AT 2017fvz: a nova in the dwarf irregular galaxy NGC 6822
AT 2017fvz: a nova in the dwarf irregular galaxy NGC 6822
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DOI：
10.1093/mnras/stz1108
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发表时间：
2019-04
影响因子：
4.8
通讯作者：
M. Healy;M. Darnley;C. Copperwheat;A. Filippenko;M. Henze;J. Hestenes;P. James;K. Page;S. W
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作者：
M. Healy;M. Darnley;C. Copperwheat;A. Filippenko;M. Henze;J. Hestenes;P. James;K. Page;S. W
2017年8月2日，在本星系群矮不规则星系NGC 6822（巴纳德星系）中发现了一颗瞬变新星，这是该星系中发现的第二颗经典新星。我们对这次喷发进行了光学、近紫外线和x射线的后续观察，我们在这里展示了结果。这颗“非常快”的新星的峰值V波段星等为- 7.41 > MV > - 8.33等，衰减时间为t2，V = 8.1±0.2 d和t3，V = 15.2±0.3 d，早期和晚期光谱属于Fe ii光谱类。H α发射线在半最大强度时的初始全宽为~ 2400 km s−1，这是该类中中等快的喷射速度。喷发后70 d， H α线单调变窄至~ 1800 km s−1。在哈勃太空望远镜的档案图像中，没有一个喷发前的同步源，这意味着供体是一颗主序星，或者可能是一颗亚巨星。相对较低的峰值亮度和快速的衰减暗示着AT 2017fvz可能是一颗“微弱而快速”的新星。
A transient in the Local Group dwarf irregular galaxy NGC 6822 (Barnard’s Galaxy) was discovered on 2017 August 2 and is only the second classical nova discovered in that galaxy. We conducted optical, near-ultraviolet, and X-ray follow-up observations of the eruption, the results of which we present here. This ‘very fast’ nova had a peak V-band magnitude in the range −7.41 > MV > −8.33 mag, with decline times of t2,V = 8.1 ± 0.2 d and t3,V = 15.2 ± 0.3 d. The early- and late-time spectra are consistent with an Fe ii spectral class. The H α emission line initially has a full width at half-maximum intensity of ∼2400 km s−1 – a moderately fast ejecta velocity for the class. The H α line then narrows monotonically to ∼1800 km s−1 by 70 d post-eruption. The lack of a pre-eruption coincident source in archival Hubble Space Telescope imaging implies that the donor is a main-sequence, or possibly subgiant, star. The relatively low-peak luminosity and rapid decline hint that AT 2017fvz may be a ‘faint and fast’ nova.