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Galactic short-period close white dwarf binaries (CWDBs) are important objects for space-borne gravitational-wave (GW) detectors in the millihertz frequency bands. Due to the intrinsically low luminosity, only about 25 identified CWDBs are detectable by the Laser Interferometer Space Antenna (LISA), which are also known as verification binaries (VBs). The Gaia Early Data Release 3 (EDR3) provids a catalog containing a large number of CWDB candidates, which also includes parallax and photometry measurements. We crossmatch the Gaia EDR3 and Zwicky Transient Facility public data release 8, and apply period-finding algorithms to obtain a sample of periodic variables. The phase-folded light curves are inspected, and finally we obtain a binary sample containing 429 CWDB candidates. We further classify the samples into eclipsing binaries (including 58 HW Vir-type binaries, 65 EA-type binaries, 56 EB-type binaries, and 41 EW-type binaries) and ellipsoidal variations (209 ELL-type binaries). We discovered four ultrashort period binary candidates with unique light-curve shapes. We estimate the GW amplitude of all of our binary candidates, and calculate the corresponding signal-to-noise ratio (S/N) for TianQin and LISA. We find two (six) potential GW candidates with S/Ns greater than 5 in the nominal mission time of TianQin (LISA), which increases the total number of candidate VBs for TianQin (LISA) to 18 (31).

It has been suggested that giant planet occurrence peaks for stars with M* ≈ 3 M⊙ at a value a factor of 4 higher than observed for solar-mass stars. This population of giant planets predicted to frequently orbit main-sequence B stars at a ≈ 10 au is difficult to characterize during the few hundred million years while fusion persists in their host stars. By the time those stars become massive, young white dwarfs, any giant planets present would still be luminous as a consequence of their recent formation. From an initial sample of 2195 Gaia-identified massive, young white dwarfs, we use homogeneous Spitzer Infrared Array Camera (IRAC) photometry to search for evidence of unresolved giant planets. For 30 systems, these IRAC data provide sensitivity to objects with M ≲ 10 MJup, and we identify one candidate with M ≈ 4 MJup orbiting the white dwarf GALEX J071816.4+373139. Correcting for the possibility that some of the white dwarfs in our sample result from mergers, we find a giant planet occurrence ηGP=0.11−0.07+0.13 for stars with initial masses M* ≳ 3 M⊙. Our occurrence inference is consistent with both the Doppler-inferred occurrence of giant planets orbiting M* ≈ 2 M⊙ giant stars and the theoretically predicted factor of 4 enhancement in the occurrence of giant planets orbiting M* ≈ 3 M⊙ stars relative to solar-mass stars. Future James Webb Space Telescope NIRCam observations of our sample would provide sensitivity to Saturn-mass planets and thereby a definitive estimate of the occurrence of giant planets orbiting stars with M* ≳ 3 M⊙.

We report the discovery of a dwarf planet candidate, 2017 OF201, currently located at a distance of 90 au. Its orbit is extremely wide and extends to the inner Oort cloud, with a semimajor axis of 830 au and a perihelion of 45 au, precisely determined from 24 observations over 20 yr. Assuming a typical albedo of 0.13, we estimate a diameter ∼700 km, making it the second-largest known object in this dynamical population and a dwarf planet candidate with the widest orbit. Its high eccentricity suggests that an unseen population of similar objects would total ∼1% of Earth’s mass. Notably, the longitude of perihelion of 2017 OF201 lies outside the clustering observed in extreme trans-Neptunian objects, posing a challenge to the proposed dynamical evidence for the hypothetical Planet Nine.

