Mode Switching in Two Blue Large-amplitude Pulsators Observed by OGLE, KMTNet, and DREAMS
Abstract
Blue large-amplitude pulsators (BLAPs) are rare, hot, short-period pulsating stars whose rapid oscillations provide a unique probe of stellar interiors and atmospheres. In this paper, we study two short-period BLAPs in the Galactic bulge, Optical Gravitational Lensing Experiment (OGLE)-BLAP-142 ( P ≈ 6.6 minutes) and OGLE-BLAP-148 ( P ≈ 7.5 minutes), by combining light curves from the OGLE, KMTNet, and DREAMS surveys, spanning 17 yr with cadences ranging from minutes to hours to days. We perform generalized Lomb–Scargle periodogram analyses of their light curves and identify, for each BLAP, three closely spaced pulsation modes separated by ∼1%. The dominant mode can switch within timescales of order a year, accompanied by a likely blueward color shift (∼0.1–0.2 mag). The yearly period excursions of the resolved mode families imply apparent ∣ P ̇ / P ∣ values of order 10 ⁻⁶ –10 ⁻⁴ yr ⁻¹ , large enough to mimic or exceed smooth evolutionary period changes. One mode family in OGLE-BLAP-148 shows a coherent decade-long drift at the ∼10 ⁻⁵ yr ⁻¹ level, but its failure to extrapolate to the earliest and latest epochs suggests a transient mode-family drift rather than secular evolution. Such close-spaced multiple pulsations and mode switching may be common among BLAPs with periods shorter than 10 minutes, and their physical origin remains unclear.
Versions
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BibTeX
@article{ma2026mode,
title = {{Mode Switching in Two Blue Large-amplitude Pulsators Observed by OGLE, KMTNet, and DREAMS}},
author = {Hao Ma and 皓 马 and Shude Mao and 淑德 毛 and Seung-Lee Kim and Hongjing Yang and 弘靖 杨 and Weicheng Zang and 伟呈 臧 and Tianjun Gan and 天君 干 and Steve Heathcote and Chung-Uk Lee and Tao Wu and Dong-Jin Kim and Zhenhao Wang and 圳豪 王 and Yaosong Yu and 耀淞 于 and Qiyue Qian and Yuchen Tang and 雨辰 唐 and Yuxin Shang and 钰欣 尚 and Zhixing Li and 知行 李 and Tomas Ahumada and Timothy Abbott and Guillermo Damke and Konstantina Boutsia and Alfredo Zenteno and Przemek Mróz and Andong Xu and 安东 徐},
journal = {The Astrophysical Journal},
year = {2026},
month = nov,
doi = {10.3847/1538-4357/aea902},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea902},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Mode Switching in Two Blue Large-amplitude Pulsators Observed by OGLE, KMTNet, and DREAMS
AU - Hao Ma
AU - 皓 马
AU - Shude Mao
AU - 淑德 毛
AU - Seung-Lee Kim
AU - Hongjing Yang
AU - 弘靖 杨
AU - Weicheng Zang
AU - 伟呈 臧
AU - Tianjun Gan
AU - 天君 干
AU - Steve Heathcote
AU - Chung-Uk Lee
AU - Tao Wu
AU - Dong-Jin Kim
AU - Zhenhao Wang
AU - 圳豪 王
AU - Yaosong Yu
AU - 耀淞 于
AU - Qiyue Qian
AU - Yuchen Tang
AU - 雨辰 唐
AU - Yuxin Shang
AU - 钰欣 尚
AU - Zhixing Li
AU - 知行 李
AU - Tomas Ahumada
AU - Timothy Abbott
AU - Guillermo Damke
AU - Konstantina Boutsia
AU - Alfredo Zenteno
AU - Przemek Mróz
AU - Andong Xu
AU - 安东 徐
PY - 2026
DA - 2026/11/02
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aea902
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aea902
AB - Blue large-amplitude pulsators (BLAPs) are rare, hot, short-period pulsating stars whose rapid oscillations provide a unique probe of stellar interiors and atmospheres. In this paper, we study two short-period BLAPs in the Galactic bulge, Optical Gravitational Lensing Experiment (OGLE)-BLAP-142 ( P ≈ 6.6 minutes) and OGLE-BLAP-148 ( P ≈ 7.5 minutes), by combining light curves from the OGLE, KMTNet, and DREAMS surveys, spanning 17 yr with cadences ranging from minutes to hours to days. We perform generalized Lomb–Scargle periodogram analyses of their light curves and identify, for each BLAP, three closely spaced pulsation modes separated by ∼1%. The dominant mode can switch within timescales of order a year, accompanied by a likely blueward color shift (∼0.1–0.2 mag). The yearly period excursions of the resolved mode families imply apparent ∣ P ̇ / P ∣ values of order 10 ⁻⁶ –10 ⁻⁴ yr ⁻¹ , large enough to mimic or exceed smooth evolutionary period changes. One mode family in OGLE-BLAP-148 shows a coherent decade-long drift at the ∼10 ⁻⁵ yr ⁻¹ level, but its failure to extrapolate to the earliest and latest epochs suggests a transient mode-family drift rather than secular evolution. Such close-spaced multiple pulsations and mode switching may be common among BLAPs with periods shorter than 10 minutes, and their physical origin remains unclear.
SN - 1538-4357
SN - 0004-637X
ER -