Task force 1: The underserved

Haywood, L. Julian; Francis, Charles K.; Cregler, Louis L.; Freed, Michael D.; Skorton, David J.

doi:10.1016/0735-1097(94)90278-x

Cited by 12 publications

(13 citation statements)

References 48 publications

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“…4). Recent observational results suggest that the IMF has indeed a universal Salpeter slope at the upper end and that any variability should be confined to the lower end (Haywood 1994, Meyer et al 1999). Contrary to the Salpeter IMF which raises monotically with decreasing stellar mass, the current observed IMF in the solar neighbourhood may be roughly flat at the lower end or even may peak at a mass around 0.25M ⊙ and decline into the brown dwarf regime.…”

Section: The Shape Of the Imf In A Metal Deficient Mediummentioning

confidence: 99%

The self-enrichment of galactic halo globular clusters

Parmentier

Gilmore

2001

A&A

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Abstract.We discuss the existence of a mass-metallicity relation among galactic halo globular clusters. The lack of any luminosity-metallicity correlation in globular cluster systems has been used as an argument against self-enrichment models of cluster formation. We show that such a relation is statistically present among the galactic Old Halo globulars. This observational correlation implies that the least massive old clusters are the most metal-rich. This is in contradiction with the idea that, if globular clusters were self-enriched systems, the most metal-rich clusters would also be the most massive ones. We further show that this anti-correlation is as predicted by self-enrichment models.

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Section: The Shape Of the Imf In A Metal Deficient Mediummentioning

confidence: 99%

The self-enrichment of galactic halo globular clusters

Parmentier

Gilmore

2001

A&A

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“…Andersen 2002Andersen , 1991Bahcall & Soneira 1980;Chiappini et al 1997;Bruzual & Charlot 2003;Bruzual A. & Charlot 1993;Haywood 1994;Matteucci 2009;Popper 1997;Hernandez et al 2000;Portinari & Chiosi 2000;Ribas et al 2000a,b, for representative works in the quoted fields).…”

Section: Analytical Relationsmentioning

confidence: 99%

The Pisa Stellar Evolution Data Base for low-mass stars

Dell’Omodarme

Valle

Degl’Innocenti

et al. 2012

A&A

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Context. The last decade showed an impressive observational effort from the photometric and spectroscopic point of view for ancient stellar clusters in our Galaxy and beyond, leading to important and sometimes surprising results. Aims. The theoretical interpretation of these new observational results requires updated evolutionary models and isochrones spanning a wide range of chemical composition so that the possibility of multipopulations inside a stellar cluster is also taken also into account. Methods. With this aim we built the new "Pisa Stellar Evolution Database" of stellar models and isochrones by adopting a welltested evolutionary code (FRANEC) implemented with updated physical and chemical inputs. In particular, our code adopts realistic atmosphere models and an updated equation of state, nuclear reaction rates and opacities calculated with recent solar elements mixture. Results. A total of 32 646 models have been computed in the range of initial masses 0.30 ÷ 1.10 M for a grid of 216 chemical compositions with the fractional metal abundance in mass, Z, ranging from 0.0001 to 0.01, and the original helium content, Y, from 0.25 to 0.42. Models were computed for both solar-scaled and α-enhanced abundances with different external convection efficiencies. Correspondingly, 9720 isochrones were computed in the age range 8÷15 Gyr, in time steps of 0.5 Gyr. The whole database is available to the scientific community on the web. Models and isochrones were compared with recent calculations available in the literature and with the color-magnitude diagram of selected Galactic globular clusters. The dependence of relevant evolutionary quantities, namely turn-off and horizontal branch luminosities, on the chemical composition and convection efficiency were analyzed in a quantitative statistical way and analytical formulations were made available for reader's convenience. These relations can be useful in several fields of stellar evolution, e.g. evolutionary properties of binary systems, synthetic models for simple stellar populations and for star counts in galaxies, and chemical evolution models of galaxies.

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“…However, Kuijken & Gilmore (1989) derived a scale height of 249 pc for the old-disk stars. Haywood (1994) showed, from an analysis of numerous star counts towards the pole using his self-consistent evolutionary model, that the thin disk scale height does not exceed 250 pc. Ojha (1999) also found that the scale height of the thin disk is 240 pc based on an analysis of two star count samples.…”

Section: Density Distribution In the Diskmentioning

confidence: 99%

Galactic structure studies with BATC star counts

Du¹,

Zhou²,

Ma³

et al. 2003

A&A

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Abstract.We report the first results of star counts carried out with the National Astronomical Observatories (NAOC) • 49 00 .0 (J2000) (Galactic coordinates: l = 169.95The field of view is 0.95 deg 2 , and the spatial scale was 1 .67. Since star counts at high galactic latitudes are not strongly related to the radial distribution, they are well suited to study the vertical distribution of the Galaxy. In our model, the distribution of stars perpendicular to the plane of the Galaxy is given by two exponential disks (thin disk plus thick disk) and a de Vaucouleurs halo. Also, based on star counts, we derive the scale heights of the thin disk to be 320 +14 −15 pc and of the thick disk to be 640 +30 −32 pc, respectively, with a local density of 7.0 ± 1% of the thin disk. The errors of scale heights and the corresponding space number density normalization are estimated at a 68% confidential level. The density law for the Galactic halo population is also investigated. We find that the observed counts support an axial ratio of c/a ≤ 0.6 for a de Vaucouleurs r 1/4 law, implying a more flattened halo. We consider that it is possible that the halo has two subpopulations-a flattened inner halo and a spherical outer halo in the Milky Way, and such a halo model might resolve many of the divergences in star count results. We also derive the stellar luminosity function (SLF) for the thin disk, and it partly agrees with the Hipparcos luminosity function.

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Task force 1: The underserved

Cited by 12 publications

References 48 publications

The self-enrichment of galactic halo globular clusters

The self-enrichment of galactic halo globular clusters

The Pisa Stellar Evolution Data Base for low-mass stars

Galactic structure studies with BATC star counts

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