2,391 research outputs found
Looking for outflow and infall signatures in high mass star forming regions
(Context) Many physical parameters change with time in star forming regions.
Here we attempt to correlate changes in infall and outflow motions in high mass
star forming regions with evolutionary stage using JCMT observations. (Aims)
From a sample of 45 high mass star forming regions in three phases of
evolution, we investigate the presence of established infall and outflow
tracers to determine whether there are any trends attributable to the age of
the source. (Methods) We obtained JCMT observations of HCO+/H13CO+ J=4-3 to
trace large scale infall, and SiO J=8-7 to trace recent outflow activity. We
compare the infall and outflow detections to the evolutionary stage of the host
source (high mass protostellar objects, hypercompact HII regions and
ultracompact HII regions). We also note that the integrated intensity of SiO
varies with the full width at half maximum of the H13CO+. (Results) We find a
surprising lack of SiO detections in the middle stage (Hypercompact HII
regions), which may be due to an observational bias. When SiO is detected, we
find that the integrated intensity of the line increases with evolutionary
stage. We also note that all of the sources with infall signatures onto
Ultracompact HII regions have corresponding outflow signatures as well.Comment: 9 pages, 5 figures, 5 tables. Accepted by A&
ENERGY-EXPENDITURE DURING FREE FLIGHT IN TRAINED AND FREE-LIVING EURASIAN KESTRELS (FALCO-TINNUNCULUS)
ENERGY-EXPENDITURE DURING FREE FLIGHT IN TRAINED AND FREE-LIVING EURASIAN KESTRELS (FALCO-TINNUNCULUS)
Morphologies of protostellar outflows: An ALMA view
The formation of stars is usually accompanied by the launching of
protostellar outflows. Observations with the Atacama Large
Millimetre/sub-millimetre Array (ALMA) will soon revolutionalise our
understanding of the morphologies and kinematics of these objects. In this
paper, we present synthetic ALMA observations of protostellar outflows based on
numerical magnetohydrodynamic collapse simulations. We find significant
velocity gradients in our outflow models and a very prominent helical structure
within the outflows. We speculate that the disk wind found in the ALMA Science
Verification Data of HD 163296 presents a first instance of such an
observation
Parton energy loss at strong coupling and the universal bound
The apparent universality of jet quenching observed in heavy ion collisions
at RHIC for light and heavy quarks, as well as for quarks and gluons, is very
puzzling and calls for a theoretical explanation. Recently it has been proposed
that the synchrotron--like radiation at strong coupling gives rise to a
universal bound on the energy of a parton escaping from the medium. Since this
bound appears quite low, almost all of the observed particles at high
transverse momentum have to originate from the surface of the hot fireball.
Here I make a first attempt of checking this scenario against the RHIC data and
formulate a "Universal Bound Model" of jet quenching that can be further tested
at RHIC and LHC.Comment: 8 pages, 2 figures, invited plenary talk given at "Hard Probes 2008"
Conference, 8-14 June 2008, Illa da Toxa, Galicia, Spai
Septic Arthritis Caused by Legionella dumoffii in a Patient with Systemic Lupus Erythematosus-Like Disease
We describe a patient with systemic lupus erythematosus (SLE)-like disease on immunosuppressive treatment who developed septic arthritis of the knee involving Legionella dumoffii. Cultures initially remained negative. A broad-range 16S PCR using synovial fluid revealed L. dumoffii rRNA genes, a finding that was subsequently confirmed by positive Legionella culture results
ALMA CO J=6-5 observations of IRAS16293-2422: Shocks and entrainment
Observations of higher-excited transitions of abundant molecules such as CO
are important for determining where energy in the form of shocks is fed back
into the parental envelope of forming stars. The nearby prototypical and
protobinary low-mass hot core, IRAS16293-2422 (I16293) is ideal for such a
study. The source was targeted with ALMA for science verification purposes in
band 9, which includes CO J=6-5 (E_up/k_B ~ 116 K), at an unprecedented spatial
resolution (~0.2", 25 AU). I16293 itself is composed of two sources, A and B,
with a projected distance of 5". CO J=6-5 emission is detected throughout the
region, particularly in small, arcsecond-sized hotspots, where the outflow
interacts with the envelope. The observations only recover a fraction of the
emission in the line wings when compared to data from single-dish telescopes,
with a higher fraction of emission recovered at higher velocities. The very
high angular resolution of these new data reveal that a bow shock from source A
coincides, in the plane of the sky, with the position of source B. Source B, on
the other hand, does not show current outflow activity. In this region, outflow
entrainment takes place over large spatial scales, >~ 100 AU, and in small
discrete knots. This unique dataset shows that the combination of a
high-temperature tracer (e.g., CO J=6-5) and very high angular resolution
observations is crucial for interpreting the structure of the warm inner
environment of low-mass protostars.Comment: Accepted for publication in A&A Letter
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