Probing the centre of the large circumstellar disc in M17

We investigated the nature of the hitherto unresolved elliptical infrared emission in the centre of the ~20000 AU disc silhouette in M 17. We combined high-resolution JHKsL'M' band imaging carried out with NAOS/CONICA at the VLT with [Fe II] narrow band imaging using SOFI at the NTT. The analysis is supported by Spitzer/GLIMPSE archival data and by already published SINFONI/VLT Integral Field Spectroscopy data. For the first time, we resolve the elongated central infrared emission into a point-source and a jet-like feature that extends to the northeast in the opposite direction of the recently discovered collimated H2 jet. They are both orientated almost perpendicular to the disc plane. In addition, our images reveal a curved southwestern emission nebula whose morphology resembles that of the previously detected northeastern one. Both nebulae are located at a distance of 1500 AU from the disc centre. We describe the infrared point-source in terms of a protostar that is embedded in circumstellar material producing a visual extinction of 60 <= Av <= 82. The observed Ks band magnitude is equivalent to a stellar mass range of 2.8 Msun <= Mstar <= 8 Msun adopting conversions for a main-sequence star. Altogether, we suggest that the large M 17 accretion disc is forming an intermediate to high-mass protostar. Part of the accreted material is expelled through a symmetric bipolar jet/outflow.Comment: 6 pages, 3 figures, accepted by MNRAS (16 May 2008

A multiwavelength study of young massive star forming regions: II. The dust environment

We present observations of 1.2-mm dust continuum emission, made with the Swedish ESO Submillimeter Telescope, towards eighteen luminous IRAS point sources, all with colors typical of compact HII regions and associated with CS(2-1) emission, thought to be representative of young massive star forming regions. Emission was detected toward all the IRAS objects. We find that the 1.2-mm sources associated with them have distinct physical parameters, namely sizes of 0.4 pc, dust temperatures of 30 K, masses of 2x10^3 Msun, column densities of 3x10^23 cm^-2, and densities of 4x10^5 cm^-3. We refer to these dust structures as massive and dense cores. Most of the 1.2-mm sources show single-peaked structures, several of which exhibit a bright compact peak surrounded by a weaker extended envelope. The observed radial intensity profiles of sources with this type of morphology are well fitted with power-law intensity profiles with power-law indices in the range 1.0-1.7. This result indicates that massive and dense cores are centrally condensed, having radial density profiles with power-law indices in the range 1.5-2.2. We also find that the UC HII regions detected with ATCA towards the IRAS sources investigated here (Paper I) are usually projected at the peak position of the 1.2-mm dust continuum emission, suggesting that massive stars are formed at the center of the centrally condensed massive and dense cores.Comment: 6 figures, accepted by Ap

2.3 micron CO emission and absorption from young high-mass stars in M17

We are studying the extremely young cluster of M17 to investigate the birth of high-mass stars and the initial mass function. Deep JHKL imaging and K-band spectroscopy from the VLT of 201 stars toward the cluster is presented. The majority of 104 stars show the CO band-head in absorption. Half of them emit X-rays and/or have infrared excess, indicative of very young objects. Their intrinsic IR luminosity is compatible with intermediate and high-mass pre-main sequence stars. Nine additional stars have the CO feature in emission, while sixty sources are lacking any stellar spectral feature due to veiling by circumstellar dust. We suggest that CO absorption is - as in the case of low-mass stars - also a common feature during the early evolution of stars with higher masses. According to model calculations the observed CO absorption is most likely a sign of heavily accreting protostars with mass accretion rates above 10^-5 solar masses/yr.Comment: 4 pages, 3 figure + 1 online figure, accepted for publication in A&

Metodologia de determinação do pH da temperatura da cama de aviário em tempo real.

Projeto: 03.07.09.049

Avaliação de isolantes térmicos com potencial uso em aviários.

Projeto/Plano de Ação: 03.07.94.900-04

Temperatura superficial de isolantes térmicos e cortinas para a produção animal.

Projeto: 03.07.09.049

Molecular mechanism of tanshinone IIA and cryptotanshinone in platelet anti-aggregating effects: an integrated study of pharmacology and computational analysis.

Tanshinone IIA and cryptotanshinone are two pharmacologically active diterpenoids extracted from the roots of Salvia milthiorriza Bunge, a plant used in Chinese traditional medicine for the treatment of some cardiovascular and cerebrovascular disease. Until now, the molecular mechanisms of action of these two diterpenoids on platelets are partially known. To clarify this aspect, here we utilized an integrated study of pharmacology and computational analysis. Our results demonstrate that cryptotanshinone is able to inhibit in a concentration dependent manner the rat platelet aggregation and also is endowed of Gi-coupled P2Y12 receptor antagonist as demonstrated by docking studies. This computational method was also performed for tanshinone IIA demonstrating even for this diterpenoid an interaction with the same receptor. The findings from our study enable a better understanding of tanshinone IIA and cryptotanshinone biological properties, which could ultimately lead to the development of novel pharmaceutical strategies for the treatment and/or prevention of some cardiovascular disease