References of "Hutsemekers, Damien"      in Complete repository Arts & humanities   Archaeology   Art & art history   Classical & oriental studies   History   Languages & linguistics   Literature   Performing arts   Philosophy & ethics   Religion & theology   Multidisciplinary, general & others Business & economic sciences   Accounting & auditing   Production, distribution & supply chain management   Finance   General management & organizational theory   Human resources management   Management information systems   Marketing   Strategy & innovation   Quantitative methods in economics & management   General economics & history of economic thought   International economics   Macroeconomics & monetary economics   Microeconomics   Economic systems & public economics   Social economics   Special economic topics (health, labor, transportation…)   Multidisciplinary, general & others Engineering, computing & technology   Aerospace & aeronautics engineering   Architecture   Chemical engineering   Civil engineering   Computer science   Electrical & electronics engineering   Energy   Geological, petroleum & mining engineering   Materials science & engineering   Mechanical engineering   Multidisciplinary, general & others Human health sciences   Alternative medicine   Anesthesia & intensive care   Cardiovascular & respiratory systems   Dentistry & oral medicine   Dermatology   Endocrinology, metabolism & nutrition   Forensic medicine   Gastroenterology & hepatology   General & internal medicine   Geriatrics   Hematology   Immunology & infectious disease   Laboratory medicine & medical technology   Neurology   Oncology   Ophthalmology   Orthopedics, rehabilitation & sports medicine   Otolaryngology   Pediatrics   Pharmacy, pharmacology & toxicology   Psychiatry   Public health, health care sciences & services   Radiology, nuclear medicine & imaging   Reproductive medicine (gynecology, andrology, obstetrics)   Rheumatology   Surgery   Urology & nephrology   Multidisciplinary, general & others Law, criminology & political science   Civil law   Criminal law & procedure   Criminology   Economic & commercial law   European & international law   Judicial law   Metalaw, Roman law, history of law & comparative law   Political science, public administration & international relations   Public law   Social law   Tax law   Multidisciplinary, general & others Life sciences   Agriculture & agronomy   Anatomy (cytology, histology, embryology...) & physiology   Animal production & animal husbandry   Aquatic sciences & oceanology   Biochemistry, biophysics & molecular biology   Biotechnology   Entomology & pest control   Environmental sciences & ecology   Food science   Genetics & genetic processes   Microbiology   Phytobiology (plant sciences, forestry, mycology...)   Veterinary medicine & animal health   Zoology   Multidisciplinary, general & others Physical, chemical, mathematical & earth Sciences   Chemistry   Earth sciences & physical geography   Mathematics   Physics   Space science, astronomy & astrophysics   Multidisciplinary, general & others Social & behavioral sciences, psychology   Animal psychology, ethology & psychobiology   Anthropology   Communication & mass media   Education & instruction   Human geography & demography   Library & information sciences   Neurosciences & behavior   Regional & inter-regional studies   Social work & social policy   Sociology & social sciences   Social, industrial & organizational psychology   Theoretical & cognitive psychology   Treatment & clinical psychology   Multidisciplinary, general & others     Showing results 21 to 40 of 220     1 2 3 4 5 6 7     Ejecta around evolved massive stars observed with HerschelVamvatira-Nakou, Chloi ; Hutsemekers, Damien ; Royer, P. et alConference (2012, March)Detailed reference viewed: 15 (6 ULg) The first X-ray survey of Galactic Luminous Blue VariablesNazé, Yaël ; Rauw, Grégor ; Hutsemekers, Damien in Astronomy and Astrophysics (2012), 538Aims: The X-ray emission of massive stars has been studied when these objects are in their main-sequence phase, as well as