A Be-type star with a black-hole companion

Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions (this gas is either stripped from low-mass stars or supplied as winds from massive ones). Binary evolution models also predict the existence of black holes accreting from the equatorial envelope of rapidly spinning Be-type stars (stars of the Be type are hot blue irregular variables showing characteristic spectral emission lines of hydrogen). Of the ~80 Be X-ray binaries known in the Galaxy, however, only pulsating neutron stars have been found as companions. A black hole was formally allowed as a solution for the companion to the Be star MWC 656 (also known as HD 215227), although that was based on a single radial velocity curve of the Be star, a mistaken spectral classification and rough estimates of the inclination angle. Here we report observations of an accretion disk line mirroring the orbit of the Be star. This, together with an improved radial velocity curve of the Be star through fitting sharp Fe II profiles from the equatorial disk, and a refined Be classification (to that of a B1.5-B2 III star), reveals a black hole of 3.8 to 6.9 solar masses orbiting MWC 656, the candidate counterpart of the gamma-ray source AGL J2241+4454. The black hole is X-ray quiescent and fed by a radiatively inefficient accretion flow giving a luminosity less than 1.6 x 10-7 times the Eddington luminosity. This implies that Be binaries with black-hole companions are difficult to detect by conventional X-ray surveys.

Sensory characteristics of 'Douradão' peaches submitted to modified atmosphere packaging

The sensory, physical and chemical characteristics of 'Douradão' peaches cold stored in different modified atmosphere packaging (LDPE bags of 30, 50, 60, 75µm thickness) were studied. After 14, 21 and 28 days of cold storage (1 ± 1 ºC and 90 ± 5% RH), samples were withdrawn from MAP and kept during 4 days in ambient air for ripening. Descriptive terminology and sensory profile of the peaches were developed by methodology based on the Quantitative Descriptive Analysis (QDA). The assessors consensually defined the sensory descriptors, their respective reference materials and the descriptive evaluation ballot. Fourteen individuals were selected as judges based on their discrimination capacity and reproducibility. Seven descriptors were generated showing similarities and differences among the samples. The data were analysed by ANOVA, Tukey test and Principal Component Analysis (PCA). The atmospheres that developed inside the different packaging materials during cold storage differed significantly. The PCA showed that MA50 and MA60 treatments were more characterized by the fresh peach flavour, fresh appearance, juiciness and flesh firmness, and were effective for keeping good quality of 'Douradão' peaches during 28 d of cold storage. The Control and MA30 treatments were characterized by the mealiness, the MA75 treatment showed lower intensity for all attributes evaluated and they were ineffective to maintain good quality of the fruits during cold storage. Higher correlation coefficients (positive) were found between fresh appearance and flesh firmness (0.95), fresh appearance and juiciness (0.97), ratio and intensity of fresh peach smell (0.81), as well as higher correlation coefficients (negative) between Hue angle and intensity of yellow colour (-0.91), fresh appearance and mealiness (-0.92), juiciness and mealiness (-0.95), firmness and mealiness (-0.94).

The star forming region Monoceros R2 as a gamma-ray source

After the release of the gamma-ray source catalog produced by the Fermi satellite during its first two years of operation, a significant fraction of sources still remain unassociated at lower energies. In addition to well-known high-energy emitters (pulsars, blazars, supernova remnants, etc.), theoretical expectations predict new classes of gamma-ray sources. In particular, gamma-ray emission could be associated with some of the early phases of stellar evolution, but this interesting possibility is still poorly understood. Aims: The aim of this paper is to assess the possibility of the Fermi gamma-ray source 2FGL J0607.5-0618c being associated with the massive star forming region Monoceros R2. Methods: A multi-wavelength analysis of the Monoceros R2 region is carried out using archival data at radio, infrared, X-ray, and gamma-ray wavelengths. The resulting observational properties are used to estimate the physical parameters needed to test the different physical scenarios. Results: We confirm the 2FGL J0607.5-0618c detection with improved confidence over the Fermi two-year catalog. We find that a combined effect of the multiple young stellar objects in Monoceros R2 is a viable picture for the nature of the source.

Very-High-Energy gamma rays from a Distant Quasar: How Transparent Is the Universe?

The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Because high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.

Assessment of dissolution techniques for the analysis of ceramic samples by plasma spectrometry

In this study, 13 ceramic samples were subjected to dissolution using three different procedures: (a) acid attack in open PTFE vessels with a mixture of HF-HClO4, (b) fusion of the sample with lithium metaborate and (c) microwave digestion in PTFE bombs. The samples used in the study had been previously analyzed by neutron activation analysis (NAA), X-ray fluorescence (XRF) and X-ray diffraction (XRD) and they cover a wide range of ceramics fired in different atmospheres and temperatures as well as different mineralogical and chemical compositions. The effectiveness of each procedure is evaluated in terms of its ability to dissolve the various mineralogical phases of the samples, of the number of elements that can be determined and of the time needed for the whole scheme of analysis to be completed.

