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arXiv 1002.3379astro-ph.GA
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在五重星系团附近发现一颗明亮的蓝色变星和一个喷射星云

Discovery of a Luminous Blue Variable with an Ejection Nebula Near the Quintuplet Cluster

Jon C. Mauerhan, Mark R. Morris, Angela S. Cotera, Hui Dong, Q. Daniel Wang, Susan R. Stolovy, Cornelia C. Lang, Ian S. Glass

摘要:

本文报道了在五重星系团的投影中发现了一个位于~7 pc的亮蓝变星。这个源,我们称之为LBV G0.120-0.048,被选为光谱学,因为它是最近用HST/NICMOS对银河系中心区域进行的窄带成像调查中检测到的帕邢-α过量的强源。K波段光谱与手枪星和其他已知的LBV相似。新的LBV先前被编目为光度变星,在1994年至1997年期间表现出高达1等的亮度波动,在月与月的时间尺度上也发生了显着的变化。LBV G0.120-0.048的光度,根据2 MASS测光法,近似相当于手枪星的光度。然而,LBV G0.120-0.048在1994年至1997年期间的时间平均亮度超过了手枪星; LBV G0.120-0.048也遭受了更多的消光,这表明它在1994年至1997年期间在红外线上比手枪星更明亮。帕邢-阿尔法图像显示了一个薄的圆形星云,中心位于LBV G0.120-0.048,物理半径约为0.8 pc。我们认为这个星云是一个由喷射物质组成的外壳,从5000到10,000年前发生的一次离散喷发中发射出来。由于演化中的大质量恒星在LBV阶段的时间非常短,并且LBV G0.120-0.048非常接近五重星系团,我们认为这个天体可能与五重星系团同时代,并且可能曾经居住在其中。

英文摘要:

We report on the discovery of a luminous blue variable (LBV) lying ~7 pc in projection from the Quintuplet cluster. This source, which we call LBV G0.120-0.048, was selected for spectroscopy owing to its detection as a strong source of Paschen-alpha excess in a recent narrowband imaging survey of the Galactic center region with HST/NICMOS. The K-band spectrum is similar to that of the Pistol Star and other known LBVs. The new LBV was previously cataloged as a photometric variable star, exhibiting brightness fluctuations of up to ~1 mag between 1994 and 1997, with significant variability also occurring on month-to-month time scales. The luminosity of LBV G0.120-0.048, as derived from 2MASS photometry, is approximately equivalent to that of the Pistol Star. However, the time-averaged brightness of LBV G0.120-0.048 between 1994 and 1997 exceeded that of the Pistol Star; LBV G0.120-0.048 also suffers more extinction, which suggests that it was intrinsically more luminous in the infrared than the Pistol Star between 1994 and 1997. Paschen-alpha images reveal a thin circular nebula centered on LBV G0.120-0.048 with a physical radius of ~0.8 pc. We suggest that this nebula is a shell of ejected material launched from a discrete eruption that occurred between 5000 and 10,000 years ago. Because of the very short amount of time that evolved massive stars spend in the LBV phase, and the close proximity of LBV G0.120-0.048 to the Quintuplet cluster, we suggest that this object might be coeval with the cluster and may have once resided within it.

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