16,567 research outputs found
The space of complete embedded maximal surfaces with isolated singularities in the 3-dimensional Lorentz-Minkowski space \l^3
We show that a complete embedded maximal surface in the 3-dimensional
Lorentz-Minkowski space with a finite number of singularities is, up to a
Lorentzian isometry, an entire graph over any spacelike plane asymptotic to a
vertical half catenoid or a horizontal plane and with conelike singular points.
We study the space of entire maximal graphs over in
with conelike singularities and vertical limit normal vector at
infinity. We show that is a real analytic manifold of dimension
and the coordinates are given by the position of the singular points in
and the logarithmic growth at the end. We also introduce the moduli space
of {\em marked} graphs with singular points (a mark in a graph is an
ordering of its singularities), which is a -sheeted covering of
We prove that identifying marked graphs differing by translations, rotations
about a vertical axis, homotheties or symmetries about a horizontal plane, the
corresponding quotient space is an analytic manifold of dimension Comment: 32 pages, 4 figures, corrected typos, former Theorem 3.3 (now Theorem
2.2) modifie
The abundance of 28Si32S, 29Si32S, 28Si34S, and 30Si32S in the inner layers of the envelope of IRC+10216
We present high spectral resolution mid-IR observations of SiS towards the
C-rich AGB star IRC+10216 carried out with the Texas Echelon-cross-Echelle
Spectrograph mounted on the NASA Infrared Telescope Facility. We have
identified 204 ro-vibrational lines of 28Si32S, 26 of 29Si32S, 20 of 28Si34S,
and 15 of 30Si32S in the frequency range 720-790 cm-1. These lines belong to
bands v=1-0, 2-1, 3-2, 4-3, and 5-4, and involve rotational levels with
Jlow<90. About 30 per cent of these lines are unblended or weakly blended and
can be partially or entirely fitted with a code developed to model the mid-IR
emission of a spherically symmetric circumstellar envelope composed of
expanding gas and dust. The observed lines trace the envelope at distances to
the star <35R* (~0.7 arcsec). The fits are compatible with an expansion
velocity of 1+2.5(r/R*-1) km/s between 1 and 5R*, 11 km/s between 5 and 20R*,
and 14.5 km/s outwards. The derived abundance profile of 28Si32S with respect
to H2 is 4.9e-6 between the stellar photosphere and 5R*, decreasing linearly to
1.6e-6 at 20R* and to 1.3e-6 at 50R*. 28Si32S seems to be rotationally under
LTE in the region of the envelope probed with our observations and
vibrationally out of LTE in most of it. There is a red-shifted emission excess
in the 28Si32S lines of band v=1-0 that cannot be found in the lines of bands
v=2-1, 3-2, 4-3, and 5-4. This excess could be explained by an enhancement of
the vibrational temperature around 20R* behind the star. The derived isotopic
ratios 28Si/29Si, and 32S/34S are 17 and 14, compatible with previous
estimates.Comment: 11 pages, 5 figures, and 4 tables. Accepted for publication in MNRA
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