756 research outputs found
Did differences in strength and frictional behaviour of subducted sediment constrain the rupture of the great 1960 Chile earthquake?
Did differences in composition and strength of subducted sediment define the rupture of the great 1960 Chile earthquake?
Young sediments from the Southern Chile Trench: a record of active margin magmatism, tectonics, and paleoseismicity
Sedimentology, petrography and provenance of modern Southern Chile Trench Sediments (36°S-47°S)
Brorfelde Schmidt CCD Catalog (BSCC)
The Brorfelde Schmidt CCD Catalog (BSCC) contains about 13.7 million stars,
north of +49 deg Declination with precise positions and V, R photometry. The
catalog has been constructed from the reductions of 18,667 CCD frames observed
with the Brorfelde Schmidt Telescope between 2000 and 2007. The Tycho-2 catalog
was used for astrometric and photometric reference stars. Errors of individual
positions are about 20 to 200 mas for stars in the R = 10 to 18 mag range.
External comparisons with 2MASS and SDSS reveal possible small systematic
errors in the BSCC of up to about 30 mas. The catalog is supplemented with J,
H, and K_s magnitudes from the 2MASS catalog. The catalog data file (about 550
MB ASCII, compressed) will be made available at the Strasbourg Data Center
(CDS).Comment: 16 pages, 22 figures, 2 tables, accepted by A
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Implicit concurrent learning of adjacent and nonadjacent dependencies in children
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Effects of associative (sequential) learning across speech perception, speech production, reading, and typing
Optical-uv spectrum and proper motion of the middle-aged pulsar b1055-52
PSRB1055-52 is a middle-aged (~535 kyr) radio, X-ray, and gamma-ray pulsar
showing X-ray thermal emission from the neutron star (NS) surface. A candidate
optical counterpart to PSRB1055-52 was proposed by Mignani and coworkers based
on Hubble Space Telescope (HST) observations performed in 1996, in one spectral
band only. We report on HST observations of this field carried out in 2008, in
four spectral bands. The astrometric and photometric analyses of these data
confirm the identification of the proposed candidate as the pulsar's optical
counterpart. Similarly to other middle-aged pulsars, its optical-UV spectrum
can be described by the sum of a power-law (PLO) component, presumably emitted
from the pulsar magnetosphere, and a Rayleigh-Jeans (RJ) component emitted from
the NS surface. The spectral index of the PLO component, alpha_O=1.05+/-0.34,
is larger than for other pulsars with optical counterparts. The RJ component,
with the brightness temperature TO=(0.66+/-0.10) d_350**2 R_O,13**-2 MK (where
d_350 and R_O,13 are the distance to the pulsar in units of 350 pc and the
radius of the emitting area in units of 13 km), shows a factor of 4 excess with
respect to the extrapolation of the X-ray thermal component into the
UV-optical. This hints that the RJ component is emitted from a larger, colder
area, and suggests that the distance to the pulsar is smaller than previously
thought. From the absolute astrometry of the HST images we measured the pulsar
coordinates with a position accuracy of 0.15". From the comparison with
previous observations we measured the pulsar proper motion, mu = 42+/-5 mas/yr,
which corresponds to a transverse velocity V_t = (70+/-8) d_350 km/s.Comment: 12 pages, 5 figures, accepted for publication on Astrophysical
Journal, (Fig1a available at http://www.mssl.ucl.ac.uk/~rm2/
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