Spectrophotometric Monitoring of Comet C/1995 O1 (Hale-Bopp): Pre- and Post-Perihelion

in Bulletin of the American Astronomical Society (1998, September 01)

Spectrophotometric observations of comet C/1995 O1 (Hale-Bopp) were performed at the European Southern Observatory (ESO), Chile. From April to September 1996 its gaseous activity was monitored over a ... [more ▼]

Spectrophotometric observations of comet C/1995 O1 (Hale-Bopp) were performed at the European Southern Observatory (ESO), Chile. From April to September 1996 its gaseous activity was monitored over a heliocentric distance range from 4.6 AU to 2.9 AU. The monitoring is continued on Hale-Bopp's outbound path since September 1997 and covers up to now 3 AU to 5 AU heliocentric distance. Medium resolution spectra in the optical wavelength range from about 350 nm to 700 nm were taken at the 1.54m Danish and the 1.52m ESO telescope. Emission bands of the CN, C_3, C_2 and NH_2 radicals can be followed over the comet's orbit. We will present a first analysis of the post-perihelion activity evolution and compare to the pre-perihelion path. Currently, at 4.7 AU on the outbound path, we still see emission of CN, C_3, C_2 and NH_2. The production rate of CN showed a sudden increase around this heliocentric distance pre-perihelion (Rauer et al., Science 275, 1909). The post-perihelion activity evolution of CN and the other observed radicals in this distance range will be evaluated. [less ▲]

Spectrophotométrie dans le proche infrarouge : Une méthode d'analyse adaptée au secteur agro-alimentaire.

in Agoratech (1997), (8),

Spectropolarimetry of WR66

in Wolf-Rayet stars in the framework of stellar evolution ; 33rd Liege International Astrophysical Coll (1996)

We have carried out spectropolarimetric observations of the Wolf-Rayet star WR66 (WN8) with EFOSC1 mounted on the ESO 3.6m telescope of La Silla. The results indicate a polarization level of about 5 to 6 ... [more ▼]

We have carried out spectropolarimetric observations of the Wolf-Rayet star WR66 (WN8) with EFOSC1 mounted on the ESO 3.6m telescope of La Silla. The results indicate a polarization level of about 5 to 6 % in the continuum which is most probably due to interstellar polarization. [less ▲]

Spectroscopic analysis of extreme metal-poor 'dwarfs'. II - Improved model atmospheres and detailed abundances

in Astronomy and Astrophysics (1985), 146

High resolution spectrophotometric data were obtained for the stellar objects HD 19445 and HD 140283. The spectra gathered were well-matched by model stellar atmospheres for the continuous flux and Fe I ... [more ▼]

High resolution spectrophotometric data were obtained for the stellar objects HD 19445 and HD 140283. The spectra gathered were well-matched by model stellar atmospheres for the continuous flux and Fe I excitation equilibrium. HD 19445 was identified as a dwarf star and HD 140283 as a subgiant. Abundance analyses indicated an Fe abundance lower than previously estimated, oxygen overabundant relative to C and Fe, Mg, Si and Ca overabundant relative to Fe, and deficiencies of Al and Mn. Sr was overabundant relative to Ba. The abundance discrepancies are in disagreement with the standard nucleosynthesis model. Further such spectroscopic data are needed to develop accurate galactic chemical evolution models. [less ▲]

Spectroscopic anatomy of a meteor trail cross section with the European Southern Observatory Very Large Telescope

in Meteoritics & Planetary Science (2004), 39

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 ... [more ▼]

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 × 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 N2, N, and O 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(a) * H (km)/90 m, where a 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. [less ▲]

Spectroscopic anatomy of a meteor with the Very Large Telescope (ESO)

in 35th COSPAR Scientific Assembly (2004)

A meteor spectrum in the range 637 - 1050 nm was recorded serendipitously at the ESO Very Large Telescope during a long exposure in long-slit spectroscopic mode with FORS1. The meteor crossed the narrow 1 ... [more ▼]

