AT 2017fvz: a nova in the dwarf irregular galaxy NGC 6822
Healy, M. W. and Darnley, M. J. and Copperwheat, C. M. and Filippenko, A. V. and Henze, M. and Hestenes, J. C. and James, P. A. and Page, K. L. and Williams, S. C. and Zheng, W. (2019) AT 2017fvz: a nova in the dwarf irregular galaxy NGC 6822. Monthly Notices of the Royal Astronomical Society, 486 (3). pp. 4334-4347. ISSN 0035-8711
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Official URL: https://doi.org/10.1093/mnras/stz1108
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.
This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version 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, AT 2017fvz: a nova in the dwarf irregular galaxy NGC 6822, Monthly Notices of the Royal Astronomical Society, Volume 486, Issue 3, July 2019, Pages 4334–4347, https://doi.org/10.1093/mnras/stz1108 is available online at: https://academic.oup.com/mnras/article/486/3/4334/5475125