References of "Arpigny, Claude"
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See detailProduction and kinematics of sodium atoms in the coma of comet Hale-Bopp
Arpigny, Claude ULg; Rauer, H.; Manfroid, Jean ULg et al

in Astronomy and Astrophysics (1998), 334(Letters), 53-56

High-resolution spectra of sodium D line emission in comet Hale-Bopp (C/1995 O1) were obtained at the Observatoire de Haute-Provence, France, on 25-27 March and on 15-17 April, 1997. The observations have ... [more ▼]

High-resolution spectra of sodium D line emission in comet Hale-Bopp (C/1995 O1) were obtained at the Observatoire de Haute-Provence, France, on 25-27 March and on 15-17 April, 1997. The observations have been used to measure the velocity of sodium atoms in the coma within 2 10(5) km from the nucleus. A comparison between the March and April data provides an illustration of the influence of the heliocentric radial velocity on the strength of the fluorescence (Swings effect), and on the velocity of Na atoms achieved by solar radiation pressure acceleration. Evidence for the presence of a distributed source in the coma is found from the relatively high tailward velocities on the sunward side of the coma, in addition to the sunward extent of sodium emission up to 1.4 10(5) km in April. Based on observations secured at OHP (France) [less ▲]

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See detailOn the (13) CN/(12) CN Isotopic Ratio in Comet Hale-Bopp
Schulz, R.; Arpigny, Claude ULg; Manfroid, Jean ULg et al

in Bulletin of the American Astronomical Society (1997, July 01)

The carbon isotope abundance ratio, (12) C/(13) C, in comets is a key number to their origin. Its accurate determination from ground-based spectroscopy is, however, a difficult task since the observable ... [more ▼]

The carbon isotope abundance ratio, (12) C/(13) C, in comets is a key number to their origin. Its accurate determination from ground-based spectroscopy is, however, a difficult task since the observable emissions of (13) C-containing molecules are very weak. Due to its exceptional brightness, comet Hale-Bopp provided a unique opportunity to look for (13) C and derive the (12) C/(13) C isotopic ratio. We observed the comet with the high-resolution spectrograph SOFIN mounted on the 2.56m Nordic Optical Telescope on La Palma, Canary Islands. High-resolution spectra of the R-branch of the CN (0-0) band were obtained between Apr. 7 and 13, 1997, when the comet was at r = 0.9 AU and Delta = 1.4 AU. Owing to the heliocentric velocity effect on the fluorescence excitation rates, this period was particularly favourable to search for the R(8) and R(7) emission lines of the (13) CN isotope. Because of the strong continuum in the coma of Hale-Bopp we took our measurements at a certain location in the coma away from the nucleus and from any dust jets. Our first preliminary reduction and analysis show, after careful continuum subtraction, a clear detection of a line at the position predicted for R(8) and and an indication of a line at the predicted position of R(7). The R(8) line can be used to determine the (12) C/(13) C isotopic ratio and the first preliminary values will be given. [less ▲]

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See detailThe European Hale-Bopp Team Observations of Comet Hale-Bopp
Cremonese, G.; Arpigny, Claude ULg; Manfroid, Jean ULg et al

in Bulletin of the American Astronomical Society (1997, July 01)

The poster reports some preliminary results obtained by the the European HB Team during an observational campaign, carried out with a substantial number of telescopes on the Canary Islands within a ... [more ▼]

The poster reports some preliminary results obtained by the the European HB Team during an observational campaign, carried out with a substantial number of telescopes on the Canary Islands within a programme supported by the European Union. The observations were devoted to a variety of spectroscopic and photometric topics and have already provided important results. A highlight of this work was the discovery of a third tail composed of neutral sodium and the detection of substantial amount of sodium in the dust tail. Potassium was found in the nuclear region and it was possible to obtain good definition of the rotation state of the comet nucleus. Other results are expected from the analysis of high resolution spectra, for instance the carbon isotopic ratio, the relative abundance of some ions in the coma, and of the very large collection of images from different telescopes with which the complex jet structure of the near nucleus region was monitored. [less ▲]

