Utilizando modelos semiempíricos de los espectros de fotoabsorción de varios fullerenos individuales (C_80, C_240, C_320 y C_540) predecimos transiciones en la región de la banda difusa más intensa del medio interestelar a 4430 A que podrían explicar su origen, hasta ahora desconocido. Estos modelos también presentan una alta densidad de transiciones en el ultravioleta que reproducen el denominado "bump" a 2175 A en la curva de extinción del medio interestelar (Iglesias-Groth 2004). Parece que los fullerenos podrían ser responsables de dos de los mayores rasgos de la absorción interestelar. Haciendo uso de las secciones eficaces teóricas y de los datos empíricos estimamos que la abundancia de fullerenos es de 0.05 moléculas por millón de átomos de hidrógeno en regiones del medio interestelar con índice de exceso de color E(B-V)~ 1.0.
Advertised on
It may interest you
-
It’s been decades since the need to study other stars to understand the past, present and future of the Sun was realized. One important aspect that has been investigated is the magnetic activity of stars for which we cannot fully grasp the mechanisms involved. Indeed, the origin of stellar magnetic cycles or the dependence of the magnetic activity on the stellar properties are not completely understood. This knowledge improves not only our understanding of the physics involved in stellar evolution but also affects the study of the Sun to better predict high-energy events and the betterAdvertised on -
Dormant black holes in X-ray transients can be identified by the presence of broad Hα emission lines from quiescent accretion discs. Unfortunately, short-period cataclysmic variables can also produce broad Hα lines, especially when viewed at high inclinations, and are thus a major source of contamination. Here we compare the full width at half maximum (FWHM) and equivalent width (EW) of the Hα line in a sample of 20 quiescent black hole transients and 354 cataclysmic variables (305 from SDSS I to IV) with secure orbital periods (Porb) and find that: (1) FWHM and EW values decrease with PorbAdvertised on -
Sub-Neptunes - planets larger than Earth but smaller than Neptune - are the most common type of planet in our Galaxy, yet they are entirely absent from our own Solar System. This absence makes them a major focus for astronomers seeking to understand planetary formation and evolution. We recently conducted an international study, as part of the THIRSTEE project, to characterize two such planets orbiting very similar small, cool stars known as M dwarfs: TOI-521 and TOI-912 . THIRSTEE is an observational-based program that aims to shed light on the sub-Neptune population by providing anAdvertised on