First CMB Temperature Measurement at z = 0.68 via Molecular Absorption
Astronomers used ALMA observations of molecular absorption lines toward quasar B0218+357 at redshift z = 0.68 to measure the temperature of the cosmic microwave background at that cosmic epoch. The team analyzed the J=2-1 and J=3-2 rotational transitions of HCN, HCO+, HNC and their isotopologues H13CN and H13CO+, identifying two distinct absorption components for the main species.
Because the excitation of HCO+ was found to be biased by an additional velocity component and partial collisional excitation, this molecule was excluded from the final determination. From a weighted mean of HCN and HNC excitation temperatures, the team derived a CMB temperature of 4.50 ± 0.17 K — the most precise measurement at z=0.68 from a quasar absorption system to date, fully consistent with the standard Big Bang prediction T(z) = T₀·(1+z).
AT Pyx: An Eccentric Protoplanetary Disk Inside a Cometary Globule
Astronomers have spatially resolved for the first time a protoplanetary disk inside a cometary globule of the Gum Nebula — an unusual environment quite different from the typical low-mass star-forming regions where such disks are usually observed. Combining data from VLT instruments (XSHOOTER, ESPRESSO, SPHERE) with ALMA observations, the team measured a disk position angle of 28.06 ± 0.02° and an inclination of 42.5 ± 0.5°, along with spiral arm features.
The AT Pyx disk was found to be eccentric, with e ≈ 0.626 after deprojection, likely driven by an embedded planet with a mass between 0.004 and 3 Jupiter masses. Velocity measurements of nearby globule cloud material suggest a possible late-stage infall event, and the system itself may be a binary. This marks the first such disk observed and characterized within a radiation-driven cometary globule.
MIRACLE II: Mapping Multiphase Gas in the Nucleus of NGC 1365
Researchers conducted a multiwavelength study of the circumnuclear region of the Seyfert galaxy NGC 1365 (an area of roughly 0.9×0.9 kpc), combining data from JWST/MIRI, VLT/MUSE, and ALMA as part of the MIRACLE program. Mid-infrared observations revealed over 40 emission lines from ionized and warm molecular gas, enabling for the first time a fully self-consistent photoionization and kinematic model spanning the optical to mid-IR range.
Cold and warm molecular gas were found to rotate together with the galaxy's stellar disk, while low-ionization gas also traces this rotation. In contrast, higher-ionization gas (up to ~120 eV) traces a nuclear outflow: [OIII] and [NeV] lines outline an outflow cone toward the southeast, while [NeV] additionally reveals a counter-cone to the northwest that remains hidden in optical data due to obscuration.
ASTRAFier: A Transformer-Based Classifier for Stellar Variability
Researchers introduced ASTRAFier, a new model for classifying variable stars that combines a Transformer architecture with Bidirectional Long Short-Term Memory (BiLSTM) and Convolutional Neural Networks (CNNs). Unlike traditional approaches, the model operates directly on light curve time series without requiring manual feature engineering, making it easier to maintain and scale.
On Kepler test data the model achieved a classification accuracy of 94.26%, and 88.22% on TESS data. The authors demonstrated scalability by deploying the model on roughly 2.8 million TESS light curves from sectors 14, 15, and 26 (the Kepler field of view), processed by MIT's Quick-look Pipeline. The resulting classifications were released as a public stellar variability catalog.
GW190711 and GW200114: Two Asymmetric Binary Black Hole Mergers
Researchers from the IAS collaboration performed a detailed analysis of two binary black hole merger candidates — GW190711_030756 and GW200114_020818 — with astrophysical origin probabilities of 0.99 and 0.71, respectively, and signal-to-noise ratios of about 10.0 and 13.4. Both systems turned out to be highly asymmetric in mass, with mass ratios of 0.35 for the first event and no greater than 0.20 for the second.
GW200114_020818 stands out for its source-frame total mass of about 220 M☉ and rapidly spinning components with spin magnitudes of 0.96 and 0.84. Its effective inspiral spin is negative (χeff = -0.60), while a precession parameter of χp = 0.60 indicates strong spin precession. Together with the similar event GW231123, this system points to an emerging population of massive black holes that is difficult to explain through hierarchical mergers in globular clusters; instead, the probability that its remnant black hole was retained in an elliptical galaxy is 99.7%.
