of Type Ia supernovae or as partially deflagrated accretors producing Type Iax supernovae, have been identified. While the former have been extensively studied recently, the origins of the latter (also called łp type stars) remain under-explored, and therefore less well understood. So far seven such objects are known. In this paper we report the discovery of a new łp type runaway star that is notably hotter than previously studied members of this class. Spectral analysis confirms that its atmosphere is neon- and oxygen-dominated, consistent with earlier analyses of other łp type stars. Kinematic analysis indicates that the star has a high probability of being unbound from the Galaxy and was most likely ejected from the Galactic disc approximately 2.8 Myr ago with an ejection velocity exceeding 600 -1 . This result further emphasizes the discrepancy between the abundance yields and kick velocities predicted by white dwarf deflagration models and those observed in stars of łp type, underscoring the need for a reassessment of such systems.

We have calibrated the tip of the red giant branch (TRGB) using our recent catalogue of homogeneous globular cluster (GC) distances. The GC distances were determined via a global joint fit to optical period--Wesenheit relations of their member RR Lyrae stars and type-II Cepheids, anchored by trigonometric parallaxes; all data were taken from the ESA = mission's (early) third data release (GDR3). Using I-band measurements of 48 GCs from P. Stetson's database, we determined M_ I,0 ( = in distance). Calibrating the TRGB using homogeneous, space-based RP photometry of 53 GCs, we found M_ RP,0 ( The stated uncertainties include statistical and systematic effects, including the correlated nature of the GC distances. The robustness of our calibrations was evaluated via tests against small-number statistics and analysis choices. Within the (small) uncertainties, no significant metallicity effect is detected in our sample of old, low-metallicity GCs. We measured ∼ 2% distances to the Large and Small Magellanic Clouds, (48.9± 0.9,kpc) and (60.2± 1.4,kpc), respectively, using a single photometric system: RP (spectro-)photometry from GDR3. Our new TRGB distances, whose absolute scale derives from parallaxes, are fully independent of the well-known detached eclipsing binary (DEB) distances and agree with them to within the uncertainties. Combining our new TRGB and existing DEB distances, we illustrate how additional constraints can be incorporated into the Local Distance Network and obtain H_0=73.52 . Expected improvements thanks to the upcoming fourth -1 ,Mpc^ -1 data release are discussed.

We present results from a multi-epoch Very Long Baseline Array (VLBA) survey of compact radio sources in the Orion complex, conducted within both the DYNAMO–VLBA and GOBELINS projects. We detected 216 compact radio sources, of which 58 yielded reliable multi-epoch astrometric solutions. For these sources, we derived trigonometric parallaxes and proper motions with typical precisions of about 0.05 mas and 0.10 mas yr -1 , respectively. The measured parallaxes range between 2.26 and 2.65 mas, corresponding to distances of 380–440 pc, and delineate the depth of the Orion star-forming complex. We determined mean distances of 405 pc for NGC 2068, 403 pc for NGC 2024, 407 pc for the σ Orionis region, 388.5 for the Orion Nebula Cluster, and 438 DR3 astrometry for 28 common sources revealed negligible mean parallax offsets (Deltǎarpi=-0.02 pc for L1641. A comparison with Gaia and small systematic differences in proper motions (∼0.07, reference frame. Our results demonstrate the capability of high-precision radio astrometry to map embedded stellar populations and to provide an independent calibration of the reference system in obscured regions. likely due to the residual rotation of the Gaia Gaia

Type Ibn supernovae (SNe) are characterized by narrow helium ( ) lines from photons produced by the unshocked circumstellar material (CSM). About 80 SNe Ibn have been discovered to date and only a handful of them have extensive observational records. Thus, many open questions remain regarding the progenitor system and the origin of CSM. He i Here, we investigate potential correlations between the spectral features of the prominent łambda 5876 Å line and the optical and X-ray light curve properties of Type Ibn SNe (SNe Ibn). He i We compiled the largest sample of 61 SNe Ibn to date, of which 24 SNe have photometric and spectroscopic data available from the Young Supernova Experiment and 37 SNe benefit from archival datasets. We fit 24 SNe Ibn with sufficient photometric coverage (B to z bands) using semi-analytical models from . We demonstrate that the light curves of SNe Ibn are more diverse than previous analyses suggest, with absolute r-band peak magnitudes (r_̊m max) of -19.4± 0.6 mag, along with rise (from -10 days to peak, γ_-10) and decay rates (from peak to +10 days; γ_+10) of -0.08 ± 0.06 and 0.08± 0.03 mag/day, respectively. We find that the majority of SNe Ibn in the subsample are consistent with a low-energy explosion (<10^51 erg) of a star with a compact envelope surrounded by ∼0.1 of helium-rich CSM. The inferred ejecta masses are small (M_ ej ∼ 1 lines, associated with the CSM, peaks at ∼ 1100 km/s. and expand with a velocity of ∼5000 km/s. Our spectroscopic analysis shows that the mean velocity of the narrow component of the The mean CSM and ejecta masses inferred for a subsample of SNe Ibn indicate that their progenitors are not massive (sim10 single stars at the moment of explosion; rather, they are likely to be binary systems. This finding is in agreement with detections of potential companion stars of SNe Ibn progenitors and inferred CSM properties from stellar evolution models.