121 research outputs found
First Detection of HCO Absorption in the Magellanic System
We present the first detection of HCO absorption in the Magellanic
System. Using the Australia Telescope Compact Array (ATCA), we observed 9
extragalactic radio continuum sources behind the Magellanic System and detected
HCO absorption towards one source located behind the leading edge of the
Magellanic Bridge. The detection is located at LSR velocity of , with a full width at half maximum of and optical depth of .
Although there is abundant neutral hydrogen (HI) surrounding the sightline in
position-velocity space, at the exact location of the absorber the HI column
density is low, , and there is little evidence for dust
or CO emission from Planck observations. While the origin and survival of
molecules in such a diffuse environment remains unclear, dynamical events such
as HI flows and cloud collisions in this interacting system likely play an
important role.Comment: Accepted for publication in ApJ. 6 pages, 2 figures, 2 table
A survey for hydroxyl in the THOR pilot region around W43
We report on observations of the hydroxyl radical (OH) within The H{\sc I}, OH Recombination line survey (THOR) pilot region. The region is bounded approximately between Galactic coordinates l=29.2 to 31.5 ∘ and b=-1.0 to +1.0 ∘ and includes the high-mass star forming region W43. We identify 103 maser sites, including 72 with 1612\,MHz masers, 42 showing masers in either of the main line transitions at 1665 and 1667\,MHz and four showing 1720\,MHz masers. Most maser sites with either main-line or 1720\,MHz emission are associated with star formation, whereas most of the 1612\,MHz masers are associated with evolved stars. We find that nearly all of the main-line maser sites are co-spatial with an infrared source, detected by GLIMPSE. We also find diffuse OH emission, as well as OH in absorption towards selected unresolved or partially resolved sites. Extended OH absorption is found towards the well known star forming complex W43 Main
A survey for hydroxyl in the THOR pilot region around W43
We report on observations of the hydroxyl radical (OH) within The Hι, OH, Recombination line survey (THOR) pilot region. The region is bounded approximately between Galactic coordinates l = 29 .2 to 31 .5 and b = −1 .0 to +1 .0 and includes the high-mass star-forming region W43. We identify 103 maser sites, including 72 with 1612 MHz masers, 42 showing masers in either of the main-line transitions at 1665 and 1667 MHz and four showing 1720 MHz masers. Most maser sites with either main-line or 1720 MHz emission are associated with star formation, whereas most of the 1612 MHz masers are associated with evolved stars. We find that nearly all of the main-line maser sites are co-spatial with an infrared source, detected by GLIMPSE. We also find diffuse OH emission, as well as OH in absorption towards selected unresolved or partially resolved sites. Extended OH absorption is found towards the well-known star-forming complex W43 Main
Associations between a Universal Free Breakfast Policy and School Breakfast Program Participation, School Attendance, and Weight Status: A District-Wide Analysis
Breakfast consumption among youth is associated with improved diet quality, weight, cognition, and behavior. However, not all youth in the United States consume breakfast. Participation in the School Breakfast Program (SBP) is also low relative to the lunch program. Universal free breakfast (UFB) policies have been implemented to increase breakfast participation by reducing cost and stigma associated with the SBP. This study examined whether a UFB policy implemented in a school district in the Southeast US was associated with changes in breakfast participation, school attendance, and student weight. A longitudinal study of secondary data was conducted, and a mixed modeling approach was used to assess patterns of change in SBP participation. General linear models were used to assess attendance and student weight change. On average, across schools in the district, there was an increase in breakfast participation of 4.1 percentage points following the implementation of the policy. The change in breakfast participation in schools differed by the percent of students in the school who received school meals for free or at a reduced price, the percent of students of color, and the grade level of the school. Increases in SBP participation were not associated with significant changes in attendance or weight. UFB policies may be effective in increasing participation in the SBP
First detection of HCO+ absorption in the magellanic system
We present the first detection of HCO+ absorption in the Magellanic System. Using the ATCA, we observed
nine extragalactic radio continuum sources behind the Magellanic System and detected HCO+ absorption
toward one source located behind the leading edge of the Magellanic Bridge. The detection is located at an LSR
velocity of v 214.0 0.4 km s = -1
, with an FWHM of v 4.5 1.0 km s D = -1
, and an optical depth of
t (HCO ) 0.10 0.0 = 2 + . Although there is abundant neutral hydrogen (H I) surrounding the sight line in
position–velocity space, at the exact location of the absorber the H I column density is low, <10 cm 20 2 - , and
there is little evidence for dust or CO emission from Planck observations. While the origin and survival of
molecules in such a diffuse environment remain unclear, dynamical events such as H I flows and cloud
collisions in this interacting system likely play an important role
MAGMO: polarimetry of 1720-MHz OH masers towards southern star-forming regions
