The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES
Bibliographic record
Abstract
ABSTRACT Small temperate planets are prime targets for exoplanet studies due to their possible similarities with the rocky planets in the Solar system. M dwarfs are promising hosts since the planetary signals are within our current detection capabilities. Gliese 12 b is a Venus-sized temperate planet orbiting a quiet M dwarf. We present here the first precise mass measurement of this small exoplanet. We performed a detailed analysis using HARPS-N (High Accuracy Radial velocity Planet Searcher for the Northern Hemisphere), ESPRESSO (Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations), and CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs) radial velocities, along with new and archival TESS (Transiting Exoplanet Survey Satellite), CHEOPS (CHaracterising ExOPlanet Satellite), and MuSCAT2/3 (Multicolor Simultaneous Camera for studying Atmospheres of Transiting exoplanets) photometry data. From fitting the available data, we find that the planet has a radius of $R_\mathrm{p} = 0.93\pm 0.06 \, \mathrm{R_{\rm{\oplus }}}$ and a mass of $M_\mathrm{p} = 0.95^{+0.29}_{-0.30} \, \mathrm{M_{\rm{\oplus }}}$ (a $3.2\sigma$ measurement of the semi-amplitude $K=0.67\pm 0.21\, \mathrm{m\, s^{-1}}$), and is on an orbit with a period of $12.761418^{+0.000060}_{-0.000055}\, \mathrm{d}$. A variety of techniques were utilized to attenuate stellar activity signals. Gliese 12 b has an equilibrium temperature of $T_\mathrm{eq}=317 \pm 8\, \mathrm{K}$, assuming an albedo of zero, and a density consistent with that of Earth and Venus ($\rho _\mathrm{p}=6.4\pm 2.4\, \mathrm{g\, cm^{-3}}$). We find that Gliese 12 b has a predominantly rocky interior and simulations indicate that it is unlikely to have retained any of its primordial gaseous envelope. The bulk properties of Gliese 12 b place it in an extremely sparsely populated region of both mass–radius and density–$T_\mathrm{eq}$ parameter space, making it a prime target for follow-up observations, including Lyman-$\alpha$ studies.
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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 | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".