MODELING THE SYSTEM PARAMETERS OF 2M 1533+3759: A NEW LONGER PERIOD LOW-MASS ECLIPSING sdB+dM BINARY
Bibliographic record
Abstract
We present new photometric and spectroscopic observations for 2M 1533+3759 (= NSVS 07826147), the seventh eclipsing subdwarf B star + M dwarf (sdB+dM) binary ever found. It has an orbital period of 0.16177042 days, or ∼3.88 hr, significantly longer than the 2.3–3.0 hr periods of the other known eclipsing sdB+dM systems. Spectroscopic analysis of the hot primary yields T eff = 29230 ± 125 K, log g = 5.58 ± 0.03, and log N (He)/ N (H) = −2.37 ± 0.05. The sdB velocity amplitude is K 1 = 71.1 ± 1.0 km s −1 . The only detectable light contribution from the secondary is due to the surprisingly strong reflection effect, whose peak-to-peak BVRI amplitudes are 0.10, 0.13, 0.15, and 0.19 mag, respectively. Light-curve modeling produced several solutions corresponding to different values of the system mass ratio, q ( M 2 / M 1 ), but only one is consistent with a core helium burning star, q = 0.301. The orbital inclination is 86 6. The sdB primary mass is M 1 = 0.376 ± 0.055 M ☉ and its radius is R 1 = 0.166 ± 0.007 R ☉ . 2M 1533+3759 joins PG 0911+456 (and possibly also HS 2333+3927) in having an unusually low mass for an sdB star. SdB stars with masses significantly lower than the canonical value of 0.48 M ☉ , down to as low as 0.30 M ☉ , were theoretically predicted by Han et al., but observational evidence has only recently begun to confirm the existence of such stars. The existence of core helium burning stars with masses lower than 0.40–0.43 M ☉ implies that at least some sdB progenitors have initial main-sequence masses of 1.8–2.0 M ☉ or more, i.e., they are at least main-sequence A stars. The orbital separation in 2M 1533+3759 is a = 0.98 ± 0.04 R ☉ . The secondary has M 2 = 0.113 ± 0.017 M ☉ , R 2 = 0.152 ± 0.005 R ☉ , and K, consistent with a main-sequence M5 star. If 2M 1533+3759 becomes a cataclysmic variable (CV), its orbital period will be 1.6 hr, below the CV period gap.
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 | 0.000 | 0.000 |
| 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".