“School of Astronomy”
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| Paper IPM / Astronomy / 18205 |
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We present the first attempt of exploring the stellar halo of M33 using ultra-deep broad-band imaging. Deep images using the star counting technique by the PAndAS survey reveals that M33 is undergoing a tidal interaction with its massive neighbor, M31. Due to this interaction, the stellar halo of M33 is currently experiencing a tidal disruption. These features are only visible at extremely low surface brightness levels (i.e. >30 mag/arcsec^2). For this reason, M33 is a perfect test-bed for comparing ultra-deep broad-band imaging with the star counting techniques to characterize the faintest surface brightness stellar emission. The outcome of this experiment is, therefore, key for interpreting the low surface brightness information in galactic systems where the stellar population can not be resolved (i.e. >16 Mpc).
Our experiment is conducted using the Iranian National Observatory Lens Array (INOLA). INOLA's field-of-view is 1.9 by 2.5 degrees, with a pixel size of 2.8 arcsec/pixel, easily covering M33 and its halo in one single exposure.
We will present a detailed description of all the technical challenges we have dealt with. Including the construction of a very extended non-parametric point spread function (PSF) out to a radius of 45 arcminutes and a massive scattered light removal of 4400 stars within each exposure for improved sky background estimation before creating the final stack. The results obtained by broad-band imaging are in excellent agreement with the star counting technique, which opens the study of stellar halo to the distant Universe on solid ground.
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