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首页> 外文期刊>The Astrophysical journal >AUSTRALIA TELESCOPE COMPACT ARRAY RADIO IMAGING OF THE PROPLYD-LIKE OBJECTS IN THE GIANT H Ⅱ REGION NGC 3603
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AUSTRALIA TELESCOPE COMPACT ARRAY RADIO IMAGING OF THE PROPLYD-LIKE OBJECTS IN THE GIANT H Ⅱ REGION NGC 3603

机译：巨大的HⅡ区NGC 3603的类似对象的澳大利亚望远镜致密阵列无线电成像

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摘要

Three cometary-shaped objects in the giant H Ⅱ region NGC 3603, originally found and identified as proto-planetary disks (proplyds) by Brandner and coworkers using the Hubble Space Telescope and the Very Large Telescope in the optical and near-infrared, have been detected with the Australia Telescope Compact Array in the radio continuum at 3 and 6 cm. All three proplyd-like objects are clearly resolved with an extent of a few arcseconds. The integrated 6 cm fluxes are up to 1.3 times higher than the 3 cm fluxes with spectral indices averaged over the whole clump between α = -0.1 and -0.5 (S_ν ∝ ν~α), indicating the likely presence of nonthermal emission in at least some of the sources. We present spectral-index maps and show that the sites of negative radio spectral indices are predominantly concentrated in the direction of the tails in at least two of the three proplyd-like nebulae, while positive spectral indices are found in the region facing the ionizing star cluster. We propose that thermal bremsstrahlung and nonthermal synchrotron radiation are at work in all three proplyd-like sources. In at least one of the three objects, optically thin nonthermal synchrotron emission appears to dominate when averaged over its whole spatial extent, while the spectrum of a second source shows a marginal indication of a nonthermal spectrum. The average spectrum of the third source is in agreement with thermal bremsstrahlung. All measured fluxes are at least one order of magnitude higher than those predicted by Brandner and coworkers. Upper limits for mass-loss rates due to photoevaporation are calculated to be ～10~(-5) soalr mass yr~(-1) and for electron densities to be ～10~4 cm~(-3). Due to the unexpectedly large radio luminosities of the proplyd-like features and because the radio emission is extended, a (proto-) stellar origin of the nonthermal emission from a dust enshrouded star appears unlikely. Instead, we propose that magnetized regions within the envelope of the proplyd-like nebulae exist.
机译：HⅡ区域NGC 3603中的三个彗星状天体最初是由布兰德纳和同事使用哈勃太空望远镜和超大望远镜在光学和近红外中发现并识别为原行星盘（原行星）。使用澳大利亚望远镜紧凑型阵列在3厘米和6厘米的连续射电中检测到。只需几弧秒，就可以清楚地分辨出所有三个类似类物体的物体。积分的6 cm通量比3 cm通量高1.3倍，在整个团块上的光谱指数平均在α= -0.1和-0.5（S_ννν〜α）之间，这表明至少在至少一个时间里可能存在非热辐射一些来源。我们展示了光谱指数图，并显示负的光谱指数的站点主要集中在三个短尾状星云中至少两个的尾巴方向，而在面对电离星的区域中发现了正光谱指数簇。我们建议，热致辐射和非热同步加速器辐射在所有三个类似propdd的源中都在起作用。在这三个物体中的至少一个中，光学薄的非热同步加速器辐射在其整个空间范围内平均时似乎占主导地位，而第二个源的光谱则显示了非热光谱的边缘指示。第三种辐射源的平均光谱与热agreement致辐射一致。所有测得的通量都比Brandner及其同事所预测的通量至少高一个数量级。计算出由于光蒸发引起的质量损失率的上限为〜10〜（-5）碱质量yr〜（-1），电子密度的上限为〜10〜4 cm〜（-3）。由于拟峰状特征的出乎意料的大放射亮度，并且由于放射线扩展，因此尘埃包裹星体产生的非热辐射的（原始）恒星起源似乎不太可能。取而代之的是，我们建议在像拟星云的包膜中存在磁化区域。

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