Photometric follow-ups of transiting exoplanets may lead to discoveries of additional, less massive bodies in extrasolar systems. This is possible by detecting and then analysing variations in transit timing of transiting exoplanets. We present photometric observations gathered in 2009 and 2010 for exoplanet WASP-3b during the dedicated transit-timing-variation campaign. The observed transit timing cannot be explained by a constant period but by a periodic variation in the observations minus calculations diagram. Simplified models assuming the existence of a perturbing planet in the system and reproducing the observed variations of timing residuals were identified by three-body simulations. We found that the configuration with the hypothetical second planet of mass ∼15 M ⊕ , located close to the outer 2:1 mean-motion resonance, is the most likely scenario reproducing observed transit timing. We emphasize, however, that more observations are required to constrain better the parameters of the hypothetical second planet in the WASP-3 system. For final interpretation not only transit timing but also photometric observations of the transit of the predicted second planet and high-precision radial velocity data are needed.

Transit timing analysis may be an effective method of discovering additional bodies in extrasolar systems that harbour transiting exoplanets. The deviations from the Keplerian motion, caused by mutual gravitational interactions between planets, are expected to generate transit timing variations of transiting exoplanets. In 2009, we collected nine light curves of eight transits of the exoplanet WASP‐10b. Combining these data with those published, we have found that transit timing cannot be explained by a constant period but by a periodic variation. Simplified three‐body models, which reproduce the observed variations of timing residuals, were identified by numerical simulations. We have found that the configuration with an additional planet with a mass of ∼0.1 MJ and an orbital period of ∼5.23 d, located close to the outer 5 : 3 mean motion resonance, is the most likely scenario. If the second planet is a transiter, the estimated flux drop will be ∼0.3 per cent and can be observed with a ground‐based telescope. Moreover, we present evidence that the spots on the stellar surface and the rotation of the star affect the radial‐velocity curve, giving rise to a spurious eccentricity of the orbit of the first planet. We argue that the orbit of WASP‐10b is essentially circular. Using the gyrochronology method, the host star was found to be 270 ± 80 Myr old. This young age can explain the large radius reported for WASP‐10b.

We report on observations of several transit events of the transiting planet TrES-2 obtained with the Cassegrain-TeleskopKamera at the University Observatory Jena. Between March 2007 and November 2008 ten different transits and almost a complete orbital period were observed. Overall, in 40 nights of observation 4291 exposures (in total 71.52 h of observation) of the TrES-2 parent star were taken. With the transit timings for TrES-2 from the 34 events published by the TrESnetwork, the Transit Light Curve project and the Exoplanet Transit Database plus our own ten transits, we find that the orbital period is P = (2.470614 ± 0.000001) d, a slight change by ∼ 0.6 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we found a second dip after the transit which could either be due to a blended variable star or occultation of a second star or even an additional object in the system. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons.

Aims. The transiting planet WASP-12 b was identified as a potential target for transit-timing studies because a departure from a linear ephemeris has been reported in the literature. Such deviations could be caused by an additional planet in the system. We attempt to confirm the claimed variations in transit timing and interpret their origin. Methods. We organised a multi-site campaign to observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre telescopes. Results. We obtained 61 transit light curves, many of them with sub-millimagnitude precision. The simultaneous analysis of the best-quality datasets allowed us to obtain refined system parameters, which agree with values reported in previous studies. The residuals versus a linear ephemeris reveal a possible periodic signal that may be approximated by a sinusoid with an amplitude of 0.00068 ± 0.00013 d and period of 500 ± 20 orbital periods of WASP-12 b. The joint analysis of timing data and published radial velocity measurements results in a two-planet model that explains observations better than do single-planet scenarios. We hypothesise that WASP-12 b might not be the only planet in the system, and there might be the additional 0.1 M Jup body on a 3.6-d eccentric orbit. A dynamical analysis indicates that the proposed two-planet system is stable on long timescales.

We report the discovery in space of methyl silane, CHSiH, from observations of ten rotational transitions between 80 and 350 GHz ( from 4 to 16) with the IRAM 30 m radio telescope. The molecule was observed in the envelope of the C-star IRC +10216. The observed profiles and our models for the expected emission of methyl silane suggest that the it is formed in the inner zones of the circumstellar envelope, 1-40 , with an abundance of (0.5-1) × 10 relative to H. We also observed several rotational transitions of silyl cyanide (SiHCN), confirming its presence in IRC +10216 in particular, and in space in general. Our models indicate that silyl cyanide is also formed in the inner regions of the envelope, around 20 , with an abundance relative to H of 6×10. The possible formation mechanisms of both species are discussed. We also searched for related chemical species but only upper limits could be obtained.