A meteor spectrum in the range 637 - 1050 nm was recorded serendipitously at the ESO Very Large Telescope during a long exposure in long-slit spectroscopic mode with FORS1. The meteor crossed the narrow 1" x 7' slit during normal service mode operation on May 12, 2002. To our knowledge, this is the first observation of a spatially resolved spectrum across a meteor trail. The trail is wider than expected and the plasma excitation temperature varies only from about 4,300 to 4,365 K across the trail, based on the ratio of atomic and molecular nitrogen emissions. The observed width could originate from a range of fragments that have spread significantly at the time of the observation. Finally, carbon atom emission is not detected in the relatively unexplored range above 900 nm. [less ▲]

Spectroscopic and photometric observations of galaxies from the ESO/Uppsala list Second catalogue

in Astronomy and Astrophysics. Supplement Series (1978), 33

Abstract image available at: http://esoads.eso.org/abs/1978A&AS...33..243B

Spectroscopic and photometric variability of the O9.5Vp star HD93521

in Astronomy and Astrophysics (2008), 487(2), 659-670

Aims. The line profile variability and photometric variability of the O9.5Vp star HD93521 are examined in order to establish the properties of the non-radial pulsations in this star. Methods. Fourier ... [more ▼]

Aims. The line profile variability and photometric variability of the O9.5Vp star HD93521 are examined in order to establish the properties of the non-radial pulsations in this star. Methods. Fourier techniques are used to characterize the modulations of the He I lambda lambda 5876, 6678 and H alpha lines in several spectroscopic time series and to search for variations in a photometric time series. Results. Our spectroscopic data confirm the existence of two periods of 1.75 and 2.89 h. The line profiles, especially those affected by emission wings, exhibit also modulations on longer time scales, but these are epoch-dependent and change from line to line. Unlike previous claims, we find no unambiguous signature of the rotational period in our data, nor of a third pulsation period (corresponding to a frequency of 2.66 d(-1)). Conclusions. HD93521 very likely exhibits non-radial pulsations with periods of 1.75 and 2.89 h with l similar or equal to 8 +/- 1 and l similar or equal to 4 +/- 1 respectively. No significant signal is found in the first harmonics of these two periods. The 2.89 h mode is seen at all epochs and in all lines investigated, while the visibility of the 1.75 h mode is clearly epoch-dependent. Whilst light variations are detected, their connection to these periodicities is not straightforward. [less ▲]

Spectroscopic binary processing within Gaia DPAC

in Orbital Couples: Pas de Deux in the Solar System and the Milky Way (2012, May 01)

Not Available

Spectroscopic characterization of protochlorophyllide photoreduction in the greening leaf

in Photosynthetica (1993), 29(2), 185-194

Room temperature absorbance and 77 K fluorescence measurements were used in order to identify Pchlide and Chlide spectral forms involved in protochlorophyllide photoreduction in greening leaves of barley ... [more ▼]

Room temperature absorbance and 77 K fluorescence measurements were used in order to identify Pchlide and Chlide spectral forms involved in protochlorophyllide photoreduction in greening leaves of barley. Pchlide(650) (the subscript refers to the in vivo absorbance maximum of the pigment) is the main photoactive Pchlide throughout the first 8 h of greening. Its photoreduction triggers a succession of Chl(ide) spectral forms that are identical to those normally found after photoreduction in unirradiated leaves. After an actinic radiation pulse, Chlide(684) appears within 2 s from an intermediate at shorter wavelength and is transformed to Chlide(672) in less than 2 min. The time-scale of the shifts is remarkably shorter than in unirradiated leaves, which is consistent with the acceleration of Chi accumulation during greening. Pchlide(630) and Pchlide(640) act as precursors of Pchlide(650) during its regeneration, which exhibits a marked inhibition at temperatures above 30 degrees C. [less ▲]