The enigma in the heart of Ursa Minor
Département de Physique, Université de Montréal, CP 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada
2 Osservatorio Astronomico di Roma Viale del Parco Mellini 84, 00136 Roma, Italy e-mail: email@example.com
Corresponding author: S. Demers, firstname.lastname@example.org
Accepted: 9 August 2001
To investigate the physical nature of the observed deficiency of stars in the very center of the Ursa Minor Dwarf Spheroidal galaxy, we recently obtained JCMT-SCUBA 850 μm photometry of this region. The observed void could be explained by ≈0.5 mag of extinction. While the amount of dust needed to produce such absorption (under certain assumptions for the dust temperature and the β exponent in the dust emissivity term) would yield a 5 mJy signal -easily detectable by SCUBA -we found no signal at 850 μm, after 256 min of integration. This finding rules out the presence of a few solar masses of cold dust cloud as the explanation for the central lack of stars observed in Ursa Minor. We discuss possible explanations.
Key words: galaxies: individual: Ursa Minor / galaxies: ISM / ISM: dust, extinction
© ESO, 2001