scholarly journals A confusion-limited spectral-line survey of Sgr B2(N) at 1, 2, and 3mm: Establishing the organic inventory in molecular clouds

2008 ◽  
Vol 4 (S251) ◽  
pp. 27-28 ◽  
Author(s):  
DeWayne T. Halfen ◽  
Lucy M. Ziurys
Keyword(s):  
Spectral Line ◽  
Gas Phase ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Current Data ◽  
Complex Molecules ◽  
Preliminary Results ◽  
Prebiotic Molecules ◽  
Line Survey

AbstractWe present preliminary results of an spectral-line survey at 1, 2, and 3 mm of the galactic center cloud Sgr B2(N). With the current data, several simple prebiotic molecules have been conclusively identified, while several more complex molecules have not. When complete, this survey will provide an accurate database of the gas-phase organic inventory in Sgr B2(N).

scholarly journals Proper Motions and Distances of Water Maser Complexes

1984 ◽  
Vol 110 ◽  
pp. 335-338
Author(s):  
M. H. Schneps ◽  
M. J. Reid ◽  
J. M. Moran ◽  
R. Genzel ◽  
D. Downes ◽  
...  
Keyword(s):  
Spectral Line ◽  
Galactic Center ◽  
Three Dimensional ◽  
Proper Motions ◽  
Preliminary Results ◽  
First Results ◽  
Maser Sources ◽  
Water Maser

We report preliminary results of a long term spectral line VLBI experiment to observe internal proper motions of water maser sources in the vicinity of newly formed stars. This technique yields a picture of the three-dimensional kinematics of the region and a measure of the distance to the source. First results from the galactic center source SGR B2 are presented.

SMA Spectral Line Survey of the Proto-Planetary Nebula CRL 618

2018 ◽  
Vol 14 (S343) ◽  
pp. 483-484
Author(s):  
Nimesh A. Patel ◽  
Carl Gottlieb ◽  
Ken Young ◽  
Tomasz Kaminski ◽  
Michael McCarthy ◽  
...  
Keyword(s):  
Spectral Line ◽  
Planetary Nebula ◽  
Line Emission ◽  
Asymptotic Giant Branch ◽  
60 Ghz ◽  
Agb Stars ◽  
Complex Molecules ◽  
Compact Region ◽  
Line Survey ◽  
Pn Stage

AbstractCarbon-rich Asymptotic Giant Branch (AGB) stars are major sources of gas and dust in the interstellar medium. During the brief (∼1000 yr) period in the evolution from AGB to the Planetary Nebula (PN) stage, the molecular composition evolves from mainly diatomic and small polyatomic species to more complex molecules. Using the Submillimeter Array (SMA), we have carried out a spectral line survey of CRL 618, covering a frequency range of 281.9 to 359.4 GHz. More than 1000 lines were detected in the ∼60 GHz range, most of them assigned to HC3N and c-C3H2, and their isotopologues. About 200 lines are unassigned. Lines of CO, HCO+, and CS show the fast outflow wings, while the majority of line emission arises from a compact region of ∼1” diameter. We have analyzed the lines of HC3N, c-C3H2, CH3CN, and their isotopologues with rotation temperature diagrams.

The 6.4 keV Fe Line and the SiO Emission in the GC

2001 ◽  
Vol 205 ◽  
pp. 36-37
Author(s):  
J. Martín-Pintado ◽  
P. de Vicente ◽  
N. Rodríguez-Fernández ◽  
A. Fuente ◽  
P. Planesas
Keyword(s):  
Spatial Distribution ◽  
Gas Phase ◽  
Molecular Clouds ◽  
Galactic Center ◽  
X Rays ◽  
Refractory Elements

We present a map of the Galactic center in the J=l-0 line of SiO covering the region mapped with the ASCA satellite in the 6.4 keV Fe line. We find a correlation between the spatial distribution of the Fe 6.4 keV line and the SiO emission. The SiO abundance increases by more than a factor of 20 in the regions with strong Fe 6.4 keV line. This indicates that the Fe 6.4 keV line mainly arises from molecular clouds with large gas phase abundance of refractory elements. We discuss the implications of the correlation on the origin of the hard X-rays, and the heating and the chemistry of the molecular clouds in the GC.

scholarly journals SPECTRAL LINE SURVEY TOWARD MOLECULAR CLOUDS IN THE LARGE MAGELLANIC CLOUD

2016 ◽  
Vol 818 (2) ◽  
pp. 161 ◽  
Author(s):  
Yuri Nishimura ◽  
Takashi Shimonishi ◽  
Yoshimasa Watanabe ◽  
Nami Sakai ◽  
Yuri Aikawa ◽  
...  
Keyword(s):  
Spectral Line ◽  
Molecular Clouds ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Line Survey

scholarly journals An X-ray survey of the central molecular zone: variability of the FeKα emission line

