225 research outputs found
The Stellar Composition of the Star Formation Region CMa R1 -- III. A new outburst of the Be star component in Z CMa
We report on a recent event in which, after more than a decade of slowly
fading, the visual brightness of the massive young binary Z CMa suddenly
started to rise by about 1 magnitude in December 1999, followed by a rapid
decline to its previous brightness over the next six months. This behaviour is
similar to that exhibited by this system around its eruption in February 1987.
A comparison of the intrinsic luminosities of the system with recent
evolutionary calculations shows that Z CMa may consist of a 16 M_sun B0 IIIe
primary star and a ~ 3 M_sun FUOr secondary with a common age of ~ 3 x 10^5 yr.
We also compare new high-resolution spectra obtained in Jan. and Feb. 2000,
during the recent rise in brightness, with archive data from 1991 and 1996. The
spectra are rich in emission lines, which originate from the envelope of the
early B-type primary star. The strength of these emission lines increased
strongly with the brightness of Z CMa. We interpret the collected spectral data
in terms of an accretion disc with atmosphere around the Herbig B0e component
of Z CMa, which has expanded during the outbursts of 1987 and 2000. A high
resolution profile of the 6300 A [O I] emission line, obtained by us in March
2002 shows an increase in flux and a prominent blue shoulder to the feature
extending to ~ -700 km/s, which was much fainter in the pre-outburst spectra.
We propose that this change in profile is a result of a strong change in the
collimation of a jet, as a result of the outburst at the start of this century.Comment: 22 pages, 12 figures, accepted for publication in MNRA
The CHESS chemical Herschel surveys of star forming regions: Peering into the protostellar shock L1157-B1. I. Shock chemical complexity
We present the first results of the unbiased survey of the L1157-B1 bow
shock, obtained with HIFI in the framework of the key program Chemical Herschel
surveys of star forming regions (CHESS). The L1157 outflow is driven by a
low-mass Class 0 protostar and is considered the prototype of the so-called
chemically active outflows. The bright blue-shifted bow shock B1 is the ideal
laboratory for studying the link between the hot (around 1000-2000 K) component
traced by H2 IR-emission and the cold (around 10-20 K) swept-up material. The
main aim is to trace the warm gas chemically enriched by the passage of a shock
and to infer the excitation conditions in L1157-B1. A total of 27 lines are
identified in the 555-636 GHz region, down to an average 3 sigma level of 30
mK. The emission is dominated by CO(5-4) and H2O(110-101) transitions, as
discussed by Lefloch et al. (2010). Here we report on the identification of
lines from NH3, H2CO, CH3OH, CS, HCN, and HCO+. The comparison between the
profiles produced by molecules released from dust mantles (NH3, H2CO, CH3OH)
and that of H2O is consistent with a scenario in which water is also formed in
the gas-phase in high-temperature regions where sputtering or grain-grain
collisions are not efficient. The high excitation range of the observed tracers
allows us to infer, for the first time for these species, the existence of a
warm (> 200 K) gas component coexisting in the B1 bow structure with the cold
and hot gas detected from ground
Digitatio and Scientific Exploitation of the Italian and Vatican Astronomical Plate Archives
There is a widespread interest to digitize the precious information contained
in the astronomical plate archives, both for the preservation of their content
and for its fast distribution to all interested researchers in order to achieve
their better scientific exploitation. This paper presents the first results of
our large-scale project to digitize the archive of plates of the Italian
Astronomical Observatories and of the Specola Vaticana. Similar systems,
composed by commercial flat-bed retro-illuminated scanners plus dedicated
personal computers and acquisition and analysis software, have been installed
in all participating Institutes. Ad-hoc codes have been developed to acquire
the data, to test the suitability of the machines to our scientific needs, and
to reduce the digital data in order to extract the astrometric, photometric and
spectroscopic content. Two more elements complete the overall project: the
