CDS

2012A&A...541A..76L

Query : 2012A&A...541A..76L

2012A&A...541A..76L - Astronomy and Astrophysics, volume 541A, 76-76 (2012/5-1)

Surface chemistry in the interstellar medium. I. H2 formation by Langmuir-Hinshelwood and Eley-Rideal mechanisms.

LE BOURLOT J., LE PETIT F., PINTO C., ROUEFF E. and ROY F.

Abstract (from CDS):

It has been found from ISO, Spitzer, and Herschel observations that molecular hydrogen, H2, can form on warm grains. Numerical models of interstellar chemistry have failed to reproduce the observed formation rates of H2, which remains a difficulty when interpreting observations of photon-dominated regions (PDRs). We attempt to include as much experimental and theoretical information as possible to describe H2 formation in astrophysical environments to solve this problem. We modified our ``Meudon PDR code'' to include a detailed treatment of H2 formation mechanisms including: i) the Langmuir-Hinshelwood mechanism taking into account the contribution of the different sizes of dust grains in the diffusion processes; and ii) the Eley-Rideal mechanism. We are able to form H2 even in regions where the dust temperature is higher than 25K. We also show that formation by the Eley-Rideal mechanism can be a significant source of gas heating. We derive line intensities for various astrophysical conditions. Our approach results in a higher H2 formation rate than for the ``standard'' 3x10–17nHn(H)cm3/s expression.

Abstract Copyright: ∼

Journal keyword(s): astrochemistry - ISM: molecules - ISM: clouds - ISM: general

Simbad objects: 1

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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 NGC 6618 OpC 18 20 47 -16 10.3           ~ 1590 0

Query : 2012A&A...541A..76L

Basic data :
NGC 6618 -- Open Cluster
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: 		Rad (CTB,GRS,...), Cl* (2013A&A,C,...), OpC (2014A&A,OCISM,...), * (BD,GCRV,...), As* (2019AJ,[KC2019]), Cl? (2013A&A), HII (LBN), X (1E)
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) : 		18 20 47.0 -16 10 18 (Optical) [ ] E 2009MNRAS.399.2146W
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) : 		18 17 53.9 -16 11 42 [ ]
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) : 		015.0953 -00.7454 [ ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr : 		1.510 -1.740 [0.060 0.080 90] D 2017AstBu..72..257L
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz : 		V(km/s) -44.577 [0.682] / z(~) -0.000149 [0.000002] / cz -44.57 [0.68]
   (Opt) C 2014A&A...562A..54C
Syntax of parallax is : 'value quality [error] bibcode'
  • value : parallax value
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • [error] : mean error
  • bibcode : bibcode of the parallax reference
Parallaxes (mas): 		0.60 [0.04] C 2019ApJ...870...32K
Syntax of angular size is : "maj-axis min-axis angle (wtype) quality bibcode"
  • maj-axis : major axis size (arc minutes)
  • min-axis : minor axis size (arc minutes)
  • angle : orientation angle (in degrees)
  • (wtype) : wavelength class for the origin of the angular size (Rad, mm, IR, Opt, UV, Xray, Gam)
  • quality : flag of quality of the angular size values ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the angular size reference
Angular size (arcmin): 		1.63 1.63 90 (~) D 2013A&A...560A..76M
SIMBAD within arcmin
', {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 Simbad points in this preview
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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!). sed-help-icon

Hierarchy : number of linked objects
whatever the membership probability is (see description here ) :

The count displayed here is the number of children objects.
The list obtained by clicking the button may be larger, as some children may be linked with different references or probability.

%This number is the number of distinct objets linked, by using this button, you will obtain all links (may be more than one) from that object to his children

: 1406 		Display criteria :

The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (30) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

M 17 LBN 60 NAME Swan Nebula W 38
BD-16 4820 LBN 015.28-00.67 NGC 6618 [BDB2003] G015.05-00.69
C 1817-162 LMH 21 NRL 4 [KC2019] Theia 846
CTB 52 MM 20 OCISM 9 [KPR2004b] 444
1E 1818.0-1610 NAME NGC 6618 Horseshoe OCl 44 [KPS2012] MWSC 2896
GCRV 10811 NAME Checkmark Nebula OCl 44.0 [PT56] 41
GRS G015.00 -00.70 NAME Lobster Nebula Villafranca O-009
HD 168520 NAME omega Nebula WEB 15351

References (1590 between 1850 and 2023) (Total 1590)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Collections of Measurements


velocities : 4    distance : 6    PLX : 2    PM : 3   

   

Observing logs


herschel : 4    ISO : 76    XMM : 1   

   

External archives :

Archive data at HEASARC - High-Energy Astrophysics Science Archive Research Center

Data at NED - NASA/IPAC Extragalactic Database : NGC 6618

Link by name to the catalogue in VizieR :

BD-16 4820 HD 168520 NGC 6618

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2023.10.04-21:56:07

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