in their Wolf-Rayet phase. However, the X-ray properties of the transitional ... [more ▼]Aims: The X-ray emission of massive stars has been studied when these objects are in their main-sequence phase, as well as in their Wolf-Rayet phase. However, the X-ray properties of the transitional Luminous Blue Variable (LBV) phase remain unknown. Methods: Using a dedicated but limited XMM survey as well as archival XMM and Chandra observations, we performed the first X-ray survey of LBVs: about half of the known LBVs or candidate LBVs are studied. Results: Apart from the well known X-ray sources eta Car and Cyg OB2 #12, four additional LBVs are detected in this survey, though some doubt remains on the association with the X-ray source for two of these. For the other LBVs, upper limits on the flux were derived, down to $\log[L_{\rm X}/L_{\rm BOL}]-9.4$ for PCyg. This variety in the strength of the X-ray emission is discussed, with particular emphasis on the potential influence of binarity. [less ▲]Detailed reference viewed: 20 (1 ULg) New constraints on very light pseudoscalarsPayez, Alexandre ; Cudell, Jean-René ; Hutsemekers, Damien in Zioutas, K. (Ed.) 7th Patras Workshop on Axions, WIMPs and WISPs (2012, January 01)Nearly massless axion-like particles are of interest for astrophysical observations, and some constraints on their parameter space do exist in the literature. Here, we propose to put new constraints on ... [more ▼]Nearly massless axion-like particles are of interest for astrophysical observations, and some constraints on their parameter space do exist in the literature. Here, we propose to put new constraints on these particles using polarisation and, in particular, the polarisation differences observed between different quasar classes. [less ▲]Detailed reference viewed: 17 (10 ULg) Massive stars' nebulae, as seen through Herschel's eyesVamvatira-Nakou, Chloi ; Nazé, Yaël ; Hutsemekers, Damien et alPoster (2012)Detailed reference viewed: 46 (32 ULg) The C2-hydrocarbon link in cometary comaeWeiler, M.; Bockelée-Morvan, D.; Hutsemekers, Damien et alin EPSC Abstract 2012 (2012)Comet 8P/Tuttle was the target of an ESO multiwavelength observing campaign in 2008. Observations of the spatial distribution of C2 and C3 were obtained, as well as simultaneous direct detections of the ... [more ▼]Comet 8P/Tuttle was the target of an ESO multiwavelength observing campaign in 2008. Observations of the spatial distribution of C2 and C3 were obtained, as well as simultaneous direct detections of the C2 parent species C2H2 and C2H6. We combine these observations to investigate the origin of cometary C2. The observed C2 column densities are inconsistent with a production of C2 from C2H2, C2H6, and C3. Based on a photochemical model, we quantitatively discuss the influence of further potential C2 parent species. The assumption of C4H2 as an additional C2 parent species in comet 8P/Tuttle provides the best explanation for the observed C2 column densities. [less ▲]Detailed reference viewed: 24 (1 ULg) A Search For 15NH2 Lines In Comet C/2002 T7 (LINEAR)Rousselot, Philippe; Pirali, O.; Jehin, Emmanuel et alin Bulletin of the American Astronomical Society (2012), 44The determination of isotopic ratios in comets is of primary importance for a good understanding of their origin and the formation of solar system. The [SUP]14[/SUP]N/[SUP]15[/SUP]N ratio is an ... [more ▼]The determination of isotopic ratios in comets is of primary importance for a good understanding of their origin and the formation of solar system. The [SUP]14[/SUP]N/[SUP]15[/SUP]N ratio is an interesting tracer, because of its variability among various solar system bodies. So far it has only been measured in bright comets through optical observations of the CN radical (Arpigny et al., 2003; Manfroid et al., 2009) and millimeter observations of HCN (Bockelée-Morvan et al., 2005, 2008). The measurements give for both species the same non-terrestrial isotopic composition ([SUP]14[/SUP]N/[SUP]15[/SUP]N≈150 in comets versus 272 in the Earth atmosphere), but HCN and CN