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See detailOn the Production and Kinematics of Sodium Atoms in the Head of Comet Hale-Bopp
Rauer, H.; Arpigny, Claude ULg; Hutsemekers, Damien ULg et al

in Bulletin of the American Astronomical Society (1997, July 01), 29

The interpretation of the presence and extent of the atomic sodium observed in comet Hale-Bopp raises a number of questions related to the production, motion, and lifetime of these Na atoms under the ... [more ▼]

The interpretation of the presence and extent of the atomic sodium observed in comet Hale-Bopp raises a number of questions related to the production, motion, and lifetime of these Na atoms under the action of the solar radiation near 1 AU. Here we report on data which pertain to the study of sodium in the head of the comet, yielding information on the Na emission in the coma out to ~ 0.15 x 10(6) km on the sunward side, to ~ 0.2 x 10(6) km tailwards. The observations were carried out at the Observatoire de Haute-Provence, with the 1.93 m telescope and the ELODIE spectrometer, which is fed by a pair of optical fibers with 2-arcsec apertures separated by 1.8 arcmin. In particular, spectra were obtained on 15-17 April, 1997, near the discovery date of the sodium tail at the La Palma Observatory. These spectra (resolution ~ 7 km/s) were used to determine Na D line profiles, as well as the relative intensities of the emissions corresponding to the two positions observed simultaneously. The main outcome of our first analysis concerns the profiles recorded some distance away from the optical centre, which all show velocity shifts and asymmetric line broadening in the direction of anti-sunward velocities. Some evidence is found to suggest the existence of an extended or multi-source production of sodium atoms, at least in the coma. Another series of spectra secured just before perihelion, 25-27 March, was analysed in the same way as the April spectra. Comparison between the two sets of data provides a nice illustration of the marked influence of the heliocentric radial velocity, not only upon the strength of the fluorescence ("Swings effect"), but also upon the motion of the emitting atoms, which are accelerated by the radiation pressure to widely different degrees as their excitation wavelengths fall at different places within the Fraunhofer Na D line profiles. [less ▲]

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See detailOptical observations of comet Hale-Bopp (C/1995 O1) at large heliocentric distances before perihelion.
Rauer, H.; Arpigny, Claude ULg; Boehnhardt, H. et al

in Science (1997), 275

The activity of comet Hale-Bopp (C/1995 O1) was monitored monthly by optical imaging and long-slit spectroscopy of its dust and gas distribution over heliocentric distances of 4.6 to 2.9 AU. The observed ... [more ▼]

The activity of comet Hale-Bopp (C/1995 O1) was monitored monthly by optical imaging and long-slit spectroscopy of its dust and gas distribution over heliocentric distances of 4.6 to 2.9 AU. The observed band intensities of the NH[SUB]2[/SUB] radical and the H[SUB]2[/SUB]O[SUP]+[/SUP] ion cannot be explained by existing models of fluorescence excitation, warranting a reexamination of the corresponding production rates, at least at large heliocentric distances. Comparing the production rate of the CN radical to its proposed parent, HCN, shows no evidence for the need of a major additional source for CN in Hale-Bopp at large heliocentric distances. The dust and CN production rates are consistent with a significant amount of sublimation occurring from icy dust grains surrounding Hale-Bopp. [less ▲]

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See detailA Model to Explain the Activity of Comet Levy (1990c)
Samarasinha, N. H.; A'Hearn, M. F.; Weaver, H. A. et al

in Bulletin of the American Astronomical Society (1991, June 01)

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See detailHigh-resolution spectroscopy of the C2 Swan 0-0 band from Comet P/Halley
Lambert, D. L.; Sheffer, Y.; Danks, A. C. et al

in Astrophysical Journal (1990), 353

High-resolution spectra of the C2 Swan system's 0-0 band from Comet P/Halley in March 1986 show that the populations of the upper state's rotational levels may be described by two rotational temperatures ... [more ▼]

