References of "Manfroid, Jean"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailInvestigation of the stellar content in the western part of the Carina nebula
Kumar, Brajesh; Sharma, Saurabh; Manfroid, Jean ULg et al

in Astronomy and Astrophysics (2014), 567

Context. The low obscuration and proximity of the Carina nebula make it an ideal place to study the ongoing star formation process and impact of massive stars on low-mass stars in their surroundings. <BR ... [more ▼]

Context. The low obscuration and proximity of the Carina nebula make it an ideal place to study the ongoing star formation process and impact of massive stars on low-mass stars in their surroundings. <BR /> Aims: To investigate this process, we generated a new catalog of the pre-main-sequence stars in the Carina west (CrW) region and studied their nature and spatial distribution. We also determined various parameters (reddening, reddening law, age, mass), which are used further to estimate the initial mass function and K-band luminosity function for the region under study. <BR /> Methods: We obtained deep UBVRI Hα photometric data of the field situated to the west of the main Carina nebula and centered on WR 22. Medium-resolution optical spectroscopy of a subsample of X-ray selected objects along with archival data sets from Chandra, XMM-Newton and 2MASS surveys were used for the present study. Different sets of color-color and color-magnitude diagrams are used to determine reddening for the region and to identify young stellar objects (YSOs) and estimate their age and mass. <BR /> Results: Our spectroscopic results indicate that the majority of the X-ray sources are late spectral type stars. The region shows a large amount of differential reddening with minimum and maximum values of E(B - V) as 0.25 and 1.1 mag, respectively. Our analysis reveals that the total-to-selective absorption ratio R[SUB]V[/SUB] is ~3.7 ± 0.1, suggesting an abnormal grain size in the observed region. We identified 467 YSOs and studied their characteristics. The ages and masses of the 241 optically identified YSOs range from ~0.1 to 10 Myr and ~0.3 to 4.8 M[SUB]⊙[/SUB], respectively. However, the majority of them are younger than 1 Myr and have masses below 2 M[SUB]⊙[/SUB]. The high mass star WR 22 does not seem to have contributed to the formation of YSOs in the CrW region. The initial mass function slope, Γ, in this region is found to be -1.13 ± 0.20 in the mass range of 0.5 < M/M[SUB]⊙[/SUB] < 4.8. The K-band luminosity function slope (α) is also estimated as 0.31 ± 0.01. We also performed minimum spanning tree analysis of the YSOs in this region, which reveals that there are at least ten YSO cores associated with the molecular cloud, and that leads to an average core radius of 0.43 pc and a median branch length of 0.28 pc. Full Table 3 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A109">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A109</A> [less ▲]

Detailed reference viewed: 6 (3 ULg)
Full Text
Peer Reviewed
See detailExtremely Organic-rich Coma of Comet C/2010 G2 (Hill) during its Outburst in 2012
Kawakita, Hideyo; Dello Russo, Neil; Vervack, Ron et al

in Astrophysical Journal (2014), 788

We performed high-dispersion near-infrared spectroscopic observations of comet C/2010 G2 (Hill) at 2.5 AU from the Sun using NIRSPEC (R ≈ 25,000) at the Keck II Telescope on UT 2012 January 9 and 10 ... [more ▼]

We performed high-dispersion near-infrared spectroscopic observations of comet C/2010 G2 (Hill) at 2.5 AU from the Sun using NIRSPEC (R ≈ 25,000) at the Keck II Telescope on UT 2012 January 9 and 10, about a week after an outburst had occurred. Over the two nights of our observations, prominent emission lines of CH[SUB]4[/SUB] and C[SUB]2[/SUB]H[SUB]6[/SUB], along with weaker emission lines of H[SUB]2[/SUB]O, HCN, CH[SUB]3[/SUB]OH, and CO were detected. The gas production rate of CO was comparable to that of H[SUB]2[/SUB]O during the outburst. The mixing ratios of CO, HCN, CH[SUB]4[/SUB], C[SUB]2[/SUB]H[SUB]6[/SUB], and CH[SUB]3[/SUB]OH with respect to H[SUB]2[/SUB]O were higher than those for normal comets by a factor of five or more. The enrichment of CO and CH[SUB]4[/SUB] in comet Hill suggests that the sublimation of these hypervolatiles sustained the outburst of the comet. Some fraction of water in the inner coma might exist as icy grains that were likely ejected from nucleus by the sublimation of hypervolatiles. Mixing ratios of volatiles in comet Hill are indicative of the interstellar heritage without significant alteration in the solar nebula. [less ▲]

Detailed reference viewed: 3 (0 ULg)
Full Text
See detailThe binary near-Earth asteroid (175706) 1996 FG3 - An observational constraint on its orbital stability
Scheirich, P.; Pravec, P.; Jacobson, S. A. et al

E-print/Working paper (2014)

Using our photometric observations taken between April 1996 and January 2013 and other published data, we derive properties of the binary near-Earth asteroid (175706) 1996 FG3 including new measurements ... [more ▼]

Using our photometric observations taken between April 1996 and January 2013 and other published data, we derive properties of the binary near-Earth asteroid (175706) 1996 FG3 including new measurements constraining evolution of the mutual orbit with potential consequences for the entire binary asteroid population. We also refined previously determined values of parameters of both components, making 1996 FG3 one of the most well understood binary asteroid systems. We determined the orbital vector with a substantially greater accuracy than before and we also placed constraints on a stability of the orbit. Specifically, the ecliptic longitude and latitude of the orbital pole are 266{\deg} and -83{\deg}, respectively, with the mean radius of the uncertainty area of 4{\deg}, and the orbital period is 16.1508 +\- 0.0002 h (all uncertainties correspond to 3sigma). We looked for a quadratic drift of the mean anomaly of the satellite and obtained a value of 0.04 +\- 0.20 deg/yr^2, i.e., consistent with zero. The drift is substantially lower than predicted by the pure binary YORP (BYORP) theory of McMahon and Scheeres (McMahon, J., Scheeres, D. [2010]. Icarus 209, 494-509) and it is consistent with the theory of an equilibrium between BYORP and tidal torques for synchronous binary asteroids as proposed by Jacobson and Scheeres (Jacobson, S.A., Scheeres, D. [2011]. ApJ Letters, 736, L19). Based on the assumption of equilibrium, we derived a ratio of the quality factor and tidal Love number of Q/k = 2.4 x 10^5 uncertain by a factor of five. We also derived a product of the rigidity and quality factor of mu Q = 1.3 x 10^7 Pa using the theory that assumes an elastic response of the asteroid material to the tidal forces. This very low value indicates that the primary of 1996 FG3 is a 'rubble pile', and it also calls for a re-thinking of the tidal energy dissipation in close asteroid binary systems. [less ▲]

Detailed reference viewed: 4 (0 ULg)
Full Text
Peer Reviewed
See detailPhase resolved X-ray spectroscopy of HDE 288766: Probing the wind of an extreme Of+/WNLha star
Rauw, Grégor ULg; Mahy, Laurent; Nazé, Yaël ULg et al

in Astronomy and Astrophysics (2014), 566

Context. HDE 228766 is a very massive binary system hosting a secondary component, which is probably in an intermediate evolutionary stage between an Of supergiant and an WN star. The wind of this star ... [more ▼]

Context. HDE 228766 is a very massive binary system hosting a secondary component, which is probably in an intermediate evolutionary stage between an Of supergiant and an WN star. The wind of this star collides with the wind of its O8 II companion, leading to relatively strong X-ray emission. <BR /> Aims: Measuring the orbital variations of the line-of-sight absorption toward the X-ray emission from the wind-wind interaction zone yields information on the wind densities of both stars. <BR /> Methods: X-ray spectra have been collected at three key orbital phases to probe the winds of both stars. Optical photometry has been gathered to set constraints on the orbital inclination of the system. <BR /> Results: The X-ray spectra reveal prominent variations of the intervening column density toward the X-ray emission zone, which are in line with the expectations for a wind-wind collision. We use a toy model to set constraints on the stellar wind parameters by attempting to reproduce the observed variations of the relative fluxes and wind optical depths at 1 keV. <BR /> Conclusions: The lack of strong optical eclipses sets an upper limit of ~ 68° on the orbital inclination. The analysis of the variations of the X-ray spectra suggests an inclination in the range 54-61° and indicates that the secondary wind momentum ratio exceeds that of the primary by at least a factor 5. Our models further suggest that the bulk of the X-ray emission arises from the innermost region of the wind interaction zone, which is from a region whose outer radius, as measured from the secondary star, lies between 0.5 and 1.5 times the orbital separation. Based on observations collected with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and the USA (NASA), and on data collected at the San Pedro Mártir observatory (Mexico). [less ▲]

