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.

scholarly journals Nearby Blue Compact Dwarf Galaxy NGC 6789

1999 ◽  
Vol 192 ◽  
pp. 253-258
Author(s):  
I. Drozdovsky ◽  
N. Tikhonov
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxy ◽  
High Surface ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Metal Abundance ◽  
The Mean ◽  
Red Giant ◽  
Halo Population ◽  
Blue Compact Dwarf Galaxy

We present the results of a detailed BVRI and Hα study of the isolated nearby blue compact dwarf (BCD) galaxy NGC 6789. Judging from the literature the observed galaxy has not yet been resolved into stars up to now. On CCD frames obtained with 6m BTA telescope and 2.5m Nordic telescope the galaxy is well resolved. Its colour-magnitude diagram confirms the two component (core-halo) galaxy morphology, which consists of two stellar populations distinct in structure and colour: an inner high surface-brightness young population within 150 pc from the center of the galaxy, and a relatively low surface-brightness intermediate-age population extending out to at least 600 pc. The distance to the galaxy, estimated from the tip of the red giant branch (TRGB) is 2.1 Mpc which places NGC 6789 close to the Local Group. From the mean colour of the RGB, the mean metal abundance of the halo population is estimated as [Fe/H] ≃ −1 dex.

scholarly journals KKH 22, the first dwarf spheroidal satellite of IC 342

2020 ◽  
Vol 638 ◽  
pp. A111
Author(s):  
Igor D. Karachentsev ◽  
Lidia N. Makarova ◽  
R. Brent Tully ◽  
Gagandeep S. Anand ◽  
Luca Rizzi ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Spiral Galaxy ◽  
Globular Cluster ◽  
Surface Brightness ◽  
Absolute Magnitude ◽  
Peculiar Velocity ◽  
Central Surface ◽  
Red Giant ◽  
Advanced Camera For Surveys ◽  
Heliocentric Velocity

Aims. We present observations with the Advanced Camera for Surveys on the Hubble Space Telescope of the nearby dwarf spheroidal galaxy KKH 22 = LEDA 2807114 in the vicinity of the massive spiral galaxy IC 342. Methods. We derived its distance of 3.12 ± 0.19 Mpc using the tip of red giant branch (TRGB) method. We also used the 6 m BTA spectroscopy to measure a heliocentric radial velocity of the globular cluster in KKH 22 to be +30 ± 10 km s−1. Results. The dSph galaxy KKH 22 has the V-band absolute magnitude of –12.m19 and the central surface brightness μv, 0 = 24.1m/□″. Both the velocity and the distance of KKH 22 are consistent with the dSph galaxy being gravitationally bound to IC 342. Another nearby dIr galaxy, KKH 34, with a low heliocentric velocity of +106 km s−1 has the TRGB distance of 7.28 ± 0.36 Mpc residing in the background with respect to the IC 342 group. KKH 34 has a surprisingly high negative peculiar velocity of –236 ± 26 km s−1.

scholarly journals Galaxy scaling relations from the ACS Virgo and Fornax Cluster Surveys: no evidence for a dwarf-giant dichotomy

2007 ◽  
Vol 3 (S245) ◽  
pp. 395-398 ◽  
Author(s):  
Patrick Côté ◽  
Laura Ferrarese ◽  
Andrés Jordán ◽  
John P. Blakeslee ◽  
Chin-Wei Chen ◽  
...  
Keyword(s):  
Structural Properties ◽  
Surface Brightness ◽  
Local Group ◽  
Absolute Magnitude ◽  
Effective Radius ◽  
Scaling Relations ◽  
Early Type ◽  
Central Surface ◽  
Fornax Cluster

AbstractWe examine the photometric and structural properties of early-type galaxies derived from the ACS Virgo and Fornax Cluster Surveys, supplementing these data with previously published or newly reanalysed data for additional early-type galaxies in Virgo, Fornax and the Local Group. As we have noted elsewhere, Sérsic models are found to provide accurate representations of the observed brightness profiles on scales greater than a few percent of the effective radius, Re. On smaller scales, the brightness profiles of bright (MB ≳ −20) galaxies show central deficits with respect to the inward extrapolation of the Sérsic models; fainter galaxies usually show central excesses. Fainter than MB ≈ −20, we find a continuity in the photometric and structural scaling relations: i.e., between absolute magnitude, central surface brightness, Sérsic index, effective radius, and the surface brightness measured at, and averaged within, the effective radius. There is no evidence for a “dwarf/giant dichotomy” — a conclusion consistent with a number of recent studies but contrary to some earlier claims.

scholarly journals Structure of the Canes Venatici I cloud of galaxies

2014 ◽  
Vol 11 (S308) ◽  
pp. 209-210
Author(s):  
Dmitry I. Makarov ◽  
Lidia N. Makarova ◽  
Roman I. Uklein
Keyword(s):  
Total Mass ◽  
Local Group ◽  
Homogeneous Sample ◽  
Chaotic Motions ◽  
Groups Of Galaxies ◽  
System A ◽  
Central Galaxy ◽  
Luminous Matter ◽  
Red Giant ◽  
Centaurus A

AbstractWe study the spatial distribution of the sparse cloud of galaxies in the Canes Venatici constellation. We determined distances of 30 galaxies using the tip of the red giant branch (TRGB) method. This homogeneous sample allows us to distinguish the zone of chaotic motions around the center of the system. A group of galaxies around M94 is characterized by the mass-luminosity ratio of M/LB=159 (M/L)⊙. It is significantly higher than the typical ratio M/LB=159 (M/L)⊙ for the nearby groups of galaxies. The CVn I cloud of galaxies contains 4–5 times less luminous matter compared with the well-known nearby groups, such as the Local Group, M 81 and Centaurus A. The central galaxy M 94 is at least 1 mag fainter than any other central galaxy of these groups. However, the concentration of galaxies in the Canes Venatici may have a comparable total mass.

