2006/08/29 by A. Derekas, L. L. Kiss, T. R. Bedding +5 · 3 citations
Physics and Astronomy · #Amplitude #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Biology #Galaxy #Large Magellanic Cloud #Luminosity #Main sequence #Physics #Sequence (biology) #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/508686
4 pages, 4 figures, accepted for publication in ApJ Letters
arxiv created 2006/08/29 · openalex publication_date 2006/09/29 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a period-luminosity-amplitude analysis of 5899 red giant and binary stars in the Large Magellanic Cloud, using publicly available observations of the MACHO Project. For each star, we determined new periods, which were double-checked in order to exclude aliases and false periods. The period-luminosity ( P - L ) relations confirm the existence of a short-period, small-amplitude P - L sequence at periods shortward of sequence A. We point out that the widely accepted sequence of eclipsing binaries between sequences C and D, known as sequence E, does not exist. The correct position for sequence E is at periods a factor of 2 greater, and the few stars genuinely lying between sequences C and D are underluminous Mira variables, presumably enshrouded in dust. The true sequence E overlaps with the sequence of long secondary periods (LSPs; sequence D), and their P - L relation is well described by a simple model assuming Roche geometry. The amplitudes of LSPs have properties that are different from both the pulsations and the ellipsoidal variations, but they are more similar to the former than the latter, arguing for pulsation rather than binarity as the origin of the LSP phenomenon.