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We report the discovery and characterization of the multiplanetary system around TOI-4311, a K dwarf kinematically between the Galactic thick disc and Hercules stream. TOI-4311 hosts an ultra-short-period super-Earth (P$sim$0.99 d, $1.376^{+0.077}_{-0.080}$ R$_{oplus }$) and a longer period sub-Neptune (P$sim$15 d, $2.47^{+0.12}_{-0.11}$ R$_{oplus }$) that was first detected in the Transiting Exoplanet Survey Satellite photometry.…

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The atmospheres of hot rocky exoplanets are among the first primary targets of the James Webb Space Telescope (JWST). Interpreting their atmospheric spectra requires understanding the link between silicate lava compositions and overlying atmospheres. We investigate the sensitivity of simulated emission spectra of dry lava planets to variations in oxide abundances in silicate melt. Our…

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We present the first high-resolution spectroscopy of the black hole high-mass X-ray binary Cygnus X-1 with XRISM, including orbital-phase-resolved analyses and tentative evidence of short-term variability in the Fe K band on second timescales. Using data from the Performance Verification phase in 2024 April, we analyzed spectral variability across orbital phases with the Resolve microcalorimeter…

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We report evidence of the resonant scattering effect at the center of the galaxy cluster PKS 0745-191 with XRISM. We analyzed XRISM/Resolve commissioning-phase observations of the distant cluster PKS 0745-191 ($z = 0.103$) with a $54$ ks exposure. The gain drift was corrected using the onboard modulated X-ray source (MXS), and spectra were extracted from…

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The charge-exchange (CX) reaction between highly charged ions from coronal mass ejections and neutrals in Earth’s magnetosphere provides key diagnostics for understanding the dynamics of the Sun─Earth space environment. However, the accuracy of current astrophysical laboratory modeling is affected by the limited availability of reliable state-selective CX cross sections. Here, using a high-resolution cold-target recoil-ion…

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The Seyfert 1 galaxy NGC 3783 hosts a multi-phase warm absorber (WA) that has been extensively studied in the X-ray band. High-resolution spectra from 2000−2001 revealed a complex outflow with multiple ionization and velocity components. Two decades later, new XMM-Newton and XRISM observations allow us to investigate the long-term evolution of these outflows. We performed…

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