arXiv subjects

Dong-Hong Wu

Publications and source records attributed to Dong-Hong Wu.

22 records · Page 2Linked to original sources

arXiv2018

Transiting Exoplanet Monitoring Project (TEMP). IV. Refined System Parameters, Transit Timing Variations and Orbital Stability of the Transiting Planetary System HAT-P-25

We present eight new light curves of the transiting extra-solar planet HAT-P-25b obtained from 2013 to 2016 with three telescopes at two observatories. We use the new light curves, along with recent literature material, to estimate the physical and orbital parameters of the transiting planet. Specifically, we determine the mid-transit times (T$_{C}$) and update the linear ephemeris, T$_{C[0]}$=2456418.80996$\pm$0.00025 [$\mathrm{BJD}_\mathrm{TDB}$] and P=3.65281572$\pm$0.00000095 days. We carry out a search for transit timing variations (TTVs), and find no significant TTV signal at the $ΔT=$80 s-level, placing a limit on the possible strength of planet-planet interactions ($\mathrm{TTV_{G}}$). In the course of our analysis, we calculate the upper mass-limits of the potential nearby perturbers. Near the 1:2, 2:1, and 3:1 resonances with HAT-P-25b, perturbers with masses greater than 0.5, 0.3, and 0.5 $\mathrm{M_{\oplus}}$ respectively, can be excluded. Furthermore, based on the analysis of TTVs caused by light travel time effect (LTTE) we also eliminate the possibility that a long-period perturber exists with $M_{\rm p}> 3000 \,\mathrm{M_{J}}$ within $a=11.2\,{\rm AU}$ of the parent star.

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arXiv2017

Transiting Exoplanet Monitoring Project (TEMP). III. On the Relocation of the Kepler-9~b Transit

The Kepler-9 system harbors three known transiting planets. The system holds significant interest for several reasons. First, the outer two planets exhibit a period ratio that is close to a 2:1 orbital commensurability, with attendant dynamical consequences. Second, both planets lie in the planetary mass "desert" that is generally associated with the rapid gas agglomeration phase of the core accretion process. Third, there exist attractive prospects for accurately measuring both the sky-projected stellar spin-orbit angles as well as the mutual orbital inclination between the planets in the system. Following the original \textit{Kepler} detection announcement in 2010, the initially reported orbital ephemerides for Kepler-9~b and c have degraded significantly, due to the limited time base-line of observations on which the discovery of the system rested. Here, we report new ground-based photometric observations and extensive dynamical modeling of the system. These efforts allow us to photometrically recover the transit of Kepler-9~b, and thereby greatly improve the predictions for upcoming transit mid-times. Accurate ephemerides of this system are important in order to confidently schedule follow-up observations of this system, for both in-transit Doppler measurements as well as for atmospheric transmission spectra taken during transit.

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arXiv2017

Updated Masses for the TRAPPIST-1 Planets

The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date. The short baseline of the available discovery observations, however, means that the planetary masses (obtained through measurement of transit timing variations of the planets of the system) are not yet well constrained. The masses reported in the discovery paper were derived using a combination of photometric timing measurements obtained from the ground and from the Spitzer spacecraft, and have uncertainties ranging from 30\% to nearly 100\%, with the mass of the outermost, $P=18.8\,{\rm d}$, planet h remaining unmeasured. Here, we present an analysis that supplements the timing measurements of the discovery paper with 73.6 days of photometry obtained by the K2 Mission. Our analysis refines the orbital parameters for all of the planets in the system. We substantially improve the upper bounds on eccentricity for inner six planets (finding $e<0.02$ for inner six known members of the system), and we derive masses of $0.79\pm 0.27 \,M_{\oplus}$, $1.63\pm 0.63\,M_{\oplus}$, $0.33\pm 0.15\,M_{\oplus}$, $0.24^{+0.56}_{-0.24}\,M_{\oplus}$, $0.36\pm 0.12\,M_{\oplus}$, $0.566\pm 0.038\,M_{\oplus}$, and $0.086\pm 0.084\,M_{\oplus}$ for planets b, c, d, e, f, g, and h, respectively.

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arXiv2016

Detecting planet pairs in mean motion resonances via astrometry method

GAIA leads us to step into a new era with a high astrometry precision of 10 uas. Under such a precision, astrometry will play important roles in detecting and characterizing exoplanets. Specially, we can identify planet pairs in mean motion resonances(MMRs) via astrometry, which constrains the formation and evolution of planetary systems. In accordance with observations, we consider two Jupiters or two super-Earths systems in 1:2, 2:3 and 3:4 MMRs. Our simulations show the false alarm probabilities(FAPs) of a third planet are extremely small while the real two planets can be good fitted with signal-to-noise ratio(SNR)> 3. The probability of reconstructing a resonant system is related with the eccentricities and resonance intensity. Generally, when SNR >= 10, if eccentricities of both planets are larger than 0.01 and the resonance is quite strong, the probabilities to reconstruct the planet pair in MMRs >= 80%. Jupiter pairs in MMRs are reconstructed more easily than super-Earth pairs with similar SNR when we consider the dynamical stability. FAPs are also calculated when we detect planet pairs in or near MMRs. FAPs for 1:2 MMR are largest, i.e., FAPs > 15% when SNR <= 10. Extrapolating from the Kepler planet pairs near MMRs and assuming SNR to be 3, we will discover and reconstruct a few tens of Jupiter pairs and hundreds of super-Earth pairs in 2:3 and 1:2 MMRs within 30 pc. We also compare the differences between even and uneven data cadence and find that planets are better measured with more uniform phase coverage.

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