Effects of Envelope Overshoot on the Bump of the Red Giant Branch Luminosity Function

1991 ◽  
pp. 325-326
Author(s):  
M. Alongi ◽  
G. Bertelli ◽  
A. Bressan ◽  
C. Chiosi
Keyword(s):  
Luminosity Function ◽  
Red Giant

scholarly journals The dwarf galaxy satellite system of Centaurus A

2019 ◽  
Vol 629 ◽  
pp. A18 ◽  
Author(s):  
Oliver Müller ◽  
Marina Rejkuba ◽  
Marcel S. Pawlowski ◽  
Rodrigo Ibata ◽  
Federico Lelli ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
3D Structure ◽  
Major Axis ◽  
Asymptotic Giant Branch ◽  
Semi Major Axis ◽  
Distance Measurements ◽  
Red Giant

Dwarf galaxy satellite systems are essential probes to test models of structure formation, making it necessary to establish a census of dwarf galaxies outside of our own Local Group. We present deep FORS2 VI band images from the ESO Very Large Telescope (VLT) for 15 dwarf galaxy candidates in the Centaurus group of galaxies. We confirm nine dwarfs to be members of Cen A by measuring their distances using a Bayesian approach to determine the tip of the red giant branch luminosity. We have also fit theoretical isochrones to measure their mean metallicities. The properties of the new dwarfs are similar to those in the Local Group in terms of their sizes, luminosities, and mean metallicities. Within our photometric precision, there is no evidence of a metallicity spread, but we do observe possible extended star formation in several galaxies, as evidenced by a population of asymptotic giant branch stars brighter than the red giant branch tip. The new dwarfs do not show any signs of tidal disruption. Together with the recently reported dwarf galaxies by the complementary PISCeS survey, we study the luminosity function and 3D structure of the group. By comparing the observed luminosity function to the high-resolution cosmological simulation IllustrisTNG, we find agreement within a 90% confidence interval. However, Cen A seems to be missing its brightest satellites and has an overabundance of the faintest dwarfs in comparison to its simulated analogs. In terms of the overall 3D distribution of the observed satellites, we find that the whole structure is flattened along the line-of-sight, with a root-mean-square (rms) height of 130 kpc and an rms semi-major axis length of 330 kpc. Future distance measurements of the remaining dwarf galaxy candidates are needed to complete the census of dwarf galaxies in the Centaurus group.

scholarly journals Statistical analysis of the red giant distributions of old open clusters

1984 ◽  
Vol 105 ◽  
pp. 97-100
Author(s):  
G. Barbaro ◽  
L. Pigatto
Keyword(s):  
Statistical Analysis ◽  
Luminosity Function ◽  
Open Clusters ◽  
Red Giant ◽  
Hr Diagram

In order to verify the agreement with the theory of the observed HR diagram as a whole, 38 open clusters with (B-V)o, t≥0.10 at the turnoff, have been analyzed with particular regard to the RGB luminosity function.

scholarly journals The Distance Modulus of LMC

1986 ◽  
Vol 116 ◽  
pp. 513-514
Author(s):  
Cesare Chiosi ◽  
Luisa Pigatto
Keyword(s):  
Luminosity Function ◽  
Main Sequence ◽  
Bimodal Distribution ◽  
Distance Modulus ◽  
Red Giants ◽  
Ccd Photometry ◽  
Giant Stars ◽  
Red Giant Clump ◽  
Classical Models ◽  
Red Giant

Deep CCD photometry of the star clusters NGC2162 and NGC2190 in LMC presented by Schommer et al. (1984) is used togheter with new evolutionary models computed by Bertelli et al. (1985a) which take into account overshooting from convective cores, to derive the clusters ages and the distance modulus of LMC. A preliminary analysis of the two clusters indicates that NGC 2162 and NGC 2190 belong to the same class of clusters discussed by Barbaro and Pigatto (1984). In fact, for the turn-off mass estimated by means of classical models (<2.2m⊙) these clusters should possess an extended red giant branch and a bimodal distribution of red stars (cifr. Fig.2). On the contrary they show a clump of red stars. This means that ages and other properties derived from classical models for this range of masses, may not correspond to reality. With the new models, stars of mass as low as 1.6 m⊙, ignite helium in non degenerate conditions, avoid the long lived RG phase, and burn helium as more massive stars. As consequence of it, a clump of red giants is expected. In Fig.1, we show new isochrones (Bertelli et al. 1985b) derived from models with overshooting, overlaid to the CM diagram of NGC 2162. Theoretical luminosities and Teff's are converted into Mv:(B-V)o plane by means of Teff:(B-V):BC scales based on models atmospheres collected from several authors (Chiosi, 1985). At any given age, the new isochrones run brighter than those of Ciardullo and Demarque (1977). By means of the luminosity function, a method more objective (Paczsynski, 1984) than the standard one of ZAMS and/or isochrone fitting, with a reddening of E(B-V)=0.06 and chemical composition X=0.700 and Z=0.02, we find ages of 1 109yr and a true distance modulus of (m-M)O=18.6 instead of 18.2±0.2 mag given by Schommer et al.(1984). Fig.2 shows the theoretical luminosity function at age 1 109yr, (age preliminarly assigned to the clusters by isochrone fitting) for main sequence and red giant stars obtained with Salpeter's IMF (top panel), compares it with the correspondent one of Ciardullo and Demarque(1977), and finally shows the observational LF we derive from stars counts(bottom panel) for NGC 2162. By imposing coincidence between theoretical and observational LF's at the side of main sequence fall-off and rising of the red giant clump, we derive the distance modulus (m-M)O=18.6. In conclusions, models with overshooting not only interpret the morphology of this class of clusters, but assigne LMC a distance modulus in agreement with other independent determinations (Walker, 1984; Visvanathan, 1985).

