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- Frisk, Urban Olof, 1954-
(författare)
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G och K stjärnors effektiva temperaturer och deras kol-, kväve- och syrehalter
- 1983
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study is aimed at increasing our knowledge and understanding of the evolutionary stages during and after the main sequence phase. The study is based on new photometric and spectroscopic observations of stars in the region from the main sequence and up to the red giants. The observations are calibrated against existing theoretical stellar model atmospheres to give the fundamental parameters of the stars and their surface abundancies of carbon, nitrogen and oxygen. It consists of two articles in English and a summary in Swedish.In article I the the well observed nearby giant Arcturus is studied in order to obtain a relaible temperature of the star. By comparing the observed fluxdistribution with theoretical detailed model atmospheres a temperature of 4375 K is obtained. It is found that the uncertainty (50 K) is dominated by possible errors in the data for the H absorption.Article II makes use of the method developed in article I and temperatures and surface gravities are determined for 22 stars. Using the spectroscopic data, microturbulent velocities and iron abundancies are calibrated against the model calculations. With the fundamental parameters of the stars known C,N and 0 abundancies can now be obtained. It is found that material processed by the CN-cycle is found in stars more luminous than log L/L = 0.8. Stars with low 12C/13C ratios (< 15) are found down to the luminosity log L/L = 1.2. In stars where processed material is observed, C is deficent and N is enhanced. The C/N and 12C/13C and their correlation with stellar mass is found to be consistent with a slow mixing during the main sequence.
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- Lundin Frisk, Emrik, 1994, et al.
(författare)
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The geosystem services concept – What is it and can it support subsurface planning?
- 2022
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Ingår i: Ecosystem Services. - : Elsevier BV. - 2212-0416. ; 58
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Forskningsöversikt (refereegranskat)abstract
- The subsurface is a multifunctional natural resource. However, a mindset of “out of sight, out of mind” and a first-come-first-served principle are prevalent when accessing these resources, compromising fair intergenerational and intragenerational distribution and sustainable development. As with the ecosystem services (ES) concept, which acknowledges the contribution of the living part of nature to human well-being, the concept of geosystem services (GS) has been suggested as a way to highlight abiotic services and services provided by the subsurface. The overall aim of this study was to review current definitions of GS and their categorisation, and to suggest how the concept of GS can support subsurface planning. A systematic literature review on GS was carried out following the PRISMA protocol drawing from the Scopus database. The emerging picture from the reviewed articles is that the GS concept is both one of novelty and one currently showing inconsistency, with two prominent definitions: A) GS are abiotic services that are the direct result of the planet's geodiversity, independent of the interactions with biotic nature – there is no differentiation between suprasurface and subsurface features, and B) GS provide benefits specifically resulting from the subsurface. Thirty-one out of thirty-nine GS listed in the reviewed literature are included in the abiotic extension of the common ES framework CICES v5.1, but some essential services are omitted. A unified definition of GS is desirable to build a common framework for classifying and describing GS, potentially following the CICES structure for ES. Such a framework can support systematic inclusion of GS in planning processes and contribute to improved subsurface planning. In planning practice, there are examples of important GS that are already included under the ES umbrella because planners are aware of their importance but a comprehensive framework to handle these services is lacking.
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