Bibcode
Beckman, J. E.; Varela, A. M.; Munoz-Tunon, C.; Vilchez, J. M.; Cepa, J.
Referencia bibliográfica
Astronomy and Astrophysics (ISSN 0004-6361), vol. 245, no. 2, May 1991, p. 436-448.
Fecha de publicación:
5
1991
Número de citas
23
Número de citas referidas
22
Descripción
CCD maps are presented of the inner 1.4 kpc of NGC 4736 in the B, V, R,
I and Z bands, along with an ellipticity analysis of these, in which the
ellipticities and position angles of isophotal best-fit ellipses are
given as functions of galactocentric radius in each band. Also provided
are calibrated profiles through the nucleus in individual bands, and in
the B-V, V-R, and F-I color indices, as well as isochromal maps in these
colors. The ellipticity analysis reveals the presence of three zones: an
inner bulge, out to some 400 pc from the nucleus, a transition zone from
400 to 800 pc, and the disk, beyond 800 pc radius, marked by distinct
regimes of ellipticity and position angle of the elliptical isophotes.
The underlying differences in position angle between bulge and disk
strongly indicate bulge triaxiality in NGC 4736, while the variations in
ellipticity in the inner bulge and their color dependence point to
recent star-forming activity.