scholarly journals Dwarf Galaxies in Nearby Groups

1999 ◽  
Vol 171 ◽  
pp. 154-156
Author(s):  
T. Bremnes ◽  
B. Binggeli ◽  
P. Prugniel
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Photometric Data ◽  
Preliminary Results ◽  
Central Surface ◽  
Total Magnitude ◽  
Evolutionary Connection

AbstractWe present preliminary results from two observing campaigns where global photometric data for most dwarf galaxies in the M81 and M101 groups as well as some field dwarfs were obtained. The galaxies in the denser M81 group are more often of dwarf elliptical type and are redder and fainter than those of the M101 group and surrounding field, which are mostly of the dwarf irregular types. But both types follow the same total magnitude - central surface brightness relation, so there might be an evolutionary connection between the two classes.

scholarly journals Red Variable Stars in Metal Rich Globular Clusters

1973 ◽  
Vol 21 ◽  
pp. 151-163
Author(s):  
T. Lloyd Evans ◽  
J. W. Menzies
Keyword(s):  
Systematic Study ◽  
Globular Clusters ◽  
Variable Stars ◽  
Large Numbers ◽  
Magnitude Diagram ◽  
Metal Abundance ◽  
The Mean ◽  
Red Giant ◽  
Photoelectric Observations ◽  
Considerable Range

The globular clusters contain sufficiently large numbers of stars to permit a systematic study of the intrinsically rare variable stars which lie near the tip of the red giant branch. The position of the smaller amplitude stars in the colour magnitude diagram is of particular interest. Eggen (1972) has published photoelectric observations of such stars in several globular clusters, most of intermediate or low metal abundance. The mean colour of 14 stars in 5 clusters is (V-IK) = 1.40, with a spread from 1.60 to 1.12 (or 0.75 if V8 in M22 is of this type) which Eggen regards as indicating a range of temperature. The red variable stars in the metal rich globular cluster 47 Tucanae are much redder and show a considerable range of colour.

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 A new measurement of the Hubble constant using Type Ia supernovae calibrated with surface brightness fluctuations

2021 ◽  
Vol 647 ◽  
pp. A72 ◽  
Author(s):  
Nandita Khetan ◽  
Luca Izzo ◽  
Marica Branchesi ◽  
Radosław Wojtak ◽  
Michele Cantiello ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Hubble Constant ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Distance Measurements ◽  
Surface Brightness Fluctuations ◽  
Type Ia ◽  
Red Giant ◽  
Ia Supernovae

We present a new calibration of the peak absolute magnitude of Type Ia supernovae (SNe Ia) based on the surface brightness fluctuations (SBF) method, aimed at measuring the value of the Hubble constant. We build a sample of calibrating anchors consisting of 24 SNe hosted in galaxies that have SBF distance measurements. Applying a hierarchical Bayesian approach, we calibrate the SN Ia peak luminosity and extend the Hubble diagram into the Hubble flow by using a sample of 96 SNe Ia in the redshift range 0.02 < z < 0.075, which was extracted from the Combined Pantheon Sample. We estimate a value of H0 = 70.50 ± 2.37 (stat.) ± 3.38 (sys.) km s−1 Mpc−1 (i.e., 3.4% stat., 4.8% sys.), which is in agreement with the value obtained using the tip of the red giant branch calibration. It is also consistent, within errors, with the value obtained from SNe Ia calibrated with Cepheids or the value inferred from the analysis of the cosmic microwave background. We find that the SNe Ia distance moduli calibrated with SBF are on average larger by 0.07 mag than those calibrated with Cepheids. Our results point to possible differences among SNe in different types of galaxies, which could originate from different local environments and/or progenitor properties of SNe Ia. Sampling different host galaxy types, SBF offers a complementary approach to using Cepheids, which is important in addressing possible systematics. As the SBF method has the ability to reach larger distances than Cepheids, the impending entry of the Vera C. Rubin Observatory and JWST into operation will increase the number of SNe Ia hosted in galaxies where SBF distances can be measured, making SBF measurements attractive for improving the calibration of SNe Ia, as well as in the estimation of H0.

scholarly journals Galaxy Harassment—Interactions for the 90s

1999 ◽  
Vol 186 ◽  
pp. 393-400 ◽  
Author(s):  
George Lake ◽  
Ben Moore
Keyword(s):  
Surface Brightness ◽  
Luminosity Function ◽  
Local Group ◽  
High Surface ◽  
Late Type ◽  
High Surface Brightness ◽  
Dwarf Spheroidal Galaxies ◽  
Central Surface ◽  
Hubble Sequence ◽  
Spheroidal Galaxies

The origin of the Hubble sequence remains a long-standing puzzle in astronomy. Giant galaxies range from slowly-rotating dense ellipticals to thin late-type spiral disks. At the faint end, there are two distinct classes of “ellipticals/spheroids” that are easily separated in plots of nearly any two of their properties, such as central surface brightness versus luminosity (Ferguson and Binggeli 1994; Kormendy 1985). The elliptical class includes the bright giants and extends to the rare high surface brightness “dwarf ellipticals”, M32 being the prototype. The “spheroidal” galaxies have low surface brightnesses and are all ≳3 magnitudes fainter than L∗, the characteristic break in the luminosity function. The dwarf spheroidal galaxies (dSph) in our Local Group of galaxies with magnitudes in the range −8≳MB≳ - 12 are often considered to be the low luminosity extreme of this sequence, but nearly all other known galaxies in this class reside in clusters.

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