High-resolution CO images of the Galactic central molecular zone

2019 ◽  
Vol 71 (Supplement_1) ◽  
Author(s):  
Sekito Tokuyama ◽  
Tomoharu Oka ◽  
Shunya Takekawa ◽  
Yuhei Iwata ◽  
Shiho Tsujimoto ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Detailed Comparison ◽  
Molecular Gas ◽  
Data Sets ◽  
Radio Observatory ◽  
James Clerk Maxwell ◽  
The Galaxy ◽  
Special Area ◽  
First Time

Abstract We performed Nyquist-sampled mapping observations of the central molecular zone of our Galaxy in the J = 1–0 lines of CO, 13CO, and C18O using the 45 m telescope at the Nobeyama Radio Observatory. The newly obtained data sets were an improvement by a factor of four in spatial resolution of the CO data previously obtained with the same telescope 22 years ago, providing the highest angular resolution CO atlas of this special area of the Galaxy. The data cover the area: −0${^{\circ}_{.}}$8 ≤ l ≤ +1${^{\circ}_{.}}$4 and −0${^{\circ}_{.}}$35 ≤ b ≤ +0${^{\circ}_{.}}$35 with a 15″ beamwidth. Total intensity ratios for CO J = 3–2/J = 1–0, 13CO/CO J = 1–0 and C18O/13CO J = 1–0, are 0.70 ± 0.06, 0.12 ± 0.01, and 0.14 ± 0.01, respectively. The high-resolution CO images show the fine structure of the molecular gas and enable us to identify a number of compact clouds with broad velocity widths, i.e., high-velocity compact clouds. We conducted a detailed comparison of our CO J = 1–0 data with the CO J = 3–2 data obtained with the James Clerk Maxwell Telescope to derive the distribution and kinematics of the highly excited gas. Three, out of four, of the previously identified high CO J = 3–2/J = 1–0 ratio areas at l = +1${^{\circ}_{.}}$3, 0${^{\circ}_{.}}$0, and −0${^{\circ}_{.}}$4 were confirmed with a higher spatial resolution. In addition to these, we identified several very compact, high CO J = 3–2/J = 1–0 spots with broad velocity widths for the first time. These are candidates for accelerated gas in the vicinity of invisible, point-like massive objects.

scholarly journals 5.17. The NRO CO survey of nearby spiral galaxies

1998 ◽  
Vol 184 ◽  
pp. 245-246 ◽  
Author(s):  
K. Nishiyama ◽  
N. Nakai
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Spiral Galaxies ◽  
High Spatial Resolution ◽  
Molecular Gas ◽  
Characteristic Structure

Our survey observation is high spatial resolution (16″) by NRO observatory 45 m antenna and have many galaxies of sample. This high resolution observations (16″ = 1.6 kpc at 20 Mpc) could be to resolve the some characteristic structure, typical molecular gas disk, arm - interarm and optical bar.

scholarly journals High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing

2017 ◽  
Vol 10 (5) ◽  
pp. 1665-1688 ◽  
Author(s):  
Frederik Tack ◽  
Alexis Merlaud ◽  
Marian-Daniel Iordache ◽  
Thomas Danckaert ◽  
Huan Yu ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Urban Areas ◽  
High Spatial Resolution ◽  
European Space Agency ◽  
Correlation Coefficients ◽  
Time Frame ◽  
Quantitative Information ◽  
Data Sets ◽  
Vertical Column

