2001/04/06 by Alister W. Graham · 3 citations
Environmental Science · Physics and Astronomy · #Astronomy #Astrophysics #Brightness #Bulge #Disc galaxy #Elliptical galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Lenticular galaxy #Physics #Plant Water Relations and Carbon Dynamics #Stellar, planetary, and galactic studies #Surface brightness #Surface brightness fluctuation #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2001.04570.x
published as Mon.Not.Roy.Astron.Soc. 326 (2001) 543 · To appear in MNRAS
arxiv created 2001/04/06 · openalex publication_date 2001/09/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The K-band light profiles from two statistically complete, diameter-limited samples of disc galaxies have been simultaneously modelled with a seeing-convolved Sérsic r1/n bulge and a seeing-convolved exponential disc. This has enabled an accurate separation of the bulge and disc light, and hence an estimate of the central disc surface brightness μ0,K and the disc scalelength h. There exists a bright envelope of galaxy discs in the μ0,K—log h diagram; for the early-type (≤Sbc—Sc) disc galaxies μ0,K is shown to increase with log h, with a slope of ∼2 and a correlation coefficient equal to 0.75. This relation exists over a range of disc scalelengths from 0.5 to 10 kpc (H0 = 75 km s−1 Mpc−1). In general, galaxy types Scd or later are observed to deviate from this relation; they have fainter surface brightnesses for a given scalelength. With a subsample of 59 low-inclination (i ≤ 50°) and 29 high-inclination (i ≥ 50°) galaxies having morphological types ranging from S0 to Sc, the need for an inclination correction to the K-band disc surface brightness is demonstrated. Certain selection criteria biases which have troubled previous surface brightness inclination tests (for example, whether the galaxies are selected from a magnitude- or diameter-limited sample) do not operate in the μ0,K—log h diagram. Measured central disc surface brightnesses are found to be significantly (>5σ) brighter for the high-inclination disc galaxies than for the low-inclination disc galaxies. With no surface brightness inclination correction or allowance for the trend between μ0,K and log h, the standard deviation to the distribution of μ0,K values is ∼1 mag arcsec−2, while the standard deviation about the mean μ0,K—log h relation decreases from 0.69 mag arcsec−2, when no inclination correction is applied, to 0.47 mag arcsec−2 when the inclination correction is applied. Possible changes to the disc scalelength with inclination, as a result of radial gradients in the disc opacity, have been explored. The maximum possible sizes for such corrections are too small to provide a valid explanation for the difference between the low- and high-inclination disc galaxies in the μ0,K—log h diagram.