arXiv subjects

Xu Huang

Publications and source records attributed to Xu Huang.

93 records · Page 6Linked to original sources

arXiv2012

150 New transiting planet candidates from Kepler Q1-Q6 data

We have performed an extensive search for planet candidates in the publicly available Kepler Long Cadence data from quarters Q1 through Q6. The search method consists of initial de-trending of the data, applying the trend filtering algorithm, searching for transit signals with the Box Least Squares fitting method in three frequency domains, visual inspection of the potential transit candidates, and in-depth analysis of the shortlisted candidates. In this paper we present 150 new periodic planet candidates and 7 single transit events, 72 of which are in multiple systems. The periods of these planet candidates vary from $\sim$0.17\,day to $\sim$ 440\,day. 124 of the planet candidates have radii smaller than 3 \rearth. We recover 82.5% of the Batalha et al. (2012) KOI catalog. We also report 40 newly identified false positives---systems that look like transiting planets, but are probably due to blended eclipsing binaries. Our search improves the statistics in the short period and small planet radii parameter ranges.

astro-ph.EP↗

arXiv2012

Ohmic Dissipation in the Interiors of Hot Jupiters

We present models of ohmic heating in the interiors of hot jupiters in which we decouple the interior and the wind zone by replacing the wind zone with a boundary temperature Tiso and magnetic field Bphi0. Ohmic heating influences the contraction of gas giants in two ways: by direct heating within the convection zone, and by heating outside the convection zone which increases the effective insulation of the interior. We calculate these effects, and show that internal ohmic heating is only able to slow the contraction rate of a cooling gas giant once the planet reaches a critical value of internal entropy. We determine the age of the gas giant when ohmic heating becomes important as a function of mass, Tiso and induced Bphi0. With this survey of parameter space complete, we then adopt the wind zone scalings of Menou (2012) and calculate the expected evolution of gas giants with different levels of irradiation. We find that,with this prescription of magnetic drag, it is difficult to inflate massive planets or those with strong irradiation using ohmic heating, meaning that we are unable to account for many of the observed hot jupiter radii. This is in contrast to previous evolutionary models that assumed that a constant fraction of the irradiation is transformed into ohmic power.

astro-ph.EP↗

arXiv2009

The densification mechanism of squeeze casting

The solidification process during squeeze casting is analyzed based on the classical solidification and plastic deformation theory. The linear relationship between punch velocity and the solidification rate is established if the density change of molten meals is neglected. To obtain defect-free castings, the punch velocity should be larger than the solidification rate. The densification mechanism is also discussed. The plastic deformation will result in the radical movement of the central molten metals, which reduces the temperature gradient from the center to the mold wall, which provides the condition to obtain defect-free castings: simultaneous nucleation.

cond-mat.mtrl-sci↗