Uncovering the Beast: Discovery of Embedded Massive Stellar Clusters in W49A

We present subarcsecond J, H, and Ks images (FWHM ~ 0.5") of an unbiased 5'x 5' (16pc x 16pc) survey of the densest region of the W49 giant molecular cloud. The observations reveal 4 massive stellar clusters (with stars as massive as \~120 Msun), the larger (Cluster 1) about 3 pc East of the well known Welch ring of ultra-compact Hii regions. Cluster 1 is a) extincted by at least Av > 20 mag of foreground (unrelated and local) extinction, b) has more than 30 mag of internal inhomogeneous visual extinction implying that it is still deeply buried in its parental molecular cloud, and c) is powering a 6 pc diameter giant Hii region seen both at the NIR and radio continuum. We also identify the exciting sources of several UCHii regions. The census of massive stars in W49A agrees or is slightly overabundant when compared with the number of Lyman continuum photons derived from radio observations. We argue that although the formation of the Welch ring could have been triggered by Cluster 1, the entire W49A starburst region seems to have been multi-seeded instead of resulting from a coherent trigger.Comment: ApJ Letters accepted. All figures provided as nice resolution jpeg/gif files. Get full-res version at http://www.eso.org/~jalves/W49A.pd

Padronização de cortes de carcaça de caprinos e ovinos.

Este trabalho objetiva enfatizar alguns fatores que inteferem na qualidade da carne e descrever um métono de padronização de cortes de carcaça de caprinos e ovinos para comercialização no varejo.bitstream/item/36484/1/DOC-26-1.pd

Optimized cross-slot flow geometry for microfluidic extension rheometry

A precision-machined cross-slot flow geometry with a shape that has been optimized by numerical simulation of the fluid kinematics is fabricated and used to measure the extensional viscosity of a dilute polymer solution. Full-field birefringence microscopy is used to monitor the evolution and growth of macromolecular anisotropy along the stagnation point streamline, and we observe the formation of a strong and uniform birefringent strand when the dimensionless flow strength exceeds a critical Weissenberg number Wicrit 0:5. Birefringence and bulk pressure drop measurements provide self consistent estimates of the planar extensional viscosity of the fluid over a wide range of deformation rates (26 s1 "_ 435 s1) and are also in close agreement with numerical simulations performed by using a finitely extensible nonlinear elastic dumbbell model

An infrared imaging search for low-mass companions to members of the young nearby beta Pic and Tucana/Horologium associations

We present deep high dynamic range infrared images of young nearby stars in the Tucana/Horologium and beta Pic associations, all ~ 10 to 35 Myrs young and at ~10 to 60 pc distance. Such young nearby stars are well-suited for direct imaging searches for brown dwarf and even planetary companions, because young sub-stellar objects are still self-luminous due to contraction and accretion. We performed our observations at the ESO 3.5m NTT with the normal infrared imaging detector SofI and the MPE speckle camera Sharp-I. Three arc sec north of GSC 8047-0232 in Horologium a promising brown dwarf companion candidate is detected, which needs to be confirmed by proper motion and/or spectroscopy. Several other faint companion candidates are already rejected by second epoch imaging. Among 21 stars observed in Tucana/Horologium, there are not more than one to five brown dwarf companions outside of 75 AU (1.5" at 50 pc); most certainly only < 5 % of the Tuc/HorA stars have brown dwarf companions (13 to 78 Jupiter masses) outside of 75 AU. For the first time, we can report an upper limit for the frequency of massive planets (~ 10 M_jup) at wide separations (~ 100 AU) using a meaningfull and homogeneous sample: Of 11 stars observed sufficiently deep in beta Pic (12 Myrs), not more than one has a massive planet outside of ~ 100 AU, i.e. massive planets at large separations are rare (< 9 %).Comment: Astronomische Nachrichten, in pres