Search Publications
A study of opacity in SOHO-SUMER and SOHO-CDS spectral observations. I. Opacity deduction at the limb
Harrison, R. A.; Landini, M.; Innes, D. E. +9 more
A study is presented of the optical thickness of spectral lines of carbon, nitrogen and oxygen ions in the quiet sun. The observations consist of cross limb scans by the SUMER and CDS spectrometers on the SOHO spacecraft. A maximum likelihood spectral line fitting code has been adapted to analyse the multiplet profiles and to provide an assessment…
Luminosity function and mass segregation in M92
Marconi, G.; Buonanno, R.; Iannicola, G. +2 more
We present WFPC2-HST observations of the lower main sequence of the galactic globular cluster M92 (NGC6341), extending down to V ~= 27. Our data, which cover a region of the cluster extending from the very center out to r ~= 380 arcsec, show that the slope of the luminosity function becomes flatter going towards the center of the cluster, as expec…
A wind accretion wake in RW Hydrae?
Schmutz, W.; Nussbaumer, H.; Schild, H. +3 more
RW Hydrae is an eclipsing detached binary star system, consisting of a mass losing M-giant and a hot white dwarf on circular orbits. We analyze UV observations of RW Hydrae. Approximately at phi = 0.78, clearly unrelated to the primary eclipse, we detect in the UV light curve an event with significantly reduced UV flux. The spectral characteristic…
The Vela pulsar (PSR B0833-45) proper motion revisited with HST astrometry
Caraveo, P. A.; De Luca, A.; Mignani, R. P.
Using all the HST WFC/WFPC2 images of the field collected so far, we have performed an accurate relative astrometry analysis to re-assess the value of the Vela pulsar proper motion. Although covering a much shorter time span, our measurement clearly confirms the previous result obtained by Nasuti et al. (1997) using ground-based optical data and n…
Interpreting the optical data of the Hubble Deep Field South: colors, morphological number counts and photometric redshifts
Chincarini, G.; Bolzonella, M.; Saracco, P. +1 more
We present an analysis of the optical data of the Hubble Deep Field South. We derive F300WAB, F450WAB, F606WAB and F814WAB number counts for galaxies in our catalogue (Volonteri et al. 2000): the number-counts relation has an increasing slope up to the limits of the survey in all four bands. The slope is…
The observational status of the Slowly Pulsating B star iota Herculis
Garrido, R.; Mathias, P.; Chapellier, E. +3 more
New spectroscopic and photometric measurements are presented concerning the SPB binary star iota Her. Our observations are spread over 10 years, and consist of 10 spectroscopic nights in 1985, 7 spectroscopic nights and 22 photometric nights in 1987, and 15 spectroscopic nights in 1995. In addition, we analysed the photometric observations provide…
ISO observations of the Wolf-Rayet galaxy NGC 7714 and its companion NGC 7715
Hanlon, L.; McBreen, B.; Metcalfe, L. +5 more
The interacting system Arp 284 consisting of the Wolf-Rayet galaxy NGC 7714 and its irregular companion NGC 7715 was observed using the Infrared Space Observatory . Deconvolved ISOCAM maps of the galaxies using the 14.3 µm, 7.7 µm and 15 µm LW3, LW6 and LW9 filters, along with ISOPHOT spectrometry of the nuclear region of NGC 771…
ISO-SWS Observations of CO_2 and H_2O in R Cassiopeiae
Millar, T. J.; Markwick, A. J.
We present ISO-SWS spectra of the O-rich Mira variable R Cas, showing CO_2 in absorption and emission, and H_2O in absorption. The CO_2 absorption feature is the 0110-0000 ro-vibrational band at 14.97 µm. The emission features are the 1000-0110 and 1110-0220 ro-vibrational tra…
Spectrophotometric behavior of CU Virginis
Sokolov, N. A.
The spectrophotometric variability of the magnetic CP star CU Vir in the spectral region from 1150 Ä to 7850 Ä is investigated. This study is based on the archival IUE and published visual spectrophotometric data obtained at different phases of the rotational cycle. The light variations in the wavelength region longer than lambda 2000 Ä are genera…
Rotation and evolution of A stars: looking for progenitors of cool Ap stars
Hubrig, S.; North, P.; Medici, A.
We explore to what extent the study of the projected rotational velocities of normal A stars might reveal the existence of progenitors of cool Ap stars, i.e. of slowly rotating normal young A stars. Since according to a recent work, magnetic Ap stars with masses ranging from 1.7 to 2.5 M_sun are never found on the ZAMS in the HR diagram, but have …