36 research outputs found
Checks And Balances: 2015 Update
Checking accounts are a vital financial tool, utilized by 9 in 10 American households. This report provides the third annual evaluation of disclosure, overdraft, and dispute resolution policies and practices of 45 of the nation's 50 largest retail banks, totaling 66 percent of all domestic deposit volume. Pew's Model Summary Disclosure Box for Checking Accounts served as the template for rating each bank's disclosure documents to determine best or good practices for overdraft and dispute resolution. Additionally, this report identified trends among the 32 institutions examined in all three Checks and Balances reports to date. To ensure that all checking accounts are safe and transparent, Pew has also developed a set of policy recommendations and urges the Consumer Financial Protection Bureau to incorporate these policies in new rules on overdraft practices and arbitration clauses
The Complex Story of American Debt
This report explores a key element of wealth: household debt. Debt is sometimes acquired for mobility-enhancing purposes, such as to pay for college or purchase a home. But debt can also serve as a stopgap for families to cover regular expenses or deal with financial emergencies, especially if their savings are not sufficient. The type and amount of debt that households carry contribute to their wealth and their overall financial health
Early Planet Formation in Embedded Disks (eDisk). VIII. A Small Protostellar Disk around the Extremely Low-Mass and Young Class 0 Protostar, IRAS 15398-3359
Protostellar disks are a ubiquitous part of the star formation process and
the future sites of planet formation. As part of the Early Planet Formation in
Embedded Disks (eDisk) large program, we present high-angular resolution dust
continuum (mas) and molecular line (mas) observations of
the Class 0 protostar, IRAS 15398-3359. The dust continuum is small, compact,
and centrally peaked, while more extended dust structures are found in the
outflow directions. We perform a 2D Gaussian fitting to find the deconvolved
size and radius of the dust disk to be
and , respectively. We estimate the gas+dust disk mass
assuming optically thin continuum emission to be ,
indicating a very low-mass disk. The CO isotopologues trace components of the
outflows and inner envelope, while SO traces a compact, rotating disk-like
component. Using several rotation curve fittings on the PV diagram of the SO
emission, the lower limits of the protostellar mass and gas disk radius are
and from our Modified 2 single power-law
fitting. A conservative upper limit of the protostellar mass is inferred to be
. The protostellar mass-accretion rate and the specific angular
momentum at the protostellar disk edge are found to be between
and
, respectively, with an age
estimated between yr. At this young age with no clear
substructures in the disk, planet formation would likely not yet have started.
This study highlights the importance of high-resolution observations and
systematic fitting procedures when deriving dynamical properties of deeply
embedded Class 0 protostars.Comment: 28 pages, 16 figures. Accepted for publication in ApJ as one of the
first-look papers of the eDisk ALMA Large Progra
Early Planet Formation in Embedded Disks (eDisk) XII: Accretion streamers, protoplanetary disk, and outflow in the Class I source Oph IRS63
We present ALMA observations of the Class I source Oph IRS63 in the context
of the Early Planet Formation in Embedded Disks (eDisk) large program. Our ALMA
observations of Oph IRS63 show a myriad of protostellar features, such as a
shell-like bipolar outflow (in CO), an extended rotating envelope
structure (in CO), a streamer connecting the envelope to the disk (in
CO), and several small-scale spiral structures seen towards the edge of
the dust continuum (in SO). By analyzing the velocity pattern of CO and
CO, we measure a protostellar mass of ~ and confirm the presence of a disk rotating at almost Keplerian
velocity that extends up to au. These calculations also show that the
gaseous disk is about four times larger than the dust disk, which could
indicate dust evolution and radial drift. Furthermore, we model the CO
streamer and SO spiral structures as features originating from an infalling
rotating structure that continuously feeds the young protostellar disk. We
compute an envelope-to-disk mass infall rate of ~ and compare it to the disk-to-star mass accretion rate of ~, from which we infer that the protostellar
disk is in a mass build-up phase. At the current mass infall rate, we speculate
that soon the disk will become too massive to be gravitationally stable.Comment: 26 pages and 17 figure
Early Planet Formation in Embedded Disks (eDisk) III: A first high-resolution view of sub-mm continuum and molecular line emission toward the Class 0 protostar L1527 IRS
Studying the physical and chemical conditions of young embedded disks is
crucial to constrain the initial conditions for planet formation. Here, we
present Atacama Large Millimeter/submillimeter Array (ALMA) observations of
dust continuum at 0.06" (8 au) resolution and molecular line emission at
0.17" (24 au) resolution toward the Class 0 protostar L1527 IRS from the
Large Program eDisk (Early Planet Formation in Embedded Disks). The continuum
emission is smooth without substructures, but asymmetric along both the major
and minor axes of the disk as previously observed. The detected lines of
CO, CO, CO, HCO, c-CH, SO, SiO, and DCN trace
different components of the protostellar system, with a disk wind potentially
visible in CO. The CO brightness temperature and the HCO line
ratio confirm that the disk is too warm for CO freeze out, with the snowline
located at 350 au in the envelope. Both molecules show potential evidence
of a temperature increase around the disk-envelope interface. SO seems to
originate predominantly in UV-irradiated regions such as the disk surface and
the outflow cavity walls rather than at the disk-envelope interface as
previously suggested. Finally, the continuum asymmetry along the minor axis is
consistent with the inclination derived from the large-scale (100" or 14,000
au) outflow, but opposite to that based on the molecular jet and envelope
emission, suggesting a misalignment in the system. Overall, these results
highlight the importance of observing multiple molecular species in multiple
transitions to characterize the physical and chemical environment of young
disks.Comment: 27 pages, 16 figures, 2 tables, 10 pages appendix with 12 figures.
