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Neutral hydrogen clouds and stellar streams in the halo of M33

Marco Grossi
Observatório Astronómico de Lisboa, Portugal

The late-type spiral galaxy M33 is the brightest of M31's satellite companions. While M31 is known to be a disturbed galaxy, M33 seems to have not undergone any recent or past mergers having a quite undisturbed stellar disc and no prominent bulge. On the other hand, a long-standing puzzle about M33 is the existence of an extremely warped HI disk, and to sustain its current star formation rate indicate that M33 needs toaccrete gas at a rate of about 1 M/yr.
We used the 21-cm survey ALFALFA to inspect the neutral hydrogen distribution in the outer disk of M33 finding a varied population of HI clouds with masses up to few times 106 M. Particularly, we detected an extended HI complex at a projected distance of about 15 kpc. Deep optical images have been taken to search for optical counterparts to the clouds, and/or traces of stellar streams. In this talk I will present the results.

2010 February 24, 13:30

Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto

Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Fundação para a Ciência e a Tecnologia
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