Composite spectra Paper 13: 93 Leonis, a chromospherically-active binary
Bibliographic record
Abstract
We isolate the spectrum of the secondary component of the composite-binary system 93 Leonis by spectrum subtraction, classify it, and measure the mass ratio of the system. An accurate visual orbit and a well-determined parallax provide reliable measurements of orbital inclination and distance, enabling us to determine precisely the individual masses and other stellar parameters. The primary star is of type ∼G7 III, and the secondary is a rapidly rotating star of type A7 IV. Our photographic spectra at 10 Å mm−1 are invaluable for accurate spectral classification in such cases. By combining 23 measurements of the secondary's velocity with 102 of the primary's and deriving a double-lined orbit, we determine the mass ratio (q=M1/M2) of 93 Leo to be 1.09 ± 0.04. The same value is derived by cross-correlating high-dispersion spectra of 93 Leo B extracted from opposite nodal phases. That value of q is consonant with previous research, but its precision is considerably improved. We show that random errors arising from the cross-correlation of broad, weak features constitute a natural limit to that precision. The derived masses of M1= 2.2 M⊙, M2= 2.0 M⊙ for the giant and dwarf, respectively, constrain the choice of models for fitting evolutionary tracks in the (log Teff, log L) plane. The giant is almost certainly on its first ascent of the red giant branch, and the dwarf has evolved significantly from the main sequence. The stars fit an isochrone for log(age) = 8.95, about 0.9 Gyr. Metallicity near to solar is suggested by the close correspondence between the component spectra and those of the respective solar-abundance standards. The primary in 93 Leo displays a marked level of chromospheric activity. By combining our high-dispersion spectra we are able to isolate emission in the Ca ii K line. The chromospheric material has a small infall velocity, giving rise to a disc-averaged redshift of about 4 km s−1, and an unchanging velocity profile which can be attributed to a large number of small, active events like prominences across the surface. While we can say that there was no perceptible change in the emission strength over an interval of 4 months, we have not made systematic observations to monitor its long-term stability. We contrast the components of 93 Leo with those of α Equ, whose analysis was the subject of Paper 11 in this series. The primary components are very similar, but the two secondary components are extremely different in nature: whereas 93 Leo B is a broad-lined, apparently normal A star, the secondary of α Equ is a sharp-lined Am star of type ∼kA3hA4mA9. We question why that should be, and recommend that a greater emphasis be placed on extracting accurate stellar parameters from the components of spectroscopic binaries as a means towards a better understanding of the vagaries of stellar evolution. 93 Leo has a 9-mag visual companion which appears to be a physical member of the system and to be a single-lined spectroscopic binary with a period of the order of a century.
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 imitationNot 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.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
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".