564 research outputs found
Last Glacial Fluctuation of Fluvial Wetland Environment of Korea -with an Special Reference of Fluvial Organic Mud Formations
Korea Institute of Geosciences and Mineral ResourcesScedule:17-18 March 2003, Vemue: Kanazawa, Japan, Kanazawa Citymonde Hotel, Project Leader : Hayakawa, Kazuichi, Symposium Secretariat: XO kamata, Naoto, Edited by:Kamata, Naoto
KMT-2022-BLG-2397: Brown Dwarf at the Upper Shore of the Einstein Desert
We measure the Einstein radius of the single-lens microlensing event
KMT-2022-BLG-2397 to be theta_E=24.8 +- 3.6 uas, placing it at the upper shore
of the Einstein Desert, 9 < theta_E / uas < 25, between free-floating planets
(FFPs) and bulge brown dwarfs (BDs). In contrast to the six BD (25 < theta_E <
50) events presented by Gould+22, which all had giant-star source stars,
KMT-2022-BLG-2397 has a dwarf-star source, with angular radius theta_* ~ 0.9
uas. This prompts us to study the relative utility of dwarf and giant sources
for characterizing FFPs and BDs from finite-source point-lens (FSPL)
microlensing events. We find `dwarfs' (including main-sequence stars and
subgiants) are likely to yield twice as many theta_E measurements for BDs and a
comparable (but more difficult to quantify) improvement for FFPs. We show that
neither current nor planned experiments will yield complete mass measurements
of isolated bulge BDs, nor will any other planned experiment yield as many
theta_E measurements for these objects as KMT. Thus, the currently anticipated
10-year KMT survey will remain the best way to study bulge BDs for several
decades to come.Comment: 45 pages, 9 Figures, submitted to AAS Journal
KMT-2021-BLG-1122L: The first microlensing triple stellar system
We systematically inspect the microlensing data acquired by the KMTNet survey
during the previous seasons in order to find anomalous lensing events for which
the anomalies in the lensing light curves cannot be explained by the usual
binary-lens or binary-source interpretations. From the inspection, we find that
interpreting the three lensing events OGLE-2018-BLG-0584, KMT-2018-BLG-2119,
and KMT-2021-BLG-1122 requires four-body (lens+source) models, in which either
both the lens and source are binaries (2L2S event) or the lens is a triple
system (3L1S event). Following the analyses of the 2L2S events presented in
\citet{Han2023}, here we present the 3L1S analysis of the KMT-2021-BLG-1122. It
is found that the lens of the event KMT-2021-BLG-1122 is composed of three
masses, in which the projected separations (normalized to the angular Einstein
radius) and mass ratios between the lens companions and the primary are and . By conducting a
Bayesian analysis, we estimate that the masses of the individual lens
components are . The companions are separated in projection from the primary by
~AU. The lens of KMT-2018-BLG-2119
is the first triple stellar system detected via microlensing.Comment: 8 pages, 7 figures, 2 table
Mass Production of 2021 KMTNet Microlensing Planets II
We continue our program of publishing all planets (and possible planets)
found by eye in 2021 Korea Microlensing Telescope Network (KMTNet) online data.
We present 4 planets, (KMT-2021-BLG-0712Lb, KMT-2021-BLG-0909Lb,
KMT-2021-BLG-2478Lb, and KMT-2021-BLG-1105Lb), with planet-host mass ratios in
the range -3.3 < log q < -2.2. This brings the total of secure, by-eye, 2021
KMTNet planets to 16, including 8 in this series. The by-eye sample is an
important check of the completeness of semi-automated detections, which are the
basis for statistical analyses. One of the planets, KMT-2021-BLG-1105Lb, is
blended with a relatively bright star that may be the
host. This could be verified immediately by high-resolution imaging. If so, the
host is an early G dwarf, and the planet could be characterized by
radial-velocity observations on 30m class telescopes
Proximity of Iron Pnictide Superconductors to a Quantum Tricritical Point
We determine the nature of the magnetic quantum critical point in the doped
LaFeAsO using a set of constrained density functional calculations that provide
ab initio coefficients for a Landau order parameter analysis. The system turns
out to be remarkably close to a quantum tricritical point, where the nature of
the phase transition changes from first to second order. We compare with the
effective field theory and discuss the experimental consequences.Comment: 4 pages, 4 figure
KMT-2021-BLG-2010Lb, KMT-2022-BLG-0371Lb, and KMT-2022-BLG-1013Lb: Three microlensing planets detected via partially covered signals
We inspect 4 microlensing events KMT-2021-BLG-1968, KMT-2021-BLG-2010,
KMT-2022-BLG-0371, and KMT-2022-BLG-1013, for which the light curves exhibit
partially covered short-term central anomalies. We conduct detailed analyses of
the events with the aim of revealing the nature of the anomalies. We test
various models that can give rise to the anomalies of the individual events
including the binary-lens (2L1S) and binary-source (1L2S) interpretations.
Under the 2L1S interpretation, we thoroughly inspect the parameter space to
check the existence of degenerate solutions, and if they exist, we test the
feasibility of resolving the degeneracy. We find that the anomalies in
KMT-2021-BLG-2010 and KMT-2022-BLG-1013 are uniquely defined by planetary-lens
interpretations with the planet-to-host mass ratios of and , respectively. For KMT-2022-BLG-0371, a
planetary solution with a mass ratio is strongly
favored over the other three degenerate 2L1S solutions with different mass
ratios based on the and relative proper motion arguments, and a 1L2S
solution is clearly ruled out. For KMT-2021-BLG-1968, on the other hand, we
find that the anomaly can be explained either by a planetary or a binary-source
interpretation, making it difficult to firmly identify the nature of the
anomaly. From the Bayesian analyses of the identified planetary events, we
estimate that the masses of the planet and host are ,
, and for KMT-2021-BLG-2010L, KMT-2022-BLG-0371L, and
KMT-2022-BLG-1013L, respectively.Comment: 12 pages, 17 figure
Systematic KMTNet Planetary Anomaly Search. IV. Complete Statistical Sample of 2019 Prime-Field Microlensing Planets
We report the complete statistical planetary sample from the prime fields
() of the 2019 Korea Microlensing Telescope
Network (KMTNet) microlensing survey. We develop the optimized KMTNet
AnomalyFinder algorithm and apply it to the 2019 KMTNet prime fields. We find a
total of 14 homogeneously selected planets and report the analysis of three
planetary events, KMT-2019-BLG-(1042,1552,2974). The planet-host mass ratios,
, for the three planetary events are and , respectively. A Bayesian analysis indicates
the three planets are all cold giant planets beyond the snow line of their host
stars. The 14 planets are basically uniform in over the range . This result suggests that the planets below proposed by the MOA-II survey may be more common than
previously believed. This work is an early component of a large project to
determine the KMTNet mass-ratio function, and the whole sample of 2016--2019
KMTNet events should contain about 120 planets.Comment: 7 figures and 7 tables; submitte
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