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Optical and Radio Monitoring of a Sample of Late-Type Variables

Published online by Cambridge University Press:  12 April 2016

V. F. Esipov ,
E. E. Lekht ,
M. I. Pashchenko  and
G. M. Rudnitskij
V. F. Esipov
Affiliation:
Sternberg Astronomical Institute, Moscow State University, 13 Universitetskij Prospekt, Moscow, 119899 Russia
E. E. Lekht
Affiliation:
Sternberg Astronomical Institute, Moscow State University, 13 Universitetskij Prospekt, Moscow, 119899 Russia Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro No. 1, Apdo Postal 51 y 216, 72840 Tonantzintla, Puebla, México
M. I. Pashchenko
Affiliation:
Sternberg Astronomical Institute, Moscow State University, 13 Universitetskij Prospekt, Moscow, 119899 Russia
G. M. Rudnitskij
Affiliation:
Sternberg Astronomical Institute, Moscow State University, 13 Universitetskij Prospekt, Moscow, 119899 Russia

Abstract

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Results of regular observations of about 20 Miras and semiregular variables (∘ Cet, R Leo, R Aql, U Her, χ Cyg, R Tri, and others) in 1994–1999 are presented. The monitoring includes optical spectroscopy, optical (UBV) and infrared (JHKLM) photometry, high-resolution radio spectroscopy in the 1.35-cm water-vapour maser line (on the 22-m radio telescope in Pushchino). Optical spectroscopy shows that the appearance of strong Balmer emission lines in Miras may be a rare event, and the presumed shock waves are thus weak. The H2O maser flux generally correlates with visual light curves of the stars with some delay Δφ = 0.1 – 0.4P (P is the variability period). For R Leo, R Cas, and U Aur strong flares in the Hφ line, observed in 1997–1998, were followed by corresponding outbursts of the H2O maser emission about 2P later. This sequence of events is probably caused by a shock wave propagating outward in the stellar atmosphere and consecutively initiating the Hα emission and, later, the maser flare at a larger distance from the stellar surface.

Type
Part 2. Variability of High-Luminosity Stars
Information
International Astronomical Union Colloquium , Volume 176: The Impact of Large-Scale Surveys on Pulsating Star Research , 2000 , pp. 126 - 127
Copyright
Copyright © Astronomical Society of the Pacific 2000

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