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Record W2903857420 · doi:10.3847/1538-4357/aae9e6

Spectroscopy of the K0 Binary Giant α UMa

2018· article· en· W2903857420 on OpenAlexaff
David F. Gray

Bibliographic record

VenueThe Astrophysical Journal · 2018
Typearticle
Languageen
FieldPhysics and Astronomy
TopicStellar, planetary, and galactic studies
Canadian institutionsWestern University
Fundersnot available
KeywordsPhysicsAstrophysicsRadial velocityLine (geometry)Absolute magnitudeSpectral lineGiant starStarsAstronomyGeometry

Abstract

fetched live from OpenAlex

Abstract High-resolution spectroscopic observations of the K0 II–III star α UMa were taken at the Elginfield Observatory over 11 years. Radial velocities were measured for nine of these years. They do not cover enough of the 44.5 year orbital period to give definitive elements on their own, but combined with published visual orbits, the spectroscopic-orbit parameters are well constrained. The spectra show no evidence of the secondary star, which remains an unsolved puzzle. Line-depth ratios show that α UMa has temperature variations ∼3 K, possibly periodic, over the 2001–2010 interval. Fourier analysis of the line broadening gives the projected rotation velocity of 2.66 ± 0.15 km s−1 and a radial-tangential macroturbulence dispersion of 4.97 ± 0.08 km s−1. The third-granulation signature shows the granulation velocities of α UMa to be essentially solar, with a scale factor of 0.98 ± 0.10. The absolute radial velocity of the star, with granulation blueshifts removed is −10,035 ± 100 m s−1 at the mean time of the observations, 2005.2544. The line bisector of Fe i λ6253 is normal and shows the classic “C” shape with the blue-most point commensurate with its absolute magnitude. Mapping this bisector on to the third signature gives a flux deficit similar to those of other giants, with a fractional area of 0.131, suggesting a temperature difference between granules and lanes of 127 K. The velocity position of the deficit is slightly higher than that for previously analyzed giants, extending the correlation with absolute magnitude.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: Observational
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.003
Threshold uncertainty score0.005

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0010.000
Science and technology studies0.0010.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0010.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.010
GPT teacher head0.234
Teacher spread0.224 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designObservational
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations7
Published2018
Admission routes1
Has abstractyes

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