Gaia-ESO Survey: Detailed elemental abundances in red giants of the peculiar globular cluster NGC1851

A general review is given of the astrophysical information obtainable from observations of molecules in stellar photospheres. Through selected examples, the use of molecules as thermometers (e.g., the OH 3 μm V-R lines in the Sun and α Ori) and as probes of the isotopic (e.g., iMg in metal-poor dwarfs, 12C/13C in cool carbon stars) and elemental abundances (e.g., CNO in red giants) is sketched. All of the (carefully) selected analyses assume that local thermodynamic equilibrium (LTE) prevails.

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On the Behaviour of Globular Cluster Red Giants in the Color-Magnitude Diagram

Symposium - International Astronomical Union ◽

10.1017/s0074180900018301 ◽

1974 ◽

Vol 66 ◽

pp. 240-243

Author(s):

R. M. Russev

Keyword(s):

Globular Cluster ◽

Red Giants ◽

Magnitude Diagram

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The Hertzsprung-Russell Diagram of Metal-Poor Disk Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900145644 ◽

1978 ◽

Vol 80 ◽

pp. 273-276

Author(s):

Sidney van den Bergh

Keyword(s):

Velocity Field ◽

Globular Cluster ◽

High Velocity ◽

Population Model ◽

Open Cluster ◽

Ultraviolet Excess ◽

Red Giants ◽

The Sun ◽

The Galaxy ◽

Red Giant

A quarter of a century ago Keenan and Keller (1953) showed that the majority of high-velocity stars near the Sun outline a Hertzsprung-Russell diagram similar to that of old Population I. This result, which did not appear to fit into Baade's (1944) two-population model of the Galaxy was ignored (except by Roman 1965) for the next two decades. Striking confirmation of the results of Keenan and Keller was, however, obtained by Hartwick and Hesser (1972). Their work appears to show that high-velocity field stars with an ultraviolet excess (which measures Fe/H) of δ(U-B) ≃ +0m.11 lie on a red giant branch that is more than a magnitude fainter than the giant branch of the strong-lined globular cluster 47 Tuc for which δ(U-B) ≃ +0m.10. Furthermore Demarque and McClure (1977) show that the red giants in the old metal poor [δ(U-B) ≃ +0m.11] open cluster NGC 2420 are significantly fainter than are those in 47 Tuc. Calculations by these authors show that the observed differences between the giants in 47 Tuc and in NGC 2420 can be explained if either (1) 47 Tuc is richer in helium than NGC 2420 by ΔY ≃ 0.1 or (2) if 47 Tuc has a ten times lower value of Z(CNO) than does NGC 2420.

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