Abstract. We present retrieval results of tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs), mapped at high spatial resolution over three Belgian cities, based on the DOAS analysis of Airborne Prism EXperiment (APEX) observations. APEX, developed by a Swiss-Belgian consortium on behalf of ESA (European Space Agency), is a pushbroom hyperspectral imager characterised by a high spatial resolution and high spectral performance. APEX data have been acquired under clear-sky conditions over the two largest and most heavily polluted Belgian cities, i.e. Antwerp and Brussels on 15 April and 30 June 2015. Additionally, a number of background sites have been covered for the reference spectra. The APEX instrument was mounted in a Dornier DO-228 aeroplane, operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). NO2 VCDs were retrieved from spatially aggregated radiance spectra allowing urban plumes to be resolved at the resolution of 60  ×  80 m2. The main sources in the Antwerp area appear to be related to the (petro)chemical industry while traffic-related emissions dominate in Brussels. The NO2 levels observed in Antwerp range between 3 and 35  ×  1015 molec cm−2, with a mean VCD of 17.4 ± 3.7  ×  1015 molec cm−2. In the Brussels area, smaller levels are found, ranging between 1 and 20  ×  1015 molec cm−2 and a mean VCD of 7.7 ± 2.1  ×  1015 molec cm−2. The overall errors on the retrieved NO2 VCDs are on average 21 and 28 % for the Antwerp and Brussels data sets. Low VCD retrievals are mainly limited by noise (1σ slant error), while high retrievals are mainly limited by systematic errors. Compared to coincident car mobile-DOAS measurements taken in Antwerp and Brussels, both data sets are in good agreement with correlation coefficients around 0.85 and slopes close to unity. APEX retrievals tend to be, on average, 12 and 6 % higher for Antwerp and Brussels, respectively. Results demonstrate that the NO2 distribution in an urban environment, and its fine-scale variability, can be mapped accurately with high spatial resolution and in a relatively short time frame, and the contributing emission sources can be resolved. High-resolution quantitative information about the atmospheric NO2 horizontal variability is currently rare, but can be very valuable for (air quality) studies at the urban scale.

scholarly journals A High Resolution HI Survey of M31

1983 ◽  
Vol 100 ◽  
pp. 23-26
Author(s):  
E. Brinks
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Radio Telescope ◽  
Milky Way ◽  
Milky Way Galaxy ◽  
The Galaxy ◽  
First Results ◽  
Line Survey

The first results of a new high resolution 21-cm HI line survey of M31 made with the Westerbork Synthesis Radio Telescope are presented. Five areas were mapped, covering the galaxy except for the extreme northern and southern parts, at a resolution of δα × δδ × δV = 24″ × 36″ × 3.2 km s−1. The spatial resolution corresponds to 30 × 120 pc at the distance of M31. This is of the same order as the resolution at the distance of the center or our own galaxy given by a 25-m dish. Consequently the M31 survey is comparable to surveys of the Milky Way galaxy in wealth of detail as well as in amount of data (∼ 1 Gigabyte).

scholarly journals Time Series High-Resolution Land Surface Albedo Estimation Based on the Ensemble Kalman Filter Algorithm

2019 ◽  
Vol 11 (7) ◽  
pp. 753 ◽  
Author(s):  
Guodong Zhang ◽  
Hongmin Zhou ◽  
Changjing Wang ◽  
Huazhu Xue ◽  
Jindi Wang ◽  
...  
Keyword(s):  
Time Series ◽  
Kalman Filter ◽  
High Resolution ◽  
Spatial Resolution ◽  
Ensemble Kalman Filter ◽  
Land Surface ◽  
Surface Albedo ◽  
Data Sets ◽  
Broadleaf Forest ◽  
Kalman Filter Algorithm

Continuous, long-term sequence, land surface albedo data have crucial significance for climate simulations and land surface process research. Sensors such as the Moderate-Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer (VIIRS) provide global albedo product data sets with a spatial resolution of 500 m over long time periods. There is demand for new high-resolution albedo data for regional applications. High-resolution observations are often unavailable due to cloud contamination, which makes it difficult to obtain time series albedo estimations. This paper proposes an “amalgamation albedo“ approach to generate daily land surface shortwave albedo with 30 m spatial resolution using Landsat data and the MODIS Bidirectional Reflectance Distribution Functions (BRDF)/Albedo product MCD43A3 (V006). Historical MODIS land surface albedo products were averaged to obtain an albedo estimation background, which was used to construct the albedo dynamic model . The Thematic Mapper (TM) albedo derived via direct estimation approach was then introduced to generate high spatial-temporal resolution albedo data based on the Ensemble Kalman Filter algorithm (EnKF). Estimation results were compared to field observations for cropland, deciduous broadleaf forest, evergreen needleleaf forest, grassland, and evergreen broadleaf forest domains. The results indicated that for all land cover types, the estimated albedos coincided with ground measurements at a root mean squared error (RMSE) of 0.0085–0.0152. The proposed algorithm was then applied to regional time series albedo estimation; the results indicated that it captured spatial and temporal variation patterns for each site. Taken together, our results suggest that the amalgamation albedo approach is a feasible solution to generate albedo data sets with high spatio-temporal resolution.

