Modeling the Infrared Bow Shock at δ Velorum: Implications for Studies of Debris Disks and λ Boötis Stars
Modeling the Infrared Bow Shock at δ Velorum: Implications for Studies of Debris Disks and λ Boötis Stars
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模拟 δ Velorum 处的红外弓激波：对碎片盘和 λ Bootis 星研究的启示
DOI：
10.1086/523299
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Caltech
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文献类型：
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作者：
A. G'asp'ar;K. Su;G. Rieke;Z. Balog;I. Kamp;J. R. Mart'inez;K. Observatory;UofA;Tucson;Stsci;Baltimore;L. Observatory;Leiden;The Netherlands.;Jpl;Caltech
我们利用斯皮策多波段成像光度计所获得的24μm的观测数据，在斯皮策的前方发现了一个弓形的中红外超额区。虽然弓激波形态只在24μm的观测中被观测到，但它的过剩也在70μm被分辨出来。我们证明了周围星际介质云的恒星加热可以产生测量到的通量。由于δVelorum之前被归类为碎片盘恒星，我们的发现可能会对其他恒星的相同分类提出质疑。我们模拟了恒星和ISM的相互作用，产生的图像显示了与观测到的相同的几何形状和表面亮度。与平均局部气泡值相比，模拟的ISM的密度是平均局部气泡值的~15倍，考虑到δVelorum非常接近(24个PC)，这是令人惊讶的。此前，λBoötis恒星的丰度异常被解释为是由恒星与ISM的同一类型相互作用引起的。δVelorum的低分辨光谱表明，它不属于这个恒星类。因此，这颗恒星是λBoötis现象的ISM吸积理论的有趣试验台。
We have discovered a bow shock shaped mid-infrared excess region in front of δ Velorum using 24 μm observations obtained with the Multiband Imaging Photometer for Spitzer (MIPS). Although the bow shock morphology was only detected in the 24 μm observations, its excess was also resolved at 70 μm. We show that the stellar heating of an ambient interstellar medium (ISM) cloud can produce the measured flux. Since δ Velorum was classified as a debris disk star previously, our discovery may call into question the same classification of other stars. We model the interaction of the star and ISM, producing images that show the same geometry and surface brightness as is observed. The modeled ISM is ~15 times overdense relative to the average Local Bubble value, which is surprising considering the close proximity (24 pc) of δ Velorum. The abundance anomalies of λ Boötis stars have been previously explained as arising from the same type of interaction of stars with the ISM. Low-resolution optical spectra of δ Velorum show that it does not belong to this stellar class. The star therefore is an interesting testbed for the ISM accretion theory of the λ Boötis phenomenon.