Effects of main-sequence brightening on the luminosity evolution of elliptical galaxies

1976 ◽  
Vol 203 ◽  
pp. 63 ◽  
Author(s):  
B. M. Tinsley
Keyword(s):  
Main Sequence ◽  
Elliptical Galaxies ◽  
Luminosity Evolution

Questions on Pure Luminosity Evolution for Elliptical Galaxies

1999 ◽  
Vol 511 (2) ◽  
pp. 574-584 ◽  
Author(s):  
Ping He ◽  
Yuan‐Zhong Zhang
Keyword(s):  
Elliptical Galaxies ◽  
Luminosity Evolution

scholarly journals Infrared Observations of Giant Elliptical Galaxies: (V-K) Colors and the Infrared Hubble Diagram

1980 ◽  
Vol 92 ◽  
pp. 269-277
Author(s):  
Gary L. Grasdalen
Keyword(s):  
Elliptical Galaxies ◽  
Cosmological Models ◽  
Hubble Diagram ◽  
Infrared Observations ◽  
Color Evolution ◽  
Magnitude Diagram ◽  
Luminosity Evolution

The (V-K) colors of giant elliptical galaxies as a function of redshift are discussed. Present data are consistent with mild color evolution at z ~ 0.45. An infrared Hubble (redshift-magnitude) diagram is given. Cosmological models with qo = 0 and no luminosity evolution are clearly excluded by the present data. A wide variety of models including those with qo = 0 are permissible if luminosity evolution is included. Instrumental and programmatic implications of these results are summarized.

scholarly journals Visual–IR Color Gradients in Elliptical Galaxies

1987 ◽  
Vol 127 ◽  
pp. 443-444
Author(s):  
R. F. Peletier ◽  
E. A. Valentijn ◽  
R. F. Jameson
Keyword(s):  
Population Model ◽  
Stellar Population ◽  
Main Sequence ◽  
Elliptical Galaxies ◽  
Strong Constraint ◽  
Average Temperature ◽  
Simultaneous Measurements ◽  
Continuity Of Solutions ◽  
Different Populations ◽  
Color Gradients

Dissipational formation theories (e.g. Larson 1974) predict a metallicity change with distance from the center in elliptical galaxies. Several authors have reported small color gradients in visual colors like B–V and B–R. The interpretation of these data is not easy, due to uncertainties caused by the short wavelength–baseline, and by the presence of a hot stellar population suggested by IUE–data (e.g. Burstein et al. 1986). Simultaneous measurements of visual and visual-infrared colors provide the means to determine both the average temperature of the giant branch and the turnoff–temperature of the main sequence. This allows to model fractional contributions of different populations, including age– and metallicity–effects. The required continuity of solutions at different radii provides a strong constraint in selecting a more unique overall population model, and relieves the ambiguous interpretation of single measurements.

scholarly journals On the relation between rotation, convection and activity in intermediate-mass giants

2006 ◽  
Vol 2 (S239) ◽  
pp. 154-156
Author(s):  
P. Gondoin
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Empirical Relation ◽  
Rotation Period ◽  
Surface Flux ◽  
Type Systems ◽  
Intermediate Mass ◽  
X Ray ◽  
Red Giant ◽  
Luminosity Evolution

AbstractI found evidence that the X-ray surface flux of intermediate-mass G and K giants is correlated with their rotation period and Rossby number. Confidence in the degree of correlation is significantly higher when stellar gravity is taken into account. An empirical relation is found that accounts for the X-ray luminosity evolution of single intermediate-mass giants and giants in close or long-period binary systems, such as RS CVn-type systems, as they evolve off the main sequence towards the top of red giant branch.

scholarly journals The Stellar Content of the Nuclei of Spiral Galaxies

1983 ◽  
Vol 6 ◽  
pp. 157-163
Author(s):  
D. Crampton ◽  
R.D. McClure ◽  
A.P. Cowley
Keyword(s):  
Spectral Type ◽  
Stellar Population ◽  
Main Sequence ◽  
Spiral Galaxies ◽  
Elliptical Galaxies ◽  
Solar Neighbourhood ◽  
Stellar Content ◽  
Late Type ◽  
Metal Abundances ◽  
Hydrogen Lines