2013 ◽  
Vol 9 (S303) ◽  
pp. 94-96
Author(s):  
Simona Soldi ◽  
Maïca Clavel ◽  
Andrea Goldwurm ◽  
Mark R. Morris ◽  
Gabriele Ponti ◽  
...  
Keyword(s):  
Emission Line ◽  
Molecular Clouds ◽  
Galactic Center ◽  
X Ray ◽  
Preliminary Results ◽  
Sgr A ◽  
Flux Increase ◽  
C Complex ◽  
First Time

AbstractThe bulk of the FeKα emission detected in the central molecular zone (CMZ) is thought to be associated with reflection by the central molecular clouds of enhanced past emission from an external X-ray source, most likely Sgr A*. In order to follow the propagation of the reflected emission through the Galactic center (GC), we analyzed all XMM-Newton observations carried out from 2000 to 2012. Preliminary results indicate that while most of the regions that were bright at 6.4 keV in 2000–2001 have a significantly lower flux in 2012, a few other experienced a flux increase. We report for the first time a significant decrease of the FeKα emission in the Sgr C complex, supporting the reflection origin of the 6.4 keV emission detected in this region.

Gas-phase reactivity of CH3OH+OH down to 11.7 K: Astrophysical implications

2019 ◽  
Vol 15 (S350) ◽  
pp. 365-367
Author(s):  
Antonio J. Ocaña ◽  
Sergio Blázquez ◽  
Daniel González ◽  
Alexey Potapov ◽  
Bernabé Ballesteros ◽  
...  
Keyword(s):  
Gas Phase ◽  
Molecular Clouds ◽  
Organic Molecules ◽  
Rate Coefficients ◽  
Reaction Networks ◽  
Oh Radicals ◽  
Temperature Reaction ◽  
Starting Point ◽  
Prebiotic Molecules ◽  
Complex Organic

AbstractMethanol (CH3OH) and hydroxyl (OH) radicals are two species abundant in cold and dense molecular clouds which are important for the chemistry of the interstellar medium (ISM). CH3OH is a well-known starting point for the formation of more complex organic molecules (COMs) in these molecular clouds. Thus, the reactivity of CH3OH in the gas-phase with OH may play a crucial role in the formation of species as complex as prebiotic molecules in the ISM and reliable rate coefficients should be used in astrochemical models describing low temperature reaction networks.

scholarly journals Millimeter-wave observations of diffuse clouds

1997 ◽  
Vol 178 ◽  
pp. 421-430 ◽  
Author(s):  
R. Lucas ◽  
H. S. Liszt
Keyword(s):  
Gas Phase ◽  
Molecular Clouds ◽  
Radio Sources ◽  
Collisional Excitation ◽  
Molecular Absorption ◽  
Microwave Background ◽  
Dark Cloud ◽  
Complex Molecules ◽  
Millimeter Wavelength ◽  
Diffuse Clouds

Using the IRAM instruments (interferometer on Plateau de Bure and 30-m telescope on Pico Veleta) we have made numerous observations of molecular absorption lines in front of extragalactic millimeter wavelength radio sources. Observations of HCO+, CO and OH show that the lines of sight studied in this way sample the outer edges of molecular clouds or the diffuse clouds with highest column densities. Collisional excitation of the rotational levels is not significant in this density range for most molecular species, and accurate column densities may be derived by assuming radiative equilibrium with the cosmic microwave background. Using this technique we have measured column densities of CO, HCO+, H2CO, CN, HCN, HNC, CS, SO, H2S, C2H, and C3H2 in several lines of sight, intersecting about 20 individual clouds with CO column densities in the range 2 1014 to ∼ 1016 cm−2. These results confirm that complex molecules achieve dark-cloud abundances at low extinctions, either by formation in the gas phase or on grains.

scholarly journals Unbiased line surveys of molecular clouds in the Galactic center region

2013 ◽  
Vol 9 (S303) ◽  
pp. 117-118
Author(s):  
D. Riquelme ◽  
R. Aladro ◽  
S. Martín ◽  
M. Requena-Torres ◽  
J. Martín-Pintado ◽  
...  
Keyword(s):  
Organic Chemistry ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Physical Activities ◽  
Molecular Line ◽  
X Ray ◽  
Center Region ◽  
Different Types ◽  
Line Survey

AbstractUsing the IRAM 30 m telescope, we perform a molecular line survey of the 3 and 2 mm wavelength ranges towards 5 selected positions in the Galactic center region, sampling shocked regions, ultraviolet (UV) and X-ray pervaded regions, and positions with rich organic chemistry. These surveys have the potential to be used as chemical templates for different types of activity, such as photodissociated regions (PDRs), shocks and X-ray dominated regions (XDRs). Complementary, molecular surveys done towards extragalactic nuclei, that are also dominated by these physical activities, were carried by our group.

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