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000002213 005__ 20160706143520.0
000002213 0247_ $$2DOI$$a10.1051/0004-6361/201219520
000002213 037__ $$aASTROimport-370
000002213 100__ $$aSmolders, K.
000002213 245__ $$aDiscovery of a TiO emission band in the infrared spectrum of the S star NP Aurigae
000002213 260__ $$c2012
000002213 520__ $$aWe report on the discovery of an infrared emission band in the Spitzer spectrum of the S-type AGB star NP Aurigae that is caused by TiO molecules in the circumstellar environment. We modeled the observed emission to derive the temperature of the TiO molecules (˜600 K), an upper limit on the column density (˜1017.25 cm-2) and a lower limit on the spatial extent of the layer that contains these molecules. (˜4.6 R?). This is the first time that this TiO emission band is observed. A search for similar emission features in the sample of S-type stars yielded two additional candidates. However, owing to the additional dust emission, the identification is less stringent. By comparing the stellar characteristics of NP Aur to those of the other stars in our sample, we find that all stars with TiO emission show large-amplitude pulsations, s-process enrichment, and a low C/O ratio. These characteristics might be necessary requirements for a star to show TiO in emission, but they are not sufficient.
000002213 700__ $$aVerhoelst, T.
000002213 700__ $$aNeyskens, P.
000002213 700__ $$aBlommaert, J. A. D. L.
000002213 700__ $$aDecin, L.
000002213 700__ $$aVan Winckel, H.
000002213 700__ $$aVan Eck, S.
000002213 700__ $$aSloan, G. C.
000002213 700__ $$aCami, J.
000002213 700__ $$aHony, S.
000002213 700__ $$aDe Cat, P.
000002213 700__ $$aMenu, J.
000002213 700__ $$aVos, J.
000002213 773__ $$cL2$$pAstronomy and Astrophysics$$v543$$y2012
000002213 85642 $$ahttp://esoads.eso.org/abs/2012A%26A...543L...2S
000002213 905__ $$apublished in
000002213 980__ $$aREFERD