Tom Lloyd Evans

An Unusual Carbon-rich RV Tauri Star in the Large Magellanic Cloud

We present the first spectra of an RV Tauri star in the Large Magellanic Cloud. MACHO* 04:55:43.2-67:51:10 is a recently identified RV Tauri variable with a double period of 112.448 days. Three low-resolution (210 A mm-1, or 7 A resolution) spectrograms obtained of this star show strong C2 bands with a pronounced phase dependence, their strength being greatest at minimum light. The overall spectrum of MACHO*04:55:43.2-67:51:10 is similar to those observed in proto–planetary nebulae. This unusual star therefore combines the main spectral anomaly of the proto–planetary nebulae with RV Tauri–like photometric variability. The occurrence of a luminous, carbon-rich RV Tauri–like star may be explained by assuming that it is a star of 1–2 solar masses that has evolved through the M-S-C transition on the extended asymptotic giant branch (AGB) and is now moving to the blue in the pre–planetary nebula stage. This star may therefore represent a link between these two types of star and strengthen the post-AGB interpretation of RV Tauri stars.

Post-AGB stars in the LMC and SMC

The chemical diversity displayed by Galactic post-AGB stars is much larger than anticipated, but the theoretical interpretation is hampered by a general lack of accurate distances and hence luminosities. We initiated therefore a large project to find and study optically bright post-AGB stars in the Large and Small Magellanic clouds. In this contribution we give a short overview on the chemical diversity in the Galactic sample and a status report of our LMC and SMC project. We highlight a few detailed studies of individual sources to illustrate the scientific potential of finding and studying extragalactic post-AGB stars.

V Hya B: A born‐again T Tauri star?

The pulsating, mass‐losing carbon star V Hydrae, has a companion which exhibits characteristics of both cataclysmic variables and T Tauri stars. It is suggested that mass accretion from the primary has rejuvenated the companion.

Joint Discussion 13 Exploiting large surveys for Galactic astronomy

This summary of JD13, Exploiting large surveys for Galactic astronomy, is based on the talks that were given during the meeting and/or submitted to the full proceedings which appeared in MemSAI 77 no. 4, 2006. The electronic version of this MemSAI volume also has the abstracts and images of the posters that were displayed and discussed during JD13. Here cans and images of the posters that were displayed and discussed during JD13. Here can only be listed their titles and authors. A panel discussion followed the talks, and a summary of the topics covered is added. Finally, there come the concluding remarks.

Commission 45: Stellar Classification

1. Business The Business Meeting of Commission 45 was held on 16 August 2006. It was attended by the president and vice-president of the Commission as well as by twenty other members of the Commission. Attendance was limited, as usual, by the unavoidable occurrence of parallel sessions. The memories of our colleague Dr. Charles Perry were recalled at the meeting. Subsequently in September 2006, and with deep regret, we learnt of the death of Dr. Laura Pasinetti, one of the retiring members of the Organizing Committee. New members of the IAU who are known to be joining Commission 45 are Carlos Allende Prieto, Cassio L. Barbosa, Johan Holmberg, Yuri V. Pakhomov, and Allyn John Smith. These were warmly welcomed. The President reported that a proposal, initiated by the Commission, for an IAU Joint Discussion during the IAU XXVI General Assembly on Exploiting Large Surveys for Galactic Astronomy had been approved by the Executive Committee. Vigorous support from four participating Divisions and five additional Commissions, leading to a Scientific Organizing Committee of ten persons, had resulted in a stimulating programme. The main goals of this Joint Discussion were to review the major surveys in astronomy whose targets are stars, to appreciate the scientific goals and the byproducts of these surveys with respect to our understanding of Galactic astronomy, to consider how well the techniques employed achieve these goals, and to exchange ideas on how best to exploit the opportunities of future surveys. A report of this meeting is given in Highlights of Astronomy, Volume 14 (CUP, 2007, ed. K.A. van der Hucht), and full proceedings are published in the Memorie della Societá Astronomica Italiana, volume 77, n.4. The president also drew the attention of the meeting to the Commission 45 contribution to Transactions IAU XXVIA, Reports on Astronomy 2002-2005 (CUP, 2007, ed. O. Engvold), where activity in stellar classification over the last several years is cited, and he thanked all the contributors to this report. Two major developments have been the unification of the T-dwarf standards and an ongoing project, the new general catalogue of stellar spectral classification by Brian Skiff. See <http://cdsweb.u-strasbg.fr/viz-bin/VizieR?-source=III/233B>. The third major activity of Commission 45, the Working Group on Standard Stars, and the production of its newsletter is reported in the following pages of these Transactions.

Commission 45: Stellar Classification: (Classification Stellaire)

This report, like its predecessor, focuses on areas which have been especially active since the last General Assembly. A major development has been the appearance of the first data and results from such large-scale surveys as 2MASS and the Sloan Digital Spectroscopic Survey, as well as major projects conducted from the ground. We give, for the first time, electronic addresses for selected catalogues and atlases.

A Spectroscopic Study of RV Tauri Stars in the LMC

Preliminary results from a low-resolution spectroscopic survey of RV Tauri stars and Type II Cepheids in the LMC are presented.