scholarly journals A Concise Reference to (Projected) Sérsic R1/n Quantities, Including Concentration, Profile Slopes, Petrosian Indices, and Kron Magnitudes

2005 ◽  
Vol 22 (2) ◽  
pp. 118-127 ◽  
Author(s):  
Alister W. Graham ◽  
Simon P. Driver
Keyword(s):  
Power Law ◽  
Concentration Profile ◽  
Surface Brightness ◽  
Intensity Profile ◽  
Total Flux ◽  
Effective Surface ◽  
The Core ◽  
Central Surface ◽  
Mathematical Expressions ◽  
The Mean

AbstractGiven the growing use of Sérsic's (1963, 1968) R1/n model for describing the stellar distributions in galaxies, and the lack of any single reference that provides the various associated mathematical expressions, we have endeavoured to compile such a resource here. We present the standard intensity profile, and its various guises such as the luminosity, surface-brightness, and aperture–magnitude profile. Expressions to transform the effective surface brightness into the mean effective and central surface brightness are also given, as is the expression to transform between effective radii and exponential scale-lengths. We additionally provide expressions for deriving the ‘concentration’ of an R1/n profile, and two useful equations for the logarithmic slope of the light-profile are given. Petrosian radii and fluxes are also derived for a range of Sérsic profiles and compared with the effective radii and total flux. Similarly, expressions to obtain Kron radii and fluxes are presented as a function of the Sérsic index n and the number of effective radii sampled. Illustrative figures are provided throughout. Finally, the core–Sérsic model, consisting of an inner power-law and an outer Sérsic function, is presented.

scholarly journals The Structure of Collapsed Cluster Cores

1988 ◽  
Vol 126 ◽  
pp. 657-658
Author(s):  
Phyllis M. Lugger ◽  
Haldan Cohn ◽  
Jonathan E. Grindlay ◽  
Charles D. Bailyn ◽  
Paul Hertz
Keyword(s):  
Power Law ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Core Collapse ◽  
Central Surface ◽  
Core Profile ◽  
Galactic Globular Clusters ◽  
Cluster Cores

In order to test the prediction that many Galactic globular clusters have undergone core collapse (Lightman 1982, Cohn and Hut 1984) and should therefore have central surface brightness cusps, we have obtained UBVR CCD frames of the cores of 72 clusters. We present and analyze U-band surface brightness profiles for three clusters: one “control cluster” with a normal flat core profile — NGC 6388 — and two with central power law cusps — NGC 6624 and M15 (NGC 7078).

scholarly journals Systematics of Bulge-to-Disk Ratios

1983 ◽  
Vol 100 ◽  
pp. 375-376
Author(s):  
F. Simien ◽  
G. de Vaucouleurs
Keyword(s):  
Surface Brightness ◽  
Systematic Difference ◽  
List Type ◽  
Large Scatter ◽  
Late Type ◽  
Effective Surface ◽  
Central Surface ◽  
Hubble Sequence ◽  
Total Luminosity ◽  
Absolute Magnitudes

The main results of a new analysis of the spheroidal (I) and disk (II) components of 98 lenticular and spiral galaxies are : (i)on the average, the magnitude difference between spheroid and total luminosity, ΔmI = BT(I) - BT, varies smoothly along the Hubble sequence from early lenticulars to late-type spirals (Fig. 1);(ii)the trend of ΔmI confirms the concept of the lenticular class as intermediate between E and S classes, not as a parallel sequence;(iii)the large scatter at any given type, σ(ΔmI) ≃ 0.7 mag, is still dominated by measuring and decomposition errors.(iv)The effective surface brightness of the spheroid, μce(I), corrected for galactic extinction AB, decreases by ~2 mag from early to late types, but with a large range (~ 3 mag) at T = const. (Fig. 2a).(v)The effective surface brightness of the disks, corrected for galactic extinction and inclination, μce(II) = μe(II)- AB + 3 log R2s, is almost independent of type, with <μce(II)> ≃ 23.5 for spirals. This implies a corrected central surface brightness μc(0) = μce −1.82 ≃ 21.7, in good agreement with the Freeman rule, but with a large scatter. However, the disks of lenticulars (T< 0) tend to be ~ 0.5 mag fainter than the disks of spirals (Fig. 2b).(vi)The linear effective radii of the spheroidal components are largest, <re (I)> ≳ 1 kpc, among the early type spirals, in agreement with the Hubble classification criterion. The spheroid of lenticulars and late-type spirals tend to be smaller, <re(I)> ≃ 0.5 kpc, but with a large scatter (Fig. 3a). There is no indication of systematic difference between ordinary (SA) and barred (SB) spirals.(vii)The linear effective radii of the disk components are largest <re (I)> ≳ 5 kpc, among intermediate type spirals. The disks of lenticular and late type spirals tend to be smaller (Fig. 3b).(viii)The mean absolute magnitudes of the disk and spheroidal components depend on type (Fig. 4). On the average the disks are brighter (MII ≃ −19.5) among types Sb-Sbc, spheroids (MI ⋍ −19) among types L+ to Sa, but, again, with a large scatter. Disks and spheroids are about equally bright (MI ⋍ MII ⋍ − 19) at stage SO/a (T = 0).

scholarly journals The HST/LCO Measurement of the Optical Extragalactic Background Light

1999 ◽  
Vol 171 ◽  
pp. 341-348 ◽  
Author(s):  
R.A. Bernstein
Keyword(s):  
Standard Method ◽  
Surface Brightness ◽  
Detection Limits ◽  
Data Sets ◽  
Effective Surface ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Minimum Surface ◽  
The Mean ◽  
Galaxy Populations

AbstractWe present the first detection of the mean flux of the optical extragalactic background light (EBL) at 3000, 5500, and 8000Å, derived from coordinated data sets from HST and Las Campanas Observatory. To isolate the extragalactic component, we have measured and subtracted the flux from foreground sources explicitly. In addition to detections in all three bands, we identify the minimum surface brightness contributed by resolved galaxies (23 < V < 28 AB mag) using a non-standard method of aperture photometry to which these data are uniquely suited. Individually resolved galaxies account for ~ 30% of the mean EBL coming from galaxies fainter than V = 23 AB mag. Taking into account the effective surface brightness detection limits of the deepest galaxy counts, and the results of LSB surveys at low redshift, the EBL we detect can be explained by galaxy populations already cataloged.

scholarly journals Dwarf Elliptical Galaxies in the M81 Group: The Structure and Stellar Populations of BK5N and F8D1

1998 ◽  
Vol 11 (1) ◽  
pp. 132-133
Author(s):  
Taft E. Armandroff ◽  
Nelson Caldwell ◽  
G.S. Da Costa ◽  
Patrick Seitzer
Keyword(s):  
Surface Brightness ◽  
Local Group ◽  
Absolute Magnitude ◽  
Groups Of Galaxies ◽  
Central Surface ◽  
Luminous Matter ◽  
Total Magnitude ◽  
Metal Abundance ◽  
The Mean ◽  
Red Giant

The M81 group is one of the nearest groups of galaxies, but its properties are quite different from those of the Local Group. It has therefore provided a different environment for the evolution of its member galaxies. We have carried out a CCD survey of the M81 group to search for analogs to Local Group dwarf elliptical (dE) galaxies. All the M81 dwarfs previously identified in photographic surveys were recovered and we also discovered several new systems whose surface brightnesses fall within the range found for Local Group dE’s. We have obtained HST WFPC2 images through the F555W and F814W filters of two M81 group dE’s: BK5N and a new system, designated F8D1. The resulting color-magnitude diagrams show the upper two magnitudes of the red giant branch. The I magnitudes of the red giant branch tip in both galaxies yield distances that are consistent with membership in the M81 group. Surface brightness and total magnitude measurements indicate that BK5N and F8D1 have similar central surface brightness (24.5 and 25.4 mag arcsec-2 in V, respectively), but F8D1 is larger length scale results in it being 3 magnitudes more luminous than BK5N. BK5N lies on the relation between central surface brightness and absolute magnitude defined by Local Group dwarf ellipticals, but F8D1 does not. F8D1 is more luminous for its central surface brightness than the relation predicts, similar to the large low surface brightness dwarf galaxies found in, for example, Virgo. The mean color of the giant branch is used to establish the mean abundance of each galaxy. F8D1, the more luminous galaxy, is significantly more metal rich ([Fe/H] ≈ -1.0) than BK5N ([Fe/H] ≈ -1.7). Both BK5N and F8D1 lie on the relation between absolute magnitude and metal abundance defined by Local Group dwarf ellipticals. However, as regards the relation between central surface brightness and metal abundance, BK5N again follows the Local Group dwarfs, while F8D1 deviates significantly from this relation. This suggests that the total amount of luminous matter is more fundamental in controlling metal enrichment than the surface density of luminous matter. We have also used the color width of the giant branch compared with the photometric errors to establish abundance ranges in both galaxies, the sizes of which are comparable to those in Local Group dE’s.

Evaluation of Road Utilisation as Space For Holding Social Ceremonies in Indigenous Residential Area of Ogbomoso, Nigeria

2018 ◽  
Vol 1 (March 2018) ◽  
Author(s):  
S.A Okanlawon ◽  
O.O Odunjo ◽  
S.A Olaniyan
Keyword(s):  
Transport Infrastructure ◽  
Noisy Environment ◽  
Policy Makers ◽  
The Core ◽  
Local Roads ◽  
Strict Enforcement ◽  
The Mean ◽  
The One ◽  
The City ◽  
The Town

This study examined Residents’ evaluation of turning transport infrastructure (road) to spaces for holding social ceremonies in the indigenous residential zone of Ogbomoso, Oyo State, Nigeria. Upon stratifying the city into the three identifiable zones, the core, otherwise known as the indigenous residential zone was isolated for study. Of the twenty (20) political wards in the two local government areas of the town, fifteen (15) wards that were located in the indigenous zone constituted the study area. Respondents were selected along one out of every three (33.3%) of the Trunk — C (local) roads being the one mostly used for the purpose in the study area. The respondents were the residents, commercial motorists, commercial motorcyclists, and celebrants. Six hundred and forty-two (642) copies of questionnaire were administered and harvested on the spot. The Mean Analysis generated from the respondents’ rating of twelve perceived hazards listed in the questionnaire were then used to determine respondents’ most highly rated perceived consequences of the practice. These were noisy environment, Blockage of drainage by waste, and Endangering the life of the sick on the way to hospital; the most highly rated reasons why the practice came into being; and level of acceptability of the practice which was found to be very unacceptable in the study area. Policy makers should therefore focus their attention on strict enforcement of the law prohibiting the practice in order to ensure more cordial relationship among the citizenry, seeing citizens’ unacceptability of the practice in the study area.

scholarly journals Sublinear domination and core–periphery networks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marios Papachristou
Keyword(s):  
Network Model ◽  
Power Law ◽  
Real World ◽  
Random Network ◽  
Small World ◽  
The Core ◽  
Entire Network

AbstractIn this paper we devise a generative random network model with core–periphery properties whose core nodes act as sublinear dominators, that is, if the network has n nodes, the core has size o(n) and dominates the entire network. We show that instances generated by this model exhibit power law degree distributions, and incorporates small-world phenomena. We also fit our model in a variety of real-world networks.

The density variation of the earth's central core*

1942 ◽  
Vol 32 (1) ◽  
pp. 19-29
Author(s):  
K. E. Bullen
Keyword(s):  
Pure Iron ◽  
Outer Boundary ◽  
Density Variation ◽  
Central Core ◽  
Good Precision ◽  
Wide Margin ◽  
The Core ◽  
The Earth ◽  
The Mean ◽  
Published Paper

ABSTRACT A detailed analysis of the problem of the earth's density variation has been extended to the earth's central core. It is shown that in the region between the outer boundary of the core and a distance of about 1400 km. from the earth's center the density ranges from 9.4 gm/cm.3 to 11.5 gm/cm.3 within an uncertainty which, if certain general assumptions are true, does not exceed 3 per cent. The density and pressure figures are, moreover, compatible with the existence of fairly pure iron in this part of the earth. The result for the earth's outer mantle as given in a previously published paper, together with those in the present paper, are found to give with good precision the density distribution in a region occupying 99 per cent of the earth's volume. Values of the density within 1400 km. of the earth's center are subject, however, to a wide margin of uncertainty, and there appears to be no means of resolving this uncertainty for the present. The most that can be said is that the mean density in the latter region is greater than 12.3 gm/cm.3 and may quite possibly be several gm/cm.3 in excess of this figure. In the present paper figures are also included for the variation of gravity and the distribution of pressure within the central core. The gravity results are shown to be subject to an appreciable uncertainty except within about 1000 km. of the outer boundary of the core, but the pressure results are expected to be closely accurate at all depths.

Early Clinical Outcomes of the Active Seal Technology of the AFX Endovascular Aortic Aneurysm System With the VELA Cuff for Patients With a Conical Proximal Neck

2022 ◽  
pp. 152660282110709
Author(s):  
Naoki Fujimura ◽  
Hideaki Obara ◽  
Takaaki Nagano ◽  
Yukihisa Ogawa ◽  
Taira Kobayashi ◽  
...  
Keyword(s):  
Aortic Aneurysm ◽  
Endovascular Aneurysm Repair ◽  
Aortic Aneurysms ◽  
Proximal Neck ◽  
Landing Zone ◽  
The Core ◽  
The Mean ◽  
Instructions For Use ◽  
Lost To Follow Up

Purpose: To evaluate the efficacy of the Active Seal technology employed in the AFX endovascular aortic aneurysm system (AFX), during endovascular aneurysm repair (EVAR) in patients with abdominal aortic aneurysms (AAAs) having a conical proximal neck. Materials and Methods: A retrospective analysis of the EVAR for AAA with a conical proximal neck using the AFX was performed at 17 Japanese hospitals between January 2016 and August 2020. The conical proximal neck was defined as a cone-shaped proximal neck, with more than 10% diameter increase within a 15 mm length at the proximal landing zone. All anatomical analyses were performed in the core laboratory, and cases with parallel walls within the proximal neck adequate for the landing zone were excluded from the study. Results: This study included 53 patients, but only 39 patients (mean age, 76.6 ± 6.7 years; 87.0% males; mean aneurysm diameter, 52.0 ± 8.0 mm) were analyzed after being characterized as having a pure conical neck by the core laboratory. The mean proximal neck diameters at the lower renal artery and proximal edge of the aneurysm were 20.0 ± 2.9 mm and 27.5 ± 4.9 mm, respectively. The mean proximal neck length was 21.5 ± 6.0 mm. Instructions for use violations other than the conical neck were observed in 15 patients (38.5%). The VELA cuff was used in all cases; however, additional proximal cuff was required in 9 more cases (23.1%). The Active Seal technology was able to significantly extend the proximal sealing zone from 21.5 ± 6.0 to 26.0 ± 12.2 mm ( p = .047). Thirty-six patients completed the 12-month follow-up (one patient was lost to follow-up, and 2 patients died from causes unrelated to the aneurysm), and there were no type-1a and 3 endoleaks with only one reintervention (2.6%) related to type 1b endoleak in the 12-month period. Furthermore, there was no significant enlargement of the proximal neck diameter at 12 months (at 1 month: 20.6 ± 3.4 mm and at 12 months: 21.3 ± 3.8 mm; p = .420). Conclusion: The Active Seal technology of the AFX significantly extended the proximal seal zone and no type-1a endoleak and proximal neck dilation was observed in patients with conical proximal neck at 12 months.

scholarly journals Effect of Core Training Program on Physical Functional Performance in Female Soccer Players

2016 ◽  
Vol 9 (5) ◽  
pp. 115 ◽  
Author(s):  
Cengiz Taskin
Keyword(s):  
Functional Performance ◽  
Vertical Jump ◽  
Training Group ◽  
Soccer Players ◽  
Control Group ◽  
The Core ◽  
Standing Long Jump ◽  
Long Jump ◽  
The Mean ◽  
Core Training

<p class="apa">The purpose of this study was to determine the effect of core training program on speed, acceleration, vertical jump, and standing long jump in female soccer players. A total of 40 female soccer players volunteered to participate in this study. They were divided randomly into 1 of 2 groups: core training group (CTG; n = 20) and control group (CG; n = 20). The mean (SD) age was 19.05 ± 1.15 years, height was 160.60 ± 4.22 cm, weight was 56.45 ± 3.33 kg, and sport age was 4.50 ± 1.24 for the core training group; the mean (SD) age was 18.55 ± 0.76 years, height was 159.10 ± 3.86 cm, weight was 52.20 ± 3.60 kg, and sport age was 3.35 ± 0.75 years for the control group. Following randomization, the 2 groups did not differ significantly (p&gt;0.05) in any of the dependent variables. The subjects in the control group did not participate in the training and participated only in the pre- and posttest measurements. To evaluate the effect of core training over the functional performance, we applied a testing procedure that included measurements of speed, acceleration, vertical jump, and standing long jump. The core training group showed a 3.4%, 5.9%, 13.3%, 4.2% improvement in speed, acceleration, vertical jump, and standing long jump (respectively) (P&lt;0.05), whereas the control group did not change (P&gt;0.05). In conclusion, Core exercises were improved speed, acceleration, vertical jump, and standing long jump in 18-19 years-old female soccer players. Therefore, it is believed core training is necessary for optimal sport performance and should not be dismissed for all sport branches.</p>

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