13 research outputs found
Measurement of the Free-Floating Planet Mass Function with Simultaneous Euclid and WFIRST Microlensing Parallax Observations
Free-floating planets are the remnants of violent dynamical rearrangements of
planetary systems. It is possible that even our own solar system ejected a
large planet early in its evolution. WFIRST will have the ability to detect
free-floating planets over a wide range of masses, but it will not be able to
directly measure their masses. Microlensing parallax observations can be used
to measure the masses of isolated objects, including free-floating planets, by
observing their microlensing events from two locations. The intra-L2 separation
between WFIRST and Euclid is large enough to enable microlensing parallax
measurements, especially given the exquisite photometric precision that both
spacecraft are capable of over wide fields. In this white paper we describe how
a modest investment of observing time could yield hundreds of parallax
measurements for WFIRST's bound and free-floating planets. We also describe how
a short observing campaign of precursor observations by Euclid can improve
WFIRST's bound planet and host star mass measurements.Comment: Astro2020 White Pape
Adaptive Optics Imaging Breaks the Central Caustic Cusp Approach Degeneracy in High Magnification Microlensing Events
We report new results for the gravitational microlensing target
OGLE-2011-BLG-0950 from adaptive optics (AO) images using the Keck observatory.
The original analysis by Choi et al. 2012 reports degenerate solutions between
planetary and stellar binary lens systems. This is due to a degeneracy in high
magnification events where the shape of the light curve peak can be explained
by a source approach to two different cusp geometries with different source
radius crossing times. This particular case is the most important type of
degeneracy for exoplanet demographics, because the distinction between a
planetary mass or stellar binary companion has direct consequences for
microlensing exoplanet statistics. The 8 and 10-year baselines between the
event and the Keck observations allow us to directly measure a relative proper
motion of mas/yr, which confirms the detection of the lens star
system and directly rules out the planetary companion models that predict a
smaller relative proper motion. The combination of the lens
brightness and close stellar binary light curve parameters yield primary and
secondary star masses of and at a distance of kpc, and a primary-secondary projected separation of
AU. Since this degeneracy is likely to be common, the
high resolution imaging method described here will be used to disentangle the
central caustic cusp approach degeneracy for events observed by the
\textit{Roman} exoplanet microlensing survey using the \textit{Roman} images
taken near the beginning or end of the survey.Comment: Revised version, 19 pages, 8 figures. AJ, 164, 21
Measurement of the Free-Floating Planet Mass Function with Simultaneous Euclid and WFIRST Microlensing Parallax Observations
Free-floating planets are the remnants of violent dynamical rearrangements of planetary systems. It is possible that even our own solar system ejected a large planet early in its evolution. WFIRST will have the ability to detect free-floating planets over a wide range of masses, but it will not be able to directly measure their masses. Microlensing parallax observations can be used to measure the masses of isolated objects, including free-floating planets, by observing their microlensing events from two locations. The intra-L2 separation between WFIRST and Euclid is large enough to enable microlensing parallax measurements, especially given the exquisite photometric precision that both spacecraft are capable of over wide fields. In this white paper we describe how a modest investment of observing time could yield hundreds of parallax measurements for WFIRST's bound and free-floating planets. We also describe how a short observing campaign of precursor observations by Euclid can improve WFIRST's bound planet and host star mass measurements
The Galactic Center with Roman
We advocate for a Galactic center (GC) field to be added to the Galactic
Bulge Time Domain Survey (GBTDS). The new field would yield high-cadence
photometric and astrometric measurements of an unprecedented 3.3
million stars toward the GC. This would enable a wide range of science cases,
such as finding star-compact object binaries that may ultimately merge as
LISA-detectable gravitational wave sources, constraining the mass function of
stars and compact objects in different environments, detecting populations of
microlensing and transiting exoplanets, studying stellar flares and variability
in young and old stars, and monitoring accretion onto the central supermassive
black hole. In addition, high-precision proper motions and parallaxes would
open a new window into the large-scale dynamics of stellar populations at the
GC, yielding insights into the formation and evolution of galactic nuclei and
their co-evolution with the growth of the supermassive black hole. We discuss
the possible trade-offs between the notional GBTDS and the addition of a GC
field with either an optimal or minimal cadence. Ultimately, the addition of a
GC field to the GBTDS would dramatically increase the science return of Roman
and provide a legacy dataset to study the mid-plane and innermost regions of
our Galaxy.Comment: 19 pages, 3 figures. Submitted to the NASA Roman Core Community
Surveys White Paper Cal
Masses and Distances of Planetary Microlens Systems with High Angular Resolution Imaging
Microlensing is the only method that can detect and measure mass of wide
orbit, low mass, solar system analog exoplanets. Mass measurements of such
planets would yield massive science on planet formation, exoplanet
demographics, free floating planets, planet frequencies towards the galaxy.
