A High-Resolution H I Study of the Interstellar Medium Local to HD 193793
A High-Resolution H I Study of the Interstellar Medium Local to HD 193793
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HD 193793 局部星际介质的高分辨率 H I 研究
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发表时间：
2001
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通讯作者：
E. M. Arnal
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作者：
E. M. Arnal
使用 Dominion 射电天体物理观测站干涉仪，在 H I 21 cm 线和 1420 MHz 射电连续谱中对以沃尔夫-拉叶 (WR) 星 HD 193793 (≡ WR 140) 光学位置为中心的 2° 视场进行了测量。此次观测的目的是寻找 WR 恒星与其本地星际介质 (ISM) 之间相互作用的证据。我们的 H I 数据显示出一个大的椭圆形最小值，速度为 Vsys ≃ -12 km s-1，接近 HD 193793 的光学位置。我们相信这个 H I 空洞是由 WR 140 及其巨大伴星（HD 193793 是著名双星系统的成员）创建的。 H I 空洞的长轴为~11.5 pc，其轴比（长轴与短轴之比）为~1.4。该结构可在约 11 km s-1 的速度范围内观测到。 H I 最小值出现在发射中的 H I 块状壳层周围，中性氢的总质量为 MHI ∼ 1300 个太阳质量。与当地标准静止速度-12 km s-1 对应的运动学距离约为5.4 kpc，这与HD 193793 的距离不一致，即1 kpc 左右。因此，可以得出结论，H I 气泡是在具有不可忽略的特殊运动的 ISM 中吹出的。依巴谷自行测量表明，HD 193793 沿着在主 H I 腔内部检测到的 H I 最小值之一的长轴，具有 28 ± 3 km s-1 的切向速度。为了使这种运动与双星系统风吹动的H I结构的物理尺寸相一致，可以得出这样的切向速度是该系统不久前获得的，即~1.3×105年。 IRAS 数据库的地图显示了大范围的红外特征，与主要 H I 空洞周围的 H I 壳层具有良好的空间相关性。我们相信红外壳的发射来自于被恒星物体发射的高能恒星连续光子加热的尘埃颗粒。
A 2° field centered at the optical position of the Wolf-Rayet (WR) star HD 193793 (≡ WR 140) was surveyed in the H I 21 cm line and in the 1420 MHz radio continuum, using the Dominion Radio Astrophysical Observatory interferometer. The aim of this observations was to look for evidence of an interaction between the WR star and its local interstellar medium (ISM). Our H I data displays a large oval minimum at a velocity of Vsys ≃ -12 km s-1, close to the optical position of HD 193793. We believe this H I void was created by WR 140 and its massive companion (HD 193793 is a member of a well-known binary system). The major axis of the H I void is ∼11.5 pc and its axial ratio, the ratio of major to minor axis, is ∼1.4. This structure is observable over a velocity range of around 11 km s-1. The H I minimum appears surrounded by a clumpy shell of H I in emission that has a total mass of neutral hydrogen of MHI ∼ 1300 solar masses. The kinematical distance corresponding to a local standard of rest velocity of -12 km s-1 is approximately 5.4 kpc, which disagrees with the distance of HD 193793, namely, around 1 kpc. Therefore, it is concluded that the H I bubble was blown in an ISM having nonnegligible peculiar motions. Hipparcos proper-motion measurements indicate that HD 193793 has a tangential velocity of 28 ± 3 km s-1 along the major axis of one of the H I minima detected in the interior of the main H I cavity. To reconcile this motion with the physical size of the H I structure blown by the winds of the binary system, it is concluded that such tangential velocity was acquired by the system a short while ago, namely, ∼1.3 × 105 yr. Maps from the IRAS database show a large-scale IR feature, with good spatial correlation with the H I shell surrounding the main H I void. We believe the emission from the IR shell arises from dust grains heated by the energetic stellar continuum photons emitted by the stellar objects.