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

In English

Författare

  • Nathan Smith
  • Jon A. Morse
  • Theodore R. Gull
  • D. John Hillier
  • Robert D. Gehrz
  • Nolan R. Walborn
  • Manuel Bautista
  • Nicholas R. Collins
  • Michael F. Corcoran
  • Augusto Damineli
  • Fred Hamann
  • Henrik Hartman
  • Sveneric Johansson
  • Otmar Stahl
  • Kerstin Weis
Visa allt

Summary, in English

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.

Publiceringsår

2004

Språk

Engelska

Sidor

405-424

Publikation/Tidskrift/Serie

Astrophysical Journal

Volym

605

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

American Astronomical Society

Ämne

  • Astronomy, Astrophysics and Cosmology

Nyckelord

  • Stars: Circumstellar Matter
  • Stars: Individual: Constellation Name: η Carinae
  • Ultraviolet: Stars

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0004-637X