The periodicity of the η Carinae events

Extensive spectral observations of η Carinae over the last cycle, and particularly around the 2003.5 low-excitation event, have been obtained. The variability of both narrow and broad lines, when combined with data taken from two earlier cycles, reveal a common and well-defined period. We have combi...

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Detalhes bibliográficos
Autores: Damineli, A., Hillier, D. J., Corcoran, M. F., Stahl, O., Levenhagen, R. S., Leister, N. V., Groh, J. H., Teodoro, M., Albacete Colombo, Juan Facundo, Gonzalez, F., Arias, Julia Inés, Levato, Orlando Hugo, Grosso, M., Morrell, Nidia Irene, Gamen, Roberto Claudio, Wallerstein, G., Niemelä, Virpi Sinikka
Formato: artículo
Estado:Versión publicada
Fecha de publicación:2008
País:Argentina
Recursos:Universidad Nacional de La Plata
Repositorio:SEDICI (UNLP)
Idioma:inglés
OAI Identifier:oai:sedici.unlp.edu.ar:10915/84324
Acesso em linha:http://sedici.unlp.edu.ar/handle/10915/84324
Access Level:acceso abierto
Palavra-chave:Ciencias Astronómicas
Stars: binary
Stars: general
Stars: individual: eta Carinae
Descrição
Resumo:Extensive spectral observations of η Carinae over the last cycle, and particularly around the 2003.5 low-excitation event, have been obtained. The variability of both narrow and broad lines, when combined with data taken from two earlier cycles, reveal a common and well-defined period. We have combined the cycle lengths derived from the many lines in the optical spectrum with those from broad-band X-rays, optical and near-infrared observations, and obtained a period length of P<SUB>pres</SUB> = 2022.7 ± 1.3 d. Spectroscopic data collected during the last 60 yr yield an average period of P<SUB>avg</SUB> = 2020 ± 4 d, consistent with the present-day period. The period cannot have changed by more than ΔP/P = 0.0007 since 1948. This confirms the previous claims of a true, stable periodicity, and gives strong support to the binary scenario. We have used the disappearance of the narrow component of He I 6678 to define the epoch of the Cycle 11 minimum, T<SUB>0</SUB> = JD 245 2819.8. The next event is predicted to occur on 2009 January 11 (±2 d). The dates for the start of the minimum in other spectral features and broad-bands are very close to this date, and have well-determined time-delays from the He I epoch.

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