Uncovering extraplanar gas in UGCA 250 with the Ultra-deep MHONGOOSE Survey
Résumé
We use the neutral atomic hydrogen (H I ) observations of the edge-on galaxy UGCA 250, taken as part of the MeerKAT H I Observations of Nearby Galactic Objects-Observing Southern Emitters (MHONGOOSE) surv e y to inv estigate the amount, morphology, and kinematics of extraplanar gas. The combination of high column density sensitivity and high spatial resolution of the surv e y o v er a large field of view is ideal for studying the underlying physics go v erning the e xtraplanar gas. These data reveal nine additional detections within the field of view along with UGCA 250, with eight of them being within ∼200 km s -1 of the galaxy's systemic velocity. The galaxy seems to have a tail-like feature e xtending a way from it in the southern direction up to ∼41 kpc (in projection). We also detect a cloud at anomalous velocities, but we did not find any optical counterpart. We construct a detailed tilted ring model for this edge-on galaxy to gain a deeper understanding of the vertical structure of its neutral hydrogen. The model that best matches the data features a thick disc with a scale height of ∼3 ±1 kpc and an H I mass of about 15 per cent of the total H I mass. This extraplanar gas is detected for the first time in UGCA 250. Our analysis fa v ours a mixed origin for the extraplanar gas in UGCA 250, likely arising from a combination of internal stellar feedback and external tidal interactions.
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