Results 1 - 10 of 2522
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[en] As part of the NASA EPOXI Mission of Opportunity, we observed seven known transiting extrasolar planet systems in order to construct time series photometry of extremely high phase coverage and precision. Here we present the results for four 'hot-Jupiter systems' with near-solar stars-HAT-P-4, TrES-3, TrES-2, and WASP-3. We observe 10 transits of HAT-P-4, estimating the planet radius Rp = 1.332 ± 0.052 RJup, the stellar radius R* = 1.602 ± 0.061 Rsun, the inclination i = 89.67 ± 0.30 deg, and the transit duration from first to fourth contact τ = 255.6 ± 1.9 minutes. For TrES-3, we observe seven transits and find Rp = 1.320 ± 0.057 RJup, R* = 0.817 ± 0.022 Rsun, i = 81.99 ± 0.30 deg, and τ = 81.9 ± 1.1 minutes. We also note a long-term variability in the TrES-3 light curve, which may be due to star spots. We observe nine transits of TrES-2 and find Rp = 1.169 ± 0.034 RJup, R* = 0.940 ± 0.026 Rsun, i = 84.15 ± 0.16 deg, and τ = 107.3 ± 1.1 minutes. Finally, we observe eight transits of WASP-3, finding Rp = 1.385 ± 0.060 RJup, R* = 1.354 ± 0.056 Rsun, i = 84.22 ± 0.81 deg, and τ = 167.3 ± 1.3 minutes. We present refined orbital periods and times of transit for each target. We state 95% confidence upper limits on the secondary eclipse depths in our broadband visible bandpass centered on 650 nm. These limits are 0.073% for HAT-P-4, 0.062% for TrES-3, 0.16% for TrES-2, and 0.11% for WASP-3. We combine the TrES-3 secondary eclipse information with the existing published data and confirm that the atmosphere likely does not have a temperature inversion.
[en] We measure secondary eclipses of the hot giant exoplanets CoRoT-1 at 3.6 and 4.5 μm, and CoRoT-2 at 3.6 μm, both using Warm Spitzer. We find that the Warm Spitzer mission is working very well for exoplanet science. For consistency of our analysis we also re-analyze archival cryogenic Spitzer data for secondary eclipses of CoRoT-2 at 4.5 and 8 μm. We compare the total data for both planets, including optical eclipse measurements by the CoRoT mission, and ground-based eclipse measurements at 2 μm, to existing models. Both planets exhibit stronger eclipses at 4.5 than at 3.6 μm, which is often indicative of an atmospheric temperature inversion. The spectrum of CoRoT-1 is best reproduced by a 2460 K blackbody, due either to a high altitude layer that strongly absorbs stellar irradiance, or an isothermal region in the planetary atmosphere. The spectrum of CoRoT-2 is unusual because the 8 μm contrast is anomalously low. Non-inverted atmospheres could potentially produce the CoRoT-2 spectrum if the planet exhibits line emission from CO at 4.5 μm, caused by tidal-induced mass loss. However, the viability of that hypothesis is questionable because the emitting region cannot be more than about 30% larger than the planet's transit radius, based on the ingress and egress times at eclipse. An alternative possibility to account for the spectrum of CoRoT-2 is an additional opacity source that acts strongly at wavelengths less than 5 μm, heating the upper atmosphere while allowing the deeper atmosphere seen at 8 μm to remain cooler. We obtain a similar result as Gillon et al. for the phase of the secondary eclipse of CoRoT-2, implying an eccentric orbit with e cos(ω) = -0.0030 ± 0.0004.
[en] V 566 Oph is a W Ursae Majoris-type eclipsing binary system which undergoes complete eclipses; secondary eclipse is total. Approximately 2000 photoelectric observations of this system were obtained with B and V filters within a three-week interval in 1973. Observations covering the eclipse portions of the curves yielded eight epochs of minimum light. A study of all the available times of minimum light indicates that the period of the system, which had remained constant for at least 14 years, has increased. Single, well-defined curves were formed from the observations at each effective wavelength. The V curve is in agreement with the curve observed in 1966 by Bookmyer, but there is now a slight asymmetry in the secondary eclipse curve defined by the B observations that is not apparent in the 1966 curve. Solutions of the system based on the Russell model and on the centrally condensed Roche model are compared and discussed
[en] Photoelectrically determined times of primary and secondary minimum are presented for the eclipsing binary RT And. These times of primary minima, when combined with other published minima, indicate that the system has undergone two sudden decreases in period since its discovery in 1901. The possibility of smaller amplitude, sporadic period jumps is also indicated. (U.S.)
[en] We report the serendipitous discovery of a disk-eclipse system OGLE-LMC-ECL-11893. The eclipse occurs with a period of 468 days, a duration of about 15 days, and a deep (up to ΔmI ≈ 1.5), peculiar, and asymmetric profile. A possible origin of such an eclipse profile involves a circumstellar disk. The presence of the disk is confirmed by the H-α line profile from the follow-up spectroscopic observations, and the star is identified as Be/Ae type. Unlike the previously known disk-eclipse candidates, the eclipses of OGLE-LMC-ECL-11893 retain the same shape throughout the span of ∼17 yr (13 orbital periods), indicating no measurable orbital precession of the disk.