2005MNRAS.357.1330S -
Mon. Not. R. Astron. Soc., 357, 1330-1336 (2005/March-2)
Doppler tomography of the Little Homunculus: high-resolution spectra of [FeII]λ16435 around Eta Carinae.
SMITH N.
Abstract (from CDS):
High-resolution spectra of [Feii]λ16435 around η Carinae provide powerful diagnostics of the geometry and kinematics of the `Little Homunculus' (LH) growing inside the larger Homunculus nebula. The LH expansion is not perfectly homologous: while low latitudes are consistent with linear expansion since 1910, the polar caps imply ejection dates around 1920-1930. However, the expansion speed of the LH is much slower than the post-eruption wind, so the star's powerful wind may accelerate the LH. With an initial ejection speed of 200 km/s in 1890, the LH would have been accelerated to its present speed if the mass is roughly 0.1 M☉. This agrees with an independent estimate of the LH mass based on its density and volume. In any case, an ejection after 1930 is ruled out. Using the LH as a probe of the 1890 event then, it is evident that its most basic physical parameters (total mass and kinetic energy, which are 0.1 M☉and 1046.9 erg, respectively) are orders of magnitude less than during the giant eruption in the 1840s. Thus, the ultimate energy sources were different for these two events - yet their ejecta have the same bipolar geometry. This clue may point toward a collimation mechanism separate from the underlying causes of the outbursts.
Abstract Copyright:
2005 RAS
Journal keyword(s):
circumstellar matter - stars: individual: η Carinae - stars: mass-loss - stars: winds, outflows - ISM: jets and outflows
Simbad objects:
6
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