We analyse a wealth of optical spectroscopic and photometric observations of the bright (V = 11.9) cataclysmic variable BG Tri. The Gaia DR2 parallax gives a distance d = 334(8) pc to the source, making the object one of the intrinsically brightest nova-like variables seen under a low orbital inclination angle. Time-resolved spectroscopic

We explore unsupervised machine learning for galaxy morphology analyses using a combination of feature extraction with a vector-quantized variational autoencoder (VQ-VAE) and hierarchical clustering (HC). We propose a new methodology that includes: (1) consideration of the clustering performance simultaneously when learning features from images; (2

Context. More than 10% of barred galaxies with a direct measurement of the bar pattern speed host an ultrafast bar. These bars extend well beyond the corotation radius and challenge our understanding of the orbital structure of barred galaxies. Most of the bars are found in spiral galaxies, rather than in lenticular galaxies. Aims: We analyse the

Planetesimals—the initial stage of the planetary formation process—are considered to be initially very porous aggregates of dusts 1,2, and subsequent thermal and compaction processes reduce their porosity 3. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30-50% (refs. 4-6), higher

The cool white dwarf WD 1856+534 was found to be transited by a Jupiter-sized object with a mass at or below 14 M Jup. We used the GTC telescope to obtain and analyse the photometry and low-resolution spectroscopy of six transits of WD 1856+534 b, with the intention of deriving the slope of the transmission spectrum. Such a slope, assuming a cloud

We report the discovery of the third tidally tilted pulsator, TIC 63328020. Observations with the TESS satellite reveal binary eclipses with an orbital period of 1.1057 d, and δ Scuti-type pulsations with a mode frequency of 21.09533 d -1. This pulsation exhibits a septuplet of orbital sidelobes as well as a harmonic quintuplet. Using the oblique