SCYON Abstract

Received on January 4 2006

The first 8-13 μm spectra of globular cluster red giants: circumstellar silicate dust grains in 47 Tucanae (NGC 104)

AuthorsJacco Th. van Loon (1),
Iain McDonald (1),
Joana M. Oliveira (1),
A. Evans (1),
Martha L. Boyer (2),
Robert D. Gehrz (2),
Elisha Polomski (2),
Charles E. Woodward (2)
(1) Astrophysics Group, School of Physical & Geographical Sciences,
Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG, UK
(2) Department of Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455, USA
Accepted byAstronomy & Astrophysics


We present 8-13 μm spectra of eight red giants in the globular cluster 47 Tucanae (NGC 104), obtained at the European Southern Observatory 3.6m telescope. These are the first mid-infrared spectra of metal-poor, low-mass stars. The spectrum of at least one of these, namely the extremely red, large-amplitude variable V1, shows direct evidence of circumstellar grains made of amorphous silicate.