Bibcode
DOI
Knapen, J. H.; Beckman, J. E.; Shlosman, I.; Peletier, R. F.; Heller, C. H.; de Jong, R. S.
Referencia bibliográfica
Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X), vol. 443, no. 2, p. L73-L76
Fecha de publicación:
4
1995
Revista
Número de citas
109
Número de citas referidas
84
Descripción
New optical and near-infrared (NIR) K-band images of the inner 3 kpc
region of the nearby Virgo spiral M100 (NGC 4321) display remarkable
morphological changes with wavelength. While in the optical the light is
dominated by circumnuclear zone of enhanced star formation, the
morphological features in the 2.2 micrometer image correspond to a newly
discovered kiloparsec-size stellar bar and a pair of leading arms
situated inside an ovally shaped region. Analysis of the K image
confirms its symmetry: only a very small percentage of the flux, some
5%, is emitted in antisymmetric structures. This indicates that the
overall morphology observed in the NIR is dominated by a global density
wave. Making a first-order correction for the presence of localized dust
extinction in the K light using the I-K image, we find that the observed
leading arm morphology is not caused or enhanced but in fact slightly
hidden by dust. Possible mechanisms responsible for the optical and NIR
morphology are discussed, and tests are proposed to discriminate between
them. Our dynamical conclusions are supported with an evolutionary
stellar population model reproducing the observed optical and NIR colors
in a number of star-forming zones. We argue that the observed morphology
is compatible with the presence of a pair of inner Lindblad resonances
in the region and show this explicitly in an accompanying paper by
detailed numerical modeling. The phenomena observed in NGC 4321 may
provide insight into physical process leading to central activity in
galaxies.