Structure and kinematics of edge-on galaxy discs - IV. The kinematics of the stellar discs

Kregel, M.; Kruit, van der

doi:10.1111/j.1365-2966.2005.08811.x

Cited by 37 publications

(22 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To answer the fundamental question of how typical are the Local Group massive galaxies, and to constrain the assembly history of spirals, we need to probe beyond the Local Group, and we have therefore been studying the resolved extra‐planar stellar populations of NGC 891 (Mouhcine, Rejkuba & Ibata 2007, hereafter Paper I; Rejkuba et al, in preparation, hereafter Paper II). This galaxy is particularly interesting because (i) it is the nearest galaxy with similar morphology and mass to the Galaxy; (ii) previous studies have presented no indications of disturbance in the stellar component and (iii) it is almost perfectly edge‐on (; Kregel & van der Kruit 2005), essential to disentangle the halo and disc in the absence of kinematic information.…”

Section: Introductionmentioning

confidence: 99%

AnHST/ACS investigation of the spatial and chemical structure and sub-structure of NGC 891, a Milky Way analogue

Ibata

Mouhcine

Rejkuba³

2009

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present a structural analysis of NGC 891, an edge‐on galaxy that has long been considered to be an analogue of the Milky Way. Using star‐counts derived from deep Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) images, we detect the presence of a thick disc component in this galaxy with vertical scaleheight hZ= 1.44 ± 0.03 kpc and radial scalelength hR= 4.8 ± 0.1 kpc, only slightly longer than that of the thin disc. A stellar spheroid with a de Vaucouleurs‐like profile is detected from a radial distance of r∼ 0.5 kpc to the edge of the survey at r∼ 25 kpc; the structure appears to become more flattened with distance, reaching q= 0.50 in the outermost halo region probed. The halo inside of r∼ 15 kpc is moderately metal‐rich (median [Fe/H]∼−1.1) and approximately uniform in median metallicity. Beyond that distance, a modest chemical gradient is detected, with the median reaching [Fe/H]∼−1.3 at r∼ 20 kpc. We find evidence for subtle, but very significant, small‐scale variations in the median colour and density over the halo survey area. We argue that the colour variations are unlikely to be due to internal extinction or foreground extinction, and reflect instead variations in the stellar metallicity. Their presence suggests a startling conclusion: that the halo of this galaxy is composed of a large number of incompletely mixed sub‐populations, testifying to its origin in a deluge of small accretions.

show abstract

Section: Introductionmentioning

confidence: 99%

AnHST/ACS investigation of the spatial and chemical structure and sub-structure of NGC 891, a Milky Way analogue

Ibata

Mouhcine

Rejkuba³

2009

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…• , Kregel & van der Kruit 2005) make NGC 891 an excellent candidate for the study of the vertical structure of spiral galaxies.…”

Section: Introductionmentioning

confidence: 99%

A dust component ~2 kpc above the plane in NGC 891

Kamphuis¹,

Holwerda

Allen

et al. 2007

A&A

Self Cite

View full text Add to dashboard Cite

Context. The halo of NGC 891 has been the subject of studies for more than a decade. One of its most striking features is the large asymmetry in Hα emission. In this letter, we will take a quantitative look at this asymmetry at different wavelengths for the first time. Aims. We suggest that NGC 891 is intrinsically almost symmetric and the large asymmetry in Hα emission is mostly due to dust attenuation. We will quantify the additional optical depth needed to cause the observed asymmetry in this model. Methods. By comparing large strips on the North East side of the galaxy with strips covering the same area in the South West we can quantify and analyze the asymmetry in the different wavelengths. Results. From the 24 µm emission we find that the intrinsic asymmetry in star formation in NGC 891 is small i.e., ∼30%. The additional asymmetry in Hα is modeled as additional symmetric dust attenuation which extends up to ∼40 (1.9 kpc) above the plane of the galaxy with a mid-plane value of τ = 0.8 and a scale height of 0.5 kpc

show abstract

“…For galaxies with high inclinations as NGC 6503, the line-of-sight velocity dispersion is given by a weighted combination of the radial (σR) and tangential (σ φ ) components of the velocity dispersion. Using that σ φ ≃ 0.7σR from the epicyclic approximation and following Bershady et al (2010), it is easy to infer that the line-ofsight velocity dispersion, in highly inclined galaxies, is smaller than the radial velocity dispersion by 20% at most (see also Kregel et al 2005a). Bottema (1989) observed at 5020Å, and the line-of-sight velocity dispersion profile is shown in the corresponding panel in Figure 10.…”

Section: Supression Of Bar Instabilities: Dynamically-hot Discs?mentioning

confidence: 99%

Low-mass disc galaxies and the issue of stability: MOND versus dark matter

Sánchez-Salcedo

Martínez‐Gómez

Aguirre-Torres

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

We analyse the rotation curves and gravitational stability of a sample of six bulgeless galaxies for which detailed images reveal no evidence for strong bars. We explore two scenarios: Newtonian dark matter models and MOdified Newtonian Dynamics (MOND). By adjusting the stellar mass-to-light ratio, dark matter models can match simultaneously both the rotation curve and bar-stability requirements in these galaxies. To be consistent with stability constraints, in two of these galaxies, the stellar mass-to-light ratio is a factor of ∼ 1.5 − 2 lower than the values suggested from galaxy colours. In contrast, MOND fits to the rotation curves are poor in three galaxies, perhaps because the gas tracer contains noncircular motions. The bar stability analysis provides a new observational test to MOND. We find that most of the galaxies under study require abnormally-high levels of random stellar motions to be bar stable in MOND. In particular, for the only galaxy in the sample for which the line-of-sight stellar velocity dispersion has been measured (NGC 6503), the observed velocity dispersion is not consistent with MOND predictions because it is far below the required value to guarantee bar stability. Precise measurements of mass-weighted velocity dispersions in (unbarred and bulgeless) spiral galaxies are crucial to test the consistency of MOND.

show abstract

Structure and kinematics of edge-on galaxy discs - IV. The kinematics of the stellar discs

Cited by 37 publications

References 64 publications

AnHST/ACS investigation of the spatial and chemical structure and sub-structure of NGC 891, a Milky Way analogue

AnHST/ACS investigation of the spatial and chemical structure and sub-structure of NGC 891, a Milky Way analogue

A dust component ~2 kpc above the plane in NGC 891

Low-mass disc galaxies and the issue of stability: MOND versus dark matter

Contact Info

Product

Resources

About