ar X iv : a st ro - p h / 96 02 14 2 v 1 2 7 Fe b 19 96 A Counter - rotating Bulge in the Sb Galaxy NGC 7331
نویسنده
چکیده
We have found that the bulge of the large, nearby Sb galaxy NGC 7331 rotates retrograde to its disk. Analysis of spectra in the region of the near-IR Ca II triplet along the major axis shows that, in the radial range between 5 and ∼20, the line of sight velocity distribution of the absorption lines has two distinct peaks, and can be decomposed into a fast-rotating component with v/σ > 3, and a slower rotating, retrograde component with v/σ ∼ 1 – 1.5. The radial surface brightness profile of the counter-rotating component follows that of the bulge, obtained from a 2-dimensional bulge-disk decomposition of a near-infrared K-band image, while the fast rotating component follows the disk. At the radius where the disk starts to dominate the isophotes change from being considerably boxy to very disky. Although a number of spiral galaxies have been found that contain cold, couterrotating disks, this is the first galaxy known to have a boxy, probably triaxial, fairly warm, counter-rotating component, which is dominating in the central regions. If it is a bar seen end-on, this bar has to be thicker than the disk. We find that NGC 7331, even though it is a fairly early-type spiral, does not have a conventional, co-rotating bulge. The fact that the inner component is retrograde makes us believe that it was formed from infalling material, in either stellar or gaseous form (e.g. Balcells & Quinn 1990). Another possibility
منابع مشابه
ar X iv : a st ro - p h / 96 02 14 2 v 2 1 4 M ar 1 99 6 A Counter - rotating Bulge in the Sb Galaxy NGC 7331
We have found that the bulge of the large, nearby Sb galaxy NGC 7331 rotates retrograde to its disk. Analysis of spectra in the region of the near-IR Ca II triplet along the major axis shows that, in the radial range between 5 and ∼20, the line of sight velocity distribution of the absorption lines is has two distinct peaks, and can be decomposed into a fast-rotating component with v/σ > 3, and...
متن کاملar X iv : a st ro - p h / 02 03 02 7 v 1 3 M ar 2 00 2 HYDRODYNAMIC SIMULATIONS FOR THE NUCLEAR MORPHOLOGY OF NGC 4314
Received ; accepted – 2 – ABSTRACT We performed SPH simulations to study the nuclear morphology of a barred galaxy NGC 4314. We have constructed the mass models based on the results of a profile decomposition into disk, bulge, and bar components. Our models have three different nuclear structures according to the assumption about the nuclear bar: no nuclear bar, a synchronous nuclear bar and a ...
متن کاملar X iv : a st ro - p h / 99 01 38 1 v 1 2 7 Ja n 19 99 Central UV Spikes in two Galactic
FOS spectra and FOC photometry of two centrally located, UV-bright spikes in the elliptical galaxy NGC 4552 and the bulge-dominated early spiral NGC 2681, are presented. These spectra reveal that such point-like UV sources detected by means of HST within a relatively large fraction (∼ 15%) of bulges can be related to radically different phenomena. While the UV unresolved emission in NGC 4552 re...
متن کاملar X iv : h ep - t h / 96 02 14 9 v 1 2 7 Fe b 19 96 UAHEP - 9603 DSFNA - T - 9606 ESI - 310 February 1996
Integrability of the Wess–Zumino–Witten model as a non–ultralocal theory * Abstract We consider the 2–dimensional Wess–Zumino–Witten (WZW) model in the canon-ical formalism introduced in [5]. Using an r–s matrix approach to non–ultralocal field theories we find the Poisson algebra of monodromy matrices and of conserved quantities with a new, non–
متن کامل