PRECISE RADIAL VELOCITY MEASUREMENTS FORKEPLERGIANTS HOSTING PLANETARY CANDIDATES: KEPLER-91 AND KOI-1894

Analysis of the exoplanet containing system Kepler-91

“…Given the relatively large fractional size of the star in the present case the higher power terms are significant and we can expect a systematic improvement in the mass ratio (reduced by ∼ 40% from that determined by Lillo-Box et al, 2014a). Our derived value q ≈ 0.00044 ± 0.00006 for the mass ratio is then in good agreement with that which can be inferred from the relatively high-accuracy radial velocity data of Barclay et al (2015) and perhaps even more with the greater coverage and higher mean accuracy results of Sato et al (2015).…”

“…Mass ratio The preceding presentation on the Kepler Mission's photometric data on the Kepler-91 system to a large extent supports the picture given by Lillo-Box et al (2014a, b), Barclay et al (2015), Sato et al (2015) and Esteves et al (2015). The close binary system photometry analysis program WinFitter that we have adapted and applied, however, includes a fuller description of the surface distortions due to tides and rotation, as well as the reflection effect, than has generally been used in similar studies hitherto.…”

“…But the first 3 fittings (reference point only, linear, and parabolic trends, have no significant difference in corresponding BIC values (23.3, 25.0, 24.2; respectively), though a 4-parameter fit (BIC = 27.0) would not be supported, by the assessment table of Kass & Raftery. In fact, the implications of such a period reduction would be the highly unexpected circumstance of catching a planet within a few thousand of years before its demise. On the contrary, Sato et al (2015) gave a slightly increased period value from that given by Tenenbaum et al (2013) (see Table 4). There are, however, interesting alternative physical scenarios relating to period changes that we discuss later.…”

“…On the other hand, there appears some suggestion, from the results of Sato et al (2015) that the period may be increasing in the short term. In a similar way, an apparent trend to decrease of the longitude of periastron over the full range of the Kepler Mission surveillance cannot be taken so seriously given the relatively high errors of the determination.…”

“…In fact, if eccentricity is allowed to be simultaneously adjustable the χ 2 Hessian becomes non-positive-definite, so that regular error estimates lose meaning. Table 4 We list here the Lillo-Box et al (2014a) (LB) parameters, as well as those of Barclay et al (2015), Sato et al (2015) and Esteves et al (2015), alongside those of the present paper (P). Error estimates, influenced by the compilation of results, are listed in the final column.…”