provision of high quality BVRI CCD sequences in selected fields with the Campo
Imperatore telescopes, and the distribution of the digitized information to all
interested researchers via the Web. The methods we have derived in the course
of this project have been already applied successfully to plates taken by other
Observatories, for instance at Byurakan and at Hamburg.Comment: To appear in Experimental Astronom
CHESS, Chemical Herschel surveys of star forming regions:Peering into the protostellar shock L1157-B1
The outflow driven by the low-mass class 0 protostar L1157 is the prototype
of the so-called chemically active outflows. The bright bowshock B1 in the
southern outflow lobe is a privileged testbed of magneto-hydrodynamical (MHD)
shock models, for which dynamical and chemical processes are strongly
interdependent. We present the first results of the unbiased spectral survey of
the L1157-B1 bowshock, obtained in the framework of the key program "Chemical
Herschel Surveys of Star Forming Regions" (CHESS). The main aim is to trace the
warm and chemically enriched gas and to infer the excitation conditions in the
shock region. The CO 5-4 and H2O lines have been detected at high-spectral
resolution in the unbiased spectral survey of the HIFI-Band 1b spectral window
(555-636 GHz), presented by Codella et al. in this volume. Complementary
ground-based observations in the submm window help establish the origin of the
emission detected in the main-beam of HIFI, and the physical conditions in the
shock.}{Both lines exhibit broad wings, which extend to velocities much higher
than reported up to now. We find that the molecular emission arises from two
regions with distinct physical conditions: an extended, warm (100K), dense (3e5
cm-3) component at low-velocity, which dominates the water line flux in Band~1;
a secondary component in a small region of B1 (a few arcsec) associated with
high-velocity, hot (> 400 K) gas of moderate density ((1.0-3.0)e4 cm-3), which
appears to dominate the flux of the water line at 179mu observed with PACS. The
water abundance is enhanced by two orders of magnitude between the low- and the
high-velocity component, from 8e-7 up to 8e-5. The properties of the
high-velocity component agree well with the predictions of steady-state C-shock
models.Comment: Accepted for Publication in Astronomy and Astrophysics (Herschel
Special Issue
Análise bibliomĂ©trica da produção cientĂfica brasileira sobre Tecnologia de Construção e Edificações na base de dados Web of Science
Resumo Este estudo trata da análise da produção cientĂfica brasileira sobre tecnologias de construção e edificações por meio de indicadores bibliomĂ©tricos. A área foi escolhida em razĂŁo de sua relevância para o desenvolvimento econĂ´mico do paĂs. A bibliometria Ă© um mĂ©todo de análise quantitativa para a pesquisa cientĂfica. Os dados elaborados por meio dos estudos bibliomĂ©tricos mensuram a contribuição do conhecimento cientĂfico derivado das publicações em determinadas áreas. Os indicadores de produção sĂŁo Ăşteis para o planejamento e a execução de polĂticas pĂşblicas, e para o conhecimento da comunidade cientĂfica sobre o sistema em que está inserida. O objetivo deste trabalho Ă© estudar a produção cientĂfica brasileira na área da construção e tecnologia da construção civil a partir da análise de artigos cientĂficos publicados em periĂłdicos e anais de congressos indexados na base de dados Web of Science (WoS). Os dados foram coletados utilizando como critĂ©rio de seleção a categoria "Construction & Building Technology", sendo analisados dados de 910 artigos de autores brasileiros no perĂodo de 1982 a 2014. A interpretação dos dados permite confirmar o expressivo crescimento da produção cientĂfica brasileira e da grande contribuição da regiĂŁo Sudeste para essa evolução
A New Academic Quality at Work Tool (AQ@workT) to Assess the Quality of Life at Work in the Italian Academic Context
