Polar bulges and polar nuclear discs: the case of NGC 4698

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Polar bulges and polar nuclear discs: the case of NGC 4698

Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/227599

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Title: Polar bulges and polar nuclear discs: the case of NGC 4698
Author(s): Corsini, E. M.; Mendez-Abreu, J.; Pastorello, N.; Dalla Bonta, E.; Morelli, L.; Beifiori, A.; Pizzella, A.; Bertola, F.
Abstract: The early-type spiral NGC 4698 is known to host a nuclear disc of gas and stars which is rotating perpendicularly with respect to the galaxy main disc. In addition, the bulge and main disc are characterized by a remarkable geometrical decoupling. Indeed, they appear elongated orthogonally to each other. In this work, the complex structure of the galaxy is investigated by a detailed photometric decomposition of optical and near-infrared images. The intrinsic shape of the bulge was constrained from its apparent ellipticity, its twist angle with respect to the major axis of the main disc and the inclination of the main disc. The bulge is actually elongated perpendicular to the main disc and it is equally likely to be triaxial or axisymmetric. The central surface brightness, scalelength, inclination and position angle of the nuclear disc were derived by assuming that it is infinitesimally thin and exponential. Its size, orientation and location do not depend on the observed passband. These findings support a scenario in which the nuclear disc is the end result of the acquisition of external gas by the pre-existing triaxial bulge on the principal plane perpendicular to its shortest axis and perpendicular to the galaxy main disc. The subsequent star formation either occurred homogeneously all over the extension of the nuclear disc or through an inside-out process that ended more than 5 Gyr ago.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing
Source: Monthly Notices of the Royal Astronomical Society: Letters, Vol. 423, no. 1 (Jun 2012), pp. L79-L83
Publication year: 2012
FOR Code(s): 0201 Astronomical and Space Sciences
Keyword(s): Galaxy bulges; Galaxy formation; Galaxy structure; NGC 4698; Nuclear discs; Photometry; Polar bulges
Publisher: Wiley-Blackwell Publishing
ISSN: 0035-8711
Publisher URL: http://dx.doi.org/10.1111/j.1745-3933.2012.01261.x
Peer reviewed