Thermal Emission and Tidal Heating of the Heavy and Eccentric Planet XO-3b

We determined the flux ratios of the heavy and eccentric planet XO-3b to its parent star in the four IRAC bands of the Spitzer Space Telescope: 0.101% +- 0.004% at 3.6 micron; 0.143% +- 0.006% at 4.5 micron; 0.134% +- 0.049% at 5.8 micron and 0.150% +- 0.036% at 8.0 micron. The flux ratios are within [-2.2,0.3, -0.8, -1.7]-sigma of the model of XO-3b with a thermally inverted stratosphere in the 3.6 micron, 4.5 micron, 5.8 micron and 8.0 micron channels, respectively. XO-3b has a high illumination from its parent star (Fp ~(1.9 - 4.2) x 10^9 ergs cm^-2 s^-1) and is thus expected to have a thermal inversion, which we indeed observe. When combined with existing data for other planets, the correlation between the presence of an atmospheric temperature inversion and the substellar flux is insufficient to explain why some high insolation planets like TrES-3 do not have stratospheric inversions and some low insolation planets like XO-1b do have inversions. Secondary factors such as sulfur chemistry, atmospheric metallicity, amounts of macroscopic mixing in the stratosphere or even dynamical weather effects likely play a role. Using the secondary eclipse timing centroids we determined the orbital eccentricity of XO-3b as e = 0.277 +- 0.009. The model radius-age trajectories for XO-3b imply that at least some amount of tidal-heating is required to inflate the radius of XO-3b, and the tidal heating parameter of the planet is constrained to Qp < 10^6 .Comment: Accepted for publications in The Astrophysical Journa

GJ 3236: a new bright, very low-mass eclipsing binary system discovered by the MEarth observatory

We report the detection of eclipses in GJ 3236, a bright (I = 11.6) very low mass binary system with an orbital period of 0.77 days. Analysis of light- and radial velocity curves of the system yielded component masses of 0.38 +/- 0.02 and 0.28 +/- 0.02 Msol. The central values for the stellar radii are larger than the theoretical models predict for these masses, in agreement with the results for existing eclipsing binaries, although the present 5% observational uncertainties limit the significance of the larger radii to approximately 1 sigma. Degeneracies in the light curve models resulting from the unknown configuration of surface spots on the components of GJ 3236 currently dominate the uncertainties in the radii, and could be reduced by obtaining precise, multi-band photometry covering the full orbital period. The system appears to be tidally synchronized and shows signs of high activity levels as expected for such a short orbital period, evidenced by strong Halpha emission lines in the spectra of both components. These observations probe an important region of mass-radius parameter space around the predicted transition to fully-convective stellar interiors, where there are a limited number of precise measurements available in the literature.Comment: 14 pages, 5 figures, 10 tables, emulateapj format. Accepted for publication in Ap

Spitzer secondary eclipses of WASP-18b

The transiting exoplanet WASP-18b was discovered in 2008 by the Wide Angle Search for Planets project. The Spitzer Exoplanet Target of Opportunity Program observed secondary eclipses of WASP-18b using Spitzer's Infrared Array Camera in the 3.6 mu m and 5.8 mu m bands on 2008 December 20, and in the 4.5 mu m and 8.0 mu m bands on 2008 December 24. We report eclipse depths of 0.30% +/- 0.02%, 0.39% +/- 0.02%, 0.37% +/- 0.03%, 0.41% +/- 0.02%, and brightness temperatures of 3100 +/- 90, 3310 +/- 130, 3080 +/- 140, and 3120 +/- 110 K in order of increasing wavelength. WASP-18b is one of the hottest planets yet discovered-as hot as an M-class star. The planet's pressure-temperature profile most likely features a thermal inversion. The observations also require WASP-18b to have near-zero albedo and almost no redistribution of energy from the day side to the night side of the planet

Measurement of pseudorapidity distributions of charged particles in proton-proton collisions at sqrt(s) = 8 TeV by the CMS and TOTEM experiments

Pseudorapidity ( $\eta$ ) distributions of charged particles produced in proton–proton collisions at a centre-of-mass energy of 8 $~\text {TeV}$ are measured in the ranges $|\eta | < 2.2$ and $5.3 < |\eta | < 6.4$ covered by the CMS and TOTEM detectors, respectively. The data correspond to an integrated luminosity of $\mathcal {L} = 45 \mu {\mathrm {b}}^{-1}$ . Measurements are presented for three event categories. The most inclusive category is sensitive to 91–96 % of the total inelastic proton–proton cross section. The other two categories are disjoint subsets of the inclusive sample that are either enhanced or depleted in single diffractive dissociation events. The data are compared to models used to describe high-energy hadronic interactions. None of the models considered provide a consistent description of the measured distributions

Search for high-mass exclusive diphoton production with tagged protons in proton-proton collisions at s\sqrt{s} = 13 TeV

International audienceA search is presented for high-mass exclusive diphoton production via photon-photon fusion in proton-proton collisions at $\sqrt{s}$ = 13 TeV in events where both protons survive the interaction. The analysis utilizes data corresponding to an integrated luminosity of 103 fb$^{-1}$ collected in 2016-2018 with the central CMS detector and the CMS and TOTEM precision proton spectrometer (PPS). Events that have two photons with high transverse momenta ($p_\mathrm{T}^\gamma >$ 100 GeV), back-to-back in azimuth, and with a large diphoton invariant mass ($m_{\gamma\gamma} \gt$ 350 GeV) are selected. To remove the dominant inclusive diphoton backgrounds, the kinematic properties of the protons detected in PPS are required to match those of the central diphoton system. Only events having opposite-side forward protons detected with a fractional momentum loss between 0.035 and 0.15 (0.18) for the detectors on the negative (positive) side of CMS are considered. One exclusive diphoton candidate is observed for an expected background of 1.1 events. Limits at 95% confidence level are derived for the four-photon anomalous coupling parameters $\lvert\zeta_1\rvert \lt$ 0.073 TeV$^{-4}$ and $\lvert\zeta_2\rvert \lt$ 0.15 TeV$^{-4}$, using an effective field theory. Additionally, upper limits are placed on the production of axion-like particles with coupling strength to photons $f^{-1}$ that varies from 0.03 TeV$^{-1}$ to 1 TeV$^{-1}$ over the mass range from 500 to 2000 GeV