scholarly journals Very High Resolution Observations of the Luminous Water Masers in NGC 4258

1988 ◽  
Vol 129 ◽  
pp. 231-232
Author(s):  
M. J. Claussen ◽  
M. J. Reid ◽  
M. H. Schneps ◽  
K.-Y. Lo ◽  
J. M. Moran ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Molecular Gas ◽  
Nearby Galaxy ◽  
Active Nucleus ◽  
Maser Emission ◽  
Water Masers ◽  
Very High

We summarize the results and interpretation of a four station transcontinental VLBI experiment of the luminous water masers in the nearby galaxy NGC 4258. At a distance of 5 Mpc, the longest baseline of the experiment provides spatial resolution of less than 1016 cm. The strongest maser emission was detected on all baselines, and was found to consist of at least two features separated by about 0.1 mas (1016 cm). Weaker features are possibly spread over a region up to 1 mas in size. These results provide evidence that supports the scenario described by Claussen and Lo (1986) which suggests that the very luminous water masers reside in molecular gas that immediately surrounds the central, active nucleus.

scholarly journals The kinematically decoupled core of MCG–6-30-15

2013 ◽  
Vol 9 (S304) ◽  
pp. 270-273
Author(s):  
Sandra I. Raimundo
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Seyfert Galaxy ◽  
Very High Spatial Resolution ◽  
The Galaxy ◽  
First Time ◽  
Very High

AbstractThe Seyfert galaxy MCG–6-30-15 has recently been observed in the infrared using SINFONI on the VLT, reaching a very high spatial resolution of 0.1 arcsec. This allowed us for the first time to detect a stellar kinematically decoupled core in the inner r < 125 pc of the galaxy. Here we summarise the main theories for the formation of the decoupled core and the implications on the study of this galaxy.

scholarly journals Objective Grating Soft X-Ray Spectroscopy of Compact Binary X-Ray Sources

1984 ◽  
Vol 86 ◽  
pp. 80-83
Author(s):  
S.M. Kahn ◽  
S.D. Vrtilek ◽  
L. Chiappetti ◽  
N.E. White
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Grazing Incidence ◽  
Optical Path ◽  
X Ray ◽  
Compact Binary ◽  
First Time

The presence of objective transmission gratings on the two recent X-ray telescope experiments, the Einstein and EXOSAT Observatories, has opened up a new avenue of research in X-ray astronomy by enabling us, for the first time, to obtain moderate-to-high resolution spectra of cosmic sources in the soft X-ray band (λ ~ 5–200 Å). Both experiments incorporated gold bar transmission gratings with line densities of 500 1/mm and 1000 1/mm which could be inserted into the X-ray optical path at the exit from a grazing incidence mirror. At short wavelengths, the resolution was determined principally by the spatial resolution of the detector-telescope combination. For Einstein, this was Δλ ~ 0.4 Å for the 1000 1/mm grating and ~ 0.8 Å for the 500 1/mm grating. For EXOSAT, the resolution was somewhat worse: Δλ ~ 1.5 Å for the 1000 1/mm grating, and ~ 3 Å for the 500 1/mm grating. (More complete descriptions of these instruments can be found in Seward et al. 1982 and de Korte et al. 1981.)

scholarly journals High Resolution Observations of Molecular Gas in the Outflow of M 82