Räjähdyssuojausasiakirjan vaatima riskin arviointi muille kuin sähkölaitteille

Turvatekniikan keskuksella (TUKES) on valvottavanaan noin 1 000 teollisuuslaitosta, joissa on räjähdysvaarallisia tiloja. Olosuhdedirektiivin (1999/92/EY) mukainen kansal-linen asetus (VNa 576/2003) tuli voimaan 1.9.2003. Asetus koskee uusia räjähdysvaa-rallisia tiloja välittömästi, kun taas käytössä olevat tilat on saatettava sen mukaisiksi 30.6.2006 mennessä. Asetus edellyttää, että työnantaja laatii räjähdysvaarallisille tiloille räjähdyssuojausasiakirjan ja arvioi kirjallisesti näissä tiloissa käytettävien, ilman Ex-merkkiä olevien työvälineiden riskin. Räjähdyssuojausasiakirjan ja kirjallisena tehdyn riskin arvioinnin eräs keskeinen tarkoitus on varmistaa mahdollisten syttymislähteiden laaja-alainen hallinta ja pienentää onnettomuusriskiä. Tässä diplomityössä selvitetään, mitä riskin arvioinnin täytyy sisältää ja etsitään tehokas menetelmä arvioinnin tekoon. Kolmelta yritykseltä saatiin tutkittavaksi niiden alalle tyypillinen muu kuin sähkölaite, jota käytetään räjähdysvaarallisessa tilassa. Laitteiden tuli olla Ex-merkittömiä ja olla ollut käytössä ennen asetuksen voimaan tuloa. Laitteiden ja niiden dokumenttien tutkimisella testattiin eri menetelmien soveltuvuutta riskin arviointiin. Samalla selvitettiin jo käytössä olevien laitteiden turvallisuustaso. Jokaisen pilottitapauksen kohdalla on arvioinnissa menetelty eri tavoin. Työssä esitellään keskeisimmät menetelmät, joilla riskin arviointi voidaan tehdä. Suosi-tuksena esitellään ratkaisumalli, jonka avulla voidaan päätellä laitteen tarvitsema riskinarviointimenetelmä. Pilottitapauksia arvioitiin laitteiden sijoituksen ja lukumäärän pohjalta. Suosituksena on, että riskin arvioinnissa lähdetään liikkeelle itse laitteesta ja sen soveltuvuudesta räjähdysvaaralliseen tilaan. Tällä tavalla pystytään kohdistamaan käytössä olevat resurssit paremmin niihin laitteisiin, jotka vaativat tarkemman riskin arvioinnin. Pilottitapausten perusteella räjähdysvaaralliseen tilaan tarkoitetut laitteet soveltuivat käytettäväksi tarkoitetussa käytössään. Räjähdyssuojausasiakirjaa varten on dokumentoitava tiedot niiden käytöstä, mahdollisista syttymislähteistä ja suojaavista toimenpiteistä.

Gaia photometry for white dwarfs

Context. White dwarfs can be used to study the structure and evolution of the Galaxy by analysing their luminosity function and initial mass function. Among them, the very cool white dwarfs provide the information for the early ages of each population. Because white dwarfs are intrinsically faint only the nearby (~ 20 pc) sample is reasonably complete. The Gaia space mission will drastically increase the sample of known white dwarfs through its 5-6 years survey of the whole sky up to magnitude V = 20-25. Aims. We provide a characterisation of Gaia photometry for white dwarfs to better prepare for the analysis of the scientific output of the mission. Transformations between some of the most common photometric systems and Gaia passbands are derived. We also give estimates of the number of white dwarfs of the different galactic populations that will be observed. Methods. Using synthetic spectral energy distributions and the most recent Gaia transmission curves, we computed colours of three different types of white dwarfs (pure hydrogen, pure helium, and mixed composition with H/He = 0.1). With these colours we derived transformations to other common photometric systems (Johnson-Cousins, Sloan Digital Sky Survey, and 2MASS). We also present numbers of white dwarfs predicted to be observed by Gaia. Results. We provide relationships and colour-colour diagrams among different photometric systems to allow the prediction and/or study of the Gaia white dwarf colours. We also include estimates of the number of sources expected in every galactic population and with a maximum parallax error. Gaia will increase the sample of known white dwarfs tenfold to about 200 000. Gaia will be able to observe thousands of very cool white dwarfs for the first time, which will greatly improve our understanding of these stars and early phases of star formation in our Galaxy.

