Nuclear stellar disk-like nature in the kinematics of SiO maser stars around Sagittarius A*
Bibliographic record
Abstract
Abstract We present a detailed analysis of the kinematics of SiO maser stars around the center of the Milky Way, Sagittarius A$^\ast$ (Sgr A$^\ast$). We used the archive data in the SiO $v=1$, J = 2–1 emission line obtained by the Atacama Large Millimeter/Submillimeter Array (ALMA) in 2017 and 2021 (#2016.1.00940.S, PI J. Darling and #2019.1.00292.S, PI J. Paine). We detected 37 SiO maser stars in the channel maps and derived their angular offsets relative to Sgr A$^\ast$ and LSR radial velocities. We derived the proper motions of 35 stars by comparing their angular offsets in the two epochs. The proper motions of Wolf–Rayet and O star in the nuclear star cluster are reported to be rather random, except for the co-moving clusters IRS13E and IRS13N (Tsuboi et al. 2022, PASJ, 74, 738). However, the derived proper motions of SiO maser stars do not look completely random. The proper motions of the SiO maser stars show a tendency to lie along the Galactic plane. The proper motion amplitudes of SiO maser stars are larger than the local standard of rest (LSR) velocity amplitudes. We estimated the 3D motions from the proper motions and LSR velocities. Many 3D velocities are near to or larger than the upper limit velocities for Kepler orbits around Sgr A$^\ast$, whose mass is assumed to be $4\times 10^6$ M$_{\odot }$. These indicate that the SiO maser stars around Sgr A$^\ast$ are members of the nuclear stellar disk rather than the nuclear star cluster.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".