Browsing by Author "Cabanac, RA"

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    A fresh view of Henize 2-10 with VLT NAOS-CONICA
    (2005) Cabanac, RA; Vanzi, L; Sauvage, M
    We present high-resolution observations of Henize 2-10 in K-s (2.2 mu m), L ' (3.8 mu m), and M ' (4.8 mu m) bands. These allow us, for the first time, to track accurately the structures at the heart of the galaxy from the optical to the radio. All radio knots previously observed can now be associated with L '- and K-s-emitting regions. This implies a revision of their physical nature. Instead of highly extinguished ultradense H II regions, we propose that two of the five radio knots are either supernova remnants or normal H II regions, while the remaining three are bona fide ultradense H II regions, although less obscured than previously thought.
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    Discovery of a high-redshift Einstein ring
    (2005) Cabanac, RA; Valls-Gabaud, D; Jaunsen, AO; Lidman, C; Jerjen, H
    We report the discovery of a partial Einstein ring of radius 1.''48 produced by a massive (and seemingly isolated) elliptical galaxy. The spectroscopic follow-up at the VLT reveals a 2L(star) galaxy at z = 0.986, which is lensing a post-starburst galaxy at z = 3.773. This unique configuration yields a very precise measure of the mass of the lens within the Einstein radius, (8.3 +/- 0.4) x 10(11)h(70)(-1) M-circle dot. The fundamental plane relation indicates an evolution rate of dlog(M/L)(B)/dz = -0.57 +/- 0.04, similar to other massive ellipticals at this redshift. The source galaxy shows strong interstellar absorption lines indicative of large gas-phase metallicities, with fading st phase populations after a burst stellar Higher resolution spectra and will allow the detailed imaging study of an unbiased representative of the galaxy population when the universe was just 12% of its current age.
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    Spectroscopic anatomy of a meteor trail cross section with the European Southern Observatory Very Large Telescope
    (2004) Jenniskens, P; Jehin, E; Cabanac, RA; Laux, CO; Boyd, ID
    A meteor spectrum was recorded serendipitously at the European Southern Observatory (ESO) Very Large Telescope (VLT) during a long exposure in long-slit spectroscopic mode with FORS1. The -8 magnitude fireball crossed the narrow 1" x 7' slit during the observation of a high z supernova in normal service mode operation on May 12, 2002. The spectrum covered the range of 637-1050 nm, where the meteor's air plasma emissions from N-2, N, and 0 dominate. Carbon atom emission was not detected in the relatively unexplored wavelength range above 900 nm, but the observed upper limit was only 3 sigma less than expected from the dissociation of atmospheric CO2, The meteor trail was resolved along the slit, and the emission had a Gaussian distribution with a dimension of FWHM = 7.0 (+/-0.4) * sin(alpha) * H (km)/90 m, where alpha is the unknown angle between the orientation of the meteor path and slit and H the assumed altitude of the meteor in km. To our knowledge, this is the first observation of a spatially resolved spectrum across a meteor trail. Unlike model predictions, the plasma excitation temperature varied only from about 4,300 to 4,365 K across the trail, based on the ratio of atomic and molecular nitrogen emissions. Unfortunately, we conclude that this was because the meteor at 100 km altitude was out of focus.