Discovery of a High-Energy Gamma-Ray-Emitting Persistent Microquasar

Microquasars are stellar x-ray binaries that behave as a scaled down version of extragalactic quasars. The star LS 5039 is a new microquasar system with apparent persistent ejection of relativistic plasma at a 3 kiloparsec distance from the sun. It may also be associated with a gamma-ray source discovered by the Energetic Gamma Ray Experiment Telescope (EGRET) on board the COMPTON-Gamma Ray Observatory satellite. Before the discovery of LS 5039, merely a handful of microquasars had been identified in the Galaxy, and none of them was detected in high-energy gamma-rays.

Deep GMRT radio observations and a multi-wavelength study of the region around HESS J1858+020

Context. There are a number of very high energy sources in the Galaxy that remain unidentified. Multi-wavelength and variability studies, and catalogue searches, are powerful tools to identify the physical counterpart, given the uncertainty in the source location and extension. Aims. This work carries out a thorough multi-wavelength study of the unidentified, very high energy source HESS J1858+020 and its environs. Methods. We have performed Giant Metrewave Radio Telescope observations at 610 MHz and 1.4 GHz to obtain a deep, low-frequency radio image of the region surrounding HESS J1858+020. We analysed archival radio, infrared, and X-ray data as well. This observational information, combined with molecular data, catalogue sources, and a nearby Fermi gamma-ray detection of unidentified origin, are combined to explore possible counterparts to the very high energy source. Results. We provide with a deep radio image of a supernova remnant that might be related to the GeV and TeV emission in the region. We confirm the presence of an H ii region next to the supernova remnant and coincident with molecular emission. A potential region of star formation is also identified. We identify several radio and X-ray sources in the surroundings. Some of these sources are known planetary nebulae, whereas others may be non-thermal extended emitters and embedded young stellar objects. Three old, background Galactic pulsars also neighbour HESS J1858+020 along the line of sight. Conclusions. The region surrounding HESS J1858+020 is rich in molecular structures and non-thermal objects that may potentially be linked to this unidentified very high energy source. In particular, a supernova remnant interacting with nearby molecular clouds may be a good candidate, but a star forming region, or a non-thermal radio source of yet unclear nature, may also be behind the gamma-ray source. The neighbouring pulsars, despite being old and distant, cannot be discarded as candidates. Further observational studies are needed, however, to narrow the search for a counterpart to the HESS source.

Optical spectroscopy of microquasar candidates at low Galactic latitudes

We report optical spectroscopic observations of a sample of 6 low-galactic latitude microquasar candidates selected by cross-identification of X-ray and radio point source catalogs for |b|<5 degrees. Two objects resulted to be of clear extragalactic origin, as an obvious cosmologic redshift has been measured from their emission lines. For the rest, none exhibits a clear stellar-like spectrum as would be expected for genuine Galactic microquasars. Their featureless spectra are consistent with being extragalactic in origin although two of them could be also highly reddened stars. The apparent non-confirmation of our candidates suggests that the population of persistent microquasar systems in the Galaxy is more rare than previously believed. If none of them is galactic, the upper limit to the space density of new Cygnus X-3-like microquasars within 15 kpc would be 1.1\times10^{-12} per cubic pc. A similar upper limit for new LS 5039-like systems within 4 kpc is estimated to be 5.6\times10^{-11} per cubic pc.

LS 5039: A runaway microquasar ejected from the galactic plane

We have compiled optical and radio astrometric data of the microquasar LS 5039 and derived its proper motion. This, together with the distance and radial velocity of the system, allows us to state that this source is escaping from its own regional standard of rest, with a total systemic velocity of about 150 km/s and a component perpendicular to the galactic plane larger than 100 km/s. This is probably the result of an acceleration obtained during the supernova event that created the compact object in this binary system. We have computed the trajectory of LS 5039 in the past, and searched for OB associations and supernova remnants in its path. In particular, we have studied the possible association between LS 5039 and the supernova remnant G016.8-01.1, which, despite our efforts, remains dubious. We have also discovered and studied an HI cavity in the ISM, which could have been created by the stellar wind of LS 5039 or by the progenitor of the compact object in the system. Finally, in the symmetric supernova explosion scenario, we estimate that at least 17 solar masses were lost in order to produce the high eccentricity observed. Such a mass loss could also explain the observed runaway velocity of the microquasar.

High mass microquasars and low latitude gamma-ray sources

Population studies of unidentified EGRET sources suggest that there exist at least three different populations of galactic gamma-ray sources. One of these populations is formed by young objects distributed along the galactic plane with a strong concentration toward the inner spiral arms of the Galaxy. Variability, spectral and correlation analysis indicate that this population is not homogeneous. In particular, there is a subgroup of sources that display clear variability in their gamma-ray fluxes on timescales from days to months. Following the proposal by Kaufman Bernad\'o et al. (2002), we suggest that this group of sources might be high-mass microquasars, i.e. accreting black holes or neutron stars with relativistic jets and early-type stellar companions. We present detailed inhomogeneous models for the gamma-ray emission of these systems that include both external and synchrotron self-Compton interactions. We have included effects of interactions between the jet and all external photon fields to which it is exposed: companion star, accretion disk, and hot corona. We make broadband calculations to predict the spectral energy distribution of these objects from radio up to GeV energies. The results and predictions can be tested by present and future gamma-ray instruments like INTEGRAL, AGILE, and GLAST.

