ABSTRACT IC 10 X‐1, located in the starburst galaxy IC 10, is a nearby extragalactic X‐ray binary containing a Wolf—Rayet donor and an accreting black hole compact object. Active accretion from the massive Wolf–Rayet star onto the companion black hole is considered a possible source of high‐energy emission produced by the interaction between the black hole and the accretion disk formed by the optical counterpart. The results of the first very‐high‐energy observations of the IC 10 X‐1 system and the IC 10 starburst galaxy with the SHALON telescope are presented. The fluxes of gamma‐ray emission detected from the direction of IC 10 X‐1 binary and the IC 10 starburst galaxy may indicate both active accretion in the massive X‐ray binary and efficient cosmic ray acceleration in the processes of supernova explosions in the starburst galaxy.
ABSTRACT Since cataclysmic variable (CV) catalogues are compiled via magnitude‐limited surveys, we investigate whether the bias due to brightness and distance‐dependence of detectability can explain the well‐known ∼2–3 h orbital period gap. We apply the selection criteria to 1214 CVs obtained from Gaia DR3 with orbital periods from the literature, reducing the final sample to 563 CVs with reliable astrometry and extinction‐corrected magnitudes at . Using the gap range of 2.45–3.18 h determined independently by SDSS I–IV, we examine two possible biases due to observations: weighting of the uncorrected histogram and comparing extinction‐corrected absolute magnitude, , inside and outside the gap. The reweighted histogram demonstrates an even larger deficit in comparison with the unweighted histogram and is detected in of bootstrap samples ( CIs). The 32 gap systems have a brighter median than outside‐gap systems ( vs. ), disproving the hypothesis of a faint gap population. While these results favour an astrophysical origin over magnitude‐ and distance‐dependent incompleteness as the main cause of the period deficit, they neither confirm it nor rule out other selection effects.
ABSTRACT We collect, analyze, and discuss in this work the known candidates of stellar black holes in the galaxy. Masses are re‐derived using adequate probability functions, to obtain individual mass distributions, later combined to study the population mass distribution of the 42 object sample. A pictorial representation for each of these systems is given to visualize the black holes and their companions. A hint of a similar mass distribution than the one obtained for the extragalactic gravitational waves merging events is suggested by our results.
ABSTRACT The Thirteen Towers of Chankillo (fourth century bce , Peru) form a solar observatory whose 47° visual span matches the Sun's annual declination range, achieved through deliberate architectural design along a curving ridge. This article addresses how the builders arrived at this design without knowledge of Earth's axial tilt. We develop three nonexclusive pathways: empirical (measuring the solar arc over generations), cosmological (the Andean concept of pacha as motivation for materialising celestial order) and geometric (compensating the ∼43.4° flat‐horizon arc via ridge height and observer distance to stretch the visual angle to 47°). This correspondence reflects a deliberate conceptual shift: from measuring the Sun's motion projected on the local horizon (azimuth, 43.4°) to measuring its true celestial motion (declination, 47°). The fixed observer distance (∼235 m) and the 13 calibrated gaps (∼0.5° resolution) transformed the ridge into a topological horizon—a precision instrument for reading the rhythms of the sky. None of these pathways is definitively established, but together they illuminate the depth of Chankillo's enigma.
ABSTRACT We present a preliminary multiwavelength spectral energy distribution (SED) analysis of the Galactic supersoft X‐ray source QR Andromedae (QR And). The longer‐wavelength portion, spanning from the ultraviolet to the infrared, was built from compiled archival and catalogue measurements, while the soft X‐ray component was represented using the XMM‐Newton /EPIC‐pn spectrum. Based on earlier work on this source, we compare the resulting SED with an irradiated accretion disk plus irradiated companion scenario, revisited here with updated source information, including a Gaia‐based distance and a revised system geometry. We explored plausible parameter combinations to examine how well this framework can reproduce the measurements. We find that the broad SED can be described with an inclination more consistent with the eclipsing nature of QR And and without requiring extreme parameter values. The results indicate that irradiation and reprocessing remain important in shaping the multiwavelength emission of QR And, although residual discrepancies at the longest wavelengths suggest that an additional contributor may still be required.