scholarly journals The Red Giant Branch luminosity function bump

2003 ◽  
Vol 410 (2) ◽  
pp. 553-563 ◽  
Author(s):  
M. Riello ◽  
S. Cassisi ◽  
G. Piotto ◽  
A. Recio-Blanco ◽  
F. De Angeli ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Red Giant

scholarly journals BVIPhotometry and the Red Giant Branch Luminosity Function of M15

2014 ◽  
pp. 000-000
Author(s):  
Diane K. Feuillet ◽  
Nathaniel E. Q. Paust ◽  
Brian Chaboyer
Keyword(s):  
Luminosity Function ◽  
Red Giant

scholarly journals The Distance Modulus of LMC

1986 ◽  
Vol 116 ◽  
pp. 513-514
Author(s):  
Cesare Chiosi ◽  
Luisa Pigatto
Keyword(s):  
Luminosity Function ◽  
Main Sequence ◽  
Bimodal Distribution ◽  
Distance Modulus ◽  
Red Giants ◽  
Ccd Photometry ◽  
Giant Stars ◽  
Red Giant Clump ◽  
Classical Models ◽  
Red Giant

Deep CCD photometry of the star clusters NGC2162 and NGC2190 in LMC presented by Schommer et al. (1984) is used togheter with new evolutionary models computed by Bertelli et al. (1985a) which take into account overshooting from convective cores, to derive the clusters ages and the distance modulus of LMC. A preliminary analysis of the two clusters indicates that NGC 2162 and NGC 2190 belong to the same class of clusters discussed by Barbaro and Pigatto (1984). In fact, for the turn-off mass estimated by means of classical models (<2.2mO) these clusters should possess an extended red giant branch and a bimodal distribution of red stars (cifr. Fig.2). On the contrary they show a clump of red stars. This means that ages and other properties derived from classical models for this range of masses, may not correspond to reality. With the new models, stars of mass as low as 1.6 mO, ignite helium in non degenerate conditions, avoid the long lived RG phase, and burn helium as more massive stars. As consequence of it, a clump of red giants is expected. In Fig.1, we show new isochrones (Bertelli et al. 1985b) derived from models with overshooting, overlaid to the CM diagram of NGC 2162. Theoretical luminosities and Teff's are converted into Mv:(B-V)o plane by means of Teff:(B-V):BC scales based on models atmospheres collected from several authors (Chiosi, 1985). At any given age, the new isochrones run brighter than those of Ciardullo and Demarque (1977). By means of the luminosity function, a method more objective (Paczsynski, 1984) than the standard one of ZAMS and/or isochrone fitting, with a reddening of E(B-V)=0.06 and chemical composition X=0.700 and Z=0.02, we find ages of 1 109yr and a true distance modulus of (m-M)O=18.6 instead of 18.2±0.2 mag given by Schommer et al.(1984). Fig.2 shows the theoretical luminosity function at age 1 109yr, (age preliminarly assigned to the clusters by isochrone fitting) for main sequence and red giant stars obtained with Salpeter's IMF (top panel), compares it with the correspondent one of Ciardullo and Demarque(1977), and finally shows the observational LF we derive from stars counts(bottom panel) for NGC 2162. By imposing coincidence between theoretical and observational LF's at the side of main sequence fall-off and rising of the red giant clump, we derive the distance modulus (m-M)O=18.6. In conclusions, models with overshooting not only interpret the morphology of this class of clusters, but assigne LMC a distance modulus in agreement with other independent determinations (Walker, 1984; Visvanathan, 1985).

scholarly journals The effect of diffusion on the red giant luminosity function ‘bump’

1997 ◽  
Vol 290 (3) ◽  
pp. 515-520 ◽  
Author(s):  
Santi Cassisi ◽  
Scilla Degl'Innocenti ◽  
Maurizio Salaris
Keyword(s):  
Luminosity Function ◽  
Red Giant

scholarly journals The Planetary Nebulae Luminosity Function (PNLF): current perspectives

2016 ◽  
Vol 12 (S323) ◽  
pp. 298-302 ◽  
Author(s):  
Roberto H. Méndez
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Surface Brightness ◽  
Luminosity Function ◽  
Recent Progress ◽  
Historical Review ◽  
Stellar Populations ◽  
Surface Brightness Fluctuations ◽  
Distance Indicator ◽  
Red Giant

AbstractThis paper starts with a brief historical review about the PNLF and its use as a distance indicator. Then the PNLF distances are compared with Surface Brightness Fluctuations (SBF) distances and Tip of the Red Giant Branch (TRGB) distances. A Monte Carlo method to generate simulated PNLFs is described, leading to the last subject: recent progress in reproducing the expected maximum final mass in old stellar populations, a stellar astrophysics enigma that has been challenging us for quite some time.

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