Blue Large-Amplitude Pulsators (BLAPs): possible origin, evolutionary status, and nature of their pulsations

Abstract

The Blue Large-Amplitude Pulsators (BLAPs) constitute a new class of pulsating stars. They are hot stars with effective temperatures of $T_{\mathrm{eff}}\sim 30000$ K and surface gravities of $\log g\sim 4.9$, that pulsate with periods in the range $\sim 20-40$ min. In Romero et al. (2018), we proposed that BLAPs are hot low-mass He-core pre-white dwarf (WD) stars that pulsate either in high-order non-radial $g$(gravity) modes or low-order radial modes, including the fundamental radial mode. The theoretical modes with periods in the observed range are unstable due to the $\kappa$ mechanism associated with the $Z$ bump in the opacity at $\log T\sim 5.25$. In this work, we extend the study of Romero et al. (2018) by assessing the rate of period changes of nonradial $g$ modes and radial modes and comparing them with the values measured for BLAPs, in an attempt to validate the proposed evolutionary scenario, and to discern whether the observed modes are high-order $g$ modes or radial modes.

7 pages and 9 figures. Submitted as Proceedings for the 21st European White Dwarf Workshop held July 23-27, 2018, Austin, Texas

References in corpus (1)

• On the Properties of Blue Large-Amplitude Pulsators. No BLAPs in the Magellanic Clouds

Cited by in corpus (4)

• A new class of pulsating hot subdwarfs
• Pulsation in faint blue stars
• Shell helium-burning hot subdwarf B stars as candidates for blue large-amplitude pulsators
• Identifying Blue Large Amplitude Pulsators from Gaia DR2 & ZTF DR3