2004 ◽  
Vol 217 ◽  
pp. 314-315
Author(s):  
Fabian Walter ◽  
Axel Weiss ◽  
Nick Scoville
Keyword(s):  
High Resolution ◽  
Mechanical Energy ◽  
Opening Angle ◽  
Molecular Gas ◽  
Molecular Outflow ◽  
Outflow Velocity ◽  
Line Splitting ◽  
Total Mechanical Energy ◽  
First Time ◽  
Absorption Features

We present a high-resolution (3.6“, 70 pc) CO(1-0) mosaic of the molecular gas in M 82 covering an area of 2.5'x3.5’ (2.8 kpc x 3.9 kpc) obtained with the OVRO millimeter interferometer. The observations reveal the presence of huge amounts of molecular gas (> 70% of the total molecular mass, Mtot ≈ 1.3 × 109M⊙) outside the central 1 kpc disk. Molecular streamers are detected in and below M 82's disk out to distances from the center of ~1.7 kpc. Some of these streamers are well correlated with optical absorption features; they form the basis of some of the prominent tidal HI features around M 82. This provides evidence that the molecular gas within M 82's optical disk is disrupted by the interaction with M 81. Molecular gas is found in M 82's outflow/halo, reaching distances up to 1.2 kpc below the plane; CO line-splitting has been detected for the first time in the outflow. The maximum outflow velocity is ~ 230 km s−1; we derive an opening angle of ~ 55° for the molecular outflow cone. The total amount of gas in the outflow is > 3 × 108 M⊙ and its kinetic energy is of order 1055 erg, about one percent of the estimated total mechanical energy input of M 82's starburst. Our study implies that extreme starburst environments can move significant amounts of molecular gas in to a galaxy's halo (and even to the intergalactic medium).

scholarly journals Large-Scale Molecular Gas Survey in 12CO, 13CO and C18O (J = 2–1) with the Osaka 1.85m mm-submm Telescope

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Toshikazu Onishi ◽  
Atsushi Nishimura ◽  
Kazuki Tokuda ◽  
Ryohei Harada ◽  
Kazuhito Dobashi ◽  
...  
Keyword(s):  
Physical Properties ◽  
Molecular Clouds ◽  
Large Scale ◽  
Molecular Gas ◽  
Beam Size ◽  
Radio Observatory ◽  
Target Frequency ◽  
Scientific Goal ◽  
The Galaxy ◽  
Scientific Results

AbstractWe have developed a new mm-submm telescope with a diameter of 1.85 m (hereafter, Osaka 1.85-m telescope) installed at the Nobeyama Radio Observatory. The scientific goal is to precisely reveal physical properties of molecular clouds in the Galaxy by obtaining a large-scale distribution of molecular gas, which also can be compared with large-scale observations in various wavelengths. The target frequency is ~230 GHz; simultaneous observations in J = 2–1 lines of 12CO, 13CO and C18O are achieved with a beam size (HPBW) of 2.7 arcmin. Here we present the progress of observations and the scientific results obtained by Osaka 1.85-m telescope. We note that these J = 2–1 data of the Galactic molecular clouds will be precious for the comparison with those of extra-galactic ones that will be obtained with the ALMA with the comparable spatial resolutions.

scholarly journals The Galactic Center

1984 ◽  
Vol 110 ◽  
pp. 265-273
Author(s):  
K. Y. Lo
Keyword(s):  
High Resolution ◽  
Radio Source ◽  
Galactic Center ◽  
Minor Axis ◽  
Ionized Gas ◽  
Nonthermal Radio ◽  
The Galaxy ◽  
First Time ◽  
Source Structure

The center of our Galaxy contains an extremely compact nonthermal radio source. For the first time, elongation in the source structure has been detected. The long axis is nearly aligned with the minor axis of the Galaxy. Recent high resolution observations of the ionized gas within the central 3 parsecs suggest that matter may be falling in towards the center. This has interesting implications on the processes within our Galactic nucleus.

Sign in / Sign up

Export Citation Format

Share Document