Discovery of a TiO emission band in the infrared spectrum of the S star NP Aurigae

被引：8

作者：

Smolders, K. ^{[1
]}

Verhoelst, T. ^{[1
,2
]}

Neyskens, P. ^{[3
]}

Blommaert, J. A. D. L. ^{[1
]}

Decin, L. ^{[1
]}

VanWinckel, H. ^{[1
]}

Van Eck, S. ^{[3
]}

Sloan, G. C. ^{[4
]}

Cami, J. ^{[5
,6
]}

Hony, S. ^{[7
]}

De Cat, P. ^{[8
]}

Menu, J. ^{[1
]}

Vos, J. ^{[1
]}

机构：

[1] Katholieke Univ Leuven, IvS, B-3001 Louvain, Belgium

[2] Belgian Inst Space Aeron BIRA IASB, B-1180 Brussels, Belgium

[3] Univ Libre Bruxelles, IAA, B-1050 Brussels, Belgium

[4] Cornell Univ, Dept Astron, Ithaca, NY 14853 USA

[5] Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada

[6] SETI Inst, Mountain View, CA 94043 USA

[7] CENS, Serv Astrophys, F-91191 Gif Sur Yvette, France

[8] Koninklijke Sterrenwacht Belgie, B-1180 Brussels, Belgium

来源：

ASTRONOMY & ASTROPHYSICS | 2012年 / 543卷

关键词：

stars: AGB and post-AGB; circumstellar matter; infrared: stars; techniques: spectroscopic; DUST FORMATION; AB-INITIO; SPECTROGRAPH; OXIDES; WATER;

D O I：

10.1051/0004-6361/201219520

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We 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 (approximate to 600K), an upper limit on the column density (approximate to 10(17.25) cm(-2)) and a lower limit on the spatial extent of the layer that contains these molecules. (approximate to 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.

引用

页数：4

共 36 条

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