scholarly journals On the nomenclature of diffuse fragmentary objects

1982 ◽  
Vol 64 ◽  
pp. 207-210
Author(s):  
P. Polechova
Keyword(s):  
Molecular Clouds ◽  
Beam Width ◽  
Hii Regions ◽  
Decimal Digit ◽  
Galactic Latitude ◽  
Wide Range ◽  
Half Power ◽  
5 Ghz ◽  
Galactic Longitude ◽  
Reflection Nebulae

AbstractFor the purpose of Cataloguing diffuse objects in a wide range of dimensions, two alternative proposals are presented.Problems similar to those discussed in connection with the nomenclature of optical HII-regions may occur with any diffuse objects such as molecular clouds, large reflection nebulae, HI-regions, and, of course, radio HII-regions.The radio HII-regions are most commonly designated by the galactic numbers “G”. The galactic longitude forms the first part of this number, the galactic latitude the second part, both parts being usually accurate to the first decimal digit and separated by the sign of latitude. This system (also used sometimes for optical objects) was introduced by Mezger and Henderson (1967) in a survey at 5 GHz, with a half power beam width of the telescope of about 6'. The angular dimensions of their objects were in the range from 3 to 11'.

scholarly journals Observations of Anomalous Microwave Emission from HII Regions

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Clive Dickinson
Keyword(s):  
High Resolution ◽  
High Latitude ◽  
Hii Regions ◽  
Microwave Emission ◽  
Complex Environments ◽  
High Frequencies ◽  
Dust Temperature ◽  
Wide Range ◽  
5 Ghz

I give a summary of the observations of Anomalous Microwave Emission (AME) from HII regions. AME has been detected in, or in the vicinity of, HII regions. Given the difficulties in measuring accurate SEDs over a wide range of frequencies and in complex environments, many of these detections require more data to confirm them as emitting significant AME. The contribution from optically thick free-free emission from UCHII regions may be also be significant in some cases. The AME emissivity, defined as the ratio of the AME brightness to the 100 μm brightness, is comparable to the value observed in high-latitude diffuse cirrus in some regions, but is significantly lower in others. However, this value is dependent on the dust temperature. More data, both at high frequencies (>~5 GHz) and high resolution (~1′ or better) is required to disentangle the emission processes in such complex regions.

scholarly journals Molecular Clouds in the Central 100-pc of the Galactic Center

1989 ◽  
Vol 136 ◽  
pp. 135-140 ◽  
Author(s):  
M. Tsuboi ◽  
T. Handa ◽  
M. Inoue ◽  
J. Inatani ◽  
N. Ukita
Keyword(s):  
Molecular Clouds ◽  
Large Scale ◽  
Galactic Center ◽  
Galactic Latitude ◽  
Center Region ◽  
Elliptical Shape ◽  
Latitude Region ◽  
Galactic Longitude

We have observed CS (J=1–0/2–1) lines in a 60′×30′(1×b) area of the Galactic center region. There are two large-scale features with elliptical shape in the position–velocity maps, which suggest shell–like structures in the region. One is the ring with a radius of ~40 pc in the positive galactic latitude region and another is the shell with a radius of ~20 pc in the negative galactic longitude region. These could be due to suggest star bursts occurred in the Galactic center region.

scholarly journals Observations of CII, CI and CO in Interface Regions

1992 ◽  
Vol 150 ◽  
pp. 303-308
Author(s):  
Jürgen Stutzki
Keyword(s):  
Carbon Monoxide ◽  
Transition Zone ◽  
Uv Radiation ◽  
Molecular Clouds ◽  
Hii Regions ◽  
Atomic Carbon ◽  
Wide Range ◽  
Photodissociation Region

UV-radiation longward of the Lyman edge (912 Å) can escape from HII-regions. It photodissociates carbon monoxide (λ < 1118 Å) and photoionizes neutral atomic carbon (λ < 1101 Å). The resulting CII/CI/CO transition zone on the edges of molecular clouds (photodissociation region or photodominated region: PDR) has been studied in great detail theoretically (Tielens & Hollenbach, 1985; van Dishoek & Black, 1988; Sternberg & Dalgarno, 1989) and these investigations have recently been extended to cover a wide range of densities and UV-intensities (Burton, Hollenbach & Tielens, 1990; Hollenbach, Takahashi & Tielens, 1991; see also A. Sternberg, this volume).