High-resolution spectra of the C2 Swan system's 0-0 band from Comet P/Halley in March 1986 show that the populations of the upper state's rotational levels may be described by two rotational temperatures. The low rotational levels provide a low temperature, Trot = about 600 - 700 K. The higher levels correspond to about 3200 K. If a contribution from the 3200-K molecules is subtracted from the populations of the low-J-prime levels, the latter are characterized by Trot = about 190 K. A comparison with recent predictions for C2 molecules fluorescing in sunlight shows that the observed and predicted level populations are in good agreement for J-prime greater than about 15, but there is a sharp disagreement for the low rotational levels. [less ▲]

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See detailA propos de la réfraction atmosphérique. De curieuses images du ciel.
Manfroid, Jean ULg; Arpigny, Claude ULg

Article for general public (1990)

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See detailBilan annuel: Trois comètes remarquables en 1989
Arpigny, Claude ULg; Manfroid, Jean ULg

Article for general public (1990)

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See detailPre- and post-perihelion spectrographic and photometric observations of Comet Wilson (1986 l)
Arpigny, Claude ULg; Dossin, F.; Manfroid, Jean ULg et al

in The Messenger (1988), 51

The behavior of Comet Wilson before and after its passage through perihelion, which occurred on April 21, 1987, was studied on the basis of spectrographic and photometric observations. Results pertaining ... [more ▼]

The behavior of Comet Wilson before and after its passage through perihelion, which occurred on April 21, 1987, was studied on the basis of spectrographic and photometric observations. Results pertaining to spectra in the UV, blue, and red regions, and to photometry through narrow-band filters are presented. It is suggested that the fading of Comet Wilson might reflect some general trend in the comet's evolution, or that it could be the result of a geometrical effect associated with the rotation of the comet's nucleus and the presence of discrete active areas on its surface. [less ▲]

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See detailResolution of the OI + NH2 Blend in Comet p/ Halley
Arpigny, Claude ULg; Magain, Pierre ULg; Manfroid, Jean ULg et al

in Astronomy and Astrophysics (1987), 187

Abstract image available at: http://adsabs.harvard.edu/abs/1987A&A...187..485A

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See detailPhotometry of p/ Halley 1982I
Sterken, C.; Manfroid, Jean ULg; Arpigny, Claude ULg

in Astronomy and Astrophysics (1987), 187

Abstract image available at: http://cdsads.u-strasbg.fr/abs/1987A&A...187..523S

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See detailPhotoelectric scans of comet Halley.
Sterken, C.; Manfroid, Jean ULg; Hutsemekers, Damien ULg et al

in Diversity and Similarity of Comets (1987, September 01)

The authors compare radial photometric scans of comet Halley obtained in April 1986 at the European Southern Observatory, La Silla, Chile, with theoretical profiles derived from Haser's model.

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See detailHigh Resolution Spectroscopy and Analysis of the C[SUB]2[/SUB](0,0) Band in Comet P/Halley
Danks, A. C.; Lambert, D. L.; Sheffer, Y. et al

in Bulletin of the American Astronomical Society (1987, September 01)

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See detailOn the forbidden red lines of oxygen in comets
Arpigny, Claude ULg; Manfroid, Jean ULg; Magain, Pierre ULg et al

in Diversity and Similarity of Comets (1987, September 01)

Eighteen spectra of 8 different comets observed at high and medium resolution were analyzed in the 627 to 637 nm region to determine the contributions of the (OI) red doublet and of the various NH2 lines ... [more ▼]

Eighteen spectra of 8 different comets observed at high and medium resolution were analyzed in the 627 to 637 nm region to determine the contributions of the (OI) red doublet and of the various NH2 lines present in this wavelength interval. Results confirm that there exist appreciable variations not only in the (OI)/NH2 ratio, but also in the relative intensities of the NH2 features among themselves, therefore, it is not justified to derive the (OI) line flux from the 630.0 blend, as was done in previous low-resolution work, by assuming a fixed relative strength of the NH2 emission contained in this blend. Mapping of these emissions over the coma is recommended. [less ▲]

