Triaxiality in disk galaxies

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Astrophysical Journal; (United States)

DOI:https://doi.org/10.1086/186060· OSTI ID:5503084

Bertola, F; Vietri, M; Zeilinger, W W ^[1]

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1. Padova, Universita, Padua (Italy) Roma, Osservatorio Astronomico, Rome (Italy) European Southern Observatory, Garching (West Germany)

Thirty-two bulges of nearby spirals have been observed, to detect misalignment between disk and bulge apparent major axes. Such misalignment is unequivocally present in the majority of observed objects. This may be due to the triaxiality of disks, bulges, or both. The probability distribution function for the axial ratios is derived under the two extreme hypotheses, i.e., that either only disks (case I) or only bulges (case II) are triaxial: the observational data are equally well fitted by either one. Since dynamical evidence and the internal twisting of isophotes show that bulges are triaxial, case I is unlikely, but an intermediate case cannot be ruled out. These distribution functions are compared with available constraints; in particular, that of case II is projected and compared with the distribution of apparent ellipticities of minor-axis dust-lane ellipticals and of all ellipticals. Both tests show that the observed and derived distributions are consistent. 34 refs.

• OSTI ID: 5503084
• Journal Information: Astrophysical Journal; (United States), Journal Name: Astrophysical Journal; (United States) Vol. 374; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPARATIVE EVALUATIONS
CONFIGURATION
DISTRIBUTION FUNCTIONS
DYNAMICS
ELLIPTICAL CONFIGURATION
FUNCTIONS
GALAXIES
MECHANICS
MORPHOLOGY
PHOTOMETRY