scholarly journals Ground-state OH maser distributions in the Galactic Centre region

2016 ◽  
Vol 11 (S322) ◽  
pp. 141-142 ◽  
Author(s):  
Hai-Hua Qiao ◽  
Andrew J. Walsh ◽  
Zhi-Qiang Shen ◽  
Joanne R. Dawson
Keyword(s):  
Star Formation ◽  
Ground State ◽  
Planetary Nebula ◽  
Supernova Remnant ◽  
High Accuracy ◽  
Galactic Centre ◽  
Large Area ◽  
Area Survey ◽  
Centre Region ◽  
Compact Array

AbstractGround-state OH masers identified in the Southern Parkes Large-Area Survey in Hydroxyl were observed with the Australia Telescope Compact Array to obtain positions with high accuracy (~1 arcsec). We classified these OH masers into evolved star OH maser sites, star formation OH maser sites, supernova remnant OH maser sites, planetary nebula OH maser sites and unknown maser sites using their accurate positions. Evolved star and star formation OH maser sites in the Galactic Centre region (between Galactic longitudes of −5° to +5° and Galactic latitudes of −2° and +2°) were studied in detail to understand their distributions.

scholarly journals Current stage of the ATCA follow-up for SPLASH

2017 ◽  
Vol 13 (S336) ◽  
pp. 295-296
Author(s):  
Hai-Hua Qiao ◽  
Andrew J. Walsh ◽  
Zhi-Qiang Shen
Keyword(s):  
Ground State ◽  
Supernova Remnants ◽  
Unknown Origin ◽  
High Accuracy ◽  
Large Area ◽  
Evolved Stars ◽  
Area Survey ◽  
Current Stage ◽  
Compact Array

AbstractFour ground-state OH transitions were detected in emission, absorption and maser emission in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH). We re-observed these OH masers with the Australia Telescope Compact Array to obtain positions with high accuracy (~1 arcsec). According to the positions, we categorised these OH masers into different classes, i.e. star formation, evolved stars, supernova remnants and unknown origin. We found one interesting OH maser source (G336.644-0.695) in the pilot region, which has been studied in detail in Qiaoet al.(2016a). In this paper, we present the current stage of the ATCA follow-up for SPLASH and discuss the potential future researches derived from the ATCA data.

scholarly journals A new distance to the Brick, the dense molecular cloud G0.253+0.016

2021 ◽  
Vol 502 (1) ◽  
pp. 1246-1252
Author(s):  
M Zoccali ◽  
E Valenti ◽  
F Surot ◽  
O A Gonzalez ◽  
A Renzini ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Near Infrared ◽  
Formation Rate ◽  
Dynamical Evolution ◽  
Galactic Centre ◽  
The Galaxy ◽  
Centre Region ◽  
Order Of Magnitude ◽  
Red Clump

ABSTRACT We analyse the near-infrared colour–magnitude diagram of a field including the giant molecular cloud G0.253+0.016 (a.k.a. The Brick) observed at high spatial resolution, with HAWK-I@VLT. The distribution of red clump stars in a line of sight crossing the cloud, compared with that in a direction just beside it, and not crossing it, allow us to measure the distance of the cloud from the Sun to be 7.20, with a statistical uncertainty of ±0.16 and a systematic error of ±0.20 kpc. This is significantly closer than what is generally assumed, i.e. that the cloud belongs to the near side of the central molecular zone, at 60 pc from the Galactic centre. This assumption was based on dynamical models of the central molecular zone, observationally constrained uniquely by the radial velocity of this and other clouds. Determining the true position of the Brick cloud is relevant because this is the densest cloud of the Galaxy not showing any ongoing star formation. This puts the cloud off by one order of magnitude from the Kennicutt–Schmidt relation between the density of the dense gas and the star formation rate. Several explanations have been proposed for this absence of star formation, most of them based on the dynamical evolution of this and other clouds, within the Galactic centre region. Our result emphasizes the need to include constraints coming from stellar observations in the interpretation of our Galaxy’s central molecular zone.

scholarly journals Detection of new sources of 4765-MHz OH masing

2002 ◽  
Vol 206 ◽  
pp. 112-115
Author(s):  
Richard G. Dodson ◽  
Simon P. Ellingsen
Keyword(s):  
Star Formation ◽  
High Resolution ◽  
Ground State ◽  
Theoretical Models ◽  
Maser Emission ◽  
Circular Polarisation ◽  
Peak Flux ◽  
Star Formation Regions ◽  
Compact Array

We have used the Australia Telescope Compact Array (ATCA) to make a sensitive search for maser emission from the 4765-MHz transition of OH towards a sample of 55 star formation regions. Maser emission with peak flux densities in excess of 100 mJy were detected in 14 sites, with 10 of these being new discoveries. Unlike the ground-state OH transitions the 4765-MHz transition is not predicted to be circularly polarised and none of the masers observed have detectable levels of linear, or circular polarisation. Combining our results with those of previous high resolution observations of other OH transitions we are able to investigate various theoretical models for the pumping of OH masers.

scholarly journals MAGMO: polarimetry of 1720-MHz OH masers towards southern star-forming regions

2020 ◽  
Vol 493 (1) ◽  
pp. 199-233 ◽  
Author(s):  
C S Ogbodo ◽  
J A Green ◽  
J R Dawson ◽  
S L Breen ◽  
S A Mao ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Ground State ◽  
Supernova Remnants ◽  
Galactic Centre ◽  
Galactic Magnetic Field ◽  
Field Orientation ◽  
Star Forming ◽  
Star Forming Regions ◽  
Methanol Masers

ABSTRACT 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° through the Galactic Centre to 20°, 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.

