3,005 research outputs found
Circumbinary Molecular Rings Around Young Stars in Orion
We present high angular resolution 1.3 mm continuum, methyl cyanide molecular
line, and 7 mm continuum observations made with the Submillimeter Array and the
Very Large Array, toward the most highly obscured and southern part of the
massive star forming region OMC1S located behind the Orion Nebula. We find two
flattened and rotating molecular structures with sizes of a few hundred
astronomical units suggestive of circumbinary molecular rings produced by the
presence of two stars with very compact circumstellar disks with sizes and
separations of about 50 AU, associated with the young stellar objects 139-409
and 134-411. Furthermore, these two circumbinary rotating rings are related to
two compact and bright {\it hot molecular cores}. The dynamic mass of the
binary systems obtained from our data are 4 M for 139-409 and
0.5 M for 134-411. This result supports the idea that
intermediate-mass stars will form through {\it circumstellar disks} and
jets/outflows, as the low mass stars do. Furthermore, when intermediate-mass
stars are in multiple systems they seem to form a circumbinary ring similar to
those seen in young, multiple low-mass systems (e.g., GG Tau and UY Aur).Comment: Accepted by Astronomy and Astrophysic
Strongly misaligned triple system in SR 24 revealed by ALMA
We report the detection of the 1.3 mm continuum and the molecular emission of the disks of the young triple system SR24 by analyzing ALMA (The Atacama Large Millimeter/Submillimter Array) subarcsecond archival observations. We estimate the mass of the disks (0.025 M ⊙ and 4 × 10‑5 M ⊕ for SR24S and SR24N, respectively) and the dynamical mass of the protostars (1.5 M ⊙ and 1.1 M ⊙). A kinematic model of the SR24S disk to fit its C18O (2-1) emission allows us to develop an observational method to determine the tilt of a rotating and accreting disk. We derive the size, inclination, position angle, and sense of rotation of each disk, finding that they are strongly misaligned (108^circ ) and possibly rotate in opposite directions as seen from Earth, in projection. We compare the ALMA observations with 12CO SMA archival observations, which are more sensitive to extended structures. We find three extended structures and estimate their masses: a molecular bridge joining the disks of the system, a molecular gas reservoir associated with SR24N, and a gas streamer associated with SR24S. Finally, we discuss the possible origin of the misaligned SR24 system, concluding that a closer inspection of the northern gas reservoir is needed to better understand it. Fil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zapata, L. A.. Universidad Nacional Autónoma de México; MéxicoFil: Gabbasov, R.. Universidad Autónoma del Estado de Hidalgo; Méxic
Spectroscopic measurements of solar wind generation
Spectroscopically observable quantities are described which are sensitive to the primary plasma parameters of the solar wind's source region. The method is discussed in which those observable quantities are used as constraints in the construction of empirical models of various coronal structures. Simulated observations are used to examine the fractional contributions to observed spectral intensities from coronal structures of interest which co-exist with other coronal structures along simulated lines-of-sight. The sensitivity of spectroscopic observables to the physical parameters within each of those structures is discussed
Borsuk-Ulam property and Sectional Category
For a Hausdorff space , a free involution and a Hausdorff
space , we discover a connection between the sectional category of the
double covers and from the ordered
configuration space to its unordered quotient
, and the Borsuk-Ulam property (BUP) for the triple
. Explicitly, we demonstrate that the triple
satisfies the BUP if the sectional category of is
bigger than the sectional category of . This property connects a standard
problem in Borsuk-Ulam theory to current research trends in sectional category.
As application of our results, we present a new lower bound for the index in
terms of sectional category. We present several examples and for those the
lower bound coincides with sectional category minus 1. We conjecture that the
index of coincides with the sectional category of the quotient map
minus 1 for any CW complex .Comment: 16 pages. Comments are welcome. Minor change
The APEX-CHAMP+ view of the Orion Molecular Cloud 1 core - Constraining the excitation with submillimeter CO multi-line observations
A high density portion of the Orion Molecular Cloud 1 (OMC-1) contains the
prominent, warm Kleinmann-Low (KL) nebula that is internally powered by an
energetic event plus a farther region in which intermediate to high mass stars
are forming. Its outside is affected by ultraviolet radiation from the
neighboring Orion Nebula Cluster and forms the archetypical photon-dominated
region (PDR) with the prominent bar feature. Its nearness makes the OMC-1 core
region a touchstone for research on the dense molecular interstellar medium and
PDRs. Using the Atacama Pathfinder Experiment telescope (APEX), we have imaged
the line emission from the multiple transitions of several carbon monoxide (CO)
isotopologues over the OMC-1 core region. Our observations employed the 2x7
pixel submillimeter CHAMP+ array to produce maps (~ 300 arcsec x 350 arcsec) of
12CO, 13CO, and C18O from mid-J transitions (J=6-5 to 8-7). We also obtained
the 13CO and C18O J=3-2 images toward this region. The 12CO line emission shows
a well-defined structure which is shaped and excited by a variety of phenomena,
including the energetic photons from hot, massive stars in the nearby Orion
Nebula's central Trapezium cluster, active high- and intermediate-mass star
formation, and a past energetic event that excites the KL nebula. Radiative
transfer modeling of the various isotopologic CO lines implies typical H2
densities in the OMC-1 core region of ~10^4-10^6 cm^-3 and generally elevated
temperatures (~ 50-250 K). We estimate a warm gas mass in the OMC-1 core region
of 86-285 solar masses.Comment: 11 pages, 9 figures, accepted by A&
Periodic Quantum Tunneling and Parametric Resonance with Cigar-Shaped Bose-Einstein Condensates
We study the tunneling properties of a cigar-shaped Bose-Einstein condensate
by using an effective 1D nonpolynomial nonlinear Schr\"odinger equation (NPSE).
First we investigate a mechanism to generate periodic pulses of coherent matter
by means of a Bose condensate confined in a potential well with an oscillating
height of the energy barrier. We show that is possible to control the periodic
emission of matter waves and the tunneling fraction of the Bose condensate. We
find that the number of emitted particles strongly increases if the period of
oscillation of the height of the energy barrier is in parametric resonance with
the period of oscillation of the center of mass of the condensate inside the
potential well. Then we use NPSE to analyze the periodic tunneling of a
Bose-Einstein condensate in a double-well potential which has an oscillating
energy barrier. We show that the dynamics of the Bose condensate critically
depends on the frequency of the oscillating energy barrier. The macroscopic
quantum self-trapping (MQST) of the condensate can be suppressed under the
condition of parametric resonance between the frequency of the energy barrier
and the frequency of oscillation through the barrier of the very small fraction
of particles which remain untrapped during MQST.Comment: latex, 23 pages, 10 figures, to be published in J. Phys. B (Atom.
Mol.), related papers can be found at
http://www.mi.infm.it/salasnich/tdqg.htm
Nuevos datos sobre la sedimentación terciaria en La Mancha (Ciudad Real)
Los datos obtenidos de la investigación geofísica y perforación de sondeos en la parte occidental de La Mancha han permitido determinar la estructura del sustrato del Neógeno: un conjunto de fosas controladas por fallas, que se generaron en periodos de tectónica distensiva. Se han separado tres unidades litoestratigráficas: Unidad detrítica de la base, Unidad lutítica roja intermedia y Unidad carbonatada superior
Nuevos datos sobre la sedimentación terciaria en La Mancha (Ciudad Real)
Los datos obtenidos de la investigación geofísica y perforación de sondeos en la parte occidental de La Mancha han permitido determinar la estructura del sustrato del Neógeno: un conjunto de fosas controladas por fallas, que se generaron en periodos de tectónica distensiva. Se han separado tres unidades litoestratigráficas: Unidad detrítica de la base, Unidad lutítica roja intermedia y Unidad carbonatada superior
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