| 1. |
- Garcia, Lopez Ramon J, et al.
(author)
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Boron in very metal-poor stars
- 1998
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In: ASTROPHYSICAL JOURNAL. - : UNIV CHICAGO PRESS. - 0004-637X. ; 500:1, s. 241-256
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Journal article (peer-reviewed)abstract
- We have observed the B I lambda 2497 line to derive the boron abundances of two very metal-poor stars selected to help in tracing the origin and evolution of this element in the early Galaxy: BD +23 degrees 3130 and HD 84937. The observations were conduct
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| 4. |
- Karlsson, Bengt, et al.
(author)
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Thyroid dysfunction in Down's syndrome : relation to age and thyroid autoimmunity
- 1998
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In: Archives of Disease in Childhood. - 0003-9888 .- 1468-2044. ; 79:3, s. 242-245
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Journal article (peer-reviewed)abstract
- BACKGROUND: The prevalence of thyroid disease is increased in Down's syndrome. Most available data come from cross sectional studies. AIMS: To study longitudinally thyroid function in patients with Down's syndrome in Uppsala county (85 patients) up to the age of 25 years. METHODS: Observational study based on yearly follow up in a children's clinic. Thyroid function tests were performed at each visit to the clinic. RESULTS: Hypothyroidism was found in 30 and hyperthyroidism was found in two of the 85 patients. No sex difference was seen. Half of the patients with hypothyroidism acquired the condition before the age of 8 years, but only one of them displayed thyroid autoantibodies at diagnosis. Most patients who developed hypothyroidism after this age had thyroid autoantibodies. In the prepubertal patients with hypothyroidism, growth velocity was lower during the year before the start of thyroxine treatment than during the year after treatment began; it was also lower than that of sex and age matched euthyroidic children with Down's syndrome. CONCLUSION: Thyroid dysfunction in patients with Down's syndrome is common in childhood. Consequently, annual screening is important. Autoimmune thyroid disease is uncommon in young children with Down's syndrome but is common after 8 years of age.
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| 5. |
- Tomkin, Jocelyn, et al.
(author)
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The rise and fall of the NaMgAl stars
- 1997
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In: ASTRONOMY AND ASTROPHYSICS. - 0004-6361. ; 327:2, s. 587-597
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Journal article (peer-reviewed)abstract
- We have made new abundance determinations for a sample of NaMgAl stars. These stars, which are a subgroup of the nearby metal-rich field F and G disk dwarfs, were first identified by Edvardsson et al. (1993) on the basis of their apparent enrichment in Na, Mg and Al relative to other elements. The discovery of a planetary companion to the nearby solar type star 51 Peg (Mayor & Queloz 1995) combined with Edvardsson et al.'s earlier identification of 51 Peg as a NaMgAl star highlighted the group's potential importance. Our new analysis, which uses new spectra of higher resolution and better wavelength coverage than the analysis of Edvardsson et al., shows that the Na, Mg and Al abundances of the NaMgAl stars are indistinguishable from those of non-NaMgAl stars with otherwise similar properties. The group thus appears to be spurious.Our study, which includes 51 Peg, also provides the most complete set of abundances for this star available to date. The new Fe abundance, [Fe/H] = +0.20 +- 0.07, of 51 Peg confirms earlier measurements of its metal richness. Abundances for 19 other elements, including C, N and O, reveal a fairly uniform enrichment similar to that of Fe and show no evidence of abnormality compared to other metal rich stars of similar spectral type.
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| 6. |
- Ardeberg, Arne, et al.
(author)
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On the history of star formation in the bar of the Large Magellanic Cloud
- 1997
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In: ASTRONOMY AND ASTROPHYSICS. - : SPRINGER VERLAG. - 0004-6361. ; 322:2, s. L13-L16
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Journal article (peer-reviewed)abstract
- With the HST PC and uvby photometry, we investigate evolutionary signatures in a field in the centre of the LMC Bar. Field stars close to the turn off point in the HR diagram are used for a study of ages and evolution of the stellar popu lations dominatin
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| 7. |
- Asplund, Martin, et al.
(author)
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A stellar endgame - The born-again Sakurai's object
- 1997
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In: ASTRONOMY AND ASTROPHYSICS. - : SPRINGER VERLAG. - 0004-6361. ; 321:2, s. L17-L20
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Journal article (peer-reviewed)abstract
- The surface chemical composition of this remarkable star shows that it is hydrogen-deficient, carbon-rich and enriched in the light s-process elements. Spectra taken in May and October 1996 indicate a decrease in the surface hydrogen abundance by 0.7 dex
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| 8. |
- Asplund, Martin, et al.
(author)
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Abundance similarities between the R CrB star V854 Cen and the born-again Sakurai's object
- 1998
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In: ASTRONOMY AND ASTROPHYSICS. - : SPRINGER VERLAG. - 0004-6361. ; 332:2, s. 651-660
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Journal article (peer-reviewed)abstract
- The elemental abundances of the mildly hydrogen-deficient R Coronae Borealis (R CrB) star V854 Cen have been estimated. The R CrB stars have been divided into majority and minority classes judging by their abundance patterns. Class assignment has previous
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