Massive protostars as gamma-ray sources.

Massive protostars have associated bipolar outflows with velocities of hundreds of km s-1. Such outflows can produce strong shocks when they interact with the ambient medium leading to regions of nonthermal radio emission. Aims. We aim at exploring under which conditions relativistic particles are accelerated at the terminal shocks of the protostellar jets and whether they can produce significant gamma-ray emission. Methods. We estimate the conditions necessary for particle acceleration up to very high energies and gamma-ray production in the nonthermal hot spots of jets associated with massive protostars embedded in dense molecular clouds. Results. We show that relativistic bremsstrahlung and proton-proton collisions can make molecular clouds with massive young stellar objects detectable by the Fermi satellite at MeV-GeV energies and by Cherenkov telescope arrays in the GeV-TeV range. Conclusions. Gamma-ray astronomy can be used to probe the physical conditions in star-forming regions and particle acceleration processes in the complex environment of massive molecular clouds.

Simulação da Química da Atmosfera Poluída por Automóveis Movidos a Álcool

Numerical modeling studies of urban atmospheres were performed with a photochemical box submodel which incorporates primary emission rates, temperature and solar irradiance rate coefficients. Actinic flux calculations were made for an appropriate latitude for Rio de Janeiro and initial concentrations and emission rates were taken from experimental data. The relative importance of individual reactions is discussed as well as the effect of enhanced aldehyde emissions from vehicles using ethanol and ethanol-containing fuel.

Kansallisten immateriaalioikeuksien vaikutus lääkekeksintöihin Suomessa ja Ruotsissa 1980-90-luvulla

Pro gradu- tutkielman tarkoituksena oli tutkia lääkkeiden immateriaalioikeudellisia suojamuotoja Suomen ja Ruotsin osalta. Tutkimuksessa pyrittiin selvittämään lääkkeiden kansallisen patenttisuojan, lisäsuojatodistuksen ja dokumentaatiosuojan vaikutusta lääkekeksintöihin 1980–90-luvun Suomessa ja Ruotsissa. Lääkkeiden lisäsuojatodistuksella tarkoitetaan ainoastaan lääkeaineille tarkoitettua erillistä immateriaalioikeudellista lisäsuojamuotoa, joka pidentää suoja-aikaa enimmillään viidellä vuodella. Dokumentaatiosuojalla tarkoitetaan suojamuotoa, joka suojaa lääkkeiden kehittämisessä aikaan saatuja tutkimus- ja turvallisuustuloksia rinnakkaisvalmistajilta tietyn määritellyn ajan. Suomen ja Ruotsin kansallisessa lainsäädännössä oli tarkasteluajanjaksolla olennaisia eroja. Rinnakkaisongelmana tutkittiin innovaatio- ja patenttipolitiikan merkitystä lääkekeksintöjen määrään ja laatuun. Tutkimuskysymyksiä lähestyttiin virallislähteiden ja kirjallisuuden lisäksi myös teemahaastatteluin. Haastateltavat olivat alan asiantuntijoita. Tutkimus oli haasteellinen. Oli palkitsevaa saada asiaa koskeva ”hiljainen tieto” kansiin. Suomen ja Ruotsin poliittinen ja lainsäädännöllinen ilmapiiri poikkesivat toisistaan. Suomessa vallitsi protektionistinen ilmapiiri ja se näkyi politiikassa ja vaikutti lainsäädäntöön. Menetelmäpatentista ei haluttu luopua. Menetelmäpatentti on patentti, joka käsittää ainoastaan lääkeaineen valmistusmenetelmän, eikä lopputuotetta. Suomessa sallittiin lääkeaineiden tuotepatentti vasta 1995. Toisin oli Ruotsissa; siellä poliittinen ilmapiiri ja valtion sekä lääketeollisuuden näkemykset johtivat kehitystä niin, että tuotepatenttikielto poistettiin huomattavasti aiemmin kuin Suomessa. Ruotsi oli kaukonäköisempi myös muiden suojamuotojen kohdalla. Lopputuloksena tästä seurasi se, että Ruotsin lääketeollisuus on menestynyt huomattavasti paremmin kuin Suomen. Lääkekeksintöjä tehtiin enemmän. Ruotsin lääkekeksinnöistä suuri osa oli uusia molekyylejä; Suomen vastaava osuus oli selvästi pienempi. Myös Ruotsin lääkevienti oli ja on huomattavasti suurempaa kuin Suomen.