From targeted observations of ground-state hydroxyl (OH) masers towards 702 Methanol Multibeam survey 6.7-GHz methanol masers, in the Galactic longitude range from 186 degrees C through the Galactic Centre to 20 degrees C, made as part of the 'MAGMO' (Mapping the Galactic Magnetic field through OH masers) project, we present the physical and polarization properties of the 1720-MHz OH maser transition, including the identification of Zeeman pairs. We present 10 new and 23 previously catalogued 1720-MHz OH maser sources detected towards star-forming regions (SFRs). In addition, we also detected 16 1720-MHz OH masers associated with supernova remnants and two sites of diffuse OH emission. Towards the 33 star formation masers, we identify 44 Zeeman pairs, implying magnetic field strengths ranging from −11.4 to +13.2 mG, and a median magnetic field strength of |BLOS| ∼ 6 mG. With limited statistics, we present the in situ magnetic field orientation of the masers and the Galactic magnetic field distribution revealed by the 1720-MHz transition. We also examine the association statistics of 1720-MHz OH SFR masers with other ground-state OH masers, excited-state OH masers, class I and class II methanol masers, and water masers, and compare maser positions with mid-infrared images of the parent SFRs. Of the 33 1720-MHz star formation masers, 10 are offset from their central exciting sources, and appear to be associated with outflow activity.This work was presented as part of CSO’s doctoral program funded
by the International Macquarie Research Excellence Scholarship
(iMQRES) program. CSO was also a recipient of the Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Astronomy and Space Science Student Program grant for which
CSO is grateful. JRD acknowledges the support of an Australian
Research Council (ARC) DECRA Fellowship (project number
DE170101086). This paper includes archived data obtained through
the Australia Telescope Online Archive (http://atoa.atnf.csiro.au).
The Australia Telescope Compact Array (ATCA) is part of the
Australia Telescope National Facility and funded by the CSIRO.
This research made use of APLPY, an open-source plotting package
for PYTHON (Robitaille & Bressert 2012)
MAGMO: Polarimetry of 1720-MHz OH Masers towards Southern Star Forming Regions
From targeted observations of ground-state OH masers towards 702 Multibeam
(MMB) survey 6.7-GHz methanol masers, between Galactic longitudes 186
through the Galactic centre to 20, made as part of the `MAGMO'
project, we present the physical and polarisation properties of the 1720-MHz OH
maser transition, including the identification of Zeeman pairs. We present 10
new and 23 previously catalogued 1720-MHz OH maser sources detected towards
star formation regions. In addition, we also detected 16 1720-MHz OH masers
associated with supernova remnants and two sites of diffuse OH emission.
Towards the 33 star formation masers, we identify 44 Zeeman pairs, implying
magnetic field strengths ranging from 11.4 to 13.2 mG, and a median
magnetic field strength of 6 mG. With limited statistics, we
present the in-situ magnetic field orientation of the masers and the Galactic
magnetic field distribution revealed by the 1720-MHz transition. We also
examine the association statistics of 1720-MHz OH SFR masers with other
ground-state OH masers, excited-state OH masers, class I and class II methanol
masers and water masers, and compare maser positions with mid-infrared images
of the parent star forming regions. Of the 33 1720-MHz star formation masers,
ten are offset from their central exciting sources, and appear to be associated
with outflow activity
A Survey for Hydroxyl in the THOR Pilot Region around W43
We report on observations of the hydroxyl radical (OH) within The H{\sc I}, OH Recombination line survey (THOR) pilot region. The region is bounded approximately between Galactic coordinates l=29.2 to 31.5 and b=-1.0 to +1.0 and includes the high-mass star forming region W43. We identify 103 maser sites, including 72 with 1612\,MHz masers, 42 showing masers in either of the main line transitions at 1665 and 1667\,MHz and four showing 1720\,MHz masers. Most maser sites with either main-line or 1720\,MHz emission are associated with star formation, whereas most of the 1612\,MHz masers are associated with evolved stars. We find that nearly all of the main-line maser sites are co-spatial with an infrared source, detected by GLIMPSE. We also find diffuse OH emission, as well as OH in absorption towards selected unresolved or partially resolved sites. Extended OH absorption is found towards the well known star forming complex W43 Main
GSH 006-15+7: A local Galactic supershell featuring transition from HI emission to absorption
We report on the discovery of a new Galactic supershell, GSH 006-15+7, from
the Galactic All Sky Survey data. Observed and derived properties are presented
and we find that GSH 006-15+7 is one of the nearest physically large
supershells known, with dimensions of ~ 780 x 520 pc at a distance of ~ 1.5
kpc. The shell wall appears in HI emission at b <~ -6.5 deg and in HI
self-absorption (HISA) at b >~ -6.5 deg. We use this feature along with HISA
diagnostics to estimate an optical depth of tau ~ 3, a spin temperature of ~ 40
K and a swept-up mass of M ~ 3e6 solar masses. We also investigate the origin
of GSH 006-15+7, assessing the energy contribution of candidate powering
sources and finding evidence in favour of a formation energy of ~ 1e52 ergs. We
find that this structure provides evidence for the transfer of mass and energy
from the Galactic disk into the halo.Comment: 12 pages, 8 figures, accepted for publication in MNRA
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