Detailed reference viewed: 5 (1 ULg)
Full Text
Peer Reviewed
See detailToward a Unique Nitrogen Isotopic Ratio in Cometary Ices
Rousselot, Philippe; Pirali, Olivier; Jehin, Emmanuel ULg et al

in Astrophysical Journal Letters (2014), 780

Determination of the nitrogen isotopic ratios in different bodies of the solar system provides important information regarding the solar system's origin. We unambiguously identified emission lines in ... [more ▼]

Determination of the nitrogen isotopic ratios in different bodies of the solar system provides important information regarding the solar system's origin. We unambiguously identified emission lines in comets due to the [SUP]15[/SUP]NH[SUB]2[/SUB] radical produced by the photodissociation of [SUP]15[/SUP]NH[SUB]3[/SUB]. Analysis of our data has permitted us to measure the [SUP]14[/SUP]N/[SUP]15[/SUP]N isotopic ratio in comets for a molecule carrying the amine (-NH) functional group. This ratio, within the error, appears similar to that measured in comets in the HCN molecule and the CN radical, and lower than the protosolar value, suggesting that N[SUB]2[/SUB] and NH[SUB]3[/SUB] result from the separation of nitrogen into two distinct reservoirs in the solar nebula. This ratio also appears similar to that measured in Titan's atmospheric N[SUB]2[/SUB], supporting the hypothesis that, if the latter is representative of its primordial value in NH[SUB]3[/SUB], these bodies were assembled from building blocks sharing a common formation location. [less ▲]

Detailed reference viewed: 17 (6 ULg)
Full Text
Peer Reviewed
See detailExtremely Organic-rich Coma of Comet C/2010 G2 (Hill) during its Outburst in 201
Kawakita, H; Dello Russo; Vervack, R et al

in Astrophysical Journal (2014)

Detailed reference viewed: 11 (2 ULg)
Full Text
Peer Reviewed
See detailThe tumbling spin state of (99942) Apophis
Pravec, P; Scheirich, P; Ďurech, J et al

in Icarus (2014), 233

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailContinued activity in P/2013 P5 PANSTARRS - The comet that should not be
Hainaut, O. R.; Boehnhardt, H.; Snodgrass, C. et al

in Astronomy and Astrophysics (2014)

Detailed reference viewed: 18 (2 ULg)
Full Text
Peer Reviewed
See detailA ring system detected around the Centaur (10199) Chariklo
Braga-Ribas; Sicardy; Ortiz et al

in Nature (2014)

Detailed reference viewed: 16 (4 ULg)
Full Text
Peer Reviewed
See detailHerschel observations of gas and dust in comet C/2006 W3 (Christensen) at 5 AU from the Sun
de Val-Borro, M; Bockelée-Morvan, D; Jehin, Emmanuel ULg et al

in Astronomy and Astrophysics (2014)

Detailed reference viewed: 7 (1 ULg)
Full Text
See detailL'astronomie dans le monde - 12
Manfroid, Jean ULg

Article for general public (2013)

ISON; (3200) Phaéton; Titan, lacs et hydrocarbures;Titan et le Soleil; Jets; z8_GND_5296; La nébuleuse de la Crevette; Planète isolée; Nébuleuse Toby Jug; Le pulsar du Crabe; Le bulbe de la Voie lactée ... [more ▼]

ISON; (3200) Phaéton; Titan, lacs et hydrocarbures;Titan et le Soleil; Jets; z8_GND_5296; La nébuleuse de la Crevette; Planète isolée; Nébuleuse Toby Jug; Le pulsar du Crabe; Le bulbe de la Voie lactée; ALMA au grand complet; APEX, ArTéMiS; Sgr A*; Première détection de l’acétate de méthyle dans l’espace [less ▲]

Detailed reference viewed: 12 (1 ULg)
Full Text
See detailComet C/2012 S1 (Ison)
Lisse, C. M.; Wolk, S. J.; Christian, D. J. et al

in Central Bureau Electronic Telegrams (2013), 3719

CBET 3719 available at Central Bureau for Astronomical Telegrams.

