Spatially resolved images of reactive ions in the Orion Bar
| dc.contributor.author | GOICOECHEA, Javier | |
| dc.contributor.author | CUADRADO, S. | |
| hal.structure.identifier | Institut de RadioAstronomie Millimétrique [IRAM] | |
| hal.structure.identifier | Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique [LERMA] | |
| dc.contributor.author | PETY, J. | |
| hal.structure.identifier | Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique [LERMA] | |
| dc.contributor.author | BRON, E. | |
| hal.structure.identifier | Onsala Space Observatory [OSO] | |
| dc.contributor.author | BLACK, J. H. | |
| hal.structure.identifier | Instituto de Ciencia de Materiales de Madrid [ICMM] | |
| dc.contributor.author | CERNICHARO, J. | |
| hal.structure.identifier | AMOR 2017 | |
| dc.contributor.author | CHAPILLON, E. | |
| dc.contributor.author | FUENTE, A. | |
| hal.structure.identifier | Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique [LERMA] | |
| dc.contributor.author | GERIN, Maryvonne | |
| dc.date.issued | 2017-04 | |
| dc.identifier.issn | 0004-6361 | |
| dc.description.abstractEn | We report high angular resolution (4.9" x 3.0") images of reactive ions SH+, HOC+, and SO+ toward the Orion Bar photodissociation region (PDR). We used ALMA-ACA to map several rotational lines at 0.8 mm, complemented with multi-line observations obtained with the IRAM 30m telescope. The SH+ and HOC+ emission is restricted to a narrow layer of 2"- to 10"-width (~800 to 4000 AU depending on the assumed PDR geometry) that follows the vibrationally excited H2^* emission. Both ions efficiently form very close to the H/H2 transition zone, at a depth of A_V < 1 mag into the neutral cloud, where abundant C+, S+, and H2^* coexist. SO+ peaks slightly deeper into the cloud. The observed ions have low rotational temperatures (T_rot~10-30 K << T_k) and narrow line-widths (~2-3 km/s), a factor of ~2 narrower that those of the lighter reactive ion CH+. This is consistent with the higher reactivity and faster radiative pumping rates of CH+ compared to the heavier ions, which are driven relatively faster toward smaller velocity dispersion by elastic collisions and toward lower T_rot by inelastic collisions. We estimate column densities and average physical conditions from a non-LTE excitation model (n(H2)~10^5-10^6 cm^-3, n(e^-)~10 cm^-3, and T_k~200 K). Regardless of the excitation details, SH+ and HOC+ clearly trace the most exposed layers of the UV-irradiated molecular cloud surface, whereas SO+ arises from slightly more shielded layers. | |
| dc.language.iso | en | |
| dc.publisher | EDP Sciences | |
| dc.subject.en | Astrophysics - Astrophysics of Galaxies | |
| dc.title.en | Spatially resolved images of reactive ions in the Orion Bar | |
| dc.type | Article de revue | |
| dc.identifier.doi | 10.1051/0004-6361/201730716 | |
| dc.subject.hal | Planète et Univers [physics]/Astrophysique [astro-ph]/Cosmologie et astrophysique extra-galactique [astro-ph.CO] | |
| dc.identifier.arxiv | 1704.08621 | |
| bordeaux.journal | Astronomy and Astrophysics - A&A | |
| bordeaux.page | id.L9 | |
| bordeaux.volume | 601 | |
| bordeaux.peerReviewed | oui | |
| hal.identifier | hal-01516644 | |
| hal.version | 1 | |
| hal.popular | non | |
| hal.audience | Internationale | |
| hal.origin.link | https://hal.archives-ouvertes.fr//hal-01516644v1 | |
| bordeaux.COinS | ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Astronomy%20and%20Astrophysics%20-%20A&A&rft.date=2017-04&rft.volume=601&rft.spage=id.L9&rft.epage=id.L9&rft.eissn=0004-6361&rft.issn=0004-6361&rft.au=GOICOECHEA,%20Javier&CUADRADO,%20S.&PETY,%20J.&BRON,%20E.&BLACK,%20J.%20H.&rft.genre=article |
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