Vol. 698
9. The Sun and the Heliosphere

Interstellar dust measured in situ by Ulysses: New aspects of the particle size distribution and its modulation by the heliosheath

Pre-solar grains are found in meteorites, even in situ asteroid samples, and are records of the interstellar medium at the origin of the Solar System. This study presents an analysis of a few remarkable secure recoveries of the contemporary interstellar dust in the solar neighborhood, including a few massive particles that can be separated from heliospheric residents. The ULYSSES probe, tasked with surveying the pole of the Sun, exited the ecliptic and attained altitudes of more than 2 au for a decade. The result presented here is for the gold standard detections, distinguished by their distributions in space and momentum. The authors provide a comprehensive survey of the possible effects of propagation through the heliosphere that serves as a tutorial for understanding the basis of the analysis. The derived gas-to-dust mass ratio for the very local interstellar medium is around 500, but constrained to between about 60 and 1000. They conclude with a discussion of how future missions that include directionally sensitive dust detectors will improve and extend this work.

Vol. 697
8. Stellar atmospheres

New empirical mass-loss recipe for UV radiation line-driven winds of hot stars across various metallicities

Stellar winds from massive stars play a critical role in shaping their evolution and feedback, as they remove a substantial fraction of a star’s mass over its lifetime. In this study the authors present a homogeneous sample of nearly 200 hot stars (T > 12kK) across a broad metallicity range, each with well-constrained stellar and wind parameters. This sample is used to derive a physically motivated, empirically calibrated mass-loss prescription that is applicable to all hot stars. The newly derived mass-loss recipe depends only on the classical Eddington parameter and metallicity. Contrary to theoretical predictions, no clear evidence of a steep upturn in mass loss near the Eddington limit, nor a noticeable temperature dependence, can be found. The reported mass-loss relation yields mass-loss rates substantially lower than those from commonly used theoretical recipes. A first implementation of this new prescription in stellar evolution models highlights the importance of using accurate mass-loss rates by showing their impact on stellar evolution, feedback processes, and the final fates of massive stars.

Vol. 696
7. Stellar structure and evolution

The infrared counterpart and proper motion of magnetar SGR 0501+4516

Magnetars are highly magnetic neutron stars (with magnetic fields stronger than ~10^14 G). They are discovered thanks to their bursting activity and outbursts. SGR 0501+4516 was discovered by Swift in 2008 as a new source in the hard X-ray sky. At variance with most magnetars, a near-infrared counterpart was detected.

Thanks to Hubble Space Telescope observations across 10 years, SGR 0501+4516 was observed to move in the sky with a low transverse velocity (~50 km s-1). This makes it one of the slowest magnetars, and it contradicts some claims about a connection between a strong magnetic field and a high velocity. In addition, the low velocity rules out a possible association with a nearby supernova remnant from which the neutron star might have originated. This indicates that magnetars might originate from different paths than normal supernovae.

Vol. 694
7. Stellar structure and evolution

A multi-wavelength view of the isolated neutron star eRASSU J065715.3+260428

The Galactic sample of known isolated neutron stars is extremely small, so any new member of the class is important for understanding their evolution. However, most have similar high-energy properties, whether it is their gamma-ray luminosities or thermal X-rays. This study presents a multiwavelength campaign on one such source discovered in the eROSITA survey that breaks the mold. The source, J0657, is an X-ray pulsar with a roughly 0.25 sec period, but it is significantly not detected in every other energy interval from radio to gamma rays. The authors derived a spindown rate and they draw a comparison with other rotation-powered radio pulsars, highlighting the unusual properties of the source. The X-ray emission is best fit by a two-temperature thermal spectral energy distribution, but with an absorption feature that the authors investigated as a possible proton or electron cyclotron line.

Vol. 694
9. The Sun and the Heliosphere

Flaring together: A preferred angular separation between sympathetic flares on the Sun

Sympathetic solar flares are eruptions that occur nearby in space and time, driven by an apparent interaction between the active regions in which they are triggered. Their statistical existence on the Sun has yet to be firmly established. The work provides strong statistical evidence for the existence of sympathetic flares on the Sun, and we propose an interpretation of the observed angular scale of the phenomenon, based on the separation between magnetic field line footpoints derived from potential field source surface extrapolations.

Vol. 692
10. Planets, planetary systems, and small bodies

CRIRES^+ transmission spectroscopy of WASP-127b. Detection of the resolved signatures of a supersonic equatorial jet and cool poles in a hot planet

One of the most powerful methods for exploiting the high-resolution spectroscopy transit of exoplanets is the cross-correlation technique. With this method, model spectra of different atmospheric components, usually based on physically based abundance models (e.g., chemical equilibrium), are employed as templates and cross-correlated with in-transit ratioed spectra as a function of velocity. The method has not only permitted the detection of tens of atomic and molecular species in the atmosphere of hot and ultra-hot Jupiters, it has also yielded a wealth of information on atmospheric dynamics (day-to-night winds, super-rotation, vertical winds, etc.) and spatial variability (e.g., morning-to-evening asymmetries associated with condensation or cloud effects) based on the precise velocity and strength of the correlation peak. Nortmann et al. present a study of WASP-127b, a hot Jupiter orbiting a solar-type star on a 4.2-day orbit, conducted with CRIRES+/VLT in the near-IR. A strong detection of H2O and CO is achieved, with the cross-correlation signal exhibiting a remarkable two-peaked structure. This is interpreted as the combination of a supersonic equatorial jet with ~8 km/s speeds -- with the two peaks representing the signals from the planet’s morning and evening terminators, respectively -- and muted signals at the planetary poles -- due to either significantly lower temperatures or a high cloud deck -- and explains the lack of a correlation peak at the planet's orbital velocity. This study therefore features a detection of latitudinal inhomogeneity in WASP-127b, opening the field to a 3D characterization of exoplanets, as routinely achieved for Solar System planetary atmospheres.