scholarly journals Distance Measurements and Stellar Population Properties via Surface Brightness Fluctuations

2012 ◽  
Vol 29 (4) ◽  
pp. 489-508 ◽  
Author(s):  
Alexander Fritz
Keyword(s):  
Stellar Evolution ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Stellar Population ◽  
Scale Up ◽  
Asymptotic Giant Branch ◽  
Horizontal Branch ◽  
Stellar Content ◽  
Distance Measurements ◽  
Surface Brightness Fluctuations

AbstractSurface Brightness Fluctuations (SBFs) are one of the most powerful techniques to measure the distance and to constrain the unresolved stellar content of extragalactic systems. For a given bandpass, the absolute SBF magnitude M depends on the properties of the underlying stellar population. Multi-band SBFs allow scientists to probe different stages of the stellar evolution: ultraviolet and blue wavelength band SBFs are sensitive to the evolution of stars within the hot horizontal branch and post-asymptotic giant branch phases, whereas optical SBF magnitudes explore the stars within the red giant branch and horizontal branch regimes. Near- and far-infrared SBF luminosities probe the important stellar evolution stage within the asymptotic giant branch and thermally pulsating asymptotic giant branch phases. Since the first successful application by Tonry and Schneider, a multiplicity of works have used this method to expand the distance scale up to 150 Mpc and beyond. This article gives a historical background of distance measurements, reviews the basic concepts of the SBF technique, presents a broad sample of investigations and discusses possible selection effects, biases, and limitations of the method. In particular, exciting new developments and improvements in the field of stellar population synthesis are discussed that are essential to understand the physics and properties of the populations in unresolved stellar systems. Further, promising future directions of the SBF technique are presented. With new upcoming space-based satellites such as Gaia, the SBF method will remain as one of the most important tools to derive distances to galaxies with unprecedented accuracy and to give detailed insights into the stellar content of globular clusters and galaxies.

scholarly journals Surface Brightness Fluctuations and the Stellar Population in Elliptical Galaxies

1995 ◽  
Vol 164 ◽  
pp. 436-436
Author(s):  
Marianne Sodemann ◽  
Bjarne Thomsen
Keyword(s):  
Globular Clusters ◽  
Surface Brightness ◽  
Stellar Population ◽  
Elliptical Galaxy ◽  
Broad Band ◽  
Apparent Magnitude ◽  
New Information ◽  
Surface Brightness Fluctuations ◽  
The Galaxy ◽  
Fluctuation Noise

The Surface Brightness Fluctuation (SBF) method introduced by Tonry & Schneider (1988) is known as a distance indicator. However, we focus on another aspect. Our aim is to obtain new information on the stellar population that constitutes an elliptical galaxy by comparing radial gradients in SBF magnitudes with traditional broad-band colours. We have obtained I–band images of NGC 3379 with the NTT/SUSI, 0″.8–1″.2 FWHM, Sodemann & Thomsen (1994). An analysis similar to that of Tonry & Schneider (1988) is applied. However, the smoothed galaxy is obtained from (Thomsen & Baum, 1989). For NGC 3379 we find a SBF signal of 3.39 ± 0.02 ADU, see Figure 1, corresponding to an object with apparent magnitude Ī = 28m.62 ± 0m.03. If the image is subdivided into 4 annular regions, we find the gradient in I in Figure 2. As both fluctuation ‘noise’ and photon noise raise towards the centre of the galaxy, it is difficult to correct for globular clusters in a position independent way. Dealing with gradients of the SBF signal, the task is even more delicate. The weakening of Ī towards the galaxy centre is foreseen by the stellar population models of Worthey (1994).

On the Two Oosterhoff Groups of Globular Clusters

1973 ◽  
Vol 21 ◽  
pp. 196-196
Author(s):  
T. S. Van Albada ◽  
Norman Baker
Keyword(s):  
Stellar Evolution ◽  
Globular Clusters ◽  
Transition Point ◽  
Transition Period ◽  
Observational Evidence ◽  
Horizontal Branch ◽  
Average Difference ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

AbstractThe observational evidence leading to the classification, following Oosterhoff, of globular clusters containing RR Lyrae stars into two distinct groups, is summarized and discussed in the light of results of stellar evolution theory and pulsation theory. The dichotomy is caused, at least in part, by a dichotomy in the ‘transition period’ between the type-ab and type-c stars which reflects a difference in effective temperature at the transition point. When this difference is accounted for, there remains a smaller average difference between the groups, though no longer a clear dichotomy, that is probably a mass and luminosity effect. If this remaining difference is interpreted as a luminosity effect the average difference in luminosity between the two Oosterhoff groups is at most 0.1 mag. It is suggested that Christy’s theoretical relationship between transition period and luminosity cannot be valid, at least not for clusters of different Oosterhoff groups. It is conjectured that the transition-temperature dichotomy may be a reflection of different predominant directions of evolution along the horizontal branch, accompanied by a hysteresis effect in the pulsations.

scholarly journals Measuring the GC luminosity function up to z ~ 0.2

2009 ◽  
Vol 5 (S266) ◽  
pp. 351-351
Author(s):  
K. A. Alamo-Martínez ◽  
R. A. González-Lópezlira ◽  
J. Blakeslee
Keyword(s):  
Galaxy Formation ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Luminosity Function ◽  
Elliptical Galaxy ◽  
Angular Size ◽  
Spectroscopic Studies ◽  
Stellar Systems ◽  
Surface Brightness Fluctuations ◽  
Specific Frequency

