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Multiplicity of Galactic Cepheids from long-baseline interferometry: V. High-accuracy orbital parallax and mass of SU Cygni
DOI: 10.1051/0004-6361/202452346 Bibcode: 2025A&A...693A.111G

Kervella, P.; Mérand, A.; Schaefer, G. H. +23 more

Aims. We aim to accurately measure the dynamical mass and distance of Cepheids by combining radial velocity measurements with interferometric observations. Cepheid mass measurements are particularly necessary for solving the Cepheid mass discrepancy, while independent distance determinations provide a crucial test of the period–luminosity relation…

2025 Astronomy and Astrophysics
Gaia IUE 2
Rising Near-ultraviolet Spectra in Stellar Megaflares
DOI: 10.3847/1538-4357/ad9395 Bibcode: 2025ApJ...978...81K

Notsu, Yuta; Kowalski, Adam F.; Maehara, Hiroyuki +5 more

Flares from M dwarf stars can attain energies up to 104 times larger than solar flares but are generally thought to result from similar processes of magnetic energy release and particle acceleration. Larger heating rates in the low atmosphere are needed to reproduce the shape and strength of the observed continua in stellar flares, whic…

2025 The Astrophysical Journal
IUE 2
Understanding the Broad-line Region of Active Galactic Nuclei with Photoionization. I. The Moderate-accretion Regime
DOI: 10.3847/1538-4357/ada386 Bibcode: 2025ApJ...980..134W

Brandt, W. N.; Shen, Yue; Ho, Luis C. +9 more

Over three decades of reverberation mapping (RM) studies on local broad-line active galactic nuclei (AGNs) have measured reliable black hole (BH) masses for >100 AGNs. These RM measurements reveal a significant correlation between the Balmer broad-line region (BLR) size and AGN optical luminosity (the R–L relation). Recent RM studies for AGN sa…

2025 The Astrophysical Journal
IUE 1