INVESTIGADORES
GAMEN Roberto Claudio
artículos
Título:
He II λ4686 in η Carinae: Collapse of the Wind-Wind Collision Region during Periastron Passage
Autor/es:
TEODORO, M.; DAMINELI, A.; ARIAS, J.; DE ARAUJO, F.X.; BARBÁ, R.; CORCORAN, M.F.; BORGES FERNANDEZ, M.; FERNANDEZ LAJUS, E.; FRAGA, L.; GAMEN, R. C.; +16 CO-AUTORES
Revista:
ASTROPHYSICAL JOURNAL
Editorial:
IOP PUBLISHING LTD
Referencias:
Año: 2012 vol. 746 p. 73 - 88
ISSN:
0004-637X
Resumen:
The periodic spectroscopic events in η Carinae are now well
established and occur near the periastron passage of two massive stars
in a very eccentric orbit. Several mechanisms have been proposed to
explain the variations of different spectral features, such as an
eclipse by the wind-wind collision (WWC) boundary, a shell ejection from
the primary star or accretion of its wind onto the secondary. All of
them have problems explaining all the observed phenomena. To better
understand the nature of the cyclic events, we performed a dense
monitoring of η Carinae with five Southern telescopes during the
2009 low-excitation event, resulting in a set of data of unprecedented
quality and sampling. The intrinsic luminosity of the He II λ4686
emission line (L ~ 310 L ☉) just before periastron
reveals the presence of a very luminous transient source of extreme UV
radiation emitted in the WWC region. Clumps in the primary's wind
probably explain the flare-like behavior of both the X-ray and He II
λ4686 light curves. After a short-lived minimum, He II
λ4686 emission rises again to a new maximum, when X-rays are
still absent or very weak. We interpret this as a collapse of the WWC
onto the "surface" of the secondary star, switching off the hard X-ray
source and diminishing the WWC shock cone. The recovery from this state
is controlled by the momentum balance between the secondary's wind and
the clumps in the primary's wind.