![Monte Carlo period simulations for each target. The v sin i values derived from species are used for randomly oriented (sinusoidally distributed) axial inclinations (green) and for a fixed i = 90o (light grey). The respective curves using the M16 v sin i estimates are also shown (orange and dark grey). The modal periods, Pˆ, are shown for each distribution. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Three-new.png?fit=1200%2C584&ssl=1)
[astro-ph.EP] We present a radial velocity analysis of three bright, low-activity stars identified by the Dispersed Matter Planet Project (DMPP).
We use a Bayesian framework to compare purely Keplerian models with models incorporating stellar activity via a quasi-periodic Gaussian Process (GP). DMPP-7 (HD 118006) is a slightly evolved star that harbours a single 0.72 Saturn-mass giant (mpsini = 69 M⊕) with an orbital period of P = 4.93 d. A longer 21 d – 22 d period cannot be conclusively confirmed as a stellar rotation signature rather than a purely Keplerian signal.
For HD 67200, which exhibits Ca ii H&K variability, a model with only a GP is strongly favoured over a purely dynamical model. The GP model shows moderate evidence for a single Keplerian with P = 2.67 d. For HD 2134, a 21 d – 32 d rotation period signal is associated with tentative FWHM variability.
A model with a GP is not conclusively favoured, but all models considered show moderate evidence for an additional single Keplerian with P = 2.78 d. Despite our target selection favouring near edge-on orbital geometries, we find no evidence for transits in TESS photometry. DMPP-7 b lies at the transition between the high-radius population and the Neptunian ridge and savannah regions.
Further observations are required to establish whether the coherent short-period HD 67200 and HD 2134 signals are stellar or dynamical in origin. If planetary, the signals correspond to minimum masses of mpsini = 2.07 M⊕ and mpsini = 2.86 M⊕
J.R. Barnes, C.A. Haswell, Z.O.B. Ross, E. Rutherford, M.R. Standing, A.T. Stevenson, D. Staab, L. Fossati, J.S. Jenkins, D. Alves
Comments: 28 pages, 20 Figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2608.11902 [astro-ph.EP] (or arXiv:2608.11902v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2608.11902
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Related DOI:
https://doi.org/10.1093/mnras/stag1486
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Submission history
From: John Barnes
[v1] Wed, 12 Aug 2026 10:28:10 UTC (9,185 KB)
https://arxiv.org/abs/2608.11902
Astrobiology, Astronomy, exoplanet,