scholarly journals C18O and HNCO in the Galactic Centre

1996 ◽  
Vol 169 ◽  
pp. 281-282
Author(s):  
M. Lindqvist ◽  
Aa. Sandqvist ◽  
A. Winnberg ◽  
L.-Å. Nyman ◽  
F. Combes ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Radio Continuum ◽  
Galactic Centre ◽  
Galactic Latitude ◽  
Sgr A ◽  
Galactic Longitude

Using the SEST, we have observed 554 positions with a spacing of 45″ in the C18O(J = 1 → 0) and HNCO(Jkk′ = 505 → 404) lines. The data covers most of the Sgr A region including the Arc. Many of the dominant clouds in the GC region (see e.g. Güsten et al. 1981, A&A 103, 197; Bally et al. 1987, ApJS, 65, 13) are readily identified in the total integrated C18O and HNCO maps (Fig. 1). The results will be published in A&AS and will include intensity maps with 5 km s–1 velocity resolutions, as well as galactic longitude-velocity and galactic latitude-velocity maps. J = 2 → 1 C18O observations are planned for selected regions. The objectives of the project are twofold: 1. Geometrical, morphological, and dynamical relationships between the molecular regions and the radio continuum sources. 2. Heating mechanisms in GC molecular clouds.

scholarly journals THE SINO-GERMAN λ6 CM POLARIZATION SURVEY OF THE GALACTIC PLANE: A SUMMARY

2013 ◽  
Vol 23 ◽  
pp. 82-91 ◽  
Author(s):  
J. L. HAN ◽  
W. REICH ◽  
X. H. SUN ◽  
X. Y. GAO ◽  
L. XIAO ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Interstellar Medium ◽  
Radio Telescope ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
High Sensitivity ◽  
Hii Regions ◽  
Galactic Latitude ◽  
Galactic Longitude ◽  
Individual Objects

We have finished the λ6 cm polarization survey of the Galactic plane using the Urumqi 25 m radio telescope. It covers 10° ≤ l ≤ 230° in Galactic longitude and |b| ≤ 5° in Galactic latitude. The new polarization maps not only reveal new properties of the diffuse magnetized interstellar medium, but also are very useful for studying individual objects such as HII regions, which may act as Faraday screens with strong regular magnetic fields inside, and supernova remnants for their polarization properties and spectra. The high sensitivity of the survey enables us to discover two new SNRs G178.2–4.2 and G25.3–2.1 and a number of HII regions.

scholarly journals 8. Report on 21-cm. observations between l = 60° and l = 135°

1957 ◽  
Vol 4 ◽  
pp. 48-55
Author(s):  
T. A. Matthews
Keyword(s):  
Radio Telescope ◽  
Frequency Band ◽  
Beam Width ◽  
Electronic Equipment ◽  
Band Width ◽  
Galactic Latitude ◽  
Half Power ◽  
Signal Channel

Observations of the 21-cm. hydrogen profiles have been taken between galactic longitudes l = 60° and l = 135°, with the 24-ft. radio telescope at the George R. Agassiz Station. The beam-width of the antenna is approximately 1°·7 between the half-power points. The electronic equipment used was a d.c. comparison radiometer, which has a signal channel with a frequency band-width of 15 kc./s. between the half-power points. At galactic latitude b = 0° the observations are generally spaced 2°·5 apart, although a few gaps of 5° exist. At b = + 15° and b = ሢ 15° the centres are 5° apart. A strip in latitude at l = 100°, and other centres at various latitudes (mainly at l = 75° and l = 87°·5) have also been taken, but little reference will be made to this material in the present paper.

scholarly journals A New 21-cm Line Survey of the LMC

1984 ◽  
Vol 108 ◽  
pp. 395-396
Author(s):  
K. Rohlfs ◽  
J. Kreitschmann ◽  
J. V. Feitzinger
Keyword(s):  
Noise Temperature ◽  
Beam Width ◽  
Main Beam ◽  
Corrugated Waveguide ◽  
Line Survey ◽  
Single Polarization ◽  
Switching Mode ◽  
Half Power ◽  
Channel Separation ◽  
Made In

The measurements were made in Feb. 1982 with the Parkes 64 m telescope using a corrugated waveguide horn with total half-power beam width of 15′, the first sidelobes being 19 dB down, resulting in an aperture efficiency ηA=0.53±0.007, a main beam efficiency of ηmb=0.80±0.005 and a ratio of source flux to antenna temperature of Γ=0.62±0.1 K/Jy (Murray, priv. comm.). A cooled two channel FET frontend used in the frequency switching mode with Δν = 2 MHz resulted in a system noise temperature at zenith of Tsyst = 40 K for one channel and Tsyst = 50 K for the other. Each frontend channel received a single polarization mode, and this radiation was then further analysed in a 2 × 512 channel autocorrelation spectrometer set at a channel separation of 3.906 KHz corresponding to a velocity resolution of V = 0.824 km s−1. Hanning smoothed this resulted in a σT = 0.05 K for the average of both polarization.

