超短周期白矮星双星并未经历强烈的潮汐加热
Ultrashort-period WD binaries are not undergoing strong tidal heating
AI总结：
本研究通过 MESA 模拟计算双白矮星中的潮汐加热，发现超短周期下 WD 温度显著升高，但观测表明潮汐加热非主导光度，这些热 WD 本质年轻，双星可能形成于短周期且经历了低效率共同包层演化。
摘要：
双白矮星（WD）双星在短轨道周期下越来越多地被发现，在这样的周期下可能会出现强烈的潮汐效应和显著的潮汐加热特征。我们假设伴星的潮汐势在主星 WD 内激发出外向引力波，其耗散导致 WD 表面温度升高。我们在演化的 MESA 双星模拟中计算了冷却 WD 模型中波的激发和耗散。潮汐加热被自洽地计算并在每个时间步添加到模型中。随着双星旋近至轨道周期小于约 20 分钟，WD 的行为从冷却转变为加热，与未潮汐加热的模型相比，温度升高可超过 10,000 K。我们将一系列潮汐加热 WD 模型与观测到的具有热 WD 主星的短周期系统进行了比较。虽然潮汐加热影响它们的 $T_{\ m eff}$，但它可能不是主导光度。相反，这些 WD 可能本质上年轻且热，这意味着双星形成于短轨道周期。这些双星与经历共同包层演化且效率 $α_{\ m CE}$ 略低的情况一致。我们划定了行波假设最有效的参数空间，并指出对于充分冷却的 WD 该假设会失效，此时可能形成驻波。
英文摘要：
Double white dwarf (WD) binaries are increasingly being discovered at short orbital periods where strong tidal effects and significant tidal heating signatures may occur. We assume the tidal potential of the companion excites outgoing gravity waves within the WD primary, the dissipation of which leads to an increase in the WD's surface temperature. We compute the excitation and dissipation of the waves in cooling WD models in evolving MESA binary simulations. Tidal heating is self-consistently computed and added to the models at every time step. As a binary inspirals to orbital periods less than $\sim$20 minutes, the WD's behavior changes from cooling to heating, with temperature enhancements that can exceed 10,000 K compared with non-tidally heated models. We compare a grid of tidally heated WD models to observed short-period systems with hot WD primaries. While tidal heating affects their $T_{\rm eff}$, it is likely not the dominant luminosity. Instead these WDs are probably intrinsically young and hot, implying the binaries formed at short orbital periods. The binaries are consistent with undergoing common envelope evolution with a somewhat low efficiency $α_{\rm CE}$. We delineate the parameter space where the traveling wave assumption is most valid, noting that it breaks down for WDs that cool sufficiently, where standing waves may instead be formed.
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