Related papers: The Current Understanding on the UV Upturn
The rest-frame UV emission from massive stars contains a wealth of information about the physical nature and conditions of star formation in galaxies. Using studies of the rest-frame UV, the past decade has witnessed the beginning of…
The origin of the bulk of the high-energy astrophysical neutrinos seen by IceCube, with TeV--PeV energies, is unknown. If they are made in photohadronic, i.e., proton-photon, interactions in astrophysical sources, this may manifest as a…
The effects of dust opacity on the radiation of nearby and distant galaxies are reviewed. The geometrical distribution of the dust inside the galaxy plays a fundamental role in determining the wavelength dependence of the obscuration and…
We have performed a census of the UV-bright population in 78 globular clusters using wide-field UV telescopes. This population includes a variety of phases of post-horizontal branch (HB) evolution, including hot post-asymptotic giant branch…
In this PhD Thesis we study the occurrence of powerful stellar outbursts in the late phases of evolution of stars like the Sun. This is one of the most controversial topics in the field, as the extraordinary variety of shapes revealed by…
Understanding the physical formation of the Hubble sequence remains one of the most important unsolved astrophysical problems. Searches for proto-disks and proto-ellipticals can now be effectively done using deep wide-field Hubble Space…
This conference demonstrated the tremendous progress that has been made in the last decade in our observational and theoretical understanding of compact, young, massive star clusters. One of the Hubble Space Telescope's main achievements…
Ultraviolet imaging with the Galaxy Evolution Explorer (GALEX) has revealed an extensive sample of UV-bright stellar complexes in the extreme outer disk of M83, extending to about four times the radius where the majority of HII regions are…
The uncertainties which still plague our understanding of the evolution of the light nuclides D, 3He and 4He in the Galaxy are described. Measurements of the local abundance of deuterium range over a factor of 3. The observed dispersion can…
Ultra-high-energy cosmic rays (UHECRs) are known to come from outside of our Galaxy, but their origin still remains unknown. The Telescope Array (TA) experiment recently identified a high concentration in the arrival directions of UHECRs…
Ultraluminous X-ray sources (ULXs) are amongst the most intriguing of X-ray source classes. Their extreme luminosities - greater than 10^39 erg/s in the 0.3 - 10 keV band alone - suggest either the presence of black holes larger than those…
A solar eruption after a flare on 7 Jun 2011 produced EUV-bright impacts of fallbacks far from the eruption site, observed with the Solar Dynamics Observatory. These impacts can be taken as a template for the impact of stellar accretion…
The evolution of the universe from an initial dramatic event, the Big-Bang, is firmly established. Hubble's law [1] (HL) connects the velocity of galactic objects and their relative distance: v(r)=Hr, where H is the Hubble constant. In this…
Fundamental properties of the extinction curve, like the slope in the rest-frame ultraviolet (UV) and the presence/absence of a broad absorption excess centred at 2175 A (the UV bump), are investigated for a sample of 108 massive,…
In recent years surveys have identified several dozen B stars in the Milky Way halo moving faster than the local escape speed. The origin of most of these hypervelocity stars (HVSs) is still poorly constrained. Here we show that the…
We briefly review the recent results on hot horizontal-branch stars in globular clusters. Since the first Ivanfest, in 1992, there have been a number of new observational lines of evidence which have allowed significant progress in our…
We discuss the dust attenuation and the star formation rates in the nearby universe obtained from a comparison of far-infrared (IRAS) and ultraviolet (GALEX) observations. The ratio of the dust to UV flux ratio is used to derive the dust…
The James Webb Space Telescope (JWST) is unveiling astounding results about the first few hundred million years of life of the Universe, delivering images of galaxies at very high redshifts. Here, we develop a UV luminosity function model…
The evolution of massive stars even on the main sequence is not yet well understood. Due to the steep mass-luminosity relation, massive main sequence stars become very luminous. This brings their envelopes very close to the Eddington limit.…
Nearby (D < 100 Mpc) luminous blue starburst galaxies frequently show morphological evidence for recent involvement in mild collisions, or minor mergers where the disk survives. As a consequence UV-bright starbursts are preferentially seen…