arXiv subjects

Yousefali Abedini

Publications and source records attributed to Yousefali Abedini.

3 recordsLinked to original sources

arXiv2026

The UKIRT M33 Monitoring Project: A 15-Year Near-Infrared Variable Star Catalogue for the Central Kiloparsec, and Prospects for Star Formation History and Dust Return

We present results from the UKIRT M33 Monitoring Project, a near-infrared survey of variable red giants in the Local Group spiral galaxy M33. Combining four independent photometric datasets spanning UIST (2003), UFTI (2005), WFCAM (2005-2007), and a new UKIRT Hemisphere Survey epoch (2018), we construct a homogenised 15.11-year $K$-band light-curve catalogue for 847 stars in the central kiloparsec, of which 771 (91 per cent) are variable. Cross-matching with archival Spitzer photometry identifies 120 dust-enshrouded AGB candidates. We compare the spatial coverage of this central catalogue with the earlier UIST-only (Paper I) and disc-wide WFCAM (Paper IV) variable-star surveys. Building on this catalogue, two forthcoming papers will (i) measure individual pulsation periods to reconstruct the star formation history of the central kiloparsec, and (ii) refine dust and gas mass-loss rates across the disc using the extended time baseline.

astro-ph.GA↗

arXiv2025

Unveiling Long-Period Variables in M33's Central Region: Insights into Stellar Evolution and Star Formation via Near-Infrared Photometry

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.

astro-ph.SR↗

arXiv2022

Revisiting the secondary eclipses of KELT-1b using TESS observations

We present the characterization of the transiting planet KELT-1b % ($R_p \simeq 1.15 R_J, M_p \simeq 27.23 M_J $) using data from the Transiting Exoplanet Survey Satellite (TESS). % during cycle $2$ and sector $17$. Our light curve model includes primary transit and secondary eclipse. Here, we model the systematic noise using Gaussian processes (GPs) and fit it to the data using the Markov Chain Monte Carlo (MCMC) method. Modelling of the TESS light curve returns a planet-to-star radius ratio, $p =$ $0.07652_{-0.00028}^{+0.00029}$ and a relatively large secondary eclipse depth of $388_{-13}^{+12}$ ppm. The transit ephemeris of KELT-1b is updated using the MCMC method. Finally, we complement our work by searching for transit timing variations (TTVs) for KELT-1b. We do not find significant variations from the constant-period models in our transit time data.

astro-ph.EP↗