Cleaning up η Carinae

Detection of ammonia in the Homunculus Nebula

Nathan Smith, Kate J. Brooks, Bärbel S. Koribalski, John Bally

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

We report the first detection of ammonia in the Homunculus Nebula around η Carinae, which is also the first detection of emission from a polyatomic molecule in this or any other luminous blue variable (LBV) nebula. Observations of the NH3 (J, K) = (3, 3) inversion transition made with the Australia Telescope Compact Array reveal emission at locations where infrared H2 emission had been detected previously, near the strongest dust emission in the core of the Homunculus. We also detect ammonia emission from the so-called strontium filament in the equatorial disk. The presence of NH 3 around η Car hints that molecular shells around some Wolf-Rayet stars could have originated in prior LBV eruptions, rather than in cool red supergiant winds or the ambient interstellar medium. Combined with the lack of any CO detection, NH3 seems to suggest that the Homunculus is nitrogen-rich like the ionized ejecta around η Car. It also indicates that the Homunculus is a unique laboratory in which to study unusual molecule and dust chemistry, as well as their rapid formation in a nitrogen-rich environment around a hot star. We encourage future observations of other transitions like NH3 (1, 1) and (2, 2), related molecules like N2H +, and renewed attempts to detect CO.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume645
Issue number1 II
DOIs
StatePublished - Jul 1 2006
Externally publishedYes

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nebulae
cleaning
ammonia
automobile
dust
nitrogen
Wolf-Rayet stars
hot stars
polyatomic molecules
ejecta
strontium
volcanic eruptions
molecules
filaments
volcanic eruption
detection
cleaning up
telescopes
shell
chemistry

Keywords

  • Astrochemistry
  • Circumstellar matter
  • ISM: molecules
  • Stars: mass loss
  • Stars: winds, outflows

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Cleaning up η Carinae : Detection of ammonia in the Homunculus Nebula. / Smith, Nathan; Brooks, Kate J.; Koribalski, Bärbel S.; Bally, John.

In: Astrophysical Journal, Vol. 645, No. 1 II, 01.07.2006.

Research output: Contribution to journalArticle

Smith, Nathan ; Brooks, Kate J. ; Koribalski, Bärbel S. ; Bally, John. / Cleaning up η Carinae : Detection of ammonia in the Homunculus Nebula. In: Astrophysical Journal. 2006 ; Vol. 645, No. 1 II.
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