Wandering black holes, a class of black holes that are not anchored to the centres of galaxies, are a fascinating yet elusive aspect of our universe. These black holes are not formed by the typical processes that create stellar black holes, which occur when massive stars run out of fuel and collapse under their own […]
The term FGK star designates a star the spectrum of which makes it either an F-type star (yellow-white, a bit hotter than then Sun ), a G-type star (yellow, similar to the Sun), or a K-type star (orange, a bit cooler than the Sun). FGK stars come in a variety of sizes but segregating them […]
The evolution of the cosmic star formation rate density paints a dynamic picture of galaxy evolution, with rapid stellar build-up at redshifts above 2, followed by a stark drop in SFRs of galaxies towards the present day. The origins of this down-turn are likely due to a mixture of feedback processes, broadly categorized as caused […]
Stellar population synthesis (SPS) is the prevailing framework for predicting the spectral energy distribution of a galaxy (SED) from its fundamental physical properties. SPS is a mature subfield with a long history dating back to the seventies of the last century. Applications of SPS range from inferring the physical properties of individual galaxies, to forward […]
nuclear star cluster This image from the NASA/ESA/CSA James Webb Space Telescope shows the heart of M74 (or NGC 628), otherwise known as the Phantom Galaxy. Webb’s sharp vision has revealed delicate filaments of gas and dust in the grandiose spiral arms which wind outwards from the centre of this image. A lack of gas […]
wavelike All the matter that has ever been detected accounts for a mere 4.9% of the Universe. Most of the cosmos is the dark universe: a mix of dark matter (26.8%) and dark energy (68.3%), both of which have so far proved impenetrable puzzles. The existence of dark matter has been inferred from the motion […]
Population III stars are a hypothetical population of extremely massive, luminous and hot stars with virtually no metals, except possibly for intermixing ejecta from other nearby population III supernovae. Such stars are likely to have existed in the very early universe (i.e., at high redshift) and may have started the production of chemical elements heavier […]
When you collect vast amounts of data, most of them will likely be irrelevant or uninteresting. But, hidden in all that noise, you may find a jewel. The data where one scientific jewel, a supernova, has just been found is the collection of observations by the Hubble Frontier Fields (HFF) project. HFF drew on the […]
A gravitational lens is any object that deflects light by gravitation as described by the general theory of relativity; it is analogous to a lens in optics. The prediction of a gravitational lensing effect was confirmed repeatedly in observations on quasars. In 1979 an apparently double quasar was discovered, due to the multiple image of […]
White dwarfs are the degenerate remnant of stars with masses lower than 10 times that of the Sun and the endpoint of stellar evolution for more than 97% of Galactic stars. White dwarfs are an important tool in studying the star formation history of the Milky Way, the late phases of stellar evolution, and to […]