A Thermal Source with Strong 1612 MHz OH Emission

1969 ◽  
Vol 1 (5) ◽  
pp. 211-212
Author(s):  
B. J. Robinson ◽  
W. M. Goss ◽  
R. N. Manchester
Keyword(s):  
Ground State ◽  
Hii Regions ◽  
Thermal Source ◽  
Strong Source ◽  
Galactic Longitude

During 1968 we have found at Parkes several types of emission in the lines of the 18 cm quadruplet of the ground-state OH molecule. This note describes a strong source of 1612 MHz emission near galactic longitude 331°.OH emission was originally detected in the vicinity of HII regions, and a search of a large number of HII regions showed that about a third had associated OH emission. This type of emission is usually strongest at 1665 MHz, and is also seen at 1667 MHz and weakly on one of the satellite lines.

scholarly journals A STUDY OF A PULSAR WIND DRIVEN STRUCTURE IN FAR-INFRARED IRAS MAP AT LATTITUDE -10º

2017 ◽  
Vol 22 (1) ◽  
pp. 1-9
Author(s):  
Ajay Kumar Jha ◽  
Binil Aryal
Keyword(s):  
Far Infrared ◽  
Density Variation ◽  
Color Temperature ◽  
Galactic Latitude ◽  
Dust Structure ◽  
Infrared Astronomical Satellite ◽  
Mass Profile ◽  
Using Data ◽  
Astronomical Satellite ◽  
Galactic Longitude

A systematic search of dust structure in the far infrared (100 μm and 60 μm) IRAS (Infrared Astronomical Satellite) survey was performed using Sky View Observatory. In order to find the possible candidate, we used SIMBAD database to locate discrete sources in the region. A deep cavity-like isolated far infrared dust structure (size ~ 4.46 pc × 2.23 pc) at galactic longitude: 284.360o, galactic latitude: -9.549o was found at the distance of about 375 pc. We have studied the flux density variation and then calculated temperature and mass profile of the dust and excess mass using data reduction software ALADIN 7.5 within this region. The dust color temperature was found to lie in the range 23.40 K to 29.28 K. An offset temperature of about 6.0 K was found. The total mass of the dust structure was found to be about 2.55×1027 kg and the excess mass per pixel was 2.52×1024 kg. We also studied the rate of mass loading around the structure. The energy of the pulsar required to create that in homogeneity in the structure was calculated to be 5.04×1036 J. Possible explanations of results will be presented.Journal of Institute of Science and Technology, 2017, 22 (1): 1-9

scholarly journals Kinematics of Nuclei of Sc Galaxies

1980 ◽  
Vol 5 ◽  
pp. 191-191
Author(s):  
V. C. Rubin
Keyword(s):  
High Velocity ◽  
Stellar Population ◽  
Hii Regions ◽  
Emission Lines ◽  
High Luminosity ◽  
Rotation Curves ◽  
Velocity Gradients ◽  
Wide Range ◽  
Central Regions ◽  
Velocity Dispersions

For a sample of 21 Sc galaxies with a wide range of luminosities, of radii, and of masses, W. K. Ford and I have obtained spectra and determined rotation curves. By their kinematical behavior in their central regions, the Sc’s can be separated into two groups. Some galaxies, generally small and of low luminosity, have shallow central velocity gradients, reflecting their low central masses and densities. Other galaxies, most often large ones of high luminosity, have steep central velocity gradients. One reason this separation by central velocity gradients is of interest is because these galaxies exhibit other significant spectral differences which go hand-in-hand with the kinematical differences.The small, low luminosity galaxies show emission lines of Hα and [NII], with nuclear Ha sharp and stronger than [NII], and little or no stellar nuclear continuum, just as conventional HII regions. In contrast, the high luminosity galaxies show broad nuclear emission, with [NII] stronger than Ha. These galaxies have a strong red stellar continuum, arising from a red stellar population. The cause of the Hα[NII] intensity reversal in the nuclei of some galaxies remains unknown. However, the strong [NII] emission in generally high luminosity galaxies with massive nuclei, nuclei which show strong red continua, suggests that [Nil] intensity correlates with nuclear luminosity, and in turn with the density and velocity properties of the nuclear populations. We would expect high velocity dispersions and high bulge luminosities for galaxies with strong nuclear [NII] and steep central velocity gradients.

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