The fundamental parameters of the roAp star HD 24712 - A rapidly oscillator at the red edge of the instability strip
The fundamental parameters of the roAp star HD 24712 - A rapidly oscillator at the red edge of the instability strip
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roAp star HD 24712 的基本参数 - 不稳定带红边的快速振荡器
DOI：
10.1051/0004-6361/201527920
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发表时间：
2016
影响因子：
6.5
通讯作者：
Brandão
中科院分区：
文献类型：
--
作者：
Perraut;Brandão
背景对于导致快速振荡的 Ap 星的脉动激发的机制的性质仍然存在争议，这些快速振荡的 Ap 星的振荡频率高于理论上的最高声频。 HD 24712 是此类研究的一个很好的测试案例，因为它很明亮，其视差精确确定，并且其频谱众所周知。目的可见光长基线干涉测量是一种独特的技术，用于测量小至最亮的 roAp 星的目标的精确角直径，从而通过尽可能独立于大气模型的方法估计精确的半径。方法我们在 CHARA 长基线光学阵列上使用可见光谱仪 VEGA观察 HD 24712，我们得出了它的边缘变暗直径。我们还根据文献中的光谱数据估计了它的辐射热通量，并确定了它的半径、光度和有效温度。结果我们确定了 HD 24712 的临边暗角直径为 0.335 ± 0.009 mas，并得出半径为 R= 1.772 ± 0.057R⊙、光度为 L= 7.2 ± 1.8L⊙ 和有效温度ofTeff= 7235 ± 280 K，这与为这颗恒星开发的自洽分层模型提供的值非常接近。我们使用这些基本参数在 Hertzsprung-Russell 图中设置 HD 24712。它的位置与预测由 κ 机制激发高径向阶模式的区域略有一致。结论我们得出结论，这颗恒星中的振荡很可能不是由 κ 机制驱动的。
ContextThere is still a debate about the nature of the mechanism that causes the pulsation excitation of the rapidly oscillating Ap stars that oscillate above the highest theoretically acoustic frequency. HD 24712 is a good test case for such a study because it is bright, its parallax accurately determined, and its frequency spectrum is well known.AimsVisible long-baseline interferometry is a unique technique for measuring accurate angular diameters of targets as small as the brightest roAp stars, and thus estimating accurate radii by a method as independent as possible of atmosphere models.MethodsWe used the visible spectrograph VEGA at the CHARA long-baseline optical array to observe HD 24712, and we derived its limb-darkened diameter. We also estimated its bolometric flux from spectroscopic data in the literature and determined its radius, luminosity, and effective temperature.ResultsWe determined a limb-darkened angular diameter of 0.335 ± 0.009 mas for HD 24712 and derived a radius ofR= 1.772 ± 0.057R⊙, a luminosity ofL= 7.2 ± 1.8L⊙, and an effective temperature ofTeff= 7235 ± 280 K, which is in very close agreement with the values provided by the self-consistent stratified model developed for this star. We used these fundamental parameters to set HD 24712 in the Hertzsprung-Russell diagram. Its position is marginally consistent with the region where high radial order modes are predicted to be excited by theκ-mechanism.ConclusionsWe conclude that oscillations in this star are most likely not driven by theκ-mechanism.