1,197 research outputs found
The Solar Neighborhood XXVII: Discovery of New Proper Motion Stars with mu > 0.18 "/yr in the Southern Sky with 16.5 > R_59F > 18.0
Here we present 1584 new southern proper motion systems with mu > 0.18 "/yr
and 16.5 > R_59F > 18.0. This search complements the six previous
SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky for stars
within the same proper motion range, but with R_59F < 16.5. As in previous
papers, we present distance estimates for these systems and find that three
systems are estimated to be within 25 pc, including one, SCR 1546-5534,
possibly within the RECONS 10 pc horizon at 6.7 pc, making it the second
nearest discovery of the searches. We find 97 white dwarf candidates with
distance estimates between 10 and 120 pc, as well as 557 cool subdwarf
candidates. The subdwarfs found in this paper make up nearly half of the
subdwarf systems reported from our SCR searches, and are significantly redder
than those discovered thus far. The SCR searches have now found 155 red dwarfs
estimated to be within 25 pc, including 10 within 10 pc. In addition, 143 white
dwarf candidates and 1155 cool subdwarf candidates have been discovered. The
1584 systems reported here augment the sample of 4724 systems previously
discovered in our SCR searches, and imply that additional systems fainter than
R_59F = 18.0 are yet to be discovered.Comment: 11 pages of text, seven figure
The Solar Neighborhood VIII: Discovery of New High Proper Motion Nearby Stars Using the SuperCOSMOS Sky Survey
Five new objects with proper motions between 1.0 arcsec/yr and 2.6 arcsec/yr
have been discovered via a new RECONS search for high proper motion stars
utilizing the SuperCOSMOS Sky Survey. The first portion of the search,
discussed here, is centered on the south celestial pole and covers declinations
-90 degrees to -57.5 degrees.
Photographic photometry from SuperCOSMOS and JHKs near-infrared photometry
from 2MASS for stars nearer than 10 pc are combined to provide a suite of new
M_Ks-color relations useful for estimating distances to main sequence stars.
These relations are then used to derive distances to the new proper motion
objects as well as previously known stars with mu >= 1.0 arcsec/yr (many of
which have no trigonometric parallaxes) recovered during this phase of the
survey.
Four of the five new stars have red dwarf colors, while one is a nearby white
dwarf. Two of the red dwarfs are likely to be within the RECONS 10 pc sample,
and the white dwarf probably lies between 15 and 25 pc. Among the 23 known
stars recovered during the search, there are three additional candidates for
the RECONS sample that have no trigonometric parallaxes.Comment: 17 pages, 5 figures; accepted for publication in Astronomy Journa
The Solar Neighborhood XXV: Discovery of New Proper Motion Stars with 0.40 "/yr > mu > 0.18 "/yr between Declinations -47 degrees and 00 degrees
We present 2817 new southern proper motion systems with 0.40 "/yr > mu > 0.18
"/yr and declination between -47 degrees and 00 degrees. This is a continuation
of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We
use the same photometric relations as previous searches to provide distance
estimates based on the assumption that the objects are single main sequence
stars. We find 79 new red dwarf systems predicted to be within 25 pc, including
a few new components of previously known systems. Two systems - SCR 1731-2452
at 9.5 pc and SCR 1746-3214 at 9.9 pc - are anticipated to be within 10 pc. We
also find 23 new white dwarf candidates with distance estimates of 15-66 pc, as
well as 360 new red subdwarf candidates. With this search, we complete the SCR
sweep of the southern sky for stars with mu > 0.18 "/yr and R_59F < 16.5,
resulting in a total of 5042 objects in 4724 previously unreported proper
motion systems. Here we provide selected comprehensive lists from our SCR
proper motion search to date, including 152 red dwarf systems estimated to be
within 25 pc (nine within 10 pc), 46 white dwarfs (ten within 25 pc), and 598
subdwarf candidates. The results of this search suggest that there are more
nearby systems to be found at fainter magnitudes and lower proper motion limits
than those probed so far.Comment: 47 pages, 16 of text. 7 figure
Distance Dependent Offsets between Parallaxes for Nearby Stars and Gaia DR1 Parallaxes
We use 612 single stars with previously published trigonometric parallaxes
placing them within 25 pc to evaluate parallaxes released in Gaia's first data
release (DR1). We find that the Gaia parallaxes are, on average, mas smaller than the weighted mean trigonometric parallax values for
these stars in the solar neighborhood. We also find that the offset changes
with distance out to 100 pc, in the sense that the closer the star, the larger
the offset. We find no systematic trends in the parallax offsets with stellar
magnitude, color, or proper motion. We do find that the offset is
roughly twice as large for stars south of the ecliptic compared to those that
are north.Comment: 14 pages, 2 figures, 3 tables, accepted for publication in ApJ
Letter. The table 1 is available in its entirety in a machine-readable form
in the online journa
The Trigonometric Parallax of the Brown Dwarf Planetary System 2MASSW J1207334-393254
We have measured a trigonometric parallax to the young brown dwarf 2MASSW
