Evans, A, Banerjee, DPK, Geballe, TR, Shahbandeh, M, Woodward, CE, Gehrz, RD, Eyres, SPS, Starrfield, S and Zijlstra, A (2020) Infrared spectroscopy of CK Vulpeculae: revealing a remarkably powerful blast from the past. Astrophysical Journal Letters, 904 (2). ISSN 2041-8205

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CK Vulpeculae (CK Vul), which erupted in AD 1670-71, was long considered to be a nova outburst; however, recent observations have required that alternative scenarios be considered. Long-slit infrared spectroscopy of a forbidden line of iron reported here has revealed high line-of-sight velocities (similar to 900 km s(-1)) of the ansae at the tips of the bipolar lobes imaged in H alpha in 2010. The deprojected velocities of the tips are approximately 2130 km s(-1) assuming the previously derived inclination angle of 65 degrees for the axis of cylindrical symmetry of the bipolar nebula. Such high velocities are in stark contrast to previous reports of much lower expansion velocities in CK Vul. Based on the deprojected velocities of the tips and their angular expansion measured over a 10 yr baseline, we derive a revised estimate, with estimated uncertainties, of 3.2(-0.6)(+0.9) kpc for the distance to CK Vul. This implies that the absolute visual magnitude at the peak of the 1670 explosion was M-V = -12.4(-2.4)(+1.3), indicating that the 1670 event was far more luminous than previous estimates and brighter than any classical nova or any Galactic stellar merger. We propose that CK Vul belongs to the class of intermediate-luminosity optical transients (ILOTs), objects which bridge the luminosity gap between novae and supernovae. While eruptions in lower luminosity ILOTs are attributed to merger events, the origin of the highly luminous ILOT outbursts is currently not known.

Item Type: Article
Additional Information: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via American Astronomical Society at https://iopscience.iop.org/journal/2041-8205 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: stars, individual (CK Vul), peculiar, winds, outflows—infrared
Subjects: Q Science > QB Astronomy
Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 18 Nov 2020 09:53
Last Modified: 22 Dec 2020 14:41
URI: https://eprints.keele.ac.uk/id/eprint/8899

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