Search Publications
The star-forming environment of an ultraluminous X-ray source in NGC4559: an optical study
Cropper, Mark; Soria, Roberto; Wu, Kinwah +2 more
We have studied the candidate optical counterparts and the stellar population in the star-forming complex around the bright ultraluminous X-ray source (ULX) in the western part of the spiral galaxy NGC4559, using the HST Wide Field Planetary Camera 2 (WFPC2), XMM-Newton/Optical Monitor and ground-based data. We find that the ULX is located near a …
Hubble Space Telescope imaging of the progenitor sites of six nearby core-collapse supernovae
Smartt, S. J.; Maund, J. R.
The search for the progenitors of six core-collapse supernovae (CCSNe) in archival Hubble Space Telescope (HST) WFPC2 pre-explosion imaging is presented. These SNe are 1999an, 1999br, 1999ev, 2000ds, 2000ew and 2001B. Post-explosion imaging of the SNe, with the HST ACS/WFC, has been utilized with the technique of differential astrometry to identif…
Regularized orbit models unveiling the stellar structure and dark matter halo of the Coma elliptical NGC 4807
Saglia, R. P.; Thomas, D.; Thomas, J. +5 more
This is the second in a series of papers dedicated to unveiling the mass structure and orbital content of a sample of flattened early-type galaxies in the Coma cluster. The ability of our orbit libraries to reconstruct internal stellar motions and the mass composition of a typical elliptical in the sample is investigated by means of Monte Carlo si…
A photoionization-modelling study of 30 Doradus: the case for small-scale chemical inhomogeneity
Tsamis, Yiannis G.; Péquignot, Daniel
Photoionization models of the giant HII region (GHIIR) 30 Doradus are built and confronted to available ultraviolet (UV), optical, infrared (IR) [Infrared Space Observatory (ISO)] and radio spectra, under blackbody or CoStar spectral energy distributions for the primary source and various density distributions for the nebular gas. Chemically homog…
Constraints on the ionizing flux emitted by T Tauri stars
Clarke, C. J.; Pringle, J. E.; Alexander, R. D.
We present the results of an analysis of ultraviolet observations of T Tauri stars (TTs). By analysing emission measures taken from the literature, we derive rates of ionizing photons from the chromospheres of five classical TTs in the range ~1041-1044 photon s-1, although these values are subject to large uncertai…
A Chandra X-ray survey of nearby dwarf starburst galaxies - II. Starburst properties and outflows
Ott, Jürgen; Walter, Fabian; Brinks, Elias
We present a comprehensive comparison of the X-ray properties of a sample of eight dwarf starburst galaxies observed with Chandra (IZw18, VIIZw403, NGC1569, NGC3077, NGC4214, NGC4449, NGC5253 and He2-10). In PaperI, we presented in detail the data reduction and analysis of the individual galaxies. For the unresolved X-ray sources, we find the foll…
X-ray reflection in the Seyfert galaxy 1H 0419-577 revealing strong relativistic effects in the vicinity of a Kerr black hole
Iwasawa, K.; Fabian, A. C.; Miniutti, G. +1 more
We report results obtained from six XMM-Newton observations of the Seyfert galaxy 1H 0419-577. The source was observed in a wide range of different flux levels, allowing its long-term spectral variability to be studied in detail, as already reported recently by Pounds et al. Here we show that the X-ray spectrum is well described by a simple two-co…
Hubble Space Telescope spectroscopy of the Balmer lines in Sirius B*
Bond, Howard E.; Barstow, M. A.; Koester, D. +3 more
Sirius B is the nearest and brightest of all white dwarfs, but it is very difficult to observe at visible wavelengths due to the overwhelming scattered light contribution from Sirius A. However, from space we can take advantage of the superb spatial resolution of the Hubble Space Telescope (HST) to resolve the A and B components. Since the closest…
A jet-induced outflow of warm gas in 3C293
Morganti, R.; Tadhunter, C. N.; Holt, J. +3 more
Using long-slit emission-line spectra we detect a fast outflow of ionized gas, with velocities up to 1000 km s-1, in the nearby powerful radio galaxy 3C293 (z= 0.045). The fast outflow is located about 1 kpc east of the nucleus, in a region of enhanced radio emission due to the presence of a distorted radio jet. We present results that …
An old quasar in a young dark energy-dominated universe?
Friaça, A. C. S.; Alcaniz, J. S.; Lima, J. A. S.
Dark energy is the invisible fuel that seems to drive the current acceleration of the Universe. Its presence, which is inferred from an impressive convergence of high-quality observational results along with some apparently successful theoretical predictions, is also supported by the current estimates of the age of the Universe from dating of loca…