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Spectroscopy of the 2015 Outburst of AG Pegasi

Mistry, D and Steele, IA (2021) Spectroscopy of the 2015 Outburst of AG Pegasi. Research Notes of the AAS, 5 (3).

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Open Access URL: https://iopscience.iop.org/article/10.3847/2515-51... (Published version)


Between 2015 September and 2016 January, we obtained 18 spectra of the 2015 classical outburst of AG Pegasi—a symbiotic star consisting of a white dwarf (WD), red giant, and surrounding nebula. Modelling the flux contributions of these components reveals that nebular emission, from the reprocessing of high energy WD photons, dominates the 3200–6300 Å range. Nebular emission rises and falls in line with changes seen in the WD, whose properties have been derived using H<jats:italic>β</jats:italic> and He <jats:sc>ii</jats:sc> (4686 A) line flux, and emission measure calculations. WD parameters follow changes seen in visual band light curves. During the second peak of the outburst, WD temperatures reach 166,000 ± 6000 K, with a luminosity and radius of 14,000 ± 2000 <jats:italic>L</jats:italic>
<jats:sub>⊙</jats:sub> and 0.149 ± 0.014 <jats:italic>R</jats:italic>
<jats:sub>⊙</jats:sub> respectively. These features are consistent with an expansion of the WD pseudo-photosphere due to an accretion rate exceeding that required for stable hydrogen burning.</jats:p>

Item Type: Article
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: American Astronomical Society
SWORD Depositor: A Symplectic
Date Deposited: 08 Nov 2022 13:18
Last Modified: 08 Nov 2022 13:18
DOI or ID number: 10.3847/2515-5172/abeefd
URI: https://researchonline.ljmu.ac.uk/id/eprint/18067
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