Related papers: F06296$+$5743 : A Very Massive Starburster ?
The properties of starbursts in ultraluminous infrared galaxies are discussed, with particular emphasis on the fueling, the amount of extinction and the intrinsic properties of the nuclear starbursts. It is shown by the example of NGC6240…
Understanding the rapid formation of supermassive black holes (SMBHs) in the early universe requires insight into stellar mass growth in host galaxies. Here, we present NIRSpec rest-frame optical spectra and NIRCam imaging from JWST of two…
An increasing number of non-terminal giant eruptions are being observed by modern supernova and transient surveys. But very little is known about the origin of these giant eruptions and their progenitors, many of which are presumably very…
JWST has revealed a population of super-luminous early galaxies with a volume density in excess of most expectations. The spectra reveal diverse properties: while some reveal strong emission lines characteristic of galaxies in the midst of…
The behaviour of the 4000 Angstrom break index and of the equivalent width of the main Balmer lines is investigated a) for a single star as a function of effective temperature, gravity and metallicity and b) for a single stellar population…
We present our recent spectrophotometric results of the infrared luminous Seyfert 2 galaxy NGC 7679. We find compelling evidence of the presence of a recent nuclear starburst, revealed by the observations of a) the spectral features of high…
We report evidence for a recent burst of star formation located within 9 pc of the active nucleus of NGC 1097. The observational signatures of the starburst include UV absorption lines and continuum emission from young stars observed in a…
We suggest that the mass lost during the evolution of very massive stars may be dominated by optically thick, continuum-driven outbursts or explosions, instead of by steady line-driven winds. In order for a massive star to become a WR star,…
Recent XMM-Newton observations of the high-redshift, lensed, broad absorption line (BAL) quasi-stellar object APM 08279+5255, one of the most luminous objects in the universe, allowed the detection of a high column density absorber ($N_H…
We have used Hubble Space Telescope to obtain moderate resolution 1150-5700 Ang. spectroscopy of the nucleus of M33 and a blue star ~1 arcsec NNW of the nucleus in an attempt to find the optical counterpart of the nuclear X-ray source and…
All measurements of cosmic star formation must assume an initial distribution of stellar masses -- the stellar initial mass function -- in order to extrapolate from the star-formation rate measured for typically rare, massive stars (> 8…
This contribution presents the optical spectral properties of FIR-luminous galaxies, whose distinctive feature is often the simultaneous presence in the spectra of a strong $\rm H\delta$ line in absorption and of emission lines (e(a)…
We presents the main physical properties of very young stellar populations seen with FUSE in 24 individual starbursts. These characteristics have been obtained using the evolutionary spectral synthesis technique in the far-ultraviolet range…
To understand the nuclear stellar populations and star formation histories of the nuclei of spiral galaxies, we have obtained K-band nuclear spectra for 41 galaxies and H-band spectra for 20 galaxies in the ISO Atlas of Bright Spiral…
The James Webb Space Telescope (JWST) has uncovered low-luminosity active galactic nuclei (AGNs) at high redshifts of $z\gtrsim 4-7$, powered by accreting black holes (BHs) with masses of $\sim 10^{6-8}~M_\odot$. One remarkable distinction…
We study the central (inner few hundred parsecs) stellar populations of four starburst galaxies (NGC34, NGC1614, NGC3310 and NGC7714) in the near-infrared (NIR), from 0.8 to 2.4microns, by fitting combinations of stellar population models…
The discovery of galaxies with extremely strong nebular continuum emission at high redshifts provide novel, unique insights into the conditions under which the first super-massive stars formed. Here we identify a galaxy at redshift…
The optical regime is historically the best-studied wavelenght range. Gas ionized by massive stars produces optical emission lines that have been used to derive indicators of star-formation rate, metallicity, dust reddening, and the…
The identification of red, apparently massive galaxies at $z>7$ in early JWST photometry suggests a strongly accelerated timeline compared to standard models of galaxy growth. A major uncertainty in the interpretation is whether the red…
The origin of the rest-optical emission of compact, red, high-redshift sources known as `little red dots' (LRDs) poses a major puzzle. If interpreted as starlight, it would imply that LRDs would constitute the densest stellar systems in the…