Accepted for publication in ApJ as one of the first-look papers of the eDisk
ALMA Large Progra
Early Planet Formation in Embedded Disks (eDisk). VII. Keplerian Disk, Disk Substructure, and Accretion Streamers in the Class 0 Protostar IRAS 16544-1604 in CB 68
We present observations of the Class 0 protostar IRAS 16544-1604 in CB 68
from the ''Early Planet Formation in Embedded Disks (eDisk)'' ALMA Large
program. The ALMA observations target continuum and lines at 1.3-mm with an
angular resolution of 5 au. The continuum image reveals a dusty
protostellar disk with a radius of 30 au seen close to edge-on, and
asymmetric structures both along the major and minor axes. While the asymmetry
along the minor axis can be interpreted as the effect of the dust flaring, the
asymmetry along the major axis comes from a real non-axisymmetric structure.
The CO image cubes clearly show the gas in the disk that follows a
Keplerian rotation pattern around a 0.14 central protostar.
Furthermore, there are 1500 au-scale streamer-like features of gas
connecting from North-East, North-North-West, and North-West to the disk, as
well as the bending outflow as seen in the CO (2-1) emission. At the
apparent landing point of NE streamer, there are SO (6-5) and SiO (5-4)
emission detected. The spatial and velocity structure of NE streamer can be
interpreted as a free-falling gas with a conserved specific angular momentum,
and the detection of the SO and SiO emission at the tip of the streamer implies
presence of accretion shocks. Our eDisk observations have unveiled that the
Class 0 protostar in CB 68 has a Keplerian rotating disk with flaring and
non-axisymmetric structure associated with accretion streamers and outflows.Comment: 30 pages, 24 figures, accepted for publication in The Astrophysical
Journal as one of the first-look papers of the eDisk ALMA Large Progra
Early Planet Formation in Embedded Disks (eDisk). I. Overview of the Program and First Results
We present an overview of the Large Program, ``Early Planet Formation in
Embedded Disks (eDisk)'', conducted with the Atacama Large
Millimeter/submillimeter Array (ALMA). The ubiquitous detections of
substructures, particularly rings and gaps, in protoplanetary disks around T
Tauri stars raise the possibility that at least some planet formation may have
already started during the embedded stages of star formation. In order to
address exactly how and when planet formation is initiated, the program focuses
on searching for substructures in disks around 12 Class 0 and 7 Class I
protostars in nearby (200 pc) star-forming regions through 1.3 mm continuum
observations at a resolution of au (0.04"). The initial results show
that the continuum emission, mostly arising from dust disks around the sample
protostars, has relatively few distinctive substructures, such as rings and
spirals, in marked contrast to Class II disks. The dramatic difference may
suggest that substructures quickly develop in disks when the systems evolve
from protostars to Class II sources or alternatively that high optical depth of
the continuum emission could obscure internal structures. Kinematic information
obtained through CO isotopologue lines and other lines reveals the presence of
Keplerian disks around protostars, providing us with crucial physical
parameters, in particular, the dynamical mass of the central protostars. We
describe the background of the eDisk program, the sample selection and their
ALMA observations, the data reduction, and also highlight representative
first-look results.Comment: This is a publication of a series of eDisk ALMA large program
first-look paper
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure