scholarly journals The Shape of the Luminosity Profiles of Bulges

1996 ◽  
Vol 157 ◽  
pp. 86-87 ◽  
Author(s):  
Y. Andredakis ◽  
R. Peletier ◽  
M. Balcells
Keyword(s):  
Density Distribution ◽  
Decomposition Method ◽  
Surface Brightness ◽  
A Priori ◽  
Morphological Type ◽  
Early Type ◽  
Late Type ◽  
Dimensional Decomposition ◽  
The Galaxy ◽  
Light Profiles

AbstractWe extract the bulge light profiles of a sample of early type spirals, using K-band photometry and a new 2-dimensional decomposition method that does not assume a priori any surface brightness laws. We find that the shape of the light profile shows a good correlation with the morphological type of the galaxy, in the sense that the profiles tend to fall off more steeply at large radii for the later types. This trend shows that the formation of or interaction with the disk has probably affected the density distribution of the bulge. The fact that the transition in shape is continuous might also imply that most of the bulges of late type spirals were not formed by different mechanisms than the ones of early types.

scholarly journals UV-IR color profiles of the outer regions of 2K nearby S4G galaxies

2016 ◽  
Vol 11 (S321) ◽  
pp. 257-259
Author(s):  
Alexandre Y. K. Bouquin ◽  
Armando Gil de Paz
Keyword(s):  
Surface Brightness ◽  
Large Fraction ◽  
Early Type ◽  
Late Type ◽  
Quenching Mechanism ◽  
Star Forming ◽  
Spatially Resolved ◽  
Ram Pressure ◽  
Late Type Star ◽  
Radial Evolution

AbstractWe present our new, spatially-resolved, photometry in FUV and NUV from images obtained by GALEX, and IRAC1 (3.6 μm) photometry obtained by the Spitzer Space Telescope. We analyzed the surface brightness profiles μFUV, μNUV, μ[3.6], as well as the radial evolution of the (FUV-NUV), (FUV - [3.6]), and (NUV - [3.6]) colors in the Spitzer Survey of Stellar Structures in Galaxies (S4G) galaxies (d < 40 Mpc) sample. We defined the GALEX Blue Sequence (GBS) and GALEX Red Sequence (GBR) from the (FUV - NUV) versus (NUV - [3.6]) color-color diagram, populated by late-type star forming galaxies and quiescent early-type galaxies respectively. While most disk becomes radially bluer for GBS galaxies, and stay constant for GRS galaxies, a large fraction ( > 50%) of intermediary GALEX Green Valley (GGV) galaxies’ outer disks are becoming redder. An outside-in quenching mechanism such as environmentally-related mechanisms such as starvation or ram-pressure-stripping could explain our results.

scholarly journals 1.10. The effects of the disk field on the bulge surface brightness

1998 ◽  
Vol 184 ◽  
pp. 35-36
Author(s):  
Y.C. Andredakis ◽  
R.H. Sanders
Keyword(s):  
Surface Brightness ◽  
Morphological Type ◽  
Intermediate Type ◽  
Classical Description ◽  
The Galaxy ◽  
Image Position

After the classical description of bulges by a de Vaucouleurs profile was found to be inadequate, a generalized profile, Sersic's law, was used successfully to describe the surface brightness: (Andredakis et al. 1994 (APB95)). The exponent n was found to vary systematically with the morphological type of the galaxy, from n = 4 for the bulges of S0s to n = 2 for intermediate type spirals and n = 1 (pure exponential) for the late types. (APB95, de Jong 1996). This has been confirmed also by the kinematics (Heraudeau et al 1996). This variation of n has been interpreted in two ways: (i) As the effect of the disk forming around an already developed bulge (APB95) and (ii) as evidence that the bulge originated from secular processes in the galaxy, after the disk was formed (Courteau et al. 1996). This needs to be resolved.

scholarly journals The Fornax Deep Survey with the VST

2019 ◽  
Vol 623 ◽  
pp. A1 ◽  
Author(s):  
E. Iodice ◽  
M. Spavone ◽  
M. Capaccioli ◽  
R. F. Peletier ◽  
G. van de Ven ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Surface Brightness ◽  
Major Axis ◽  
Position Angle ◽  
Early Type ◽  
Semi Major Axis ◽  
Cluster Galaxies ◽  
The Galaxy ◽  
Deep Survey ◽  
Fornax Cluster

Context. This paper is based on the multi-band (ugri) Fornax Deep Survey (FDS) with the VLT Survey Telescope (VST). We study bright early-type galaxies (mB ≤ 15 mag) in the 9 square degrees around the core of the Fornax cluster, which covers the virial radius (Rvir  ∼ 0.7 Mpc). Aims. The main goal of the present work is to provide an analysis of the light distribution for all galaxies out to unprecedented limits (in radius and surface brightness) and to release the main products resulting from this analysis in all FDS bands. We give an initial comprehensive view of the galaxy structure and evolution as a function of the cluster environment. Methods. From the isophote fit, we derived the azimuthally averaged surface brightness profiles, the position angle, and ellipticity profiles as a function of the semi-major axis. In each band, we derived the total magnitudes, effective radii, integrated colours, and stellar mass-to-light ratios. Results. The long integration times, the arcsec-level angular resolution of OmegaCam at VST, and the large covered area of FDS allow us to map the light and colour distributions out to large galactocentric distances (up to about 10−15 Re) and surface brightness levels beyond μr = 27 mag arcsec−2 (μB ≥ 28 mag arcsec−2). Therefore, the new FDS data allow us to explore in great detail the morphology and structure of cluster galaxies out to the region of the stellar halo. The analysis presented in this paper allows us to study how the structure of galaxies and the stellar population content vary with the distance from the cluster centre. In addition to the intra-cluster features detected in previous FDS works, we found a new faint filament between FCC 143 and FCC 147, suggesting an ongoing interaction. Conclusions. The observations suggest that the Fornax cluster is not completely relaxed inside the virial radius. The bulk of the gravitational interactions between galaxies happens in the W-NW core region of the cluster, where most of the bright early-type galaxies are located and where the intra-cluster baryons (diffuse light and globular clusters) are found. We suggest that the W-NW sub-clump of galaxies results from an infalling group onto the cluster, which has modified the structure of the galaxy outskirts (making asymmetric stellar halos) and has produced the intra-cluster baryons (ICL and GCs), concentrated in this region of the cluster.

scholarly journals Galaxy Environments in DEEP2: The Birth of the Red Sequence

2006 ◽  
Vol 2 (S235) ◽  
pp. 167-169
Author(s):  
Michael C. Cooper ◽  
Jeffrey A. Newman
Keyword(s):  
Star Formation ◽  
Evolutionary Trends ◽  
Early Type ◽  
Number Density ◽  
Late Type ◽  
Active Star ◽  
The Galaxy ◽  
Blue Galaxies ◽  
Galaxy Population ◽  
Red Sequence

The galaxy population at z ≲ 1 is effectively described as a combination of two distinct types: red, early-type galaxies lacking much star formation and blue, late-type galaxies with active star formation. For the red galaxy population, recent work by Bell et al. (2004) has shown that the number density of ~L* galaxies on the red sequence has risen by a factor of ~2 from z ~ 1 to z ~ 0. A variety of complementary observations suggests that the build-up of galaxies on the red sequence results from 2 distinct evolutionary trends: (1) the quenching of star formation in blue galaxies and their subsequent migration onto the red sequence and (2) the dissipationless or (“dry”) merging of red-sequence galaxies.

scholarly journals The galaxy-wide initial mass function of dwarf late-type to massive early-type galaxies

2013 ◽  
Vol 436 (4) ◽  
pp. 3309-3320 ◽  
Author(s):  
C. Weidner ◽  
P. Kroupa ◽  
J. Pflamm-Altenburg ◽  
A. Vazdekis
Keyword(s):  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Early Type ◽  
Late Type ◽  
The Galaxy

scholarly journals The structure of early-type galaxies from the ACS Virgo and Fornax cluster surveys: cores, nuclei and supermassive black holes

2007 ◽  
Vol 3 (S245) ◽  
pp. 203-206
Author(s):  
Laura Ferrarese ◽  
Patrick Côté
Keyword(s):  
Black Holes ◽  
Surface Brightness ◽  
Supermassive Black Holes ◽  
Effective Radius ◽  
Core Structure ◽  
Host Galaxy ◽  
Early Type ◽  
The Core ◽  
The Galaxy ◽  
Fornax Cluster

AbstractThe core structure of early-type galaxies is revisited in light of recent results from the ACS Virgo and Fornax Cluster Surveys. These surveys are comprised of HST/ACS g, z band images for a representative sample of 143 early-type galaxies, spanning a factor 720 in B-band luminosity. The data indicates a clear transition in the core structure going from the brightest to the faintest galaxies. In contrast to previous claims, however, this transition is found to be a continuous function of galaxy magnitude. We characterize the core structure in terms of deviations of the observed surface brightness profile – measured within ~ 2% of the galaxy effective radius – relative to the inner extrapolation of the Sérsic law that best fits the profiles on larger scales. Virtually all galaxies fainter than MB ~ −20 mag contain distinct stellar nuclei, and are described by surface brightness profiles that lie above the Sérsic extrapolation, while the reverse is true for brighter galaxies. The latter are also known to host supermassive black holes. A relation between SBHs and stellar nuclei is suggested by the fact that both types of “central massive objects” contain the same fraction, 0.2% of the total mass of the host galaxy.

scholarly journals Evidence for a Morphological Evolution of Spiral Galaxies

2001 ◽  
Vol 204 ◽  
pp. 387-387
Author(s):  
Yvan Dutil ◽  
Jean-René Roy
Keyword(s):  
Detailed Analysis ◽  
Spiral Galaxies ◽  
Morphological Evolution ◽  
Theoretical Models ◽  
Morphological Type ◽  
Disk Galaxies ◽  
Early Type ◽  
Late Type ◽  
Barred Galaxies ◽  
Abundance Profile

A detailed analysis of the oxygen abundance profile has been carried out on a sample of spiral galaxies from which very good data was available. The early-type galaxies of our sample display gradients that are flatter, and overall levels of O/H abundances that are higher, than those of normal late-type galaxies. Early-type galaxies show an identical trend in the behavior of extrapolated central abundance versus morphological type to that shown by late-type galaxies with strong bars, even in the absence of a bar. On a diagram showing extrapolated central abundances versus morphological types, two clearly separated sequences appear: late-type barred galaxies and early-type (barred or unbarred) galaxies clearly fall on a sequence 0.5 dex in abundance below that of normal late-type galaxies. This behavior is consistent with theoretical models of morphological evolution of disk galaxies by the formation and dissolution of a bar over a period of a few 109 yr, where later type galaxies (Sd, Sc, SBc) evolve into earlier-type disk galaxies (Sb, Sa) through transitory SBc and SBb phases.

scholarly journals BVR CCD Photometric observation analysis of spiral galaxy Ic 467

2019 ◽  
Vol 12 (24) ◽  
pp. 81-86
Author(s):  
Sinan H. Ali
Keyword(s):  
Surface Brightness ◽  
Stellar Population ◽  
Galactic Center ◽  
Photometric Observation ◽  
Position Angle ◽  
Ccd Photometry ◽  
Optical Telescope ◽  
Star Forming ◽  
Dimensional Decomposition ◽  
The Galaxy

The structure and composition of the stellar population in the surface brightness galaxy Ic 467 is studied using BVR CCD photometry. The observations were obtained on the 1.88m optical telescope of Kottamia Astronomical Observatory, KAO, Egypt. A two-dimensional decomposition of the galaxy bulge and disk components is carried out. A powerful star forming region is observed near the galactic center. Based on the positions of the various components of the galaxy in two color diagrams and the surface brightness of the eastern arms in V filter is brighter than the western arm. From the observations, the surface brightness profiles, Ellipticity profiles, position angle profiles and color indices profiles are described and studied.

