Explanipedia

Chapter V: Report of the Executive Committee 1997-2000 Open

Robert P. Kraft, F. Pacini, J. Andersen, H. Rickman, Claudio Anguita , et al. · 2001

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Getting the Red Out: A Stellar Approach to Determining Spatial Variations of Interstellar Dust Open

Inese I. Ivans, C. Sneden, Robert P. Kraft, N. B. Suntzeff, Verne V. Smith , et al. · 2000

Physics Environmental science

By employing two different spectroscopic techniques we have mapped out the variable ISM dust extinction endemic to globular cluster M4. We derive an average E(B-V) reddening of 0.33 +/- 0.01 and R = 3.4 +/- 0.4, both in good agreement with…

Getting the Red Out: A Stellar Approach to Determining Spatial Variations of Interstellar Dust Open

Inese I. Ivans, C. Sneden, Robert P. Kraft, N. B. Suntzeff, Verne V. Smith , et al. · 2000

Physics Philosophy Computer science

By employing two different spectroscopic techniques we have mapped out the variable ISM dust extinction endemic to globular cluster M4. We derive an average E(B-V) reddening of 0.33 +/- 0.01 and R = 3.4 +/- 0.4, both in good agreement with…

Globular Cluster Giant Branch Luminosity Functions: “Extra Stars” and “Deep Mixing” Open

G. E. Langer, Michael Bolte, Eric L. Sandquist · 2000

Physics

We explore the possibility that "deep mixing" is the reason that there are "too many" red giants in the Galactic globular clusters M5 and M30. Deep mixing has often been invoked to account for the abundance anomalies observed in many brigh…

Star-to-Star Abundance Variations among Bright Giants in the Mildly Metal-poor Globular Cluster M4 Open

Inese I. Ivans, C. Sneden, Robert P. Kraft, N. B. Suntzeff, Verne V. Smith , et al. · 1999

Physics

We present a chemical composition analysis of 36 giants in the nearby mildly metal-poor (S[Fe/H]T \\[1.18) “ “ CN-bimodal ÏÏ globular cluster M4. The stars were observed at the Lick and McDonald Observatories using high-resolution e � chel…

An Extremely Lithium-rich Bright Red Giant in the Globular Cluster M3 Open

Robert P. Kraft, R. C. Peterson, Puragra Guhathakurta, C. Sneden, J. P. Fulbright , et al. · 1999

Physics Medicine

We have serendipitously discovered an extremely lithium-rich star on the red giant branch of the globular cluster M3 (NGC 5272). An echelle spectrum obtained with the Keck I HIRES reveals a Li I 6707 Angstrom resonance doublet of 520 milli…

Wide‐Field CCD Photometry of the Globular Cluster M30 Open

Eric L. Sandquist, Michael Bolte, G. E. Langer, J. E. Hesser, C. Mendes de Oliveira · 1999

Physics

Received; accepted We present new V I photometry for the halo globular cluster M30 (NGC 7099 = C2137-174), and compute luminosity functions (LFs) in both bands for samples of about 15,000 hydrogen-burning stars from near the tip of the red…

Thermonuclear Reaction Rates for the $^2^4$Mg(p,\gamma)$^2^5$Al Reaction Open

C.S. Zaidins, G. E. Langer · 1997

Physics Chemistry Materials science

There is substantial evidence that most of the material in the envelopes of some globular cluster giants is mixed so deeply into the interior that the abundances of many of the light elements, including magnesium and aluminum, are reshuffl…

Observational Constraints on the Origin of the Aluminum Enhancements and Magnesium Depletions in Bright M13 Giants Open

G. E. Langer, R. D. Hoffman, C.S. Zaidins · 1997

Physics Chemistry

The most recent observations of the abundances of oxygen, sodium, magnesium, and aluminum provide strong support for the idea that "deep mixing" occurs within M13 giants. In deep mixing scenarios, material from the envelopes of globular cl…

Aluminum-Oxygen Abundance Anticorrelations and Deep-Mixing Scenarios for Globular-Cluster Giants Open

G. E. Langer, R. D. Hoffman · 1995

Physics Computer science Sociology

We explore the conditions under which LARGE aluminum enhancements might be produced by very deep mixing and proton capture nucleosynthesis in bright globular cluster giants. We find that: (1) The initial abundances of neutron rich magnesiu…

Sodium-oxygen abundance anticorrelations and deep-mixing scenarios for globular-cluster giants Open

G. E. Langer, R. D. Hoffman, C. Sneden · 1993

Physics Chemistry Biology

We explore and extend the suggstion that 23Na might be produced in the interior of an evolving low-mass globular cluster giant and mixed to the surface (Kudryashov & Tutukov 1988, Denisenkov & Denisenkova 1990). The reaction rates alone sh…

3883 CN band strengths for 238 metal-poor halo giants - Evidence for chemical differences between globular-cluster and halo field giants Open

G. E. Langer, N. B. Suntzeff, Robert P. Kraft · 1992

Physics Chemistry Sociology

Cyanogen band strengths mCN for 238 metal-poor giants in the halo field and in 13 globular clusters are tabulated. The distribution of mCN in field giants of intermediate metallicity is compared with that of giants of similar evolutionry s…

On the evidence for a cyanogen gradient in 47 Tucanae Open

G. E. Langer, R. F. Shipman, Miles J. Weida · 1989

Geology Physics Chemistry

The evidence for a radial gradient in the distribution of CN strengths among 47 Tuc giants (Norris and Freeman, 1979) is examined. Apparent differences are found between the distribution of cyanogen strengths determined from stellar spectr…

On the carbon abundance of subgiant stars in the globular cluster M 92 Open

G. E. Langer, Robert P. Kraft, D. F. Carbon, Eileen D. Friel, J. B. Oke · 1986

Physics Materials science Biology

The authors find that >[C/Fe]< ≈ 0.0 in stars at the base of the subgiant branch and approaches +0.1 in stars near the main-sequence turnoff in the metal-poor globular cluster M92. The carbon abundance falls on the average by about 0.5 dex…

Bimodal cyanogen distributions in moderately metal-poor globular clusters. II - Evidence for 'mixing' and 'saturation' Open

G. E. Langer · 1985

Physics Materials science Chemistry

Recent work indicates that both the observed carbon and nitrogen abundances and the bimodal 3883 A cyanogen distributions that are often observed in moderately metal-poor globular clusters fit easily into a simple mixing scenario in which …

Carbon and nitrogen abundances in old, very metal-poor stars A reprise based on the low-resolution Lick survey Open

G. E. Langer, Robert P. Kraft · 1984

Physics Chemistry Materials science

A summary is given of the carbon and nitrogen abundances found in the Lick survey of nearly 300 old, very metal-poor stars (Fe/H of less than -1.3). The survey consists of population samples drawn from various stellar subsystems of the Gal…

Carbon and nitrogen abundances in extremely metal-deficient red giants Open

Robert P. Kraft, N. B. Suntzeff, G. E. Langer, C. F. Trefzger, E. D. Friel , et al. · 1982

Physics Materials science Biology

The relative carbon and nitrogen abundances of a sample of metal-poor halo giants are analyzed with respect to their similarity with the abundances of similar stars in globular clusters. Spectra of 64 giants selected from the objective pri…

FG Sagittae: The <i>s</i>-Process Episode Open

G. E. Langer, Robert P. Kraft, Kurt S. Anderson · 1974

Physics

The spectrum of the supergiant FG Sge has been studied from a series of high dispersion 120-in. coudé spectrograms obtained during the interval 1969–72, thus continuing the work of Herbig and Boyarchuk (1968). The star, of effective temper…

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