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Kinematics and Ultraviolet to Infrared Morphology of the Inner Homunculus of η Carinae

Smith, Nathan; Morse, Jon A.; Gull, Theodore R.; Hillier, D. John; Gehrz, Robert D.; Walborn, Nolan R.; Bautista, Manuel; Collins, Nicholas R.; Corcoran, Michael F. and Damineli, Augusto, et al. (2004) In Astrophysical Journal 605(1). p.405-424
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... (More)
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. (Less)
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keywords
Stars: Circumstellar Matter, Stars: Individual: Constellation Name: η Carinae, Ultraviolet: Stars
in
Astrophysical Journal
volume
605
issue
1
pages
405 - 424
publisher
University of Chicago Press
external identifiers
  • wos:000220801700035
  • scopus:2542510876
ISSN
0004-637X
DOI
10.1086/382185
language
English
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yes
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0d87d6f9-ba85-44c6-82ac-ca3a1d1482a7 (old id 134229)
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2007-07-20 12:54:32
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2017-06-11 04:23:14
@article{0d87d6f9-ba85-44c6-82ac-ca3a1d1482a7,
  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.},
  author       = {Smith, Nathan and Morse, Jon A. and Gull, Theodore R. and Hillier, D. John and Gehrz, Robert D. and Walborn, Nolan R. and Bautista, Manuel and Collins, Nicholas R. and Corcoran, Michael F. and Damineli, Augusto and Hamann, Fred and Hartman, Henrik and Johansson, Sveneric and Stahl, Otmar and Weis, Kerstin},
  issn         = {0004-637X},
  keyword      = {Stars: Circumstellar Matter,Stars: Individual: Constellation Name: η Carinae,Ultraviolet: Stars},
  language     = {eng},
  number       = {1},
  pages        = {405--424},
  publisher    = {University of Chicago Press},
  series       = {Astrophysical Journal},
  title        = {Kinematics and Ultraviolet to Infrared Morphology of the Inner Homunculus of η Carinae},
  url          = {http://dx.doi.org/10.1086/382185},
  volume       = {605},
  year         = {2004},
}