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Search for ultraviolet emission lines from a hot gaseous halo in the edge-on galaxy NGC 4244Short and long wavelength IUE spectra of the halo region in the edge-on galaxy NGC 4244 are analyzed in order to identify evidence of line emission at the level of 0.000001 ergs per cu cm sr/s. Features are found at 1245 A and 1402 A, having peaks four times greater than the rms intensity fluctuations of nearby spectra. The spectral features are identified with semi-forbidden N V, semi-forbidden S IV at 1240 A, and Si IV and semi-forbidden O IV multiplets at 1400 A, respectively. The appearance of high-peak features and the lack of astrophysically important lines in the sample are evidence of a gas near T = 10 exp 5.2 and emission measure (EM) equal to about 0.000001 pc. However, the case for the existence of such a gas is weakened due to the existence of two other similarly sized features with no identifiable astrophysical origin and the extremely faint nature of the candidate features. The assumed upper limit for the line intensities in NGC 4244 leads to the conclusion that at T less than 100,000 K any emitting gas is either highly clumped or has a p/k value of less than 1000 per cu cm K. It is suggested that if the observed low level features in the short wavelength spectrum are real, the temperature and emission measures allow for a single component gas in the halo of NGC 4244, and are in agreement with those derived by Paresce et al. (1983).
Document ID
19860042085
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Deharveng, J.-M.
(Laboratoire d'Astronomie Spatiale Marseille, France)
Joubert, M.
(CNRS Laboratoire d'Astronomie Spatiale, Marseille, France)
Bixler, J.
(Laboratoire d'Astronomie Spatiale Marseille, France)
Bowyer, S.
(Laboratoire d'Astronomie Spatiale Marseille, France)
Malina, R.
(California, University Berkeley, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1986
Publication Information
Publication: Astronomy and Astrophysics
Volume: 154
Issue: 1-2
ISSN: 0004-6361
Subject Category
Astrophysics
Accession Number
86A26823
Funding Number(s)
CONTRACT_GRANT: NAG5-69
Distribution Limits
Public
Copyright
Other

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