arXiv subjects

Bakuh Danang Setyo Budi

Publications and source records attributed to Bakuh Danang Setyo Budi.

2 recordsLinked to original sources

arXiv2026

First and Comprehensive Study of V0757 Pup : $γ-$Doradus Pulsator in Detached Eclipsing Binary

Pulsating stars in detached eclipsing binary (EA) systems are known for providing many important physical informations which constrain both stellar structure and evolution theories. To date, fewer than 50 $γ$ Doradus (GDOR) stars have been found in eclipsing binary systems, making them important targets to study \textit{g}-mode pulsation inside the stars. We present a comprehensive physical and pulsational analysis of V0757 Pup (TIC 6939791), a detached eclipsing binary system observed by the TESS mission (Sectors 7, 34, 61, and 88) and followed up with ground-based spectroscopy from the Thai National Telescope. By combining light curve modeling with radial velocities derived from medium-resolution spectra, we determined the fundamental stellar and atmospheric parameters with high precision. The system consists of an F2V primary ($M_1=1.305\pm0.026M_\odot, R_1=1.643\pm0.020R_\odot$) and a G1V secondary ($M_2=0.934\pm0.030M_\odot, R_2=0.941\pm0.079R_\odot$). We performed a detailed frequency analysis of the residual light curves, identifying two dominant independent pulsation frequencies at $f\sim0.79$ c/d and $0.98$ c/d. These frequencies, along with the derived pulsation constant ($Q\sim0.6$ d), confirm the primary component as a $γ$ Doradus pulsator. An analysis of Eclipse Timing Variations (ETV) reveals non detection of third body companions with current available dataset, strengthen by the result of \textit{Gaia} astrometric analysis. Evolutionary modeling indicates the system is $\sim2.2$ Gyr old, with the primary expected to fill its Roche lobe in $\sim1$ Gyr. Additionally, we calculate a distance of $d\approx350$ pc based on orbital and SED modeling, which is in excellent agreement with the \textit{Gaia} DR3 parallax distance.

astro-ph.SR↗

arXiv2026

Revealing α-Element's Past with Subaru/IRD: Oxygen Abundance of 35 Very Metal-Poor Stars from Near-IR OH lines

Oxygen abundances in very and extremely metal-poor (V/EMP) stars provide critical constraints on early massive stars' nucleosynthesis. An Oxygen abundance analysis is presented for 35 V/EMP stars (-4.0<[Fe/H]< -1.5) using near-infrared H-band OH vibro-rotational lines from high-resolution Subaru/IRD spectra. To examine the reliability of these NIR OH lines, the results are compared with the abundances obtained from the 3D/NLTE-insensitive forbidden [OI] 6300Å line using archival high-resolution optical spectra. After homogeneously rederiving stellar parameters and 1D/NLTE Fe abundances using Gaia photo-astrometry and literature optical Fe equivalent width data, oxygen abundance from OH and [OI] lines is determined through 1D/LTE spectral synthesis. A sensitivity analysis confirms that near-IR OH lines are highly sensitive to the adopted temperature compared to the forbidden line. A temperature-dependent discrepancy between the tracers is identified: in cool red giants (Teff <4600 K), OH-based abundances are systematically lower than [OI]-based abundance by 0.05 to 0.25 dex, while warmer red giants show higher OH-based abundances as expected from 3D effects. Despite this systematic offset, the numerous measurable NIR OH lines yield significantly smaller random abundance errors than that of the single, weak [OI] line. Leveraging this statistical precision, an empirical calibration as a function of Teff, log g, [Fe/H], and [C/Fe] is derived to align the 1D/LTE OH abundances onto the [OI] scale. Applying this correction substantially reduces the scatter and temperature dependence in the [O/Fe] versus [Fe/H] plane and flattens the trend, bringing the results into fairly good agreement with Galactic chemical evolution models.

astro-ph.SR↗