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arXiv · 1309.4307

Two rings but no fellowship: LoTr 1 and its relation to planetary nebulae possessing barium central stars

A. A. Tyndall·D. Jones·H. M. J. Boffin·B. Miszalski·F. Faedi·M. Lloyd·J. A. López·S. Martell·D. Pollacco·M. Santander-García
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Abstract

LoTr 1 is a planetary nebula thought to contain an intermediate-period binary central star system (that is, a system with an orbital period, P, between 100 and, say, 1500 days). The system shows the signature of a K-type, rapidly rotating giant, and most likely constitutes an accretion-induced post-mass transfer system similar to other PNe such as LoTr 5, WeBo 1 and A70. Such systems represent rare opportunities to further the investigation into the formation of barium stars and intermediate period post-AGB systems -- a formation process still far from being understood. Here, we present the first detailed analyses of both the central star system and the surrounding nebula of LoTr 1 using a combination of spectra obtained with VLT-FORS2, AAT-UCLES and NTT-EMMI, as well as SuperWASP photometry. We confirm the binary nature of the central star of LoTr 1 that consists of a K1 III giant and a hot white dwarf. The cool giant does not present any sign of s-process enhancement but is shown to have a rotation period of 6.4 days, which is a possible sign of mass accretion. LoTr 1 also presents broad double-peaked H-alpha emission lines, whose origin is still unclear. The nebula of LoTr 1 consists in two slightly elongated shells, with ages of 17,000 and 35,000 years, respectively, and with different orientations. As such, LoTr 1 present a very different nebular morphology than A70 and WeBo 1, which may be an indication of difference in the mass transfer episodes

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A. A. Tyndall, D. Jones, H. M. J. Boffin, B. Miszalski, F. Faedi, M. Lloyd, J. A. López, S. Martell, D. Pollacco, M. Santander-García. 2013-09-17. Two rings but no fellowship: LoTr 1 and its relation to planetary nebulae possessing barium central stars. https://doi.org/10.1093/mnras%2Fstt1713

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