A stringent upper limit to 18 cm radio emission from the extrasolar planet system τ Boötis
A stringent upper limit to 18 cm radio emission from the extrasolar planet system τ Boötis
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太阳系外行星系统 τ Boötis 的严格无线电发射上限为 18 厘米
DOI：
10.1051/0004-6361/201220006
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发表时间：
2012
影响因子：
6.5
通讯作者：
H. Röttgering
中科院分区：
文献类型：
--
作者：
A. Stroe;I. Snellen;H. Röttgering
语境。多年来人们一直推测，一些太阳系外行星可能会以 10-100 MHz 范围内的低射频发射强回旋加速器辐射。尽管进行了多次尝试，但尚未看到这种发射。目标。热木星系统Bootis 是迄今为止已知距离最近的（d=15 颗）系外行星之一。这颗巨大的热木星（M=8 Mjup）的引力影响锁定了恒星-行星系统，使恒星以P∼3.3天的时间自转，与行星的轨道周期相似。根据恒星自转和射电光度之间已建立的相关性，可以想象，布蒂斯系统会以比目前探测到的频率高得多的频率发出强烈的射电发射，我们的目的是通过这项工作来研究这一点。方法。我们使用 Westerbork 合成射电望远镜 (WSRT) 在 1.7 GHz 频率下观察了布蒂斯。在谱线模式下持续 12 小时，在目标位置达到 42 µJy/光束的噪声水平。结果。没有检测到布蒂斯的 18cm 射电发射，导致 3� 上限为 0.13 mJy，对应于 < 3.7× 10 13 erg s -1 Hz -1 的 18cm 射电光度。根据射电光度和旋转速度之间的恒星关系，我们观察到布蒂斯比预期的要暗两个数量级。结论。这意味着，与类似的快速旋转恒星相比，布蒂斯系统在射电中的发光度较低，或者我们碰巧在射电发射处于低状态时观察到了目标。
Context. It has been speculated for many years that some extrasolar planets may emit strong cyclotron emission at low radio frequen- cies in the range 10-100 MHz. Despite several attempts no such emission has yet been seen. Aims. The hot Jupiter systemBootis is one of the nearest (d=15 pc) exoplanets known to date. The gravitational influence of this massive hot Jupiter (M=8 Mjup) has locked the star-planet system, making the star rotate i n P∼3.3 days, similar to the orbital period of the planet. From the well established correlation between stellar rotation and radio luminosity, it is conceivable t hat theBootis system emits strong radio emission at significantly higher f requencies than currently probed, which we aimed to investigate with this work. Methods. We observedBootis with the Westerbork Synthesis Radio Telescope (WSRT) at a frequency of 1.7 GHz. for 12 hours in spectral line mode, reaching a noise level of 42 µJy/beam at the position of the target. Results. No 18cm radio emission is detected fromBootis, resulting in a 3� upper limit of 0.13 mJy, corresponding to a 18cm radio luminosity of < 3.7× 10 13 erg s −1 Hz −1 . We observeBootis to be two orders of magnitude fainter than expected from the stellar relation between radio luminosity and rotation velocity. Conclusions. This implies that either theBootis system is underluminous in the radio compared to similar fast-rotating stars, or that we happened to observe the target during a low state of radio emission.