are minor species. In order to get a determination of this ratio in another molecule we have searched for [SUP]15[/SUP]NH[SUB]2[/SUB] lines in a high-resolution and high signal-to-noise ratio spectrum of comet C/2002 T7 (LINEAR) obtained with the UVES spectrometer at the VLT ESO 8-m telescope (Hutsemékers et al., 2008). This work is based on a new laboratory experiment conducted with the AILES beamline spectrometer at synchrotron SOLEIL to determine the [SUP]15[/SUP]NH[SUB]2[/SUB] wavelengths by Fourier transform spectroscopy. We will present the first results obtained from these data, which have allowed to search for the first time [SUP]15[/SUP]NH[SUB]2[/SUB] emission lines in a comet. References: Arpigny et al., 2003, Science, 301, 1522 Bockelée-Morvan et al.,2005, in Comets II, ed. M. C. Festou, H. U. Keller, & H. A. Weaver (Tucson: Univ. Arizona Press), 391 Bockelée-Morvan et al., 2008, ApJ, 679, L49 Hutsemékers et al., 2008, A&A 490, L31 Manfroid et al., 2009, A&A 503, 613 [less ▲]Detailed reference viewed: 6 (4 ULg) Study of the forbidden oxygen lines in a sample of cometary spectra obtained at the VLT (ESO)Decock, Alice ; Jehin, Emmanuel ; Manfroid, Jean et alPoster (2012)Detailed reference viewed: 17 (11 ULg) Fifty Years of Quasars. Quasars Classes and Their RelationshipsD'Onofrio, Mauro; Marziani, Paola; Sulentic, Jack W. et alin D'Onofrio, M. (Ed.) Fifty Years of Quasars: From Early Observations and Ideas to Future Research (2012)Most of the questions in this chapter deal with sources that do not show the "classical" broad emission-line spectrum that characterizes the majority of known AGNs at high and low redshift. If that ... [more ▼]Most of the questions in this chapter deal with sources that do not show the "classical" broad emission-line spectrum that characterizes the majority of known AGNs at high and low redshift. If that majority represents a "parent population" of AGNs, is the apparent absence of broad lines a result of obscuration, orientation, or different physical conditions? Can all of the subclasses be unified under the AGN umbrella? With the unification scheme set in place and assumed to be fundamentally correct, there are at least four overarching questions: do all type-2 AGNs possess an obscured broad-line region? Or how can we distinguishing type-2 AGNs without a broad-line region if they exist? Where is the low end of quasar activity? The least luminous AGNs are the so-called low-ionization nuclear emission-line regions (LINERs), but it is legitimate to ask if they are all true AGNs. [less ▲]Detailed reference viewed: 24 (1 ULg) Fifty Years of Quasars. From Observations to Physical ParametersD'Onofrio, Mauro; Marziani, Paola; Sulentic, Jack W. et alin D'Onofrio, M. (Ed.) Fifty Years of Quasars: From Early Observations and Ideas to Future Research (2012)Observational measures of AGNs allow us to directly infer some basic physical properties of quasars including (1) physical conditions and chemical abundances in the broad-line emitting gas as well as (2 ... [more ▼]Observational measures of AGNs allow us to directly infer some basic physical properties of quasars including (1) physical conditions and chemical abundances in the broad-line emitting gas as well as (2) radius of the line-emitting region, (3) black hole mass, (4) and Eddington ratio. In this chapter, we seek information on how these quantities are measured. One of the surprises of recent times, that would have shocked the discoverers in the 1960s are the large BH masses and high chemical abundances inferred for even some of the highest redshift quasars known. [less ▲]Detailed reference viewed: 25 (1 ULg) Large-Scale Alignments of Quasar Polarization Vectors: Evidence at Cosmological Scales for Very Light Pseudoscalar Particles Mixing with Photons ?Hutsemekers, Damien ; Payez, Alexandre ; Cabanac, R et alin Bastien, Pierre (Ed.) Astronomical Polarimetry 2008: Science from Small to Large Telescopes. ASPC 449 (2011, November 01)Based on a sample of 355 quasars with significant optical polarization, we found that quasar polarization vectors are not randomly oriented over the sky as naturally expected. The probability that the ... [more ▼]Based on a sample of 355 quasars with significant optical polarization, we found that quasar polarization vectors are not randomly oriented over the sky as naturally expected. The probability that the observed distribution of polarization angles is due to chance is lower than 0.1%. The polarization vectors of the light from quasars are aligned although the sources span huge regions of the sky (˜ 1 Gpc). Groups of quasars located along similar lines of sight but at different redshifts (typically z ≍ 0.5 and z ≍ 1.5) are characterized by different preferred directions of polarization. These characteristics make the observed alignment effect difficult to explain in terms of a local contamination by interstellar polarization in our Galaxy. Interpreted in terms of a cosmological-size effect, we show that the dichroism and birefringence predicted by a mixing between photons and very light pseudoscalar particles within a magnetic field can qualitatively reproduce the observations. We find that circular polarization measurements could help constrain this mechanism. [less ▲]Detailed reference viewed: 51 (30 ULg) New Insights into the Quasar Type 1/Type 2 Dichotomy from Correlations between Quasar Host Orientation and PolarizationBorguet, Benoît ; Hutsemekers, Damien ; Letawe, Géraldine et alin Bastien, Pierre (Ed.) Astronomical Polarimetry 2008: Science from Small to Large Telescopes. ASPC 449 (2011, November 01)We investigate correlations between the direction of the optical linear polarization and the orientation of the host galaxy/extended emission for type 1 and type 2 radio-loud and radio-quiet quasars. We ... [more ▼]We investigate correlations between the direction of the optical linear polarization and the orientation of the host galaxy/extended emission for type 1 and type 2 radio-loud and radio-quiet quasars. We have used high resolution Hubble Space Telescope data and a deconvolution process to obtain a good determination of the host galaxy/extended emission (EE) position angle. With these new measurements and a compilation of data from the literature, we find a significant correlation, different for type 1 and type 2 objects, between the linear polarization position angle and the orientation of the EE, suggesting scattering by an extended UV/blue region in both types of objects. Our observations support the extension of the Unification Model to the higher luminosity AGNs like the quasars, assuming a two component scattering model. [less ▲]Detailed reference viewed: 49 (23 ULg) Can axionlike particles explain the alignments of the polarisations of light from quasars?Payez, Alexandre ; Cudell, Jean-René ; Hutsemekers, Damien in Physical Review. D : Particles and Fields (2011), 84The standard axion-like particle explanation of the observed large-scale coherent orientations of quasar polarisation vectors is ruled out by the recent measurements of vanishing of circular polarisation ... [more ▼]The standard axion-like particle explanation of the observed large-scale coherent orientations of quasar polarisation vectors is ruled out by the recent measurements of vanishing of circular polarisation. We introduce a more general wave-packet formalism and show that, although decoherence effects between waves of different frequencies can reduce significantly the amount of circular polarisation, the axion-like particle hypothesis is disfavoured given the bandwidth with which part of the observations were performed. Finally, we show that a more sophisticated model of extragalactic fields does not lead to an alignment of polarisations. [less ▲]Detailed reference viewed: 92 (45 ULg) TRAPPIST: TRAnsiting Planets and PlanetesImals Small TelescopeJehin, Emmanuel ; Gillon, Michaël ; Queloz, D. et alin The Messenger (2011), 145TRAPPIST is a 60-cm robotic telescope that was installed in April 2010 at the ESO La Silla Observatory. The project is led by the Astrophysics and Image Processing group (AIP) at the Department of ... [more ▼]TRAPPIST is a 60-cm robotic telescope that was installed in April 2010 at the ESO La Silla Observatory. The project is led by the Astrophysics and Image Processing group (AIP) at the Department of Astrophysics, Geophysics and Oceanography (AGO) of the University of Liège, in close collaboration with the Geneva Observatory, and has been funded by the Belgian Fund for Scientific Research (F.R.S.-FNRS) and the Swiss National Science Foundation (SNF). It is devoted to the detection and characterisation of exoplanets and to the study of comets and other small bodies in the Solar System. We describe here the goals of the project and the hardware and present some results obtained during the first six months of operation. [less ▲]Detailed reference viewed: 21 (8 ULg) EPOXI: Comet 103P/Hartley 2 Observations from a Worldwide CampaignMeech, K. J.; A'Hearn, M. F.; Adams, J. A. et alin Astrophysical Journal (2011), 734(Letters), 11-9Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible ... [more ▼]Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is small and dark, and exhibited a very rapidly changing rotation period. Prior to the onset of activity, the period was ~16.4 hr. Starting in 2010 August the period changed from 16.6 hr to near 19 hr in December. With respect to dust composition, most volatiles and carbon and nitrogen isotope ratios, the comet is similar to other Jupiter-family comets. What is unusual is the dominance of CO[SUB]2[/SUB]-driven activity near perihelion, which likely persists out to aphelion. Near perihelion the comet nucleus was surrounded by a large halo of water-ice grains that contributed significantly to the total water production. [less ▲]Detailed reference viewed: 29 (4 ULg) Zooming into the broad line region of the gravitationally lensed quasar Q2237+0305 = the Einstein Cross: III. Determination of the size and structure of the CIV and CIII] emitting regions using microlensingSluse, D.; Schmidt, R.; Courbin, F. et alin Astronomy and Astrophysics (2011), 528Aims: We aim to use microlensing taking place in the lensed quasar Q2237+0305 to study the structure of the broad line region and measure the size of the region emitting the CIV and CIII] lines. Methods ... [more ▼]Aims: We aim to use microlensing taking place in the lensed quasar Q2237+0305 to study the structure of the broad line region and measure the size of the region emitting the CIV and CIII] lines. Methods: Based on 39 spectrophotometric monitoring data points obtained between Oct. 2004 and Dec. 2007, we derive lightcurves for the CIV and CIII] emission lines. We use three different techniques to analyse the microlensing signal. Different components of the lines (narrow, broad and very broad) are identified and studied. We build a library of simulated microlensing lightcurves which reproduce the signal observed in the continuum and in the lines provided only the source size is changed. A Bayesian analysis scheme is then developed to derive the size of the various components of the BLR. Results: 1. The half-light radius of the region emitting the CIV line is found to be R_CIV ~ 66^{+110}_{-46} lt-days = 0.06^{+0.09}_{-0.04} pc = 1.7^{+2.8}_{-1.1} 10^17 cm (at 68.3% CI). Similar values are obtained for CIII]. Relative sizes of the V-band continuum and of the carbon line emitting regions are also derived with median values of R(line)/R(cont) in the range [4,29], depending of the FWHM of the line component. 2. The size of the CIV emitting region agrees with the Radius-Luminosity relationship derived from reverberation mapping. Using the virial theorem we derive the mass of the black hole in Q2237+0305 to be M_BH ~ 10^{8.3+/-0.3} M_sun. 3. We find that the CIV and CIII] lines are produced in at least 2 spatially distinct regions, the most compact one giving rise to the broadest component of the line. The broad and narrow line profiles are slightly different for CIV and CIII]. 