Utilizza questo identificativo per citare o creare un link a questo documento:
http://hdl.handle.net/20.500.12386/26736
Campo DC | Valore | Lingua |
---|---|---|
dc.contributor.author | HUNT, Leslie Kipp | en_US |
dc.contributor.author | Weiß, A. | en_US |
dc.contributor.author | Henkel, C. | en_US |
dc.contributor.author | Combes, F. | en_US |
dc.contributor.author | García-Burillo, S. | en_US |
dc.contributor.author | CASASOLA, VIVIANA | en_US |
dc.contributor.author | Caselli, P. | en_US |
dc.contributor.author | Lundgren, A. | en_US |
dc.contributor.author | Maiolino, R. | en_US |
dc.contributor.author | Menten, K. M. | en_US |
dc.contributor.author | Testi, L. | en_US |
dc.date.accessioned | 2020-08-20T09:59:39Z | - |
dc.date.available | 2020-08-20T09:59:39Z | - |
dc.date.issued | 2017 | en_US |
dc.identifier.issn | 0004-6361 | en_US |
dc.identifier.uri | http://hdl.handle.net/20.500.12386/26736 | - |
dc.description.abstract | Studying the molecular component of the interstellar medium (ISM) in metal-poor galaxies has been challenging because of the faintness of carbon monoxide emission, the most common proxy of H<SUB>2</SUB>. Here we present new detections of molecular gas at low metallicities, and assess the physical conditions in the gas through various CO transitions for 8 galaxies. For one, NGC 1140 (Z/Z<SUB>☉</SUB> 0.3), two detections of <SUP>13</SUP>CO isotopologues and atomic carbon, [Ci](1-0) and an upper limit for HCN(1-0) are also reported. After correcting to a common beam size, we compared <SUP>12</SUP>CO(2-1)/<SUP>12</SUP>CO(1-0) (R<SUB>21</SUB>) and <SUP>12</SUP>CO(3-2)/<SUP>12</SUP>CO(1-0) (R<SUB>31</SUB>) line ratios of our sample with galaxies from the literature and find that only NGC 1140 shows extreme values (R<SUB>21</SUB> R<SUB>31</SUB> 2). Fitting physical models to the <SUP>12</SUP>CO and <SUP>13</SUP>CO emission in NGC 1140 suggests that the molecular gas is cool (kinetic temperature T<SUB>kin</SUB> ≲ 20 K), dense (H<SUB>2</SUB> volume density n<SUB>H2</SUB> ≳ 10<SUP>6</SUP> cm<SUP>-3</SUP>), with moderate CO column density (N<SUB>CO</SUB> 10<SUP>16</SUP> cm<SUP>-2</SUP>) and low filling factor. Surprisingly, the [<SUP>12</SUP>CO]/[<SUP>13</SUP>CO] abundance ratio in NGC 1140 is very low ( 8-20), lower even than the value of 24 found in the Galactic Center. The young age of the starburst in NGC 1140 precludes <SUP>13</SUP>CO enrichment from evolved intermediate-mass stars; instead we attribute the low ratio to charge-exchange reactions and fractionation, because of the enhanced efficiency of these processes in cool gas at moderate column densities. Fitting physical models to <SUP>12</SUP>CO and [Ci](1-0) emission in NGC 1140 gives an unusually low [<SUP>12</SUP>CO]/[<SUP>12</SUP>C] abundance ratio, suggesting that in this galaxy atomic carbon is at least 10 times more abundant than <SUP>12</SUP>CO. <P />Based on observations carried out with the IRAM 30 m and the Atacama Pathfinder Experiment (APEX). IRAM is supported by the INSU/CNRS (France), MPG (Germany), and IGN (Spain), and APEX is a collaboration between the Max-Planck-Institut fur Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory. | en_US |
dc.language.iso | eng | en_US |
dc.title | Physical conditions of the molecular gas in metal-poor galaxies | en_US |
dc.type | Article | - |
dc.identifier.doi | 10.1051/0004-6361/201731000 | en_US |
dc.identifier.scopus | 2-s2.0-85032016826 | en_US |
dc.identifier.isi | 000413562900004 | en_US |
dc.identifier.url | https://www.aanda.org/articles/aa/abs/2017/10/aa31000-17/aa31000-17.html | en_US |
dc.relation.medium | STAMPA | en_US |
dc.relation.volume | 606 | en_US |
dc.relation.firstpage | A99 | en_US |
dc.type.referee | REF_1 | en_US |
dc.description.numberofauthors | 11 | en_US |
dc.description.international | sì | en_US |
dc.contributor.country | ITA | en_US |
dc.relation.scientificsector | FIS/05 - ASTRONOMIA E ASTROFISICA | en_US |
dc.relation.journal | ASTRONOMY & ASTROPHYSICS | en_US |
dc.type.miur | 262 Articolo in rivista | - |
dc.identifier.adsbibcode | 2017A&A...606A..99H | en_US |
dc.relation.ercsector | PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation | en_US |
dc.description.apc | no | en_US |
dc.description.oa | 1 – prodotto con file in versione Open Access (allegare il file al passo 5-Carica) | en_US |
item.openairecristype | http://purl.org/coar/resource_type/c_18cf | - |
item.openairetype | Article | - |
item.languageiso639-1 | en | - |
item.cerifentitytype | Publications | - |
item.grantfulltext | open | - |
item.fulltext | With Fulltext | - |
crisitem.author.dept | O.A. Arcetri | - |
crisitem.author.dept | IRA Bologna | - |
crisitem.author.dept | O.A. Arcetri | - |
crisitem.author.orcid | 0000-0001-9162-2371 | - |
crisitem.author.orcid | 0000-0002-3879-6038 | - |
crisitem.author.orcid | 0000-0003-1859-3070 | - |
crisitem.journal.journalissn | 0004-6361 | - |
crisitem.journal.ance | E016240 | - |
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