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See detailOn the interpretation of the CH cometary spectrum
Arpigny, Claude ULg; Zeippen, C. J.; Klutz, M. et al

in Diversity and Similarity of Comets (1987)

A procedure to compute cometary spectra taking into account radiative processes and collisional effects is described. The populations of the rotational levels are determined by solving the statistical ... [more ▼]

A procedure to compute cometary spectra taking into account radiative processes and collisional effects is described. The populations of the rotational levels are determined by solving the statistical equilibrium equations at a certain number of locations within the coma (which can be modelled with n(R), T(R), v(R) laws) and the emerging intensity is then evaluated by integrating the emissions along the line of sight. Such a program was applied to the CH radical. The importance of collisions in exciting the lower rotational levels of CH is confirmed. [less ▲]

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See detailResolution of the [O I]+NH[SUB]2[/SUB] blend in comets.
Arpigny, Claude ULg; Magain, Pierre ULg; Manfroid, Jean ULg et al

in Liege International Astrophysical Colloquia (1987)

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See detailPre- and postperihelion photometry of Comet Halley from several observatories
Sterken, C.; Manfroid, Jean ULg; Arpigny, Claude ULg

in ESLAB Symposium on the Exploration of Halley's Comet (1986, December 01)

Photoelectric observations of P/Halley were carried out during several weeks between 15 Sept. 1985 and 25 June 1986. All measurements were made using the standard IAU/IHW cometary filters. Large amplitude ... [more ▼]

Photoelectric observations of P/Halley were carried out during several weeks between 15 Sept. 1985 and 25 June 1986. All measurements were made using the standard IAU/IHW cometary filters. Large amplitude night-to-night changes over periods of several days superimposed on the general trend of slow brightness variation were seen. Smooth and irregular variations with a range up to 0.2 mag on time scales of several hours were observed. Present photometric scans of comet Halley through the various filters are presented. Successive integrations were made every 5 arc sec, radially from the center out to a distance of 5 arcmin, essentially along the sunward-antisunward direction and in the direction perpendicular to it. [less ▲]

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See detailResolution of the (OI) + NH2 blend in Comet P/Halley
Arpigny, Claude ULg; Magain, Pierre ULg; Manfroid, Jean ULg et al

in ESLAB Symposium on the Exploration of Halley's Comet (1986, December 01)

Spectra of P/Halley were taken at very high resolution (0.15A) to evaluate contamination of the forbidden oxygen doublet by NH2 features at low resolution. Comparison is made with other bright comets ... [more ▼]

Spectra of P/Halley were taken at very high resolution (0.15A) to evaluate contamination of the forbidden oxygen doublet by NH2 features at low resolution. Comparison is made with other bright comets. Appreciable variations are found in the NH2/(OI) ratio and in the relative intensities of the NH2 emissions themselves. The accuracy obtained on the oxygen abundance derived from the (OI) lines is discussed. Mapping of these emissions over the coma is required to correctly remove any important NH2 contribution at low resolution. This should also provide information on the origin of the oxygen atoms in the 1D level. [less ▲]

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See detailLong-slit pre and postperihelion spectrography of Comet P/Halley
Arpigny, Claude ULg; Dossin, F.; Zucconi, J. M. et al

in ESLAB Symposium on the Exploration of Halley's Comet (1986, December 01)

A series of about forty long-slit spectra of Halley's comet has been secured in the optical wavelength region, using different instruments, at resolution ranging from 0.05 to 1.6 nm. The interval of ... [more ▼]

A series of about forty long-slit spectra of Halley's comet has been secured in the optical wavelength region, using different instruments, at resolution ranging from 0.05 to 1.6 nm. The interval of heliocentric distance r covered by these observations is 1.7 to 0.9 a.u. before perihelion, while r = 0.95 a.u. after perihelion. The main characteristics of the pre-perihelion spectra are described. In particular, some emissions due to the OH[SUP]+[/SUP] (0,1) and CH[SUP]+[/SUP](1,0) bands have been detected for the first time. [less ▲]

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