119214223
THE ALGOL SYSTEM SZ HERCULIS: PHYSICAL NATURE AND ORBITAL BEHAVIOR
Multiband CCD photometric observations of SZ Her were obtained between 2008 February and May. The light curve was completely covered and indicated a significant temperature difference between both components. The light-curve synthesis presented in this paper indicates that the eclipsing binary is a classical Algol-type system with parameters of q = 0.472, i = 8757, and Δ(T 1 - T 2) = 2381 K; the primary component fills approximately 77% of its limiting lobe and is slightly larger than the lobe-filling secondary component. More than 1100 times of minimum light spanning more than a century were used to study an orbital behavior of the binary system. It was found that the orbital period of SZ Her varied due to a combination of two periodic variations with cycle lengths of P 3 = 85.8 yr and P 4 = 42.5 yr and semi-amplitudes of K 3 = 0.013 days and K 4 = 0.007 days, respectively. The most reasonable explanation for these variations is a pair of light-time effects driven by the possible existence of two M-type companions with minimum masses of M 3 = 0.22 M ☉ and M 4 = 0.19 M ☉ that are located close to the 2:1 mean motion resonance. If two additional bodies exist, then the overall dynamics of the multiple system may provide a significant clue to the formation and evolution of the eclipsing pair.
205218920
Enrichment by supernovae in globular clusters with multiple populations
The most massive globular cluster in the Milky Way, ω Centauri, is thought to be the remaining core of a disrupted dwarf galaxy, as expected within the model of hierarchical merging. It contains several stellar populations having different heavy elemental abundances supplied by supernovae—a process known as metal enrichment. Although M 22 appears to be similar to ω Cen, other peculiar globular clusters do not. Therefore ω Cen and M 22 are viewed as exceptional, and the presence of chemical inhomogeneities in other clusters is seen as ‘pollution’ from the intermediate-mass asymptotic-giant-branch stars expected in normal globular clusters. Here we report Ca abundances for seven globular clusters and compare them to ω Cen. Calcium and other heavy elements can only be supplied through numerous supernovae explosions of massive stars in these stellar systems, but the gravitational potentials of the present-day clusters cannot preserve most of the ejecta from such explosions. We conclude that these globular clusters, like ω Cen, are most probably the relics of more massive primeval dwarf galaxies that merged and disrupted to form the proto-Galaxy.
2150926
A Chemical Abundance Study of three RHB and two RGB stars in NGC6637 (M69)
We present a detailed chemical abundance study of three red horizontal branch and two red giant branch stars in the metal-rich globular cluster NGC 6637 (M69). The value of [Fe/H] derived from LTE calculations is $-$0.77 $\pm$ 0.02 dex. We also discuss the anticorrelation between oxygen and sodium abundances in the program stars and compare the [Si/Ti] ratio of NGC 6637 with those of other globular clusters.
11936862
Bootes II: Not a Dwarf Galaxy but Possibly Shed by One
We present moderately deep V I C photometry of Boötes II, obtained using the SOAR Telescope. While identified initially as an old, metal-poor, dwarf galaxy, Boötes II appears to be a moderately metal-rich globular cluster with [Fe/H] ≈ −0.7. The slope of the red giant branch suggests that [α/Fe] ≈ 0.0, and the turn-off indicates an age of 7 to 9 Gyrs, considerably younger than most globular clusters, but similar to Palomar 12. Like that object, Boötes II lies in the direction of the Sagittarius dwarf galaxy tidal stream, and, with a distance of almost 50 kpc, is probably associated with the more distant portion of the stream, as defined by Belokurov et al. (2006a).
118885035
INFRARED PHOTOMETRY OF NGC 6791
We present deep JHK photometry of the old and metal-rich open cluster NGC 6791. The photometry reaches below the main-sequence turnoff to K ≈ 16.5 mag. We combine our photometry with that from Stetson et al. to provide color-magnitude diagrams showing K versus J - K, K versus V - K, and V versus V - K. We study the slope of the red giant branch in the infrared but find that it is not a useful metallicity indicator for the cluster, nor any metal-rich cluster that lacks a well-populated red giant branch, because it is not linear, as has often been assumed, in K versus J - K. The mean color of the red horizontal-branch/red clump stars provide an estimate of the cluster reddening, E(B - V) = 0.14 ± 0.04 mag for [Fe/H] = +0.4 ± 0.1. The mean magnitudes of these stars also provide a good distance estimate, (m - M)0 = 13.07 ± 0.04. Finally, we find that the isochrones of Yi et al. provide optimal fits in V versus B - V and V - K and K versus J - K and V - K for such values if [Fe/H] lies between +0.3 and +0.5 (with a slight preference for +0.5) and ages between 9 Gyr ([Fe/H] = +0.3) and 7.5 Gyr ([Fe/H] = +0.5).
