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- Published on 11 February 2025
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.
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- Published on 03 February 2025
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.
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- Published on 21 January 2025
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.