Search Publications
ISO observations of the environment of the soft gamma-ray repeater SGR 1806-20
Chaty, S.; Fuchs, Y.; Claret, A. +3 more
Observations at near and mid-infrared wavelengths (1-18 mu m) of SGR 1806-20 suggest that it is associated with a cluster of giant massive stars which are enshrouded in a dense cloud of dust. The centre of the best sky position of the gamma-ray source (Hurley et al. \cite{hurley99}) lies on top of the dust cloud at only 7 arcsec ( ~ 0.5 pc at a di…
The HIPPARCOS HR diagram of nearby stars in the metallicity range: -1.0 < [Fe/H] < 0.3. A new constraint on the theory of stellar interiors and model atmospheres
Baglin, A.; Lebreton, Y.; Cayrel, R. +2 more
The Hipparcos mission has provided very high quality parallaxes of a sample of a hundred nearby disk stars, of spectral types F to K. In parallel, bolometric fluxes, effective temperatures, and accurate Fe/H ratios of many of these stars became available through infrared photometry and detailed spectroscopic analyses. These new accurate data allow…
A Variable Asymmetry in the Circumstellar Disk of HH 30
Ballester, Gilda E.; Krist, John E.; Crisp, David +13 more
We report Hubble Space Telescope observations of variability within the reflection nebulosity of HH 30, a compact bipolar nebula that is a nearly edge-on accretion disk system. A dramatic lateral asymmetry appeared in the upper reflection nebula in the spring of 1998, but was largely absent in 1994 and 1995 images. The variability timescale is muc…
A nuclear grand-design spiral within the normal disc spiral of NGC 5248
Knapen, J. H.; Laine, S.; Doyon, R. +2 more
We report the discovery of trailing grand-design nuclear spiral structure in the spiral galaxy NGC 5248. Two tightly wound red spiral arms, with widths less than 1 arcsec (~ 75 pc), emanate at 1 arcsec outside the quiescent nucleus of the galaxy, and can be followed for 3 arcsec, appearing to end before the radius of the circumnuclear starburst `r…
AgapeZ1: a large amplification microlensing event or an odd variable star towards the inner bulge of M31
Giraud-Héraud, Y.; Bouquet, A.; Soucail, G. +14 more
AgapeZ1 is the brightest and the shortest duration microlensing candidate event found to date in the Agape experiment. It occurred only 42'' from the centre of M31 at RA=0(h) 42(m) 41.47(s) and Dec=41(deg) 16' 39.1'' (J2000). Our photometry shows that the half intensity duration of the event is 5.3 days and at maximum brightness its magnitude is R…
WFPC2 Observations of the Ursa Minor Dwarf Spheroidal Galaxy
Burke, Christopher J.; Mighell, Kenneth J.
We present our analysis of archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations in F555W (~V) and F814W (~I) of the central region of the Ursa Minor dwarf spheroidal (dSph) galaxy. The V versus V-I color-magnitude diagram features a sparsely populated blue horizontal branch, a steep thin red giant branch, and a …
Infrared spectra of carbon stars observed by the ISO SWS bands at 14 µ m. II. HCN and C2H2
Ohnaka, K.; Tsuji, T.; Aoki, W.
We analyzed the mid-infrared spectra of 4 optical carbon stars and 4 candidates of infrared carbon stars obtained with the ISO SWS. It has been revealed that special care should be taken in determining the continuum levels for the analysis of the emission and absorption bands of HCN and C2H2 at 14 mu m; otherwise the SiC emis…
Upper limit on C60 and C60(+) features in the ISO-SWS spectrum of the reflection nebula NGC 7023
Léger, A.; Moutou, C.; Verstraete, L. +1 more
We present here the 7.0-8.7 mu m spectrum of the bright reflection nebula NGC 7023. Our observations are made with the Short Wavelength Spectrometer (SWS) on the European satellite Infrared Space Observatory (ISO). The vibrational bands of the ionized fullerene C60(+) are expected at 7.11 and 7.51 mu m, while those of the neutral fuller…
Hubble Space TelescopeStudies of the WLM Galaxy. I. The Age and Metallicity of the Globular Cluster
Dolphin, Andrew E.; Mateo, Mario; Hodge, Paul W. +1 more
We have obtained V and I images of the lone globular cluster that belongs to the dwarf Local Group irregular galaxy known as WLM. The color-magnitude diagram of the cluster shows that it is a normal old globular cluster with a well-defined giant branch reaching to MV=-2.5, a horizontal branch at MV=+0.5, and a subgiant branch…
Temperature and density in a polar plume - measurements from CDS/SOHO
Young, P. R.; Mason, H. E.; Klimchuk, J. A.
A detailed analysis of a particularly intense polar plume observed on the 25th of October, 1996, by the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO) is presented. Above the limb, emission measure distributions derived for both the plume and a section of coronal hole background are found to be sharply…