Search Publications
Is there really a supermassive black hole in M87?
Marconi, A.; Macchetto, F. D.; Capetti, A. +3 more
We present the first HST long-slit spectrum of a gaseous disc around a candidate supermassive black hole. The results of this study on the kinematics of the gaseous disc in M87 are a considerable improvement in both spatial resolution and accuracy over previous observations, and require a projected mass of MBH(sin i)2 = (2.0±…
Analytical dynamical models for double power-law galactic nuclei
Zhao, Hongsheng
Motivated by the finding that the observed surface brightness profiles of many galactic nuclei are fitted well by double power laws, we explore a range of spherical self-consistent dynamical models with this light profile. We find that the corresponding deprojected volume density profile, phase- space density and line-of-sight velocity distributio…
A photometric and spectroscopic study of the symbiotic binary BFCyg
Bode, M. F.; Errico, L.; Vittone, A. +3 more
We present the historical 1890-1996 photographic/B-band light curve of the symbiotic binary BF Cyg for the first time. It displays three types of eruption: (i) a slow, symbiotic nova outburst (1895-1960), probably caused by a thermonuclear event; (ii) short-term flares dependent on the orbital phase, possibly triggered by accretion events, and (ii…
Observations of the Hubble Deep Field with the Infrared Space Observatory - II. Source detection and photometry
Elbaz, D.; Danese, L.; Franceschini, A. +18 more
We present positions and fluxes of point sources found in the Infrared Space Observatory (ISO) images of the Hubble Deep Field (HDF) at 6.7 and 15 mu. We have constructed algorithmically selected `complete' flux-limited samples of 19 sources in the 15-mu image, and seven sources in the 6.7-mu image. The typical flux limit at 15 mu is ~0.2 mJy and …
Red giants in the halo of the S0 galaxy NGC 3115: a distance and a bimodal metallicity distribution
Elson, Rebecca A. W.
Using the Hubble Space Telescope, we resolve the red giant branch in the halo of the S0 galaxy NGC 3115. We measure magnitudes and (V-I) colours for stars down to 1.5mag below the tip of the red giant branch. From the brightest stars we estimate a distance modulus (m-M)_0=30.21+/-0.30, corresponding to a distance of 11.0+/-1.5Mpc. This is in excel…
The luminosity function of the globular cluster NGC 6752 with the Hubble Space Telescope: evidence of mass segregation
Bragaglia, A.; Carretta, E.; Ferraro, F. R. +2 more
We present the luminosity function (LF) for the lower main sequence of the Galactic globular cluster NGC6752, as obtained from Hubble Space Telescope (HST) observations centred 2 arcmin from the cluster centre. We present data in the F814W and F555W filters. Our LF reaches down to M_I=11 or, translated to a mass function, to M~=0.12 Msolar. The LF…
A test of Tully-Fisher distance estimates using Cepheids and SNIa
Shanks, T.
We make a direct test of Tully-Fisher distance estimates to 11 spiral galaxies with Hubble Space Telescope (HST) Cepheid distances, and to 12 spiral galaxies with Type Ia supernova (SNIa) distances. The HST Cepheid distances come from the work of Freedman, Sandage et al. and Tanvir et al. The SNIa distances come from Pierce, calibrated using the C…
The high-excitation planetary nebula NGC 6741
Hyung, Siek; Aller, Lawrence H.
The compact, bright Peimbert type I planetary nebula NGC 6741 shows an unusually rich spectrum which is studied here from 3700 to 10 370 A with the Hamilton Echelle spectrograph at the Lick Observatory. By combining Hamilton Echelle observations with archive UV data secured with the International Ultraviolet Explorer (IUE), and with available IR d…
EK TrA, a close relative of VW HYI
Gänsicke, B. T.; Beuermann, K.; Thomas, H. -C.
The southern dwarf nova EK TrA has been suggested to show the spectrum of its white dwarf primary in the single available International Ultraviolet Explorer (IUE) post-outburst spectrum. We demonstrate that this spectrum is still disc-dominated. However, a careful analysis reveals a white dwarf contribution of ~25 per cent of the SWP flux and a wh…
The nature of the broad-line region in the radio-loud active galactic nucleus 3C 390.3
Schartel, Norbert; Wamsteker, Willem; Wang, Ting-Gui +1 more
We present the results of an analysis of the ultraviolet and X-ray variability of the broad-line radio (BLR) galaxy 3C 390.3 over 15 years. The ultraviolet (UV) continuum of 3C 390.3 shows large variations with amplitudes of up to a factor of 10. We find the following results. (1) The variations of Civ and Lyalpha are highly correlated with the UV…