4. Our analysis suggests a different structure of the CIV and FeII+III emitting regions, with the latter being produced in the inner part of the BLR or in a less extended emitting region than CIV. [less ▲]Detailed reference viewed: 21 (6 ULg) Ortho-to-para Abundance Ratio (OPR) of Ammonia in 15 Comets: OPRs of Ammonia Versus 14N/15N Ratios in CNShinnaka, Yoshiharu; Kawakita, Hideyo; Kobayashi, Hitomi et alin Astrophysical Journal (2011), 729The ortho-to-para abundance ratio (OPR) of cometary molecules is considered to be one of the primordial characteristics of cometary ices. We present OPRs of ammonia (NH[SUB]3[/SUB]) in 15 comets based on ... [more ▼]The ortho-to-para abundance ratio (OPR) of cometary molecules is considered to be one of the primordial characteristics of cometary ices. We present OPRs of ammonia (NH[SUB]3[/SUB]) in 15 comets based on optical high-dispersion spectroscopic observations of NH[SUB]2[/SUB], which is a photodissociation product of ammonia in the gaseous coma. The observations were mainly carried out with the VLT/UVES. The OPR of ammonia is estimated from the OPR of NH[SUB]2[/SUB] based on the observations of the NH[SUB]2[/SUB] (0, 9, 0) vibronic band. The absorption lines by the telluric atmosphere are corrected and the cometary C[SUB]2[/SUB] emission lines blended with NH[SUB]2[/SUB] lines are removed in our analysis. The ammonia OPRs show a cluster between 1.1 and 1.2 (this corresponds to a nuclear spin temperature of ~30 K) for all comets in our sample except for 73P/Schwassmann-Wachmann 3 (73P/SW3). Comet 73P/SW3 (both B- and C-fragments) shows the OPR of ammonia consistent with nuclear spin statistical weight ratio (1.0) that indicates a high-temperature limit as nuclear spin temperature. We compared the ammonia OPRs with other properties ([SUP]14[/SUP]N/[SUP]15[/SUP]N ratios in CN, D/H ratios of water, and mixing ratios of volatiles). Comet 73P/SW3 is clearly different from the other comets in the plot of ammonia OPRs versus [SUP]14[/SUP]N/[SUP]15[/SUP]N ratios in CN. The ammonia OPRs of 1.0 and lower [SUP]15[/SUP]N-fractionation of CN in comet 73P/SW3 imply that icy materials in this comet formed under warmer conditions than other comets. Comets may be classified into two groups in the plot of ammonia OPRs against [SUP]14[/SUP]N/[SUP]15[/SUP]N ratios in CN. [less ▲]Detailed reference viewed: 22 (5 ULg) TRAPPIST: a robotic telescope dedicated to the study of planetary systemsGillon, Michaël ; Jehin, Emmanuel ; Magain, Pierre et alin EPJ Web of Conferences (2011, February 01), 11We present here a new robotic telescope called TRAPPIST1 (TRAnsiting Planets and PlanetesImals Small Telescope). Equipped with a high-quality CCD camera mounted on a 0 ... [more ▼]We present here a new robotic telescope called TRAPPIST1 (TRAnsiting Planets and PlanetesImals Small Telescope). Equipped with a high-quality CCD camera mounted on a 0.6 meter light weight optical tube, TRAPPIST has been installed in April 2010 at the ESO La Silla Observatory (Chile), and is now beginning its scientific program. The science goal of TRAPPIST is the study of planetary systems through two approaches: the detection and study of exoplanets, and the study of comets. We describe here the objectives of the project, the hardware, and we present some of the first results obtained during the commissioning phase. [less ▲]Detailed reference viewed: 16 (2 ULg) MESS (Mass-loss of Evolved StarS), a Herschel Key ProgramGroenewegen, M. A. T.; Waelkens, C.; Barlow, M. J. et alin Astronomy and Astrophysics (2011), 526MESS (Mass-loss of Evolved StarS) is a Guaranteed Time Key Program that uses the PACS and SPIRE instruments on board the Herschel Space Observatory to observe a representative sample of evolved stars ... [more ▼]MESS (Mass-loss of Evolved StarS) is a Guaranteed Time Key Program that uses the PACS and SPIRE instruments on board the Herschel Space Observatory to observe a representative sample of evolved stars, that include asymptotic giant branch (AGB) and post-AGB stars, planetary nebulae and red supergiants, as well as luminous blue variables, Wolf-Rayet stars and supernova remnants. In total, of order 150 objects are observed in imaging and about 50 objects in