Searching for long period pulsations in He-rich subdwarfs

炽热的亚矮星是失去了富氢包层的氦核心燃烧恒星。虽然大多数热矮星显示出几乎纯的H大气，但有一小部分恒星显示出混合的H/He表面成分。这些恒星预计将在氦核闪光后立即进入快速阶段，在那里引力沉降还没有使大气中的氢变得纯净。在这一阶段，他们预计将经历核子闪光，这被预测为驱动脉动。对氦核闪光驱动的恒星脉动的确认，将是对氦亚闪光本身存在的第一次直接证实。我们给了Calar Alto天文台的Busca仪器四个晚上的观测时间，对14颗混合H/He大气的热亚矮星进行了特别的恒星振荡搜索。

Hot subdwarf stars are He-core burning stars that have lost their H-rich envelopes. While most hot subdwarfs show almost pure H atmospheres, a small fraction of these stars show a mixed H/He surface composition. These stars are expected to be in a fast stage immediately after the He-core flash, where gravitational settling did not turn the atmosphere H-pure yet. During this phase they are expected to undergo He-core subflashes, which are predicted to drive pulsations. The confirmation of stellar pulsations driven by the He-core flash would be the first direct confirmation of the existence of the He-subflashes themselves. We granted four nights of observing time with the BUSCA instrument at the Calar Alto observatory to pursue an ad hoc search of stellar oscillations in 14 hot subdwarfs with mixed H/He atmospheres.