# 2001A&A...366..662N

 other querymodes : Identifierquery Coordinatequery Criteriaquery Referencequery Basicquery Scriptsubmission TAP Outputoptions Help

 Query : 2001A&A...366..662N

2001A&A...366..662N - Astronomy and Astrophysics, volume 366, 662-667 (2001/2-1)

Polyatomic species in diffuse cloud and clump interfaces.

NGUYEN T.K., HARTQUIST T.W. and WILLIAMS D.A.

Abstract (from CDS):

Diffuse clouds embedded in a flowing intercloud medium will develop warm interface layers in which the thermal pressures should significantly exceed those within the cloud. We have investigated the gas-phase formation of polyatomic molecules within such warm interfaces. If an interface occupies a few percent of the total molecular column density along that line-of-sight, then many polyatomic species in that interface should have detectable abundances. We have compared the results of interface models with observational data on polyatomic species obtained by Liszt and Lucas. Some models give results that are in harmony with measured ratios of several species including C2H, HCO+ and OH; these models have background radiation fields intensities that are lower than the standard by an order of magnitude. The number densities of molecular hydrogen are of the order of 102cm–3 in regions with temperatures of several thousand degrees. Such conditions in an interface do not conflict with the lower pressures inferred from CO data, as most of the CO is expected to be in the cold bulk of the material rather than in interfaces. The constancy of the sum of MHD wave pressure" and thermal pressure implies higher thermal pressures in interfaces than in the cold cloud and cold clump material. The radiation and thermal pressure conditions required to explain the observed abundance ratios may be more likely in interfaces around diffuse clumps within Giant Molecular Clouds than those around the isolated field" diffuse clouds observed in ultraviolet absorption. Some measured abundance ratios, the most notable of which is that of the abundances of H2CO and HCO+, are not well matched by model results, though on the basis of the models the relevant species would be expected to be observable in some cases. It is possible that the adopted chemical network is incomplete.

Journal keyword(s): ISM: abundances - clouds - molecules

Full paper

 Number of rows : 1
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME dze Oph Cloud Cld 16 37 09 -10 34.0           ~ 108 0

 Query : 2001A&A...366..662N

Basic data :
 NAME dze Oph Cloud -- Cloud Origin of the objects types : (Ref) Object type as listed in the reference "Ref" (acronym) Object type linked to the acronym according to the original reference () Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases Other object types: Cld (2007AJ) Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" : ra dec : right ascension and declination (unit and frame defined according to your Output Options) Grey values are increasing the original precision due to the computation of frame transformations (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam) [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue), position angle (in degrees North celestial pole to East) quality : flag of quality E ≥ 10" D : 1-10" (and some old data) C : 0.1-1" B : 0.01-0.1" + 2MASS, Tyc A : VLBI, Hipparcos bibcode : bibcode of the coordinates reference ICRS coord. (ep=J2000) : 16 37 09.0 -10 34 00 [ ] E ~ Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" : ra dec : right ascension and declination (unit and frame defined according to your Output Options) Grey values are increasing the original precision due to the computation of frame transformations (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam) [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue), position angle (in degrees North celestial pole to East) quality : flag of quality E ≥ 10" D : 1-10" (and some old data) C : 0.1-1" B : 0.01-0.1" + 2MASS, Tyc A : VLBI, Hipparcos bibcode : bibcode of the coordinates reference FK4 coord. (ep=B1950 eq=1950) : 16 34 23.6 -10 28 00 [ ] Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" : ra dec : right ascension and declination (unit and frame defined according to your Output Options) Grey values are increasing the original precision due to the computation of frame transformations (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam) [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue), position angle (in degrees North celestial pole to East) quality : flag of quality E ≥ 10" D : 1-10" (and some old data) C : 0.1-1" B : 0.01-0.1" + 2MASS, Tyc A : VLBI, Hipparcos bibcode : bibcode of the coordinates reference Gal coord. (ep=J2000) : 006.2802 +23.5898 [ ]
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay points in this preview
 All (CDSPortal) Send to within arcsec The VizieR photometry tool allows for easy visualization of photometry points extracted around the Simbad position from photometry-enabled catalogues in VizieR. The search radius has to be specified by the user. It is currently limited to a maximum of 30 arcsec. It depends mostly on the precision or quality of the coordinates (SIMBAD and VizieR catalogs), the resolution of the images from which the sources were extracted, source extent, and source crowding. Suggestions are: crowded field: 0.5 to 1.5 arcsec, 3 arcsec otherwise; uncertain coordinates (SIMBAD quality E or coordinates without reference): 5 to 30 arsec (risky!).

 The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature. Identifiers (2) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

 NAME dze Oph Cloud NAME zet Oph Cloud

 References (108 between 1850 and 2023) (Total 108) Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system). Follow new references on this object
Reference summaries :

from: to:

or select by : (not exhaustive, explanation here)

Annotations :
Annotations allow a user to add a note or report an error concerning the astronomical object and its data. It requires registration to post a note. See description .
Please, have a look at Best practices. The list of all annotations to SIMBAD objects can be found here .

Currently no annotations available

add an annotation to this object

report an error concerning the data of this object

To bookmark this query, right click on this link: simbad:objects in 2001A&A...366..662N and select 'bookmark this link' or equivalent in the popup menu

2023.03.22-20:50:30