J1207334-393254. The distance [54.0 (+3.2,-2.8) pc] and space motion confirm
membership in the TW Hydrae Association. The primary is a ~25 M_jup brown
dwarf. We discuss the "planetary mass" secondary, which is certainly below the
deuterium-burning limit but whose colors and absolute magnitudes pose
challenges to our current understanding of planetary-mass objects.Comment: Accepted to the Astrophysical Journal Letter
The Solar Neighborhood XXIV. Parallax Results from the CTIOPI 0.9-m Program: Stars with 1\farcs0 yr (MOTION Sample) and Subdwarfs
We present 41 trigonometric parallaxes of 37 stellar systems, most of which
have proper motions greater than 1\farcs0 yr. These are the first
trigonometric parallaxes for 24 systems. Overall, there are 15 red dwarf
systems and 22 red subdwarf systems in the sample. Five of the systems are
multiples with directly detected companions, and we have discovered
perturbations caused by unseen companions in two additional cases, the dwarf
LHS 501 and the subdwarf LHS 440. The latter system may eventually provide
important dynamical mass points on the subdwarf mass-luminosity relation. Two
additional stars of note are LHS 272, the third closest M-type subdwarf at a
distance of only 13.6 pc, and LHS 2734AB, a high velocity subdwarf binary with
700 km/sec, which likely exceeds the escape velocity of the Milky
Way. We also report the first long term variability study of cool subdwarfs
indicating that cool subdwarfs are less photometrically variable than their
main sequence counterparts.Comment: 28 pages, 7 figures, 3 tables, accepted by A
Tuning and Switching a Plasmonic Quantum Dot Sandwich in a Nematic Line Defect
We study the quantum-mechanical effects arising in a single semiconductor
core/shell quantum dot controllably sandwiched between two plasmonic nanorods.
Control over the position and the sandwich confinement structure is achieved by
the use of a linear-trap, liquid-crystal line defect and laser tweezers that
push the sandwich together. This arrangement allows for the study of exciton
plasmon interactions in a single structure, unaltered by ensemble effects or
the complexity of dielectric interfaces. We demonstrate the effect of plasmonic
confinement on the photon-antibunching behavior of the quantum dot and its
luminescence lifetime. The quantum dot behaves as a single emitter when
nanorods are far away from the quantum dot but shows possible multiexciton
emission and a significantly decreased lifetime when tightly confined in a
plasmonic sandwich. These findings demonstrate that liquid crystal defects,
combined with laser tweezers, enable a versatile platform to study plasmonic
coupling phenomena in a nanoscale laboratory, where all elements can be
arranged almost at will.Comment: Supporting information at the en
Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems
We present results of a reconnaissance for stellar companions to all 131
radial-velocity-detected candidate extrasolar planetary systems known as of
July 1, 2005. CPM companions were investigated using the multi-epoch DSS
images, and confirmed by matching the trigonometric parallax distances of the
primaries to companion distances estimated photometrically. We also attempt to
confirm or refute companions listed in the Washington Double Star Catalog, the
Catalogs of Nearby Stars, in Hipparcos results, and in Duquennoy & Mayor
(1991).
Our findings indicate that a lower limit of 30 (23%) of the 131 exoplanet
systems have stellar companions. We report new stellar companions to HD 38529
and HD 188015, and a new candidate companion to HD 169830. We confirm many
previously reported stellar companions, including six stars in five systems
that are recognized for the first time as companions to exoplanet hosts. We
have found evidence that 20 entries in the Washington Double Star Catalog are
not gravitationally bound companions. At least three, and possibly five, of the
exoplanet systems reside in triple star systems. Three exoplanet systems have
potentially close-in stellar companions ~ 20 AU away from the primary. Finally,
two of the exoplanet systems contain white dwarf companions. This comprehensive
assessment of exoplanet systems indicates that solar systems are found in a
variety of stellar multiplicity environments - singles, binaries, and triples;
and that planets survive the post-main-sequence evolution of companion stars.Comment: 52 pages, 7 figures, Accepted for publication in Ap
'Parasitic invasions' or sources of good governance: constraining foreign competition in Hong Kong banking, 1956-81
This paper investigates the operation and impact of the moratorium on new banking licences imposed in Hong Kong in 1965 and the claims that foreign banks destabilised the banking system and drained resources from the colony. First it examines foreign banks' attempts to circumvent the moratorium through claims of special circumstances and buying interests in local banks, and secondly it examines the efforts of incumbents to extend barriers to non-bank financial institutions and to branches of foreign banks. The general conclusions are that while the moratorium was aimed at increasing the stability of the banking system, it had the effect of decreasing the regulatory breadth of the government, and reducing incentives for mergers and acquisitions that might have improved governance
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