scholarly journals Dorado and its member galaxies

2020 ◽  
Vol 643 ◽  
pp. A176
Author(s):  
R. Rampazzo ◽  
S. Ciroi ◽  
P. Mazzei ◽  
F. Di Mille ◽  
E. Congiu ◽  
...  
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Star Formation Rate ◽  
Large Fraction ◽  
Formation Rate ◽  
Morphological Type ◽  
Gas Content ◽  
Early Type ◽  
Late Type ◽  
Star Formation Activity

Context. Dorado is a nearby, rich and clumpy galaxy group that extends for several degrees in the southern hemisphere. Although several studies have been dedicated to defining its members, their kinematics, and the hot and cold gas content, in particular H I, their present star formation activity remains unknown. Aims. For the first time, we map the Hα distribution as a possible indicator of the star formation activity of Dorado members, a large fraction of which show interaction and merging signatures independently of their morphological type. Methods. With the 2.5 m du Pont and the 1m Swope telescopes, we obtained narrow-band calibrated images of 14 galaxies that form the backbone of the group, mapping Hα+[N II] down to a few 10−17 erg cm−2 s−1 arcsec−2. We estimated the galaxy star formation rate from the Hα fluxes and corrected for Galaxy foreground extinction and [N II] contamination. Results. We detected Hα+[N II] emission in all galaxies. H II regions clearly emerge in late-type galaxies, while in early-type galaxies the Hα+[N II] emission is dominated by [N II], especially in the central regions. However, H II complexes are revealed in four early-type galaxies. Even in the compact group SGC 0414-5559, in the projected centre of Dorado, H II regions are found both throughout the late-type galaxies and in the very outskirts of early-type members. Considering the Dorado group as a whole, we notice that the Hα+[N II] equivalent width, a measure of the specific star formation, increases with morphological type from early- to late-type members, although it remains lower than that observed in similar surveys of spiral galaxies. The star formation rate of the spiral members is in the range of what is observed in similar galaxies surveys (James et al., 2004). However, in three spiral galaxies, NGC 1536, PGC 75125, and IC 2058, the star formation rate is well below the median for their morphological classes. Conversely, the star formation rate of some early-type members tends to be higher than the average derived from Hα+[N II] surveys of this morphological family. Conclusions. We detected Hα+[N II] in all the early-type galaxies observed and half of them show H II regions in well-shaped rings as well as in their outskirts. These findings suggest that early-type galaxies in this group are not dead galaxies: their star formation has not yet shut down. Mechanisms such as gas stripping and gas accretion through galaxy–galaxy interaction seem relevant in modifying star formation in this evolutionary phase of Dorado.

scholarly journals Morphological Distribution of Galaxies in Some Nearby Clusters

2019 ◽  
Vol 28 (1) ◽  
pp. 98-109
Author(s):  
Mariwan A. Rasheed ◽  
Khalid K. Mohammad
Keyword(s):  
Survey Data ◽  
Concentration Index ◽  
Color Space ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Late Type ◽  
Sky Survey ◽  
Data Release ◽  
The Galaxy ◽  
Morphological Distribution

Abstract We study the morphological distribution of galaxies in some nearby clusters, using the Sloan Digital Sky Survey – Data Release 9 (SDSS-DR9). The segregation between early-type galaxies and late-type ones is investigated in g – r / u – g color space, using the color cut u – r = 2.22. The results are compared with those obtained using a color cut that changes with magnitude. They are found to be consistent, particularly for late-type galaxies. The results obtained by the fixed color-cut criterion are also found to be consistent with those obtained by the inverse concentration index parameter, especially for early-type galaxies. Comparable results are obtained for the stacked sample, whose morphologies, given by the fixed color-cut criterion are compared with the visual morphologies provided by the Galaxy Zoo project. A good degree of consistency is seen, which becomes more evident for late-type galaxies.

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