J/AJ/108/111 Intrinsic shape of NGC 3379 (Statler, 1994)
The Intrinsic Shape of NGC 3379
Statler T.S.
<Astron. J. 108, 111 (1994)>
=1994AJ....108..111S 1994AJ....108..111S (SIMBAD/NED Reference)
ADC_Keywords: Galaxies, optical
Abstract:
Photometric and kinematic data from the literature are combined with
new dynamical models to derive the intrinsic shape of the "standard"
elliptical galaxy NGC 3379. The parameters that are best constrained
are the dynamical triaxiality T (essentially the triaxiality of the
total mass distribution) and the short-to-long axis ratio of the light
distribution c_L. The inferred shape is given by a Bayesian
probability distribution in the (T,c_L) plane. Assuming a uniform
prior, the most probable shape is oblate with a flattening of c_L=.87.
The distribution is strongly non-Gaussian, however, and the expectation
values, =.31, <c_L≥.75, imply a flatter and more triaxial figure.
The 68% highest posterior density region allows more triaxial shapes as
long as they are fairly round, or flatter shapes as long as they are
nearly oblate. These results are essentially unchanged if the galaxy
is assumed to rotate about its short axis, or if it is modeled as an S0
with a negligible-mass disk rather than as an elliptical. The
suggestion of Capaccioli et al. [ApJ, 371, 535 (1991)] that NGC 3379 is
a rather flat, triaxial S0 galaxy is found to be improbable at the 98%
level; this conclusion is largely independent of the bulge-to-disk
ratio or the relative rotation speeds of the two components.
Addresses:
Statler T.S.
Department of Physics and Astronomy, CB# 3255, University of North
Carolina, Chapel Hill, North Carolina 25799-3255
Objects concerned:
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RA (2000) DE Names
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10 47.8 +12 35 NGC 3379 = UGC 5902
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 43 384 NGC 3379 point estimators, see Sect. 4.3 of the
printed paper for full details
table5.tex 78 429 AASTeX version of table5.dat
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Index Index to model parameters in tables 1,2,4
5- 8 F4.2 --- T Expectation value of dynamical triaxiality
10- 13 F4.2 --- cL Exp. value of flattening of light distrib.
15- 18 F4.2 --- Tp Most probable value of T
20- 23 F4.2 --- cLp Most probable value of cL
25- 28 F4.2 --- T4 Maximum unprojected likelihood, T
30- 33 F4.2 --- cL4 Maximum unprojected likelihood, cL
36- 38 F3.0 --- phiE4 Maximum unprojected likelihood, phiE
40- 43 F4.0 --- thetaE4 Maximum unprojected likelihood, thetaE
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Origin: AAS CD-ROM series, Volume 3, 1995
(End) Lee Brotzman [ADS] 10-Oct-1994, Patricia Bauer [CDS] 16-Feb-1995