High res follow-up observations of past microlens targets provide a mass
measurement of microlens planets and hosts at an uncertainty of <20%. This will
be primary method for mass measurement with WFIRST. We advocate for the fact
that high resolution observations with AO, HST and JWST(in future) remain
necessary in coming decade to develop the methods, to determine the field and
filter selection, understand the systematics and to develop a robust pipeline
to release high quality data products from WFIRST microlensing survey such that
the astronomy community can promptly engage in the science. We also support
future high res obs with US ELTs with advanced Laser AO systems in context of
enhancing the science return of WFIRST microlensing survey.
We endorse the 2018 Exoplanet Science Strategy report published by the
National Academy. This white paper extends and complements the material
presented therein. In particular, this white paper supports the recommendation
of the National Academy Exoplanet Science Strategy report that: NASA should
launch WFIRST to conduct its microlensing survey of distant planets and to
demonstrate the technique of coronagraphic spectroscopy on exoplanet targets.
This white paper also supports to the finding from that report which states "A
number of activities, including precursor and concurrent observations using
ground- and space-based facilities, would optimize the scientific yield of the
WFIRST microlensing survey."Comment: 8 pages, 2 figures, Astro2020 decadal submissio
Masses and Distances of Planetary Microlens Systems with High Angular Resolution Imaging
Microlensing is the only method that can detect and measure mass of wide orbit, low mass, solar system analog exoplanets. Mass measurements of such planets would yield massive science on planet formation, exoplanet demographics, free floating planets, planet frequencies towards the galaxy. High res follow-up observations of past microlens targets provide a mass measurement of microlens planets and hosts at an uncertainty of <20%. This will be primary method for mass measurement with WFIRST. We advocate for the fact that high resolution observations with AO, HST and JWST(in future) remain necessary in coming decade to develop the methods, to determine the field and filter selection, understand the systematics and to develop a robust pipeline to release high quality data products from WFIRST microlensing survey such that the astronomy community can promptly engage in the science. We also support future high res obs with US ELTs with advanced Laser AO systems in context of enhancing the science return of WFIRST microlensing survey.
We endorse the 2018 Exoplanet Science Strategy report published by the National Academy. This white paper extends and complements the material presented therein. In particular, this white paper supports the recommendation of the National Academy Exoplanet Science Strategy report that: NASA should launch WFIRST to conduct its microlensing survey of distant planets and to demonstrate the technique of coronagraphic spectroscopy on exoplanet targets. This white paper also supports to the finding from that report which states "A number of activities, including precursor and concurrent observations using ground- and space-based facilities, would optimize the scientific yield of the WFIRST microlensing survey.
Safety of endoscopic retrograde cholangiopancreatography in the pediatric population: a multicenter study
INTRODUCTION: The aims of this retrospective multicenter study were to assess the technical success and adverse events of endoscopic retrograde cholangiopancreatography (ERCP) procedures in children in French and Belgian centers.
METHODS: All children aged 1 day to 17 years who underwent ERCP between January 2008 and March 2019 in 15 tertiary care hospitals were retrospectively included.
RESULTS: 271 children underwent 470 ERCP procedures. Clinical long-term follow-up was available for 72 % of our patients (340/470 procedures). The median age at intervention was 10.9 years. ERCP was therapeutic in 90 % (423/470) and diagnostic in cases of neonatal cholestasis in 10 % of the patients. The most common biliary indication was choledocholithiasis; the most common pancreatic indication was chronic pancreatitis. Biliary cannulation was successful in 92 % of cases (270/294); pancreatic cannulation in 96 % of cases (169/176); and planned therapeutic procedures in 92 % of cases (388/423). The overall complication rate was 19 % (65/340). The most common complication was post-ERCP pancreatitis (PEP) in 12 % of cases (40/340) and sepsis in 5 % (18/340). On univariate analyses, pancreatic stent removal was protective against PEP (odds ratio [OR] 0.1, 95 % confidence interval [CI] 0.01 - 0.75; P = 0.03), and sepsis was associated with history of liver transplantation (OR 7.27, 95 %CI 1.7 - 31.05; P = 0.01). Five patients had post-ERCP hemorrhage and two had intestinal perforation. All complications were managed with supportive medical care. There was no procedure-related mortality.
CONCLUSION: Our cohort demonstrates that ERCP can be performed safely with high success rates in many pancreaticobiliary diseases of children. The rate of adverse events was similar to that in previous reports