Search Publications
The runaway black hole GRO J1655-40
Mirabel, I. F.; Combi, J. A.; Mignani, R. +3 more
We have used the Hubble Space Telescope to measure the motion in the sky and compute the galactocentric orbit of the black hole X-ray binary GRO J1655-40. The system moves with a runaway space velocity of 112+/- 18 km s-1 in a highly eccentric (e = 0.34+/- 0.05) orbit. The black hole was formed in the disk at a distance greater than 3 k…
Tidal dwarfs in the M81 group: The second generation?
Sarajedini, A.; Dolphin, A. E.; Grebel, E. K. +8 more
We derive quantitative star formation histories of the four suspected tidal dwarf galaxies in the M 81 group, Holmberg IX, BK3N, Arp-loop (A0952+69), and Garland, using Hubble Space Telescope/Wide Field Planetary Camera 2 images in F606W and F814W obtained as part of a Snapshot survey of dwarf galaxies in the Local Universe. We consider the spatia…
HIPPARCOS age-metallicity relation of the solar neighbourhood disc stars
Arimoto, N.; Ibukiyama, A.
We derive age-metallicity relations (AMRs) and orbital parameters for the 1658 solar neighbourhood stars to which accurate distances are measured by the HIPPARCOS satellite. The sample stars comprise 1382 thin disc stars, 229 thick disc stars, and 47 halo stars according to their orbital parameters. We find a considerable scatter for thin disc AMR…
Combined VLT ISAAC/ISO SWS spectroscopy of two protostellar sources. The importance of minor solid state features
van Dishoeck, E. F.; Pontoppidan, K. M.; Dartois, E. +2 more
We discuss the L band infrared spectra of two massive protostars in the region of the so-called 3.47 mu m absorption feature. The high sensitivity VLT-ISAAC spectra of the two differently evolved massive protostars GL 989 and GL 2136, together with dedicated infrared laboratory experiments on ice molecular interactions, allow us to propose the ide…
Understanding the nature of FR II optical nuclei: A new diagnostic plane for radio galaxies
Capetti, A.; Chiaberge, M.; Celotti, A.
We extend our study of the nuclei of 3CR FR II radio galaxies through HST optical images up to z = 0.3. In the majority of them an unresolved nucleus (central compact core, CCC) is found. We analyze their position in the plane formed by the radio and optical nuclear luminosities in relation to their optical spectral properties. The broad-lined obj…
Oscillations above sunspots: Evidence for propagating waves?
O'Shea, E.; Muglach, K.; Fleck, B.
We present results of an analysis of time series data observed in sunspot umbral regions. The data were obtained in the context of the SOHO Joint Observing Program (JOP) 97 in September 2000. This JOP included the Coronal Diagnostic Spectrometer (CDS) and the Michelson Doppler Imaging (MDI) instrument, both part of SOHO, the TRACE satellite and va…
The PAH emission spectra of Large Magellanic Cloud H II regions
Tielens, A. G. G. M.; Peeters, E.; van der Hulst, J. M. +1 more
A set of ISOPHOT spectra from a sample of H Ii regions in the Large Magellanic Cloud (LMC) is presented. In all the spectra, emission bands arising from Polycyclic Aromatic Hydrocarbons (PAHs) are clearly present. These features are observed to vary considerably in relative strength to each other from source to source and even within 30 Doradus. T…
[CII] at 158 mu m as a star formation tracer in late-type galaxies
Boselli, A.; Gavazzi, G.; Lequeux, J. +1 more
We present a calibration of the massive star formation rate vs. [CII] luminosity relation based on a sample of nearby, late-type galaxies observed with ISO-LWS and imaged in the Hα +[NII] line. The relation holds for far-IR luminosities 108 <= LFIR <=1010.5 Lsun. The derived star formation rates ha…
Spectroscopy of large PAHs. Laboratory studies and comparison to the Diffuse Interstellar Bands
Schmidt, W.; Ehrenfreund, P.; Allamandola, L. J. +4 more
Polycyclic Aromatic Hydrocarbons (PAHs) are thought to be the carriers of the ubiquitous infrared emission bands (UIBs). Data from the Infrared Space Observatory (ISO) have provided new insights into the size distribution and the structure of interstellar PAH molecules pointing to a trend towards larger-size PAHs. The mid-infrared spectra of galac…
Water emission in NGC 1333-IRAS 4. The physical structure of the envelope
Maret, S.; Ceccarelli, C.; Caux, E. +2 more
We report ISO-LWS far infrared observations of CO, water and oxygen lines towards the protobinary system IRAS 4 in the NGC 1333 cloud. We detected several water, OH, CO rotational lines, and two [OI] and [CII] fine structure lines. Given the relatively poor spectral and spatial resolution of these observations, assessing the origin of the observed…