Search Publications
ISO-SWS spectroscopy of gas-phase C_2H_2 and HCN toward massive young stellar objects
van Dishoeck, E. F.; Lahuis, F.
Observations of gas-phase C_2H_2 and HCN along the line of sight toward a large sample of deeply embedded massive young stellar objects (YSOs) have been performed using the Short Wavelength Spectrometer on board the Infrared Space Observatory. The nu_5 vibration-rotation band of C_2H_2 around 13.7 µm and the nu_2 band of HCN around 14.0 &mic…
The anomalous Galactic globular cluster NGC 2808. Mosaic wide-field multi-band photometry
Zoccali, M.; Stetson, P. B.; Bedin, L. R. +4 more
We present Johnson UBV, and Kron-Cousins I photometry for about 60,000 stars in a region of 44x33 arcmin2 centered on the Galactic globular cluster (GGC) NGC 2808. The central r<100 arcsec region has been mapped also in the F218W, F439W, and F555W bands with the HST WFPC2 camera. Overall, we cover a field which extends from the cente…
ISOCAM observations of the Chamaeleon I dark cloud
Prusti, T.; Perault, M.; Olofsson, G. +18 more
We present the results of an ISOCAM survey of the Chamaeleon I dark cloud conducted in two broad-band filters at 6.7 and 14.3 mu m. In an area of 0.59 sq.deg. we have detected a total of 282 mid-IR sources with 103 sources observed in both filters. Combining the ISOCAM observations with the I, J, and K_s data obtained with DENIS, we have found 108…
Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Makarov, V. V.; Fabricius, C.
Using observations obtained with the Tycho instrument of the ESA Hipparcos satellite, a two-colour photometry is produced for components of more than 7 000 Hipparcos double and multiple stars with angular separations 0.1 to 2.5 arcsec. We publish 9473 components of 5173 systems with separations above 0.3 arcsec. The majority of them did not have T…
On the source regions of the fast solar wind in polar coronal holes
Wilhelm, K.; Marsch, E.; Dammasch, I. E. +1 more
Fast streams of the solar wind with speeds of up to ~ 800 km s-1 at a distance of 1 AU (astronomical unit) from the Sun are known to originate in solar coronal holes. With the Solar and Heliospheric Observatory (SOHO) detailed studies of the solar wind source regions have been made possible for the first time. We show images of solar po…
Kinematics of young stars. I. Local irregularities
Figueras, F.; Torra, J.; Fernández, D.
The local velocity field of young stars is dominated by the galactic rotation, the kinematics of the Gould Belt and the nearest OB associations and open clusters, and the kinematics of the spiral structure. We re-examined here this local velocity field by using a large sample of nearby O and B stars from the Hipparcos Catalogue. The high quality a…
ISO-SWS observations of interstellar solid 13CO2: heated ice and the Galactic 12C/13C abundance ratio
de Graauw, Th.; Prusti, T.; van Dishoeck, E. F. +7 more
We present observations of the stretching mode of 13CO_2 ice along 13 lines of sight in the Galaxy, using the Short Wavelength Spectrometer on board of the Infrared Space Observatory (ISO-SWS). Remarkable variations are seen in the absorption band profile in the different lines of sight. The main feature is attributed to 13CO…
Age and metallicity gradients in the Galactic Bulge. A differential study using HST/WFPC2
Gilmore, G.; Feltzing, S.
The Galactic Bulge has long been assumed to be a largely old stellar population. However, some recent studies based on observations with the HST WF/PC-1 and WFPC2 of stars in the Galactic Bulge have concluded that the old population may not make up more then 30% of the total. Other studies using HST/WFPC2 differential studies of `Bulge' globular c…
A high-resolution study of episodic mass loss from the carbon star TT Cygni
Eriksson, K.; Gustafsson, B.; Olofsson, H. +3 more
CO radio line observations with the IRAM Plateau de Bure interferometer show that the carbon star TT Cyg is surrounded by a large (radius ~ 35arcsec or 2.7x1017 cm), geometrically thin (average width ~ 2farcs 5 or 1.9x1016 cm) shell of gas, which has a remarkable overall spherical symmetry (e.g., its radius varies by less tha…
The composition of the circumstellar dust around the Herbig Ae stars AB Aur and HD 163296
Waters, L. B. F. M.; de Koter, A.; van den Ancker, M. E. +1 more
We have analysed the 2-200 µm ISO spectra of two bright Herbig Ae stars, AB Aur and HD 163296, in order to derive the composition and mass over temperature distribution of the circumstellar dust. We find that the two stars have a similar composition of the dust, however also with some important differences. We address the onset of the strong…