AbstractGlobular clusters (GCs) are stellar systems (~106 M⊙) with very regular symmetry, single age, and single metallicity. Spectroscopic studies have revealed very old ages, suggesting that GCs were formed in the earliest stages of galaxy formation and assembly. The aim of this work is to find out how far we can measure the GC luminosity function, specific frequency, and radial distribution, applying the surface-brightness-fluctuations (SBF) technique to deep ACS images. To this end, we apply the effects caused by higher redshift to HST/ACS images (in two optical bands, F606W and F814W) of M87, an elliptical galaxy with a very well-studied GC system. The effects involved are: (i) evolution, (ii) inverse k correction, (iii) binning of the image to smaller angular size, (iv) cosmological dimming of surface brightness, and (v) noise addition to account for different exposure times. After processing the images we detect the brightest GCs through direct photometry (e.g., with SExtractor), whereas the unresolved clusters are measured through SBFs. The above treatment is repeated for z=0.05, 0.1, 0.14, and 0.18, and the results are compared to the measurements at z=0 to estimate biases and incompleteness.

scholarly journals Stellar Populations and Hubble Type

1983 ◽  
Vol 6 ◽  
pp. 187-190
Author(s):  
Sidney van den Bergh
Keyword(s):  
Strong Correlation ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Stellar Populations ◽  
Elliptical Galaxies ◽  
Young Stars ◽  
Stellar Content ◽  
Clear Cut ◽  
Spiral Arm ◽  
Galaxy Morphology

Men are more apt to be mistaken in their generalization than in their particular observations. MachiavelliIt was already realized by Hubble (1936) that galaxy morphology and stellar content were correlated. He pointed out that resolution into stars increases along the classification sequence Sa-Sb-Sc. Simultaneously the colours of spirals become bluer and their integrated spectral types become earlier as one proceeds from Sa to Sc. Baade (1944) speculated that the red stars in ellipticals and in the nuclear bulges of spirals were identical to those in globular clusters. He suggested that stars in galaxies belong to two distinct populations: young metal-rich stars of Population I which inhabit the disc and spiral arm regions of spirals, and old metal-poor stars of Population II which dominate the light of elliptical galaxies and the nuclear bulges of spirals. Subsequently Baade (1950) emphasized the strong correlation between the occurrence of gas and dust and the presence of young stars. As Baade put it so succinctly “No dust, no Population I”. Belief in a clear cut dichotomy between Population I and Population II was strengthened by the differences in their radial luminosity distributions. The surface brightness of Population I in spirals is well represented by an exponential disc, whereas the surface brightness of Population II stars in ellipticals and the bulges of spirals may be described by an r1/4 law (de Vaucouleurs 1959).

scholarly journals A nitrogen-enhanced metal-poor star discovered in the globular cluster ESO280−SC06

2019 ◽  
Vol 490 (1) ◽  
pp. 741-751 ◽  
Author(s):  
Jeffrey D Simpson ◽  
Sarah L Martell
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Binary Systems ◽  
Asymptotic Giant Branch ◽  
Red Giants ◽  
Horizontal Branch ◽  
Term Survival ◽  
Abundance Patterns ◽  
Metal Poor Star

ABSTRACT We report the discovery of the only very nitrogen-enhanced metal-poor star known in a Galactic globular cluster. This star, in the very metal-poor cluster ESO280−SC06 , has $[\textrm{N}/\textrm{Fe}]\, \gt +2.5$, while the other stars in the cluster show no obvious enhancement in nitrogen. Around 80 NEMP stars are known in the field, and their abundance patterns are believed to reflect mass transfer from a binary companion in the asymptotic giant branch phase. The dense environment of globular clusters is detrimental to the long term survival of binary systems, resulting in a low observed binary fraction among red giants and the near absence of NEMP stars. We also identify the first known horizontal branch members of ESO280−SC06 , which allow for a much better constraint on its distance. We calculate an updated orbit for the cluster based on our revised distance of 20.6 ± 0.5 kpc, and find no significant change to its orbital properties.

scholarly journals The ACS Survey of Galactic Globular Clusters. II. Stellar Evolution Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch Models

2007 ◽  
Vol 134 (1) ◽  
pp. 376-390 ◽  
Author(s):  
Aaron Dotter ◽  
Brian Chaboyer ◽  
Darko Jevremović ◽  
E. Baron ◽  
Jason W. Ferguson ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Globular Clusters ◽  
Horizontal Branch ◽  
Luminosity Functions ◽  
Galactic Globular Clusters

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 The Brightest Stars in the Magellanic Clouds and Other Late-Type Galaxies

1984 ◽  
Vol 108 ◽  
pp. 145-156
Author(s):  
Roberta M. Humphreys
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Stellar Population ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Stellar Winds ◽  
Stellar Content ◽  
Late Type ◽  
Observational Astronomy ◽  
Distant Galaxies

The brightest stars always receive considerable attention in observational astronomy, but why are we so interested in these most luminous, and therefore most massive stars? These stars are our first probes for exploring the stellar content of distant galaxies. Admittedly, they are only the tip of the iceberg for the whole stellar population and very interesting processes are occurring among the less massive, older stars, but the most massive stars are our first indicators for studies of stellar evolution in other galaxies. They provide the first hint that stellar evolution may have been different in a particular galaxy because they evolve so quickly. The most luminous stars also highly influence their environments via their strong stellar winds and mass loss and eventually as supernovae.

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