19,460 research outputs found
Photometric brown-dwarf classification. II. A homogeneous sample of 1361 L and T dwarfs brighter than J = 17.5 with accurate spectral types
We present a homogeneous sample of 1361 L and T dwarfs brighter than J = 17.5
(of which 998 are new), from an effective area of 3070 deg2, classified by the
photo-type method to an accuracy of one spectral sub-type using izYJHKW1W2
photometry from SDSS+UKIDSS+WISE. Other than a small bias in the early L types,
the sample is shown to be effectively complete to the magnitude limit, for all
spectral types L0 to T8. The nature of the bias is an incompleteness estimated
at 3% because peculiar blue L dwarfs of type L4 and earlier are classified late
M. There is a corresponding overcompleteness because peculiar red (likely
young) late M dwarfs are classified early L. Contamination of the sample is
confirmed to be small: so far spectroscopy has been obtained for 19 sources in
the catalogue and all are confirmed to be ultracool dwarfs. We provide
coordinates and izYJHKW1W2 photometry of all sources. We identify an apparent
discontinuity, m 0.4 mag., in the Y-K colour between spectral
types L7 and L8. We present near-infrared spectra of nine sources identified by
photo-type as peculiar, including a new low-gravity source ULAS
J005505.68+013436.0, with spectroscopic classification L2{}. We provide
revised izYJHKW1W2 template colours for late M dwarfs, types M7 to M9.Comment: Accepted for publication in A & A, 17 pages, 14 figures, catalogue of
L and T dwarfs supplied here in source files (anc/ directory), and available
on CD
Loggerhead turtle (Caretta caretta) nest predation at Cape Range National Park
Most of the existing sea turtle populations worldwide are in decline. In particular, loggerhead turtles (Caretta caretta) are listed as endangered and loggerhead nesting populations in Eastern Australia have declined by 86% since the 1970s. However, whilst Eastern Australian loggerhead populations have been extensively studied and monitored, not much is known about the Western Australian nesting population
Raising the Dead: Clues to Type Ia Supernova Physics from the Remnant 0509-67.5
We present Chandra X-ray observations of the young supernova remnant (SNR)
0509-67.5 in the Large Magellanic Cloud (LMC), believed to be the product of a
Type Ia supernova (SN Ia). The remnant is very round in shape, with a distinct
clumpy shell-like structure. Our Chandra data reveal the remnant to be rich in
silicon, sulfur, and iron. The yields of our fits to the global spectrum
confirm that 0509-67.5 is the remnant of an SN Ia and show a clear preference
for delayed detonation explosion models for SNe Ia. We study the spectrum of
the single brightest isolated knot in the remnant and find that it is enhanced
in iron by a factor of roughly two relative to the global remnant abundances.
This feature, along with similar knots seen in Tycho's SNR, argues for the
presence of modest small-scale composition inhomogeneities in SNe Ia. The
presence of both Si and Fe, with abundance ratios that vary from knot to knot,
indicates that these came from the transition region between the Si- and
Fe-rich zones in the exploded star, possibly as a result of energy input to the
ejecta at late times due to the radioactive decay of 56Ni and 56Co. Two cases
for the continuum emission from the global spectrum were modeled: one where the
continuum is dominated by hydrogen thermal bremsstrahlung radiation; another
where the continuum arises from non-thermal synchrotron radiation. The former
case requires a relatively large value for the ambient density (~1 cm^-3).
