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Title: The light curve shapes as a key to resolving the origin of long secondary periods in red giant stars

We present a study of Optical Gravitational Lensing Experiment light curves of red giant stars exhibiting long secondary periods (LSPs)—an enigmatic phenomenon commonly observed in stars on the upper red giant branch and asymptotic giant branch. We show that the light curves of LSP stars are essentially identical to those of the spotted variables with one dark spot on their photospheres. Such behavior can be explained by the presence of a dusty cloud orbiting the red giant together with a low-mass companion in a close, circular orbit. We argue that the binary scenario is in agreement with most of the observational properties of LSP variables, including non-sinusoidal shapes of their radial velocity curves.
Authors:
;  [1]
  1. Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland)
Publication Date:
OSTI Identifier:
22356712
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMPTOTIC SOLUTIONS; GRAVITATIONAL LENSES; MASS; ORBITS; PHOTOSPHERE; RADIAL VELOCITY; RED GIANT STARS; VISIBLE RADIATION