The peculiar light curve of the symbiotic star ax per of the last 125 years

Elia M. Leibowitz, Liliana Formiggini

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We analyze the optical light curve (LC) of the last 125 years of the symbiotic star AX Per through some remarkable correlations that we discovered in its power spectrum (PS). The data were assembled from the literature and from the American Association of Variable Stars Observers database. A series of six major outbursts dominate the LC. They are presented in the PS as 13 harmonics of the fundamental frequency f a = 1/P a = 1/23,172 day -1. We refer to them as the "red" frequencies. Oscillations with the binary periodicity of the system P b = 1/f b = 681.48 days are also seen in the LC, with particularly large amplitudes during outbursts. The f b peak in the PS is accompanied by 13 other peaks on each side, which we refer to as the "blue" frequencies. A distinct structure in the frequency distribution of the blue peaks, as well as in their peak power, is best interpreted as reflecting beating of the 13 "red" frequencies with the binary one. We suggest, following others, that the major outbursts of the system result from events of intense mass loss from the giant star. Mass accretion onto the hot component, partially through the L1 point of the system, took place in the last 125 years at a rate that oscillated with the 13 first harmonics of the f a frequency. The binary orbit is slightly eccentric and periastron passages induced modulation of the L1 accretion at the binary frequency. Hence the f b oscillations in the brightness of the star of an amplitude that is modulated by the "red" frequencies of the system.

Original languageEnglish
Article number117
JournalAstronomical Journal
Issue number5
StatePublished - Nov 2013


  • binaries: symbiotic
  • stars: individual (AX Per)


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