Kinematics and Ultraviolet to Infrared Morphology of the Inner Homunculus of η Carinae
Smith, Nathan; Morse, Jon A.; Gull, Theodore R.; Hillier, D. John, et al. (2004). Kinematics and Ultraviolet to Infrared Morphology of the Inner Homunculus of η Carinae. Astrophysical Journal, 605, (1), 405 - 424
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Published
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English
Authors:
Smith, Nathan
;
Morse, Jon A.
;
Gull, Theodore R.
;
Hillier, D. John
, et al.
Department:
Lund Observatory - Has been reorganised
Abstract:
We present the first ultraviolet and optical images of η Car and itscircumstellar Homunculus nebula, obtained with the Advanced Camera forSurveys/High Resolution Camera (ACS/HRC) on board the Hubble SpaceTelescope (HST). Compared to those at visual wavelengths, UV imagesreveal excess emission 0.1"-0.6" from the central source along the minoraxis that may emanate from the outer parts of η Car's nonsphericalstellar wind, which dominates the UV flux from η Car. The UVemission fills the cavity inside a dust torus measured from infrared(IR) data; within 0.2" of the star the UV emission projects a morphologyreminiscent of the IR torus, but it is a factor of 10 smaller. This``little torus'' seen in the UV may be related to the ``LittleHomunculus'' discovered recently, signifying recurrent mass ejectionswith the same geometry. Finally, we reexamine the kinematics of nebularcondensations near the star (Weigelt objects C and D) in HST images andspectra obtained over the past decade. We measure heliocentricvelocities slower than previous estimates, and from proper motions wederive an ejection date of 1908+/-12 yr, assuming linear motion.However, because of radiative acceleration, these objects may have beenejected earlier-perhaps during the 1890 outburst of η Car.Based on observations made with the NASA/ESA Hubble Space Telescope,obtained at the Space Telescope Science Institute, operated by theAssociation of Universities for Research in Astronomy, Inc., under NASAcontract NAS 5-26555.
Keywords:
Stars: Circumstellar Matter ;
Stars: Individual: Constellation Name: η Carinae ;
Ultraviolet: Stars
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