''Chemical structure'' in the red giant Hertzsprung--Russell diagram, and the age of the galactic disk

Journal Article · Mon Jul 01 00:00:00 EDT 1985 · Sov. Astron. (Engl. Transl.); (United States)

OSTI ID:6100490

Marsakov, V A; Suchkov, A A

The dependence of the logarithmic metallicity parameter (Fe/H) on spectral type (or color) and luminosity is investigated, using published photometry, for about 1400 red giants in the galactic disk. Type G8 III stars are the most metal-deficient (<(Fe/H)> = -0.21) and show the least dispersion in metallicity (sigma/sub / = 0.15), comprising a group exceptionally uniform in heavy-element abundance Z. Type K2 III objects are the richest in metals (<(Fe/H)> = -0.04) and show the largest spread (sigma/sub / = 0.19); for later types (Fe/H) diminishes again. In the HR diagram the metal-poor ((Fe/H)<-0.1) giants form a ''clump'' at M/sub V/ = 1/sup m/.0--2/sup m/.0, B-Vroughly-equal1/sup m/.0. Most of these G6--K0 III stars belong to the horizontal rather than the ascending giant branch and represent the oldest disk population. Nevertheless the metal-poor disk giants evidently are no older than the ancient open cluster NGC 188 (roughly-equal7 x 10/sup 9/ yr), confirming that the disk is roughly-equal6 x 10/sup 9/ yr younger than the > or approx. =13 x 10/sup 9/ yr old halo.

• Research Organization: Rostov University
• OSTI ID: 6100490
• Journal Information: Sov. Astron. (Engl. Transl.); (United States), Vol. 29:4
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
MILKY WAY
AGE ESTIMATION
CHEMICAL COMPOSITION
ELEMENT ABUNDANCE
RED GIANT STARS
HERTZSPRUNG-RUSSELL DIAGRAM
STAR CLUSTERS
CLASSIFICATION
COLOR
LUMINOSITY
METALS
ABUNDANCE
DIAGRAMS
ELEMENTS
GALAXIES
GIANT STARS
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
PHYSICAL PROPERTIES
STARS
640102* - Astrophysics &amp; Cosmology- Stars &amp; Quasi-Stellar
Radio &amp; X-Ray Sources
640105 - Astrophysics &amp; Cosmology- Galaxies