A population of anomalous ultramassive white dwarfs discovered with Gaia, often referred to as the Q branch, show high (multi-Gyr) cooling delays produced by exotic physical mechanisms. They are believed to be the products of stellar mergers, but the exact origin and formation channel remain unclear. We obtained a spectroscopically complete, volume-limited sample of the Q branch region within 100 pc and found significant differences in atmospheric composition and rotation rates as a function of tangential velocity. In particular, we discover that stellar remnants with the longest cooling delays do not show strong magnetism nor detectable short-period rotational variability, as opposed to what is generally believed for double-degenerate mergers. This indicates that either these white dwarfs arise from a formation channel with no strong magnetism induced, or that the magnetism produced from the merger dissipates over the cooling delay timescales. Our follow-up photometry has also discovered pulsations in the second and third hydrogen-dominated DAQ white dwarfs, one hotter than 15,500 K, possibly extending the boundaries of the DAV instability strip for white dwarfs with thin hydrogen layers.

The initial–final mass relation (IFMR) links the birth mass of a star to the mass of the compact remnant left at its death. While the relevance of the IFMR across astrophysics is universally acknowledged, not all of its fine details have yet been resolved. A new analysis of a few carbon–oxygen white dwarfs in old open clusters of the Milky Way led us to identify a kink in the IFMR, located over a range of initial masses, 1.65 ≲  M i / M ⊙  ≲ 2.10. The kink’s peak in white dwarf mass of about 0.70−0.75  M ⊙ is produced by stars with M i  ≈ 1.8−1.9  M ⊙ , corresponding to ages of about 1.8−1.7 Gyr. Interestingly, this peak coincides with the initial mass limit between low-mass stars that develop a degenerate helium core after central hydrogen exhaustion, and intermediate-mass stars that avoid electron degeneracy. We interpret the IFMR kink as the signature of carbon star formation in the Milky Way. This finding is critical to constraining the evolution and chemical enrichment of low-mass stars, and their impact on the spectrophotometric properties of galaxies. An analysis of the relation between a star’s initial mass and its final mass (as a white dwarf) reveals a kink in the initial mass range 1.65–2.10  M ⊙ . This kink appears to correspond to the minimum mass required for carbon star formation in the Milky Way at solar metallicity.

Abstract Physicists routinely need probabilistic models for a number of tasks such as parameter inference or the generation of new realizations of a field. Establishing such models for highly non-Gaussian fields is a challenge, especially when the number of samples is limited. In this paper, we introduce scattering spectra models for stationary fields and we show that they provide accurate and robust statistical descriptions of a wide range of fields encountered in physics. These models are based on covariances of scattering coefficients, i.e. wavelet decomposition of a field coupled with a pointwise modulus. After introducing useful dimension reductions taking advantage of the regularity of a field under rotation and scaling, we validate these models on various multiscale physical fields and demonstrate that they reproduce standard statistics, including spatial moments up to fourth order. The scattering spectra provide us with a low-dimensional structured representation that captures key properties encountered in a wide range of physical fields. These generic models can be used for data exploration, classification, parameter inference, symmetry detection, and component separation.

Background Acute kidney injury (AKI) is a frequent and serious complication following surgery for acute type A aortic dissection (ATAAD). Nitric oxide (NO) may reduce AKI incidence through renal-protective mechanisms, but evidence in the ATAAD population remains limited. This trial aims to evaluate whether perioperative administration of NO can reduce the incidence of postoperative AKI in this population. Methods This single-center, randomized, parallel-group superiority trial will enroll 106 adult patients undergoing ATAAD emergency surgery. Participants will be randomly allocated in a 1:1 ratio to either receive 60 parts per million of NO during cardiopulmonary bypass and for 12 h post-surgery, or to receive standard care without NO. The primary outcome is AKI incidence within 48 h postoperatively, defined by Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Secondary outcomes include AKI severity, urine output, vasoactive-inotropic score, neutrophil gelatinase-associated lipocalin levels, sequential organ failure assessment score, ventilator support duration, intensive care unit (ICU) and hospital length of stay, and major adverse kidney events, cumulative mediastinal and pericardial drainage volume. Discussion This trial will evaluate whether perioperative NO administration can reduce early AKI and improve renal and clinical outcomes in high-risk ATAAD patients. Findings may provide evidence for a novel nephroprotective strategy in aortic surgery. Trial registration ClinicalTrials.gov NCT06622291. Registered on June 26, 2024.