scholarly journals A Brief Update on the CMZoom Survey

2016 ◽  
Vol 11 (S322) ◽  
pp. 90-94
Author(s):  
C. Battersby ◽  
E. Keto ◽  
Q. Zhang ◽  
S.N. Longmore ◽  
J. M. D. Kruijssen ◽  
...  
Keyword(s):  
Star Formation ◽  
Angular Resolution ◽  
Spatial Scales ◽  
Extreme Environments ◽  
Spectral Lines ◽  
Large Area ◽  
Dense Cores ◽  
Submillimeter Wavelengths ◽  
Area Survey ◽  
The Universe

AbstractThe inner few hundred parsecs of the Milky Way, the Central Molecular Zone (CMZ), is our closest laboratory for understanding star formation in the extreme environments (hot, dense, turbulent gas) that once dominated the universe. We present an update on the first large-area survey to expose the sites of star formation across the CMZ at high-resolution in submillimeter wavelengths: the CMZoom survey with the Submillimeter Array (SMA). We identify the locations of dense cores and search for signatures of embedded star formation. CMZoom is a three-year survey in its final year and is mapping out the highest column density regions of the CMZ in dust continuum and a variety of spectral lines around 1.3 mm. CMZoom combines SMA compact and subcompact configurations with single-dish data from BGPS and the APEX telescope, achieving an angular resolution of about 4″ (0.2 pc) and good image fidelity up to large spatial scales.

Exploring Star Formation in the Galactic Centre Region: From ISO to ALMA

2007 ◽  
pp. 229-230
Author(s):  
F. Schuller ◽  
F. Bertoldi ◽  
M. Felli ◽  
K.M. Menten ◽  
A. Omont ◽  
...  
Keyword(s):  
Star Formation ◽  
Galactic Centre ◽  
Centre Region

scholarly journals OH as a Probe of The Milky Way's Hidden Gas: First Results from SPLASH

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
J. R. Dawson ◽  
A. J. Walsh ◽  
Keyword(s):  
Ground State ◽  
Galactic Plane ◽  
Thermal Excitation ◽  
Large Area ◽  
Early Results ◽  
First Results ◽  
Area Survey ◽  
Deep Survey ◽  
Maser Sources ◽  
Future Plans

AbstractSPLASH (the Southern Parkes Large-Area Survey in Hydroxyl) is a deep survey of ground-state OH absorption and emission from the Galactic Plane, as well as an unbiased search for OH masers. Key early results include the detection of a rich and complex distribution of diffuse, optically thin OH with strongly non-thermal excitation temperatures, and the detection of numerous new maser sources. The survey aims to use OH as a probe of CO-dark H2 ISM Galactic scales, with future plans including comprehensive comparisons with CO and Hi, as well as non-LTE excitation modelling of the four ground-state lines.

RESULTS FROM H.E.S.S.

2005 ◽  
Vol 20 (29) ◽  
pp. 7001-7005
Author(s):  
◽  
GÖTZ HEINZELMANN
Keyword(s):  
Supernova Remnant ◽  
Gamma Ray ◽  
Field Of View ◽  
Galactic Centre ◽  
Cherenkov Telescopes ◽  
Gamma Ray Astronomy ◽  
Centre Region ◽  
Stereoscopic Observation ◽  
Unidentified Source ◽  
New Generation

H.E.S.S. is an experiment for ground based GeV/TeV gamma ray astronomy of the new generation. It consists of four large Cherenkov telescopes operating in stereoscopic observation mode. Its construction in Namibia was completed at the end of 2003. Already during the installation phase, exciting results have been achieved, and after completion several discoveries have been made. Some of the results and discoveries are reported, such as the first image of a shell-type supernova remnant resolved at arc minute scale (RXJ 1713 – 3946), the discovery of the unique binary pulsar system PSR B1259 – 63 and of a yet-unidentified source in the same field of view (HESS J1303 – 631), and the observation of the galactic centre region. Amongst the extragalactic sources, the blazers Mkn 421 and PKS 2155 – 304 have also been detected.

scholarly journals STAR FORMATION AT 4 < z < 6 FROM THE SPITZER LARGE AREA SURVEY WITH HYPER-SUPRIME-CAM (SPLASH)

2014 ◽  
Vol 791 (2) ◽  
pp. L25 ◽  
Author(s):  
Charles L. Steinhardt ◽  
Josh S. Speagle ◽  
Peter Capak ◽  
John D. Silverman ◽  
Marcella Carollo ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Area ◽  
Area Survey

scholarly journals Molecular Gas and Star-formation in Selected H-ATLAS SDP Lensed SMGs

2012 ◽  
Vol 8 (S292) ◽  
pp. 192-192
Author(s):  
Lerothodi L. Leeuw ◽  
Dominik A. Riechers ◽  
John M. Carpenter ◽  
Mattia Negrello ◽  
Rob J. Ivison ◽  
...  
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
Brightness Temperature ◽  
Millimeter Wave ◽  
Molecular Gas ◽  
Large Area ◽  
Spatially Resolved ◽  
Area Survey ◽  
Science Demonstration

AbstractWe present detections of spatially resolved CO(J = 2→1) and CO(J = 3→2) emission, respectively, from the lensed submillimeter (submm) galaxies (SMGs), ID 9 (z = 1.577) and ID 17b (z = 2.308), found in the Science Demonstration Phase (SDP) of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS, www.h-atlas.org). The detections were obtained using the Combined Array for Research in Millimeter-wave Astronomy (CARMA, www.mmarray.org) and confirm redshifts of the lensed galaxies. We exploit the CARMA data together with existing high-J observations, to determine, among other physical properties of the lensed SMGs, the CO line luminosities, brightness temperature ratios, gas masses, and spatial sizes.

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