Another estimate of the ambient density comes from using the shell structure of
the remnant in the context of dynamical models. This requires a much lower
value for the density (<0.05 cm^-3) which is more consistent with other
evidence known about 0509-67.5. We therefore conclude that the bulk of the
continuum emission from 0509-67.5 has a non-thermal origin.Comment: 34 pages, 9 figures (1 color), accepted to ApJ (10 June 2004 issue);
correction made to calculation of magnetic field, small sentence change
Distribution of the second virial coefficients of globular proteins
George and Wilson [Acta. Cryst. D 50, 361 (1994)] looked at the distribution
of values of the second virial coefficient of globular proteins, under the
conditions at which they crystallise. They found the values to lie within a
fairly narrow range. We have defined a simple model of a generic globular
protein. We then generate a set of proteins by picking values for the
parameters of the model from a probability distribution. At fixed solubility,
this set of proteins is found to have values of the second virial coefficient
that fall within a fairly narrow range. The shape of the probability
distribution of the second virial coefficient is Gaussian because the second
virial coefficient is a sum of contributions from different patches on the
protein surface.Comment: 5 pages, including 3 figure
Precision Determination of the Mass Function of Dark Matter Halos
The predicted mass function of dark matter halos is essential in connecting
observed galaxy cluster counts and models of galaxy clustering to the
properties of the primordial density field. We determine the mass function in
the concordance CDM cosmology, as well as its uncertainty, using
sixteen -particle nested-volume dark-matter simulations, spanning a
mass range of over five orders of magnitude. Using the nested volumes and
single-halo tests, we find and correct for a systematic error in the
friends-of-friends halo-finding algorithm. We find a fitting form and full
error covariance for the mass function that successfully describes the
simulations' mass function and is well-behaved outside the simulations'
resolutions. Estimated forecasts of uncertainty in cosmological parameters from
future cluster count surveys have negligible contribution from remaining
statistical uncertainties in the central cosmology multiplicity function. There
exists a potentially non-negligible cosmological dependence (non-universality)
of the halo multiplicity function.Comment: 4 pages, 3 figures, submitted to ApJ
Linear electric field frequency shift (important for next generation electric dipole moment searches) induced in confined gases by a magnetic field gradient
The search for particle electric dipole moments (edm) represents a most
promising way to search for physics beyond the standard model. A number of
groups are planning a new generation of experiments using stored gases of
various kinds. In order to achieve the target sensitivities it will be
necessary to deal with the systematic error resulting from the interaction of
the well-known field with
magnetic field gradients (often referred to as the geometric phase effect
(Commins, ED; Am. J. Phys. \QTR{bf}{59}, 1077 (1991), Pendlebury, JM
\QTR{em}{et al;} Phys. Rev. \QTR{bf}{A70}, 032102 (2004)). This interaction
produces a frequency shift linear in the electric field, mimicking an edm. In
this work we introduce an analytic form for the velocity auto-correlation
function which determines the velocity-position correlation function which in
turn determines the behavior of the frequency shift (Lamoreaux, SK and Golub,
R; Phys. Rev \QTR{bf}{A71}, 032104 (2005)) and show how it depends on the
operating conditions of the experiment. We also discuss some additional issues.Comment: 21 pages, 5 figure
BANKS AND BANKING-DEPOSITS-RESULTING TRUSTS UNDER THE CONTRACT THEORY OF JOINT BANK ACCOUNTS
A husband carried a bank account in his own name. Subsequently, he and his wife signed a signature card at the bank upon which appeared the following: \u27We agree . . . that all funds now, or hereafter, deposited to this account are, and shall be, our joint property and owned by us as joint tenants with right of survivorship, and not as tenants in common; and upon the death of either of us any balance . . . shall become the absolute property of the survivor. The entire account or any part thereof may be withdrawn by . . . either of us or the survivor. No money belonging to the wife was ever deposited. After the death of .the husband his residuary legatees filed a petition claiming the balance of the account by virtue of a resulting trust which they sought to show by parol evidence to have been intended by the husband. Judgment was for the wife. On appeal, held, affirmed. The signature card constituted a contract clearly expressing the husband\u27s intent, and could not be varied or altered by parol evidence through the device of a resulting trust. Hill v. Havens, (Iowa 1951) 48 N. W. (2d) 870
Continuous upflows and sporadic downflows observed in active regions
We present a study of the temporal evolution of coronal loops in active
regions and its implications for the dynamics in coronal loops. We analyzed
images of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics
Observatory (SDO) at multiple temperatures to detect apparent motions in the
coronal loops. Quasi-periodic brightness fluctuations propagate upwards from
the loop footpoint in hot emission at 1MK, while sporadic downflows are seen in
cool emission below 1MK. The upward motion in hot emission increases just after
the cool downflows. The apparent propagating pattern suggests a hot upflow from
the loop footpoints, and is considered to supply hot plasma into the coronal
loop, but a wavelike phenomenon cannot be ruled out. Coronal condensation
occasionally happens in the coronal loop, and the cool material flows down to
the footpoint. Emission from cool plasma could have a significant contribution
to hot AIA channels in the event of coronal condensation.Comment: 5 pages, 6 figures, A&A in pres
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