Numerous studies have been attempted to determine the stellar content of the nuclei of galaxies. In the case of elliptical galaxies observations show that there is a change in spectral type from later to earlier types correlated with a variation from high to low luminosity (e.g. Faber 1977). This has been interpreted for the most part as being due to differences in metal abundances in an old stellar population, although some recent studies suggest a variation in stellar age may be important as well (e.g. O’Connell 1980, Heckman 1980). The nuclear bulges of spiral galaxies also display a change from late to early spectral type along a sequence from high to low luminosity bulges. In this case, however, the assumption has almost universally been made that these differences are due to differences in age of the stellar population. In particular, most stellar models for the nuclear bulges of spiral galaxies have used solar neighbourhood metal- rich stars, and assumed that the strong hydrogen lines and weak metal lines in late-type spiral nuclei are due to the predominance of a very young main-sequence population rather than old metal-poor stars.

scholarly journals Infrared Observations of Elliptical Galaxies

1980 ◽  
Vol 92 ◽  
pp. 257-262 ◽  
Author(s):  
M. J. Lebofsky
Keyword(s):  
High Redshift ◽  
Elliptical Galaxies ◽  
Optical Studies ◽  
Infrared Observations ◽  
First Results ◽  
Infrared Wavelengths ◽  
Luminosity Evolution

A program to search for luminosity evolution of giant elliptical galaxies at high redshift has been begun at 2.2μm. Observing at infrared wavelengths offers the possibility of avoiding large and uncertain K corrections at redshifts near 1. First results of this program are in agreement with conclusions drawn from much larger optical studies, and demonstrate that luminosity evolution may be present.

scholarly journals Evolution of magnetic activity in intermediate-mass giants

2013 ◽  
Vol 9 (S302) ◽  
pp. 377-378
Author(s):  
Philippe Gondoin
Keyword(s):  
Main Sequence ◽  
Type Systems ◽  
Magnetic Activity ◽  
Surface Fluxes ◽  
Intermediate Mass ◽  
Empirical Relationships ◽  
X Ray ◽  
Rotation Periods ◽  
Red Giant ◽  
Luminosity Evolution

AbstractThe X-ray surface fluxes of intermediate-mass G and K giants are correlated with their rotation periods and Rossby numbers. Empirical relationships are presented that accounts for the X-ray luminosity evolution of single intermediate-mass giants, such as FK Comae-type stars, and of giants in close or long-period binaries, such as RS CVn-type systems, as they evolve off the main sequence towards the top of the red giant branch.

K-band Evolution of Elliptical Galaxies in the Cluster Abell 2390 at z=0.23

2006 ◽  
Vol 2 (S235) ◽  
pp. 187-187
Author(s):  
M. Alizadeh ◽  
A. Fritz ◽  
C. Da Rocha ◽  
B. L. Ziegler
Keyword(s):  
Near Infrared ◽  
Elliptical Galaxies ◽  
Morphological Data ◽  
Fundamental Plane ◽  
Cluster Of Galaxies ◽  
Distant Galaxies ◽  
Deep Imaging ◽  
Local Sample ◽  
Luminosity Evolution ◽  
Calar Alto

AbstractWe investigate the near-infrared K-band evolution of early-type galaxies in the cluster of galaxies Abell2390 at z = 0.23. Using the Omega-Prime camera at the 3.5-m Calar Alto telescope deep imaging (texp = 53 min) over a 6' × 6' field has been obtained. The measured K-band magnitudes of 28 galaxies are combined with the spectroscopic and morphological data of Fritz et al. (2005) to construct the Faber-Jackson and Fundamental Plane relations in the NIR. By comparing our distant galaxies to a local sample of cluster ellipticals (Pahre 1999), we find on average a mild luminosity evolution for both scaling relations (ΔMK ~ 0.6 − 0.7 mag) compatible with passive evolution of the stellar populations.

Chromospheric activity as a function of age in main-sequence stars

1966 ◽  
Vol 24 ◽  
pp. 40-43
Author(s):  
O. C. Wilson ◽  
A. Skumanich
Keyword(s):  
Main Sequence ◽  
The Sun ◽  
Main Sequence Stars ◽  
Tentative Conclusion ◽  
Chromospheric Activity ◽  
General Field ◽  
Large Clusters

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

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