# 1999A&A...342..257K

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 Query : 1999A&A...342..257K

1999A&A...342..257K - Astronomy and Astrophysics, volume 342, 257-270 (1999/2-1)

Depletion of CO in a cold dense cloud core of IC 5146.

KRAMER C., ALVES J., LADA C.J., LADA E.A., SIEVERS A., UNGERECHTS H. and WALMSLEY C.M.

Abstract (from CDS):

We have used the IRAM 30m telescope to map the C18O(1->0) and (2->1) transitions in a region of 0.5x0.5pc2 (200''x200'') in the nearby (460pc distance) molecular cloud IC5146 at resolutions of down to 0.025pc. Additionally, we have observed the corresponding C17O transitions towards 24 positions in the central region of the cloud as a check on optical depth effects. On the basis of these observations, we conclude that the C18O emission observed by us is optically thin and that the observed C18O(2->1)/(1->0) ratio is consistent with gas at 10 K and density in the range 104 to 105 cm–3. We have estimated C18O column densities over the region mapped, using an LVG program to correct for excitation effects, and have compared them, at the same spatial resolution of 30'', with the dust extinction derived from the NIR images of Lada et al. (1998ApJ...495..871L) From this, we find a roughly constant, though with considerable dispersion, ratio of C18O column density to visual extinction (AV) in directions with AV less than ∼10 magnitudes. The ratio is compatible with previous determinations of the [C18O]/[H2] abundance ratio, e.g. 1.7*10–7 as obtained by Frerking et al. (1982) At extinctions higher than ∼10 magnitudes, however, there is a systematic fall-off in the ratio N(C18O)/AV which we attribute to depletion of C18O onto dust ice mantles within the dense, n>104cm–3, and cold, Tdust≲15K, Tgas∼10K, core interior. This fall-off is also seen, though with less statistical significance, in our observed dependence of N(C17O)/AV with AV. We thus think it unlikely that optical depth effects are influencing our conclusions. We have additionally made pointed C18O(1->0) and (2->1) observations towards 94 background stars with extinction greater than 10 magnitudes from the study of Lada et al. (1994ApJ...429..694L) These in general confirm our mapping results.

Journal keyword(s): ISM: molecules - ISM: kinematics and dynamics - ISM: individual objects: IC 5146 - ISM: dust, extinction - ISM: clouds - ISM: abundances

 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 - 2022
#notes
1 IC 5146 OpC 21 53 29 +47 14.8           ~ 425 2

 Query : 1999A&A...342..257K

Basic data :
', {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
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 Some important notes on this object about identifications and objects associations. notes: cluster embedded in nebula

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 : 854 Display criteria : All >=90% stars galaxies radio IR <2 arcsec #ref>50

 The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature. Identifiers (12) :
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 IC 5146 LBN 424 NAME Cocoon Nebula OCl 213.0 C 2151+470 LBN 094.43-05.58 OCISM 43 [KC2019] Theia 88 Cl Collinder 470 Min 2-70 OCl 213 [KPS2012] MWSC 3571

 References (425 between 1850 and 2022) (Total 425) 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
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Collections of Measurements

velocities : 3    distance : 3    Fe_H : 1    PLX : 5    PM : 5

Observing logs

herschel : 4    ISO : 12

External archives :

 Indications mainly about references on other documents Notes (1) :

• message of Brent A. Archinal (27.12.2005):
the IC makes no mention of a star cluster here, and neither do the discoverersof the IC 5146 nebula (the "Cocoon Nebula"), Espin (1900) and Wolf (1904).Collinder appears to have been the first to identify a star cluster here(even though he also used the IC 5146 name incorrectly), so the preferred namewould seem to be Collinder 470. Details of this are given in Brent A. Archinaland Steven's Hynes book "Star Clusters", pp. 127-128.
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2022.05.21-08:17:50