The present study provides evidence for a valid and reliable tool, the Academic Quality at Work Tool (AQ@workT), to investigate the quality of life at work in academics within the Italian university sector. The AQ@workT was developed by the QoL@Work research team, namely a group of expert academics in the field of work and organizational psychology affiliated with the Italian Association of Psychologists. The tool is grounded in the job demands-resources model and its psychometric properties were assessed in three studies comprising a wide sample of lecturers, researchers, and professors: a pilot study (N = 120), a calibration study (N = 1084), and a validation study (N = 1481). Reliability and content, construct, and nomological validity were supported, as well as measurement invariance across work role (researchers, associate professors, and full professors) and gender. Evidence from the present study shows that the AQ@workT represents a useful and reliable tool to assist university management to enhance quality of life, to manage work-related stress, and to mitigate the potential for harm to academics, particularly during a pandemic. Future studies, such as longitudinal tests of the AQ@workT, should test predictive validity among the variables in the tool
Role of the Gut Endoderm in Relaying Left-Right Patterning in Mice
Analysis of Sox17 mutant mice reveals that gap junction coupling across the gut endoderm of the embryo transmits the left-right asymmetric signal from the node to the site of asymmetric organogenesis in mice
B[e] Stars with Warm Dust: Revealing the Nature of Unclassified B[e] Stars and Expanding the Family
Until recently, unclassified B[e] stars represented half of the entire B[e] group. Our study of these objects with strong emission-line spectra and IRAS fluxes, decreasing toward longer wavelengths, resulted in a suggestion that they currently form dust in their envelopes. The objects have been tentatively called B[e] stars with warm dust (B[e]WD). Their luminosity range (?3 orders of magnitude) is much larger compared to previous suggestions that dust formation occurs only near very luminous hot stars. A significant fraction of B[e]WD are recognized or suspected binaries. The group has been expanded with both previously detected hot emission-line stars with IR fluxes, typical for confirmed B[e]WD, and new candidates, found in recent all-sky surveys. Currently the number of B[e]WD members and candidates is ?60 with an opportunity to find more in existing stellar catalogs. Main observational and physical properties of B[e]WD and their envelopes are summarized. Our results on newly found group members are presented. Partially based on observations obtained at the Canada-France-Hawaii Telescope (CFHT).Fil: Miroshnichenko, A. S.. University of North Carolina at Greensboro; Estados UnidosFil: Bernabei, S.. Istituto Nazionale di Astrofisica; ItaliaFil: Bjorkman, K. S.. University Of Toledo (utoledo); Estados UnidosFil: Chentsov, E. L.. Russian Academy of Sciences; RusiaFil: Klochkova, V. G.. Russian Academy of Sciences; RusiaFil: Gray, R. O.. Appalachian State University; Estados UnidosFil: Levato, H.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan. Complejo AstronĂłmico "El Leoncito". Universidad Nacional de CĂłrdoba. Complejo AstronĂłmico "El Leoncito". Universidad Nacional de la Plata. Complejo AstronĂłmico "El Leoncito". Universidad Nacional de San Juan. Complejo AstronĂłmico "El Leoncito"; ArgentinaFil: Grosso, Monica Gladys. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan. Instituto de Ciencias AstronĂłmicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias AstronĂłmicas, de la Tierra y del Espacio; ArgentinaFil: Hinkle, K. H.. National Optical Astronomy Observatory; Estados UnidosFil: Kuratov, K. S.. Fesenkov Astrophysical Institute; KazajistánFil: Kusakin, A. V.. Universitetskij pr; RusiaFil: GarcĂa Lario, P.. European Space Astronomy Centre; EspañaFil: Perea CalderĂłn, J. V.. European Space Astronomy Centre; EspañaFil: Polcaro, V. F.. Istituto di Astrofisica Spaziale e Fisica Cosmica; ItaliaFil: Viotti, R. F.. Istituto di Astrofisica Spaziale e Fisica Cosmica; ItaliaFil: Norci, L.. Dublin City University; IrlandaFil: Manset, N.. Canada France Hawaii Telescope; Estados UnidosFil: Men’shchikov, A. B.. Saint Mary’s University; CanadáFil: Rudy, R. J.. The Aerospace Corporation; Estados UnidosFil: Lynch, D. K.. The Aerospace Corporation; Estados UnidosFil: Venturini, C. C.. The Aerospace Corporation; Estados UnidosFil: Mazuk, S.. The Aerospace Corporation; Estados UnidosFil: Puetter, R. C.. University of California; Estados UnidosFil: Perry, R. B.. National Aeronautics and Space Administration; Estados UnidosFil: Gandet, T. L.. Lizard Hollow Observatory; Estados Unido
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