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Gamma Cas (B0.5IVe) is the noted prototype of a subgroup of classical Be stars exhibiting hard thermal X-ray emission. This paper reports results from a 23-year optical campaign with an Automated Photometric Telescope (APT) on this star. A series of unstable long cycles of length 56--91 days has nearly ceased over the last decade. Herein, we revise the frequency of the dominant coherent signal at 0.82238 cy/d. This signal's amplitude has nearly disappeared in the last 15 years but has somewhat recovered its former strength. We confirm the presence of secondary nonradial pulsation signals found by other authors at frequencies 1.25, 2.48, and 5.03 cy/d. The APT data from intensively monitored nights reveal rapidly variable amplitudes among these frequencies. We show that peculiarities in the 0.82 cy/d waveform exist that can vary even over several days. Although the 0.82 cy/d frequency is near the star's presumed rotation frequency. However, because of its phase slippage with respect to a dip pattern in the star's far-UV light curve it is preferable to consider the latter pattern, not the 0.82 cy/d signal, that carries a rotation signature. We also find hints of the UV dip pattern in
We outline a definition of accessible and presentable objects in a 2-category $\mathcal K$ endowed with a "KZ context", that is to say a pair of lax-idempotent monads interacting in a prescribed way; this perspective suggests a unified treatment of many "Gabriel-Ulmer like" theorems, asserting how presentable objects arise as reflections of generating ones. We outline the notion of "(Gabriel-Ulmer) envelope" for a KZ context, sufficient to concoct Gabriel-Ulmer duality. We end the paper with a roundup of examples, involving classical (set-based and enriched), low dimensional category theory, and a perspective for future work, rooted in higher category theory and homotopy theory.
A surprisingly simple fuel modification could help tackle one of diesel engines’ biggest problems: pollution。 Researchers reviewing studies from around the world found that mixing small amounts of water into diesel fuel can dramatically reduce harmful emissions, including nitrogen oxides and soot, while maintaining or even improving engine efficien
Two newly confirmed "super-puff" planets are so diffuse that they are less dense than cotton candy, despite being about the size of Jupiter。 Their rare orbital relationship and enormous, lightweight atmospheres could provide valuable clues about how some of the strangest planets in the galaxy come to exist
A rare meteorite has revealed evidence of a massive lost world that once orbited the young Sun before being destroyed in a catastrophic collision。 The discovery suggests some early planets formed from dramatically different materials than Earth and Mars, rewriting part of the solar system’s origin story
Scientists have uncovered a surprising connection between quantum gravity and an exotic quantum state of matter that could explain why the universe isn’t expanding wildly fast。 The study suggests that the very shape of space-time may protect the cosmological constant from disruptive quantum effects
Hubble has captured a spectacular view of LH 95, where about 2,500 young stars are still on their journey to becoming full-fledged stars。 Scientists discovered these growing stars can keep pulling in gas and dust for millions of years, extending an important stage of stellar development。 The region also contains multiple generations of stars living
A new AI-powered framework could transform how astronomers measure the expansion of the Universe。 By analyzing images of Type Ia supernovae and modeling their environments in unprecedented detail, researchers can estimate cosmic distances with near-spectroscopic accuracy。 The technique is designed for the flood of data expected from the upcoming Ve
NASA's Hubble Space Telescope has captured a spectacular red, white, and blue view of one of the Milky Way's oldest star clusters to celebrate the nation's 250th anniversary。 Hidden within the ancient cluster are clues to how exploding stars helped transform the young universe into one capable of forming planets and, eventually, life
NASA is marking the United States' 250th birthday with four striking red, white, and blue images of deep space from the Chandra X-ray Observatory。 The collection features an exploded star, a stellar nursery, a galaxy where stars are rapidly forming, and a galaxy cluster that provides evidence for dark matter
A major breakthrough in quantum technology has turned magnons, tiny magnetic waves once considered too short-lived for practical use, into promising carriers of quantum information。 Researchers extended their lifetime by nearly 100 times, reaching up to 18 microseconds, and discovered that the main limitation is not a law of physics but the purity