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arXiv · 1904.08151

AT 2017fvz: a nova in the dwarf irregular galaxy NGC 6822

M. W. Healy·M. J. Darnley·C. M. Copperwheat·A. V. Filippenko·M. Henze·J. C. Hestenes·P. A. James·K. L. Page·S. C. Williams·W. Zheng
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Abstract

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 $-7.41>M_V>-8.33$ mag, with decline times of $t_{2,V} = 8.1 \pm 0.2$ d and $t_{3,V} = 15.2 \pm 0.3$ d. The early- and late-time spectra are consistent with an Fe II spectral class. The H$\alpha$ emission line initially has a full width at half-maximum intensity of $\sim 2400$ km s$^{-1}$ - a moderately fast ejecta velocity for the class. The H$\alpha$ line then narrows monotonically to $\sim1800$ 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.

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M. W. Healy, M. J. Darnley, C. M. Copperwheat, A. V. Filippenko, M. Henze, J. C. Hestenes, P. A. James, K. L. Page, S. C. Williams, W. Zheng. 2019-04-17. AT 2017fvz: a nova in the dwarf irregular galaxy NGC 6822. https://doi.org/10.1093/mnras/stz1108

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