scholarly journals Oxygen isotopic ratios in intermediate-mass red giants

2015 ◽  
Vol 578 ◽  
pp. A33 ◽  
Author(s):  
T. Lebzelter ◽  
O. Straniero ◽  
K. H. Hinkle ◽  
W. Nowotny ◽  
B. Aringer
Keyword(s):  
Isotopic Ratios ◽  
Red Giants ◽  
Intermediate Mass ◽  
Oxygen Isotopic

Changes of Ionic and Oxygen Isotopic Composition of the Snowpack at the Glacier Austre Okstindbreen, Norway, 1995

1998 ◽  
Vol 29 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Peter Raben ◽  
Wilfred H. Theakstone
Keyword(s):  
Isotopic Composition ◽  
Sea Level ◽  
Oxygen Isotopes ◽  
Oxygen Isotopic Composition ◽  
Isotopic Ratios ◽  
Vertical Variations ◽  
Oxygen Isotopic ◽  
The Difference ◽  
Liquid Precipitation ◽  
Different Altitudes

Marked vertical variations of ions and oxygen isotopes were present in the snowpack at the glacier Austre Okstindbreen during the pre-melting phase in 1995 at sites between 825 m and 1,470 m above sea level. As the first meltwater percolated from the top of the pack, ions were moved to a greater depth, but the isotopic composition remained relatively unchanged. Ions continued to move downwards through the pack during the melting phase, even when there was little surface melting and no addition of liquid precipitation. The at-a-depth correlation between ionic concentrations and isotopic ratios, strong in the pre-melting phase, weakened during melting. In August, concentrations of Na+ and Mg2+ ions in the residual pack were low and vertical variations were slight; 18O enrichment had occurred. The difference of the time at which melting of the snowpack starts at different altitudes influences the input of ions and isotopes to the underlying glacier.

scholarly journals OXYGEN ISOTOPIC RATIOS IN COOL R CORONAE BOREALIS STARS

2010 ◽  
Vol 714 (1) ◽  
pp. 144-154 ◽  
Author(s):  
D. A. García-Hernández ◽  
David L. Lambert ◽  
N. Kameswara Rao ◽  
Ken H. Hinkle ◽  
Kjell Eriksson
Keyword(s):  
Isotopic Ratios ◽  
Oxygen Isotopic ◽  
R Coronae Borealis Stars

scholarly journals Nucleosynthesis of Light-Element Isotopes in Evolved Stars Experiencing Extended Mixing

2009 ◽  
Vol 26 (3) ◽  
pp. 161-167 ◽  
Author(s):  
S. Palmerini ◽  
M. Busso ◽  
E. Maiorca ◽  
R. Guandalini
Keyword(s):  
Mass Transport ◽  
Isotopic Composition ◽  
Light Element ◽  
Asymptotic Giant Branch ◽  
Red Giants ◽  
Agb Stars ◽  
Intermediate Mass ◽  
Evolved Stars ◽  
Magnetic Buoyancy ◽  
Slow Mixing

AbstractWe present computations of nucleosynthesis in red giants and Asymptotic Giant Branch (AGB) stars of Population I experiencing extended mixing. The assumed physical cause for mass transport is the buoyancy of magnetized structures, according to recent suggestions. The peculiar property of such a mechanism is to allow for both fast and slow mixing phenomena, as required for reproducing the spread in Li abundances displayed by red giants and as discussed in an accompanying paper. We explore here the effects of this kind of mass transport on CNO and intermediate-mass nuclei and compare the results with the available evidence from evolved red giants and from the isotopic composition of presolar grains of AGB origin. It is found that a good general accord exists between predictions and measurements; in this framework we also show which type of observational data best constrains the various parameters. We conclude that magnetic buoyancy, allowing for mixing at rather different speeds, can be an interesting scenario to explore for explaining together the abundances of CNO nuclei and of Li.

scholarly journals Red Giants as Precursors of Planetary Nebulae

1983 ◽  
Vol 103 ◽  
pp. 267-280 ◽  
Author(s):  
Alvio Renzini
Keyword(s):  
Binary Stars ◽  
Planetary Nebulae ◽  
Mass Range ◽  
Dust Formation ◽  
Red Giants ◽  
Circumstellar Envelopes ◽  
Physical Processes ◽  
Intermediate Mass ◽  
Intermediate Mass Stars ◽  
Thermal Pulses

Several physical processes taking place during the red (super)giant phase of intermediate-mass stars have direct observational consequences for the subsequent nebular stage. These processes include: the regular wind and the envelope ejection, the thermal pulses during the AGB phase, the dredge-up processes, and the dust formation in expanding circumstellar envelopes. In this paper it is briefly discussed how such processes affect the mass range of PN nuclei and their evolution, and the PN lifetime, composition and dust content. The last section is devoted to a cursory discussion of PNe which can be generated by binary stars.

scholarly journals Temporal variations of the CO2 concentration and its carbon and oxygen isotopic ratios in a temperate forest in the central part of the main island of Japan

Tellus B ◽  
1997 ◽  
Vol 49 (4) ◽  
pp. 364-381 ◽  
Author(s):  
Takakiyo Nakazawa ◽  
Shohei Murayama ◽  
Mitsuko Toi ◽  
Misa Ishizawa ◽  
Kaori Otonashi ◽  
...  
Keyword(s):  
Temperate Forest ◽  
Co2 Concentration ◽  
Temporal Variations ◽  
Isotopic Ratios ◽  
Main Island ◽  
Oxygen Isotopic

scholarly journals Recent ice-core climate records from the Cordillera Blanca, Peru

1995 ◽  
Vol 21 ◽  
pp. 225-230 ◽  
Author(s):  
M. E. Davis ◽  
L. G. Thompson ◽  
E. Mosley-Thompson ◽  
P. N. Lin ◽  
V. N. Mikhalenko ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Warming Trend ◽  
Isotopic Ratios ◽  
Weather Station ◽  
Climate Record ◽  
Climatic Variations ◽  
Recent Warming ◽  
Lower Elevation ◽  
Oxygen Isotopic

Ice cores recently drilled to bedrock on the col of Huascarán (9°06′ S, 77°36′ W, 6047 m a.s.l.) offer the potential for a long, annually resolved climate record from tropical South America. This paper presents the record from 1950 to 1993 preserved in microparticle and nitrate concentrations and oxygen-isotopic ratios. Average monthly temperatures from a satellite-linked automatic weather station installed on nearby Hualcán in 1991 are presented. Annual temperatures from local high-altitude meteorological stations, along with the annual Huascarán isotopic record, show a warming trend over the last two decades. The marked preservation of the climate record in oxygen-isotopic ratios on Huascarán is absent at lower-elevation sites, which have been affected by the recent warming. This paper demonstrates the establishment of a time-scale for the Huascarán core, the preservation of the climatic signal with depth and the linkage of the ice-core “proxy-climate” parameters with measured climatic variations.

scholarly journals Oxygen isotopic ratios of some Himalayan glaciers

Tellus B ◽  
1984 ◽  
Vol 36 (4) ◽  
pp. 300-302
Author(s):  
V. N. Nijampurkar ◽  
N. Bhandari
Keyword(s):  
Isotopic Ratios ◽  
Himalayan Glaciers ◽  
Oxygen Isotopic
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