Detailed reference viewed: 21 (2 ULg)
Full Text
See detailComet C/2012 S1 (Ison)
Opitom, Cyrielle ULg; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Central Bureau Electronic Telegrams (2013), 3693

CBET 3693 available at Central Bureau for Astronomical Telegrams.

Detailed reference viewed: 12 (4 ULg)
Full Text
See detailComet C/2012 S1 (Ison)
Crovisier, J.; Colom, P.; Biver, N. et al

in Central Bureau Electronic Telegrams (2013), 3711

CBET 3711 available at Central Bureau for Astronomical Telegrams.

Detailed reference viewed: 18 (4 ULg)
Full Text
See detailStudy of the Forbidden Oxygen Lines in Comets at Different Heliocentric and Nucleocentric Distances
Decock, Alice ULg; Rousselot, P.; Jehin, Emmanuel ULg et al

in Bulletin of the American Astronomical Society (2013, October 01), 45

Oxygen is an important element in the chemistry of the solar system objects given its abundance and its presence in many molecules including H2O 80% of cometary ices). The analysis of oxygen atoms in ... [more ▼]

Oxygen is an important element in the chemistry of the solar system objects given its abundance and its presence in many molecules including H2O 80% of cometary ices). The analysis of oxygen atoms in comets can provide information not only on the comets themselves but also on the solar system. These atoms have been analyzed using the 3 forbidden oxygen lines [OI] observed in emission in the optical region at 5577.339 Å (the green line), 6300.304 Å and 6363.776 Å (the red lines) (Swings, 1962). Our analysis is based on a sample of 12 comets of various origins. The observing material is made of 53 high signal-to-noise spectra obtained with the high-resolution UVES spectrograph at the ESO VLT from 2002 to 2012 (Manfroid et al, 2009). After noticing that the green line is blended with one C2 line, we built synthetic spectra of C2 for each observing circumstances and we subtracted its contribution to the cometary spectra in order to ensure the decontamination of the 5577 Å line. Then, we measured the intensity of the 3 [OI] lines at different heliocentric distances. By comparing the green to red lines ratio (G/R) with the Bhardwaj & Raghuram (2012) effective excitation rates, we found that H2O is the main parent molecule when the comet is observed at 1 au. When the comet is located beyond 2.5 au from the Sun, CO2 also contributes to the production of oxygen. Studying forbidden oxygen lines could be a new way to estimate the abundances of CO2 in comets, a very difficult task from the ground (Decock et al. 2013). In order to estimate the effect of the quenching on our results, we analyzed the evolution of the G/R ratio at different nucleocentric distances. For nearby comets, we divided the extended 2D spectrum into several zones in order to analyze the oxygen lines as close as possible to the nucleus (down to ~10 km for the closest comets). Their analysis will allow us to study the link of the oxygen lines with the nucleocentric distance. We found a clear variation of the G/R ratio close to the comet nucleus that is in agreement with a contribution from CO2 as predicted by Raghuram & Bhardwaj (2013). [less ▲]

Detailed reference viewed: 31 (6 ULg)
Full Text
See detailA Search For 15NH2 Emission Lines In Comets
Rousselot, Philippe; Pirali, O.; Jehin, Emmanuel ULg et al

in Bulletin of the American Astronomical Society (2013, October 01), 45

The determination of nitrogen isotopic ratios in solar system objects is important for a good understanding of their origin. The measurements of [SUB]14[/SUB]N/[SUB]15[/SUB]N isotopic ratio done so far in ... [more ▼]