spectroscopy. This paper describes the target selection and target list, and the observing strategy. Key science projects are described, and illustrated using results obtained during Herschel's science demonstration phase. Aperture photometry is given for the 70 AGB and post-AGB stars observed up to October 17, 2010, which constitutes the largest single uniform database of far-IR and sub-mm fluxes for late-type stars. [less ▲]Detailed reference viewed: 46 (28 ULg) (596) ScheilaJehin, Emmanuel ; Manfroid, Jean ; Hutsemekers, Damien et alin Central Bureau Electronic Telegrams (CBETs) (2011), 2632E. Jehin, J. Manfroid, D. Hutsemekers, M. Gillon, and P. Magain, Fonds National de la Recherche Scientifique, Liege University, report on broad- and narrow-band imaging of the (596) Scheila outburst (CBET ... [more ▼]E. Jehin, J. Manfroid, D. Hutsemekers, M. Gillon, and P. Magain, Fonds National de la Recherche Scientifique, Liege University, report on broad- and narrow-band imaging of the (596) Scheila outburst (CBET 2583) with the TRAPPIST 0.60-m telescope at La Silla, and on optical spectroscopy with the European Southern Observatory's Very Large Telescope (VLT) at Paranal. R-band imaging from 2010 Dec. 12.3 to 21.3 UT revealed two arc-like coma features expanding at a regular pace. The first such feature was 1' long on 2010 Dec. 12, oriented to the northeast and bending to p.a. 280 deg (the anti-solar direction). The second feature was shorter, 30" on Dec. 12, oriented to the south and bending to p.a. 230 deg. Both features were getting larger and fainter with time (4' and 2' long, respectively, on Dec. 21.3). A narrow 45"-long tail, opposite the sun (p.a. 280 deg), was also observed in good seeing. R-band images taken on 2011 Jan. 4.3 and 5.3 after the full moon allowed Jehin et al. to again observe these features, seen as 7' and 4' long, respectively -- and much fainter. This discards any sustained activity of the minor planet. Narrow-band images obtained on 2010 Dec. 12.3 with cometary filters do not show any contribution from gases. A 20-min optical spectrum was obtained with FORS2 at the VLT on Dec. 13.3; it does not show any extended cometary gaseous emissions, but only a spatially extended continuum due to dust-scattered sunlight. Short B, V, R, and I exposures performed nearly every two nights from 2010 Dec. 12.3 to 2011 Jan. 5.3 give a magnitude for the nuclear condensation of V = 14.2 +/- 0.1 over the whole period, in agreement with the "APmag" value reported in the Jet Propulsion Laboratory ephemeris. No flux variation of the nuclear condensation was observed. Those preliminary results are in favor of a collisional scenario to explain the outburst of (596) Scheila, rather than a cometary driven activity. This case might be similar to the outburst of comet P/2010 A2, which may have resulted from an impact of a minor planet (Snodgrass 2010, Nature 467, 814). [less ▲]Detailed reference viewed: 26 (3 ULg) Herschel-PACS observations of Nebulae Ejected by Massive StarsVamvatira Nakou, Chloi ; Royer, Pierre; Hutsemekers, Damien et alin Bulletin de la Société Royale des Sciences de Liège (2011), 80The study of the nebulae ejected from Luminous Blue Variables and the circumstellar bubbles around Wolf-Rayet stars, which radiate strongly in the infrared due to the heating of dust, is crucial for the ... [more ▼]The study of the nebulae ejected from Luminous Blue Variables and the circumstellar bubbles around Wolf-Rayet stars, which radiate strongly in the infrared due to the heating of dust, is crucial for the understanding of the massive stars evolution. With Herschel we are able to observe these objects in the far-infrared region. In the context of the Mass-loss from Evolved StarS guaranteed time key program, we obtained imaging and spectroscopic observations of nebulae associated with Luminous Blue Variable and Wolf-Rayet stars using PACS, one of the three instruments on-board Herschel. A description of these observations, data analysis and preliminary results are presented. [less ▲]Detailed reference viewed: 44 (29 ULg)