119279392
THE RR LYRAE VARIABLES AND HORIZONTAL BRANCH OF NGC 6656 (M22)
The first calibrated broadband UBVI time-series photometry is presented for the RR Lyrae variable stars in NGC 6656 (M22), with observations spanning a range of 22 years. We have also redetermined the variability types and periods for the RR Lyrae stars identified previously by photographic observations, revising the number of fundamental-mode RR Lyrae variables (RR0) to 10 and the number of first-overtone variables (RR1) to 16. The mean periods of the RR0 and RR1 variables are (P) {sub RR0} = 0.66 ± 0.02 days and (P) {sub RR1} = 0.33 ± 0.01 days, respectively, supporting an Oosterhoff II classification for the cluster. The number ratio of RR1-type to all RR-type variables is N {sub 1}/N{sub RR} = 0.61, also consistent with an Oosterhoff II designation. Both the RR Lyrae stars' minimum light colors and the blue edge of the RR Lyrae instability strip suggest E( B – – V) = 0.36 ± 0.02 mag toward M22. Regarding the HB morphology of M22, we find (B-R)/(B+V+R) = +0.97 ± 0.1 and at least one ''gap'' located in an unusual part of the blue HB, in the middle of the so-called hot HB stars.
119253557
Listening to Noise
We show how sign problems in simulations of many-body systems can manifest themselves in the form of heavy-tailed correlator distributions, similar to what is seen in electron propagation through disordered media. We propose an alternative statistical approach for extracting ground state energies in such systems, illustrating the method with a toy model and with lattice data for unitary fermions and for baryons in QCD.
119852910
Measurement of the mass difference between top and anti-top quarks in pp collisions at √s = 7 TeV using the ATLAS detector
A measurement of the mass difference between top and anti-top quarks is presented. In a 4.7 fb(-1) data sample of proton-proton collisions at root s = 7 TeV recorded with the ATLAS detector at the ...
119270585
Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin
Aims. The transiting planet WASP-12 b was identified as a potential target for transit-timing studies because a departure from a linear ephemeris has been reported in the literature. Such deviations could be caused by an additional planet in the system. We attempt to confirm the claimed variations in transit timing and interpret their origin. Methods. We organised a multi-site campaign to observe transits by WASP-12 b in three observing seasons, using 0.5–2.6-metre telescopes. Results. We obtained 61 transit light curves, many of them with sub-millimagnitude precision. The simultaneous analysis of the best-quality datasets allowed us to obtain refined system parameters, which agree with values reported in previous studies. The residuals versus a linear ephemeris reveal a possible periodic signal that may be approximated by a sinusoid with an amplitude of 0.00068 ± 0.00013 d and period of 500 ± 20 orbital periods of WASP-12 b. The joint analysis of timing data and published radial velocity measurements results in a two-planet model that explains observations better than do single-planet scenarios. We hypothesise that WASP-12 b might not be the only planet in the system, and there might be the additional 0.1 MJup body on a 3.6-d eccentric orbit. A dynamical analysis indicates that the proposed two-planet system is stable on long timescales.
119110893
Resummation of relativistic corrections to exclusive productions of charmonia in e+e- collisions
We investigate two exclusive processes, ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\eta}}_{c}+\ensuremath{\gamma}$ and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}+J/\ensuremath{\psi}$, at the center-of-momentum energy $\sqrt{s}=10.58\text{ }\text{ }\mathrm{GeV}$ within the framework of the nonrelativistic QCD factorization approach. A class of relativistic corrections is resummed to all orders in the heavy-quark velocity $v$ and the corrections are large negative. We further improve the prediction by including available QCD next-to-leading-order corrections and the interference between the QCD and relativistic corrections. The prediction for $\ensuremath{\sigma}[{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\eta}}_{c}+\ensuremath{\gamma}]$ is about 50 fb. In the case of ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}+J/\ensuremath{\psi}$ the standard nonrelativistic QCD prediction for the cross section is negative. As an alternative, the vector-meson-dominance approach is employed to compute the photon-fragmentation contribution of the process, which gives the cross section $\ensuremath{\sim}1\text{ }\text{ }\mathrm{fb}$. This is an indication that the uncalculated QCD higher-order corrections may be significant. Our results can be tested against the forthcoming data from Belle II and super $B$ factories.
14107601
Cosmological Imprint of the Second Law of Thermodynamics
We study the evolution of the universe in the presence of inflaton, matter, radiation and holographic dark energy. The time evolution of the scale factor is obtained by solving the Friedmann equation of the universe with a good approximation. We present two independent ways which determine the value of the dark energy constant d~1 from the observational data. The two ways are measuring the deceleration parameter and measuring a universal constant depending only on d. The universal constant is given by a dimensionless combination of three scale factors at the equipartition times of radiation–matter, radiation–dark energy and matter–dark energy. We also discuss that the second law of thermodynamics determines the point of time when the dark-energy-dominated era begins in the universe.