Theoretical Considerations on the Properties of Accreting Millisecond Pulsars
Bibliographic record
Abstract
We examine a number of evolutionary scenarios for the recently discovered class of accretion-powered millisecond X-ray pulsars in ultracompact binaries, including XTE J0929-314 and XTE J1751-305, with orbital periods of 43.6 and 42.4 minutes, respectively. We focus on a particular scenario that can naturally explain the present-day properties of these systems. This model invokes a donor star that was either very close to the TAMS (i.e., main-sequence turnoff) at the onset of mass transfer or had sufficient time to evolve during the mass-transfer phase. We have run a systematic set of detailed binary evolution calculations with a wide range of initial donor masses and degrees of (nuclear) evolution at the onset of mass transfer. In general, the models whose evolutionary tracks result in the best fits to these ultracompact binaries start mass transfer with orbital periods of ~15 hr, then decrease to a minimum orbital period of less than or about 40 minutes, and finally evolve back up to about 43 minutes. We also carry out a probability analysis based on the measured mass functions of XTE J0929-314 and XTE J1751-305, and combine this with the results of our binary evolution models and find that the donor stars currently have masses in the range of about 0.012 - 0.025 solar masses, and radii of about 0.042 - 0.055 solar radii, and that these radii are likely to be factors of about 1.1 - 1.3 times larger than the corresponding zero-temperature ones. We also find that the interiors of the donors are largely composed of helium and that the surface hydrogen abundances are almost certainly less than 10% (by mass).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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.
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 teacher head, 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".