Search Publications
The dynamical evolution of stellar superclusters
Kroupa, Pavel
Recent images taken with the Hubble Space Telescope (HST) of the interacting disc galaxies NGC 4038/4039 (the Antennae) reveal clusters of many dozens and possibly hundreds of young compact massive star clusters within projected regions spanning about 100 to 500 pc. It is shown here that a large fraction of the individual star clusters merge withi…
Testing CNO Enrichment Scenarios in Metal-poor Galaxies with Hubble Space Telescope Spectroscopy
Kobulnicky, Henry A.; Skillman, Evan D.
Using Hubble Space Telescope ultraviolet and ground-based optical spectroscopy, we measure the C/O and N/O ratios of three metal-poor galaxies with similar metallicity but differing N/O. These observations, in conjunction with photoionization models, indicate that the C/O ratios estimated from C III] λ1909 and [O III] λ5007 lines are consistent wi…
Ice segregation toward massive protostars
Ehrenfreund, P.; Dartois, E.; Demyk, K. +1 more
Recent ISO results allow new insights into the evolution of interstellar ices in the vicinity of massive protostars. The presence of CO2 ice has recently been confirmed with the SWS (Short Wavelength Spectrometer) on-board ISO as a dominant ice component of interstellar grain mantles. The bending mode of CO2 ice, currently ob…
Ultraviolet Diagnostics for the Emission-Line Gas in Active Galaxies
Dopita, Michael A.; Allen, Mark G.; Tsvetanov, Zlatan I.
Optical diagnostic diagrams are frequently ambiguous as tests of the photoionization or fast-shock models of the narrow-line regions of active galaxies. Here, we present a set of UV line ratio diagrams that can discriminate between pure shock and photoionization modes of excitation and can, to some extent, also discriminate shocks with ionized pre…
Determination of the temperatures of selected ISO flux calibration stars using the Infrared Flux Method
Lynas-Gray, A. E.; Blackwell, D. E.
Effective temperatures for 420 stars with spectral types between A0 and K3, and luminosity classes between II and V, selected for a flux calibration of the Infrared Space Observatory, ISO, have been determined using the Infrared Flux Method (IRFM). The determinations are based on narrow and wide band photometric data obtained for this purpose, and…
The Radio Properties of NGC 5253 and Its Unusual H II Regions
Turner, Jean L.; Beck, Sara C.; Ho, Paul T. P.
We present VLA images of the radio continuum emission of the starburst in NGC 5253 at wavelengths of 6, 3.6, and 2 cm, with resolutions of 1"-2", and at 20 cm with resolution of ~9". A spectral index map constructed from the 6 and 2 cm images indicates that thermal free-free emission from ionized gas, most of it from a single source, dominates the…
On-line determination of stellar atmospheric parameters Teff, log g, [Fe/H] from ELODIE echelle spectra. II. The library of F5 to K7 stars
Soubiran, C.; Katz, D.; Cayrel, R.
A library of 211 echelle spectra taken with ELODIE at the Observatoire de Haute-Provence is presented. It provides a set of spectroscopic standards covering the full range of gravities and metallicities in the effective temperature interval [4000 K, 6300 K]. The spectra are straightened, wavelength calibrated, cleaned of cosmic ray hits, bad pixel…
Circumstellar Silicate Mineralogy
Waters, L. B. F. M.; Justtanont, K.; Tielens, A. G. G. M. +1 more
This paper reviews spectra obtained with the SWS on board of ISO of dust shells around O-rich objects. These spectra reveal the presence of many new emission features between 10 and 45 µm. These bands are generally much narrower than the well-known 10 and 20 µm silicates features. The strength of these features relative to the underlying broad con…
F- and G-type stars with planetary companions: upsilon Andromedae, rho (1) Cancri, tau Bootis, 16 Cygni and rho Coronae Borealis
Fuhrmann, Klaus; Pfeiffer, Michael J.; Bernkopf, Jan
Accurate stellar parameters are presented for the F- and G-type stars upsilon And, rho (1) Cnc, tau Boo, 16 Cyg, and rho CrB, which are deemed to possess planetary companions from intense Doppler monitoring. Evolutionary tracks that employ detailed model atmospheres as upper boundary condition and allow for helium diffusion are computed for the in…
The z=2.72 galaxy cB58: a gravitational fold arc lensed by the cluster MS1512+36
Saglia, R. P.; Bender, Ralf; Seitz, Stella +3 more
Using HST WFPC2 V- and R-band data of the z=0.37 cluster MS 1512+36, we show that the z=2.72 `protogalaxy' cB58 is not extraordinarily luminous intrinsically but lensed into a gravitational fold arc by the cluster. The arc has a surface- brightness-weighted axis ratio of 1:7, is marginally resolved in width and about 3 arcsec long. Its counterimag…