TY - JOUR
T1 - Herschel Planetary Nebula Survey (HerPlaNS)
T2 - First detection of OH + in planetary nebulae
AU - Aleman, I.
AU - Ueta, T.
AU - Ladjal, D.
AU - Exter, K. M.
AU - Kastner, J. H.
AU - Montez, R.
AU - Tielens, A. G.G.M.
AU - Chu, Y. H.
AU - Izumiura, H.
AU - McDonald, I.
AU - Sahai, R.
AU - Siódmiak, N.
AU - Szczerba, R.
AU - Van Hoof, P. A.M.
AU - Villaver, E.
AU - Vlemmings, W.
AU - Wittkowski, M.
AU - Zijlstra, A. A.
PY - 2014/6
Y1 - 2014/6
N2 - Aims. We report the first detections of OH+ emission in planetary nebulae (PNe). Methods. As part of an imaging and spectroscopy survey of 11 PNe in the far-IR using the PACS and SPIRE instruments aboard the Herschel Space Observatory, we performed a line survey in these PNe over the entire spectral range between 51μm and 672μm to look for new detections. Results. The rotational emission lines of OH+ at 152.99, 290.20, 308.48, and 329.77μm were detected in the spectra of three planetary nebulae: NGC 6445, NGC 6720, and NGC 6781. Excitation temperatures and column densities derived from these lines are in the range of 27-47 K and 2 × 1010-4 × 1011 cm-2, respectively. Conclusions. In PNe, the OH+ rotational line emission appears to be produced in the photodissociation region (PDR) in these objects. The emission of OH+ is observed only in PNe with hot central stars (Teff> 100 000 K), suggesting that high-energy photons may play a role in OH+ formation and its line excitation in these objects, as seems to be the case for ultraluminous galaxies.
AB - Aims. We report the first detections of OH+ emission in planetary nebulae (PNe). Methods. As part of an imaging and spectroscopy survey of 11 PNe in the far-IR using the PACS and SPIRE instruments aboard the Herschel Space Observatory, we performed a line survey in these PNe over the entire spectral range between 51μm and 672μm to look for new detections. Results. The rotational emission lines of OH+ at 152.99, 290.20, 308.48, and 329.77μm were detected in the spectra of three planetary nebulae: NGC 6445, NGC 6720, and NGC 6781. Excitation temperatures and column densities derived from these lines are in the range of 27-47 K and 2 × 1010-4 × 1011 cm-2, respectively. Conclusions. In PNe, the OH+ rotational line emission appears to be produced in the photodissociation region (PDR) in these objects. The emission of OH+ is observed only in PNe with hot central stars (Teff> 100 000 K), suggesting that high-energy photons may play a role in OH+ formation and its line excitation in these objects, as seems to be the case for ultraluminous galaxies.
KW - Astrochemistry
KW - Circumstellar matter
KW - Planetary nebulae: general
KW - Planetary nebulae: individual: NGC 6445
KW - Planetary nebulae: individual: NGC 6720
KW - Planetary nebulae: individual: NGC 6781
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U2 - 10.1051/0004-6361/201322940
DO - 10.1051/0004-6361/201322940
M3 - Article
AN - SCOPUS:84902459049
VL - 566
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A79
ER -