Search Publications
Resolved 200mu M images of nearby galaxies - evidence for an extended distribution of cold dust
Bianchi, S.; Gear, W.; Davies, J. I. +6 more
We present resolved 200mu m images for 8 nearby galaxies observed with the Infrared Space Observatory (ISO). By comparing the 200mu m observations with IRAS 60mu m and 100mu m data, we find that cold dust becomes more dominant at larger radii. We infer a grain temperature of 18-21 K for this cold component i.e. about 10 K lower than the warm dust …
How many low-mass stars do destroy (3) He?
Charbonnel, C.; Do Nascimento, J. D., Jr.
We recall the current status of the long-standing (3) He problem, and its possible connection with chemical anomalies on the red giant branch. In this context, we collect in the literature all the available observations of the carbon isotopic ratio in field and cluster giant stars. Using the HIPPARCOS parallaxes, we get constraints on the evolutio…
The shape of the unidentified infra-red bands: analytical fit to ISOCAM spectra
Boulanger, F.; Cesarsky, D.; Ryter, C. +1 more
Modelling the unidentified infrared dust bands at 6.2 7.7, 8.6, 11.3, and 12.7 µm by Lorentz profiles is shown to produce excellent fits to the spectra obtained with the Continuous Variable Filter (CVF) of the instrument ISOCAM, on-board the Infrared Space Observatory (ISO). The feature pedestals are accounted for by the wide wings of the Lo…
Cold dust in the Andromeda Galaxy mapped by ISO
Lemke, D.; Haas, M.; Hippelein, H. +4 more
A complete 175 mu m map of the Andromeda galaxy (M31) at 1farcm 3 resolution shows the distribution of cold dust. It is dominated by a ring at 10 kpc radius supplemented by a faint outer one at 14 kpc. No clear spiral pattern is recognisable. The azimuthally averaged radial brightness profile is rather flat within the 10 kpc ring and decreases exp…
Discovery of a late-type stellar population associated with the Gould Belt
Schmitt, J. H. M. M.; Motch, C.; Guillout, P. +2 more
We report the detection of a late-type stellar population in the direction of the Gould Belt among stars found by cross-correlating the ROSAT All-Sky Survey with the Tycho catalog. Regions of the Gould Belt located between l = 195°\ and l = 15°\ exhibit a strong density enhancement of X-ray active stars with associated X-ray luminosities LX
On the age of the nearby blue compact dwarf galaxy SBS 0335-052
Thuan, T. X.; Izotov, Y. I.; Papaderos, P. +2 more
UBVRI surface photometry and long-slit spectrophotometric observations are used to investigate the evolutionary status and put constraints on the age of the underlying stellar population of the eastern component of a nearby pair of dwarf galaxies, the blue compact dwarf galaxy SBS\ 0335-052E. We show that ionized gas emission extending out to dist…
Revised ages for stars in the solar neighbourhood
Bertelli, G.; Ng, Y. K.
New ages are computed for the stars from the Edvardsson et al. (1993) data set. The revised values are systematically larger toward older ages (t>4 Gyr), while they are slightly lower for t<4 Gyr. A similar, but considerably smaller trend is present when the ages are computed with the distances based on Hipparcos parallaxes. The resulting ag…
The Castor moving group. The age of Fomalhaut and VEGA
Barrado y Navascues, D.
We have recomputed the kinematic properties of several of dozens nearby stars, to try to verify if Castor (alpha Gem) indeed has a cohort of stars sharing the same space motion and age. We used kinematics, the location of the stars in Color-Magnitude Diagrams, their lithium abundances, and their activity, to establish that the moving group seems t…
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…
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…