Measuring galaxy sizes is essential for understanding how they were formed and evolved across time. However, traditional methods based on l ight concentration or isophotal densities often lack a clear physical meaning. A recent study from Trujillo+20 explores a more physically motivated definition: the radius R 1, where the stellar surface density falls to 1 solar masses per parsec square —roughly the threshold for gas to form stars in galaxies like the Milky Way. In this work, Arjona-Gálvez+25 uses over 1,000 galaxies from several state-of-the-art cosmological simulations (AURIGA, HESTIA

WISEA J181006.18-101000.5 (WISE1810) is the nearest metal-poor ultracool dwarf to the Sun. It has a low effective temperature and has been classified as an extreme early-T subdwarf. However, methane--the characteristic molecule of the spectral class T--was not detected in the previous low-resolution spectrum. Constraining the metallicity--the abundance of elements heavier than helium-- of these cold objects has been a challenge. Using the 10.4 m Gran Telescopio Canarias, the largest optical-infrared telescope in the world, we collected a high-quality near-infrared intermediate-resolution

The solar corona—the outermost layer of the Sun’s atmosphere—is extremely hot and very low in density. One of the main challenges in solar physics is understanding why the corona reaches temperatures of over a million degrees. This heating is believed to be closely related to the Sun’s magnetic field. However, quantifying the coronal magnetic field is difficult because the light emitted by the corona is extremely faint, and its polarization signals, which encode the information on the magnetic field, are subtle. Thanks to recent advances in technology, telescopes like the Daniel K. Inouye