Discovering and characterizing exoplanets at the outer edge of the transit
method's sensitivity has proven challenging owing to geometric biases and the
practical difficulties associated with ...acquiring long observational baselines.
Nonetheless, a sample of giant exoplanets on orbits longer than 100 days has
been identified by transit hunting missions. We present long-term Doppler
spectroscopy for 11 such systems with observation baselines spanning a few
years to a decade. We model these radial velocity observations jointly with
transit photometry to provide initial characterizations of these objects and
the systems in which they exist. Specifically, we make new precise mass
measurements for four long-period giant exoplanets (Kepler-111 c, Kepler-553 c,
Kepler-849 b, and PH-2 b), we place new upper limits on mass for four others
(Kepler-421 b, KOI-1431.01, Kepler-1513 b, and Kepler-952 b), and we show that
several "confirmed" planets are in fact not planetary at all. We present these
findings to complement similar efforts focused on closer-in short-period giant
planets, and with the hope of inspiring future dedicated studies of cool giant
exoplanets.
We present the discovery of a pair of transiting giant planets, TOI-216b and c, using four sectors of TESS photometry. TOI-216 is a \(0.87 M_{\odot}\) dwarf orbited by two transiters with radii of ...\(8.2 R_{\oplus}\) and \(11.3 R_{\oplus}\), and periods of \(17.01\)d and \(34.57\)d, respectively. Anti-correlated TTVs are clearly evident indicating that the transiters orbit the same star and interact via a near 2:1 mean motion resonance. By fitting the TTVs with a dynamical model, we infer masses of \(26_{-11}^{+24} M_{\oplus}\) and \(190_{-80}^{+220} M_{\oplus}\), establishing that the objects are planetary in nature and have likely sub-Kronian and Kronian densities. TOI-216 lies close to the southern ecliptic pole and thus will be observed by TESS throughout the first year, providing an opportunity for continuous dynamical monitoring and considerable refinement of the dynamical masses presented here. TOI-216 closely resembles Kepler-9 in architecture, and we hypothesize that in such systems these Saturn-analogs failed to fully open a gap and thus migrated far deeper into the system before becoming trapped into resonance, which would imply that future detections of new analogs may also have sub-Jupiter masses.
Exomoons represent an outstanding challenge in modern astronomy, with the potential to provide rich insights into planet formation theory and habitability. In this work, we stack the phase-folded ...transits of 284 viable moon hosting Kepler planetary candidates, in order to search for satellites. These planets range from Earth-to-Jupiter sized and from \({\sim}\)0.1-to-1.0 AU in separation - so-called "warm" planets. Our data processing includes two-pass harmonic detrending, transit timing variations, model selection and careful data quality vetting to produce a grand light curve with an r.m.s. of 5.1 ppm. We find that the occurrence rate of Galilean-analog moon systems for planets orbiting between \({\sim}\)0.1 and 1.0 AU can be constrained to be \(\eta<0.38\) to 95% confidence for the 284 KOIs considered, with a 68.3% confidence interval of \(\eta=0.16_{-0.10}^{+0.13}\). A single-moon model of variable size and separation locates a slight preference for a population of short-period moons with radii \({\sim}0.5\) \(R_{\oplus}\) orbiting at 5-10 planetary radii. However, we stress that the low Bayes factor of just 2 in this region means it should be treated as no more than a hint at this time. Splitting our data into various physically-motivated subsets reveals no strong signal. The dearth of Galilean-analogs around warm planets places the first strong constraint on exomoon formation models to date. Finally, we report evidence for an exomoon candidate Kepler-1625b I, which we briefly describe ahead of scheduled observations of the target with the Hubble Space Telescope.
A role for elevated glycogen synthase kinase-3 (GSK-3) activity in the multifactorial etiology of insulin resistance is now emerging. However, the utility of specific GSK-3 inhibition in modulating ...insulin resistance of skeletal muscle glucose transport is not yet fully understood. Therefore, we assessed the effects of novel, selective organic inhibitors of GSK-3 (CT-98014 and CT-98023) on glucose transport in insulin-resistant muscles of Zucker diabetic fatty (ZDF) rats. Incubation of type IIb epitrochlearis and type I soleus muscles from ZDF rats with CT-98014 increased glycogen synthase activity (49 and 50%, respectively, P < 0.05) but did not alter basal glucose transport (2-deoxyglucose uptake). In contrast, CT-98014 significantly increased the stimulatory effects of both submaximal and maximal insulin concentrations in epitrochlearis (37 and 24%) and soleus (43 and 26%), and these effects were associated with increased cell-surface GLUT4 protein. Lithium enhanced glycogen synthase activity and both basal and insulin-stimulated glucose transport in muscles from ZDF rats. Acute oral administration (2 × 30 mg/kg) of CT-98023 to ZDF rats caused elevations in GSK-3 inhibitor concentrations in plasma and muscle. The glucose and insulin responses during a subsequent oral glucose tolerance test were reduced by 26 and 34%, respectively, in the GSK-3 inhibitor-treated animals. Thirty minutes after the final GSK-3 inhibitor treatment, insulin-stimulated glucose transport was significantly enhanced in epitrochlearis (57%) and soleus (43%). Two hours after the final treatment, insulin-mediated glucose transport was still significantly elevated (26%) only in the soleus. These results indicate that specific inhibition of GSK-3 enhances insulin action on glucose transport in skeletal muscle of the insulin-resistant ZDF rat. This unique approach may hold promise as a pharmacological treatment against insulin resistance of skeletal muscle glucose disposal.
A Transiting Jupiter Analog Kipping, David M; Torres, Guillermo; Henze, Chris ...
arXiv.org,
02/2016
Paper, Journal Article
Odprti dostop
Decadal-long radial velocity surveys have recently started to discover analogs to the most influential planet of our solar system, Jupiter. Detecting and characterizing these worlds is expected to ...shape our understanding of our uniqueness in the cosmos. Despite the great successes of recent transit surveys, Jupiter analogs represent a terra incognita, owing to the strong intrinsic bias of this method against long orbital periods. We here report on the first validated transiting Jupiter analog, Kepler-167e (KOI-490.02), discovered using Kepler archival photometry orbiting the K4-dwarf KIC-3239945. With a radius of \((0.91\pm0.02)\) \(R_{\mathrm{Jup}}\), a low orbital eccentricity (\(0.06_{-0.04}^{+0.10}\)) and an equilibrium temperature of \((131\pm3)\) K, Kepler-167e bears many of the basic hallmarks of Jupiter. Kepler-167e is accompanied by three Super-Earths on compact orbits, which we also validate, leaving a large cavity of transiting worlds around the habitable-zone. With two transits and continuous photometric coverage, we are able to uniquely and precisely measure the orbital period of this post snow-line planet (\(1071.2323\pm0.0006\) d), paving the way for follow-up of this \(K=11.8\) mag target.
