Search for HI in Dwarf Spheroidal Galaxies

Claude Carignan, PASA, 16 (1), in press.

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Previous HI observations of dSph galaxies

The first claim that HI could be associated with a dSph-like system was for the dIrr/dSph system Phoenix (Carignan, Demers & Côté 1991). They identified a component, corresponding to $\sim 10^5$${\cal M}$$_\odot$, around 50kms-1, between the Galactic HI $\sim 0$kms-1and gas $\sim 150$kms-1, associated with the Magellanic Stream (MS: Mathewson, Cleary & Murray 1974; Haynes & Roberts 1979). More recently, Young & Lo (1997b) identified another velocity component $\sim -23$kms-1, nearly superposed on the optical.

The other system, in the field of which HI was detected, is the more distant (

$\Delta \simeq 900$ kpc) dSph Tucana (Oosterloo, Da Costa & Staveley-Smith 1996). However, since most of the HI is located $\sim 15'$ ($\sim 4$ kpc) east of the optical and since the detected gas, if associated with Tucana, would imply a mass in excess of 106${\cal M}$$_\odot$, they discarded this possibility and suggested that it was most probably gas associated with the MS. Unfortunately, in both cases, no optical velocities are yet available to disentangle which velocity component could be truly associated with those galaxies.


Next Section: HI associated with Sculptor
Title/Abstract Page: Search for HI in
Previous Section: HI distribution in extreme
Contents Page: Volume 16, Number 1

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