The determination of nitrogen isotopic ratios in solar system objects is important for a good understanding of their origin. The measurements of [SUB]14[/SUB]N/[SUB]15[/SUB]N isotopic ratio done so far in various solar system objects and molecules have revealed a great diversity (from 50 to 441), all of them, except Jupiter, being enriched in [SUB]15[/SUB]N compared to the protosolar nebula. Different explanations have been proposed to explain this enrichement. One of them suggests that these differences reflect the different interstellar N reservoirs from which N-bearing molecules are originating (Hily-Blant et al., 2013). These authors, from observations of H[SUB]13[/SUB]CN and HC[SUB]15[/SUB]N in two prestellar cores, suggest that the molecules carrying the nitrile- (-CN) functional group would be more enriched in [SUB]15[/SUB]N than the molecules carrying the amine (-NH) functional group. Comets are interesting targets to test this theory because they contain both HCN and NH[SUP]3[/SUP] molecules. So far the [SUB]14[/SUB]N/[SUB]15[/SUB]N ratio has only been measured in CN (Arpigny et al., 2003; Manfroid et al., 2009) and HCN (Bockelée-Morvan et al., 2005, 2008) in comets, leading for both species to [SUB]14[/SUB]N/[SUB]15[/SUB]N ≈ 150. Our work aimed at measuring the [SUB]14[/SUB]N/[SUB]15[/SUB]N isotopic ratio in NH[SUP]2[/SUP], which comes from NH[SUP]3[/SUP]. We have determined accurately the wavelengths of [SUB]15[/SUB]NH[SUP]2[/SUP] emission lines with the AILES beamline spectrometer at synchrotron SOLEIL by Fourier transform spectroscopy. The analysis of this spectrum has permitted to extract the [SUB]15[/SUB]NH[SUP]2[/SUP] emission lines wavelengths and to search for [SUB]15[/SUB]NH[SUP]2[/SUP] cometary emission lines. Thanks to a collection of spectra of 12 different comets obtained from 2002 to 2011 with the UVES spectrometer at the VLT ESO 8-m telescope (Manfroid et al., 2009), it has been possible to search for [SUB]15[/SUB]NH[SUP]2[/SUP] emission lines with a high sensitivity. We will present the results obtained from these data. Arpigny et al., Science, 301, 1522-1525, 2003 Bockelée-Morvan et al., in Comets II, ed. M. C. Festou, H. U. Keller, & H. A. Weaver (Tucson: Univ. Arizona Press), 391-423, 2005 Bockelée-Morvan et al., ApJ, 679, L49-L52, 2008 Hily-Blant et al., Icarus 223, 582-590, 2013 Manfroid et al., A&A, 503, 613-624, 2009 [less ▲]

Detailed reference viewed: 22 (1 ULg)
Full Text
See detailL'astronomie dans le monde - 10
Manfroid, Jean ULg

Article for general public (2013)

Alignement des nébuleusesplanétaires; Jumeau solaire; HH46/47; M87; Nébuleuses du Grand Nuage; Champ magnétique galactique; Aux frontières du Système solaire; Supernova; Sgr A*; Le courant magellanique ... [more ▼]

Alignement des nébuleusesplanétaires; Jumeau solaire; HH46/47; M87; Nébuleuses du Grand Nuage; Champ magnétique galactique; Aux frontières du Système solaire; Supernova; Sgr A*; Le courant magellanique; Naines brunes; 4C12.50 [less ▲]

Detailed reference viewed: 9 (1 ULg)
Full Text
See detailISON (C/2012 S1)
Manfroid, Jean ULg

Article for general public (2013)

Detailed reference viewed: 9 (0 ULg)
Full Text
See detailComet dust profiles from PACS images obtained in the framework of the HSSO project
Opitom, Cyrielle ULg; Bockelée-Morvan, D.; Hutsemekers, Damien ULg et al

Poster (2013, October)

In the framework of the HssO project the Herschel PACS instrument acquired images of 7 comets between June 2010 and February 2013. Three of these comets have been imaged at several heliocentric distances ... [more ▼]

In the framework of the HssO project the Herschel PACS instrument acquired images of 7 comets between June 2010 and February 2013. Three of these comets have been imaged at several heliocentric distances allowing us to follow up the evolution of the dust coma . Radial profiles have been derived for each image. We measured flux densities at 70, 110 and 160 μm in order to determine the comet dust production rate. In some cases, after deconvolution by the instrumental PSF, we might have detected the nucleus signal in the central pixels. [less ▲]

Detailed reference viewed: 8 (3 ULg)