Background: Coagulation disorders are potentially one of the most important pathogeneses of acute respiratory distress syndrome (ARDS) following acute type A aortic dissection (ATAAD). This study aimed to determine whether aortic dissection singularly and cardiopulmonary bypass (CPB) surgery can activate coagulation pathways, promoting ARDS development in patients with ATAAD. Methods: A total of 450 patients who received treatment at Beijing Anzhen Hospital, Capital Medical University, between March 2023 and February 2024 were consecutively enrolled in this prospective cohort study. We analyzed the clinical factors and measured serum coagulation biomarkers by enzyme-linked immunosorbent assay (ELISA) among patients with ATAAD, aortic aneurysm (AA), or unstable angina (UA). Logistic regression, two-way analysis of variance (ANOVA), and Spearman's correlation analysis were performed. Furthermore, the patients with ATAAD were divided into ARDS (based on chest radiographic findings and an oxygenation index ≤300 mmHg) and non-ARDS groups for subgroup comparisons. Results: The incidence of postoperative ARDS among patients with ATAAD was 20.7% (13.3% in the AA group and 7.3% in the UA group). Preoperatively, prothrombin time (PT) was longer in patients with ATAAD than in those with AA or UA ((odds ratio (OR): 12.0, 95% confidence interval (CI): 11.5–12.6) vs. (OR: 11.4, 95% CI: 10.9–12.1) vs. (OR: 11.2, 95% CI: 10.8–11.6), respectively; p < 0.001). The D-dimer levels, fibrin degradation products (FDPs), factor XIIa, and factor VIII-Ag (FVIII-Ag) were significantly elevated preoperatively and postoperatively in patients with ATAAD. The FDP levels in the ATAAD subgroup immediately after surgery were significantly higher in the ARDS group compared with those in the non-ARDS group (OR: 2.26, 95% CI: 1.13–4.54; p = 0.022). In addition, a negative correlation existed between the FXII level (correlation coefficient r = –0.682, p = 0.043) at 24 hours after surgery and the oxygenation index. Conclusion: Coagulation activation may be caused by aortic dissection singularly and CPB, which promotes postoperative ARDS in patients with ATAAD.

White dwarfs are stellar remnants devoid of a nuclear energy source, gradually cooling over billions of years 1 , 2 and eventually freezing into a solid state from the inside out 3 , 4 . Recently, it was discovered that a population of freezing white dwarfs maintains a constant luminosity for a duration comparable with the age of the universe 5 , signalling the presence of a powerful, yet unknown, energy source that inhibits the cooling. For certain core compositions, the freezing process is predicted to trigger a solid–liquid distillation mechanism, owing to the solid phase being depleted in heavy impurities 6 – 8 . The crystals thus formed are buoyant and float up, thereby displacing heavier liquid downward and releasing gravitational energy. Here we show that distillation interrupts the cooling for billions of years and explains all the observational properties of the unusual delayed population. With a steady luminosity surpassing that of some main-sequence stars, these white dwarfs defy their conventional portrayal as dead stars. Our results highlight the existence of peculiar merger remnants 9 , 10 and have profound implications for the use of white dwarfs in dating stellar populations 11 , 12 . A population of freezing white dwarf stars maintaining a constant luminosity for a duration comparable with the age of the universe can be explained by a solid–liquid distillation mechanism interrupting cooling for billions of years.

By comparing two age indicators of high-mass white dwarfs (WDs) derived from Gaia data, two discoveries have been made recently: one is the existence of a cooling anomaly that produces the Q branch structure on the Hertzsprung–Russell diagram, and the other is the existence of high-mass WDs as double-WD merger products. The former poses a challenge for WD cooling models, and the latter has implications on binary evolution and type-Ia supernovae.