Search Publications
A spectroscopic study of coronal dimming associated with a coronal mass ejection
Harrison, R. A.; Lyons, M.
Extreme ultraviolet spectroscopic observations of one coronal mass ejection event are used to examine the onset phase of the eruption. We find significant dimming of million K plasmas in the low corona under the ascending CME, the activation of an adjacent prominence and 2 million K `hot spots' which may be associated with the CME footpoints. In p…
The C-C-C bending modes of PAHs: a new emission plateau from 15 to 20 µm
Waters, L. B. F. M.; Hony, S.; Tielens, A. G. G. M. +9 more
We have obtained 2.5-45 mu m spectra of a sample of compact H ii regions, YSOs and evolved stars in order to study the origin and evolution of interstellar Polycyclic Aromatic Hydrocarbon molecules (PAHs). Besides the well-known, strong PAH bands at 3.3, 6.2, 7.7, 8.6, and 11.2 mu m, these spectra reveal for the first time, a ubiquitous emission p…
Mass-radius relations for white dwarf stars of different internal compositions
Althaus, L. G.; Panei, J. A.; Benvenuto, O. G.
The purpose of this work is to present accurate and detailed mass-radius relations for white dwarf (WD) models with helium, carbon, oxygen, silicon and iron cores, and with and without a hydrogen envelope, by using a fully updated stellar evolutionary code. We considered masses from 0.15 Msun to 0.5 Msun for the case of hel…
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…