{"paper":{"title":"XO-2b: a Prograde Planet with a Negligible Eccentricity, and an Additional Radial Velocity Variation","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.SR"],"primary_cat":"astro-ph.EP","authors_text":"Akihiko Fukui, Bun'ei Sato, Hiroki Harakawa, Motohide Tamura, Norio Narita, Teruyuki Hirano, Wako Aoki","submitted_at":"2011-10-27T16:31:59Z","abstract_excerpt":"We present precise radial velocities of XO-2 taken with the Subaru HDS, covering two transits of XO-2b with an interval of nearly two years. The data suggest that the orbital eccentricity of XO-2b is consistent with zero within 2$\\sigma$ ($e=0.045\\pm0.024$) and the orbit of XO-2b is prograde (the sky-projected spin-orbit alignment angle $\\lambda=10^{\\circ}\\pm72^{\\circ}$). The poor constraint of $\\lambda$ is due to a small impact parameter (the orbital inclination of XO-2b is almost 90$^{\\circ}$). The data also provide an improved estimate of the mass of XO-2b as $0.62\\pm0.02$ $M_{\\rm Jup}$. We"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1110.6136","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}