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Alizadeh, Mina ; Abedini, Yousefali ; Abdollahi, Hedieh
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evolution – stars ; long-period variables – stars ; mass-loss – galaxies ; M33 – galaxies ; central regions – photometry ; near-infrared – telescopes ; UKIRT
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Abstract:
We present an analysis of UKIRT observations obtained between 2003 and 2007 to investigate the evolved stellar populations within the central square kiloparsec of M33. Point-spread function (PSF) photometry is employed to mitigate the effects of stellar crowding and to ensure accurate measurements in this densely populated region. This method, applied to merged observations from UIST and WFCAM in the J, H, and K bands, extracts 211, 179 stars by cross-matching frame-by-frame across 39 observing nights in three bands. From this, we identify approximately 750 long-period variables (LPVs), predominantly Asymptotic Giant Branch (AGB) stars, by cross-matching PSF results with aperture photometry, focusing on the UIST field for robust variability confirmation. The PSF approach proves particularly effective for resolving blended sources and detecting faint, dusty variables that might remain undetected. We also examined aperture photometry data to validate our results; however, the PSF-derived measurements provide superior depth and completeness, particularly for obscured stellar populations. The resulting master catalog provides a basis for future analyses of variability amplitudes, periods, and star-formation history (SFH), paving the way for a deeper understanding of mass-loss and the dynamical evolution of the central region of M33.