Access to Astronomical Catalogues

← Click to display the menu
J/MNRAS/446/4039   Stellar kinematics for NGC 2859 and NGC 4371   (Erwin+, 2015)

Composite bulges: the coexistence of classical bulges and discy pseudo-bulges in S0 and spiral galaxies. Erwin P., Saglia R.P., Fabricius M., Thomas J., Nowak N., Rusli S., Bender R., Vega Beltran J.C., Beckman J.E. <Mon. Not. R. Astron. Soc., 446, 4039-4077 (2015)> =2015MNRAS.446.4039E (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra ; Radial velocities ; Velocity dispersion Keywords: galaxies: bulges - galaxies: elliptical and lenticular, cD - galaxies: evolution - galaxies: kinematics and dynamics - galaxies: spiral - galaxies: structure Abstract: We present an analysis of nine S0-Sb galaxies which have (photometric) bulges consisting of two distinct components. The outer component is a flattened, kinematically cool, disc-like structure: a 'discy pseudo-bulge'. Embedded inside is a rounder, kinematically hot spheroidal structure: a `classical bulge'. This indicates that pseudo-bulges and classical bulges are not mutually exclusive phenomena: some galaxies have both. The discy pseudo-bulges almost always consist of an exponential disc (scalelengths=125-870 pc, mean size ∼440 pc) with one or more disc-related subcomponents: nuclear rings, nuclear bars, and/or spiral arms. They constitute 11-59 percent of the galaxy stellar mass (mean PB/T=0.33), with stellar masses ∼7x109-9x1010 M. The classical-bulge components have Sersic indices of 0.9-2.2, effective radii of 25-430 pc and stellar masses of 5x108-3x1010 M; they are usually <10 percent of the galaxy's stellar mass (mean B/T=0.06). The classical bulges do show rotation, but are clearly kinematically hotter than the discy pseudo-bulges. Dynamical modelling of three systems indicates that velocity dispersions are isotropic in the classical bulges and equatorially biased in the discy pseudo-bulges. In the mass-radius and mass-stellar mass density planes, classical-bulge components follow sequences defined by ellipticals and (larger) classical bulges. Discy pseudo-bulges also fall on this sequence; they are more compact than large-scale discs of similar mass. Although some classical bulges are quite compact, they are as a class clearly distinct from nuclear star clusters in both size and mass; in at least two galaxies they coexist with nuclear clusters. Since almost all the galaxies in this study are barred, they probably also host boxy/peanut-shaped bulges (vertically thickened inner parts of bars). NGC 3368 shows isophotal evidence for such a zone just outside its discy pseudo-bulge, making it a clear case of a galaxy with all three types of 'bulge'. Description: We obtained long-slit spectroscopy of NGC 2959 with the ISIS spectrograph of the WHT on 2000 December 13, using the blue arm with the R600B grating. NGC 4371 was observed with an almost identical instrumental setup as part of ING service-time observations on 2001 June 4. Following standard MIDAS reduction of the ISIS observations, including bias subtraction, flat-fielding and wavelength calibration using CuAr and CuNe+CuAr lamp exposures, the extracted galaxy spectra were analysed using the Fourier Correlation Quotient method (Bender 1990A&A...229..441B; Bender, Saglia & Gerhard 1994MNRAS.269..785B) in order to determine the stellar kinematics. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file galaxy.dat 34 2 List of galaxy tableb2.dat 67 79 Major-axis stellar kinematics for NGC 2859 and NGC 4371
See also: J/AJ/136/773 : Structure of classical bulges and pseudobulges (Fisher+, 2008) Byte-by-byte Description of file: galaxy.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name Galaxy Name 10- 11 I2 h RAh Simbad Hour of Right Ascension (J2000) 13- 14 I2 min RAm Simbad Minute of Right Ascension (J2000) 16- 21 F6.3 s RAs Simbad Second of Right Ascension (J2000) 23 A1 --- DE- Simbad Sign of the Declination (J2000) 24- 25 I2 deg DEd Simbad Degree of Declination (J2000) 27- 28 I2 arcmin DEm Simbad Arcminute of Declination (J2000) 30- 34 F5.2 arcsec DEs Simbad Arcsecond of Declination (J2000)
Byte-by-byte Description of file: tableb2.dat
Bytes Format Units Label Explanations
1- 3 A3 --- --- [NGC] 5- 8 I4 --- NGC [2859/4371] Galaxy name 10- 11 I2 deg PA [85/92] Position angle of the telescope 13- 18 F6.2 arcsec Rad [] Radius along the major axis 20- 25 F6.1 km/s RV Radial velocity 27- 30 F4.1 km/s e_RV Uncertainty in RV 32- 36 F5.1 km/s sigma Velocity dispersion 38- 41 F4.1 km/s e_sigma Uncertainty in sigma 43- 48 F6.3 --- h3 Gauss-Hermite coefficient h3 50- 54 F5.3 --- e_h3 Uncertainty in h3 56- 61 F6.3 --- h4 Gauss-Hermite coefficient h4 63- 67 F5.3 --- e_h4 Uncertainty in h4
History: From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 08-Nov-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

catalogue service

© UDS/CNRS

Contact