THE VERY YOUNG TYPE Ia SUPERNOVA 2013dy: DISCOVERY, AND STRONG CARBON ABSORPTION IN EARLY-TIME SPECTRA
Bibliographic record
Abstract
The Type Ia supernova (SN Ia) 2013dy in NGC 7250 ( d ≈ 13.7 Mpc) was discovered by the Lick Observatory Supernova Search. Combined with a prediscovery detection by the Italian Supernova Search Project, we are able to constrain the first-light time of SN 2013dy to be only 0.10 ± 0.05 days (2.4 ± 1.2 hr) before the first detection. This makes SN 2013dy the earliest known detection of an SN Ia. We infer an upper limit on the radius of the progenitor star of R 0 ≲ 0.25 R ☉ , consistent with that of a white dwarf. The light curve exhibits a broken power law with exponents of 0.88 and then 1.80. A spectrum taken 1.63 days after first light reveals a C ii absorption line comparable in strength to Si ii . This is the strongest C ii feature ever detected in a normal SN Ia, suggesting that the progenitor star had significant unburned material. The C ii line in SN 2013dy weakens rapidly and is undetected in a spectrum 7 days later, indicating that C ii is detectable for only a very short time in some SNe Ia. SN 2013dy reached a B -band maximum of M B = −18.72 ± 0.03 mag ∼17.7 days after first light.
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".