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Close binaries containing at least one white dwarf (WD) are thought to be the progenitors of some of the Galaxy.s most exotic objects comma such as cataclysmic variables comma AM CVn binaries comma hot subdwarf stars comma double degenerates and thermonuclear supernovae (SN) comma including the cosmologically important SN Ia. This zoo of possible evolutionary outcomes demonstrates the complexity of trying to study the population of WD binaries as a whole. However comma without a detailed understanding of the evolution of WD binaries comma we will remain unable to unravel the pathways towards thermonuclear SN and the conditions under which they ignite comma and equally comma we will not be able to accurately predict or model the low-frequency gravitational background from galactic WD binaries. Here we propose to take a step back in time to the last stage at which all of these systems were part of the same population of detached WD plus main-sequence star binaries. The properties of these binaries can reveal their past evolution and measure how common different evolutionary channels are. However comma at optical wavelengths the WD components are overwhelmed by their main-sequence companions making it difficult to determine their masses. Using TESS data we are able to circumvent this by measuring the rotation rate of the stars and comparing this to rotational broadening measurements comma to measure the binary inclinations and thus WD masses for dozens of systems. However comma this method relies on the alignment of the spin and orbit of the stars which is by no means proven. Here we request HST-STIS data to confirm if our method yields the correct WD masses for these powerful probes of WD binary evolution.

包含至少一颗白矮星（white dwarf，WD）的密近双星被认为是银河系中一些最奇异天体的前身，例如激变变星、AM CVn双星、热亚矮星、双简并星以及热核超新星（supernova，SN）——包括在宇宙学上具有重要意义的Ia型超新星。这些可能的演化结果的多样性体现了整体研究WD双星群体的复杂性。然而，若缺乏对WD双星演化的详细理解，我们将无法解开热核超新星的形成路径及其点火条件，同样也无法准确预测或建模银河系WD双星产生的低频引力背景。在此，我们提议回溯至所有这些系统均属于同一分离WD加主序星双星群体的最后阶段。这些双星的性质可揭示其过往演化，并测定不同演化通道的普遍程度。但在光学波段，WD成分被其主序伴星掩盖，导致难以测定其质量。利用TESS数据，我们可通过测量恒星的自转速率并与自转展宽测量结果对比，来测定双星倾角，从而得到数十个系统的WD质量。然而，该方法依赖于恒星自旋与轨道的对齐，这一点尚未得到证实。因此，我们申请HST-STIS数据，以确认我们的方法是否能为这些研究WD双星演化的有力探针提供准确的WD质量。