MCNeil’s Nebula in Orion: The Outburst History
MCNeil’s Nebula in Orion: The Outburst History
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猎户座中的麦克尼尔星云：爆发历史
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
S. Hoyer
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作者：
C. Briceño;A. K. Vivas;J. Hernández;N. Calvet;L. Hartmann;T. Megeath;P. Berlind;M. Calkins;S. Hoyer
本文给出了委内瑞拉1米施密特望远镜在J.W.猎户座L1630分子云中的麦克尼尔。我们推导出了一个包含爆发前状态和增亮本身的测光记录，这是一个包含14个历元，时间跨度约为5年的独特记录。我们限制在2003年10月28日和11月15日之间的某个时间爆发的开始。在星云顶点的物体的光变曲线，可能是爆发的兴奋源，显示它在大约4个月内变亮了~5等。该星云发展的时间尺度与光的传播时间一致，这表明我们正在观察来自中央光源的光，这些光被周围的云散射到视线中。我们还显示了最近FLWO光谱的激发源和附近的HH 22。光源的光谱是高度红化的;相比之下，HH 22的光谱显示了叠加在连续光谱上的冲击光谱，很可能是来自激发源的反射光通过红化程度低得多的路径到达HH物体的结果。光谱的蓝色部分与早期B光谱类型一致，类似于猎户座FU变星天鹅座星星V1057的早期爆发光谱;我们估计了它的光度L ~ 219 L。麦克尼尔星云的爆发行为，它的光谱特征和光度，表明我们可能正在目睹FU Ori事件的最大化。通过进一步监视这个对象，我们将能够决定它是否有资格成为这类罕见对象的成员。
We present a sequence of I-band images obtained at the Venezuela 1 m Schmidt telescope during the outburst of the nebula recently discovered by J. W. McNeil in the Orion L1630 molecular cloud. We derive photometry spanning the preoutburst state and the brightening itself, which is a unique record including 14 epochs and spanning a timescale of ~5 years. We constrain the beginning of the outburst at some time between 2003 October 28 and November 15. The light curve of the object at the vertex of the nebula, the likely exciting source of the outburst, reveals that it has brightened ~5 mag in about 4 months. The timescale for the nebula to develop is consistent with the light-travel time, indicating that we are observing light from the central source scattered by the ambient cloud into the line of sight. We also show recent FLWO optical spectroscopy of the exciting source and of the nearby HH 22. The spectrum of the source is highly reddened; in contrast, the spectrum of HH 22 shows a shock spectrum superposed on a continuum, most likely the result of reflected light from the exciting source reaching the HH object through a much less reddened path. The blue portion of this spectrum is consistent with an early B spectral type, similar to the early outburst spectrum of the FU Orionis variable star V1057 Cygni; we estimate a luminosity of L ~ 219 L☉. The eruptive behavior of McNeil's Nebula, its spectroscopic characteristics and luminosity, suggest that we may be witnessing an FU Ori event on its way to maximum. By further monitoring this object, we will be able decide whether or not it qualifies as a member of this rare class of objects.