51201355
Discovery of a Low-mass Companion to a Metal-rich F Star with the MARVELS Pilot Project
We report the discovery of a low-mass companion orbiting the metal-rich, main sequence F star TYC 2949-00557-1 during the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) pilot project. The host star has an effective temperature T_(eff) = 6135 ± 40 K, logg = 4.4 ± 0.1, and [Fe/H] = 0.32 ± 0.01, indicating a mass of M_⊙ = 1.25 ± 0.09 M_⊙ and R = 1.15 ± 0.15 R_⊙. The companion has an orbital period of 5.69449 ± 0.00023 days and straddles the hydrogen burning limit with a minimum mass of 64 M_J , and thus may be an example of the rare class of brown dwarfs orbiting at distances comparable to those of "Hot Jupiters." We present relative photometry that demonstrates that the host star is photometrically stable at the few millimagnitude level on time scales of hours to years, and rules out transits for a companion of radius ≳ 0.8 R_J at the 95% confidence level. Tidal analysis of the system suggests that the star and companion are likely in a double synchronous state where both rotational and orbital synchronization have been achieved. This is the first low-mass companion detected with a multi-object, dispersed, fixed-delay interferometer.
38052681
Eclipsing Binary Science via the Merging of Transit and Doppler Exoplanet Survey Data—A Case Study with the MARVELS Pilot Project and SuperWASP
Exoplanet transit and Doppler surveys discover many binary stars during their operation that can be used to conduct a variety of ancillary science. Specifically, eclipsing binary stars can be used to study the stellar mass-radius relationship and to test predictions of theoretical stellar evolution models. By cross-referencing 24 binary stars found in the MARVELS Pilot Project with SuperWASP photometry, we find two new eclipsing binaries, TYC 0272-00458-1 and TYC 1422-01328-1, which we use as case studies to develop a general approach to eclipsing binaries in survey data. TYC 0272-00458-1 is a single-lined spectroscopic binary for which we calculate a mass of the secondary and radii for both components using reasonable constraints on the primary mass through several different techniques. For a primary mass of M_1 = 0.92 ± 0.1 M_☉, we find M_2 = 0.610 ± 0.036 M_☉, R_1 = 0.932 ± 0.076 R_☉, and R_2 = 0.559 ± 0.102 R_☉, and find that both stars have masses and radii consistent with model predictions. TYC 1422-01328-1 is a triple-component system for which we can directly measure the masses and radii of the eclipsing pair. We find that the eclipsing pair consists of an evolved primary star (M_1 = 1.163 ± 0.034 M_☉, R_1 = 2.063 ± 0.058 R_☉) and a G-type dwarf secondary (M_2 = 0.905 ± 0.067 M_☉, R_2 = 0.887 ± 0.037 R_☉). We provide the framework necessary to apply this analysis to much larger data sets.
118446053
The Metallicity of the CM Draconis System
The CM Draconis system comprises two eclipsing mid-M dwarfs of nearly equal mass in a 1.27?day orbit. This well-studied eclipsing binary has often been used for benchmark tests of stellar models, since its components are among the lowest mass stars with well-measured masses and radii ( 1% relative precision). However, as with many other low-mass stars, non-magnetic models have been unable to match the observed radii and effective temperatures for CM Dra at the 5%-10% level. To date, the uncertain metallicity of the system has complicated comparison of theoretical isochrones with observations. In this Letter, we use data from the SpeX instrument on the NASA Infrared Telescope Facility to measure the metallicity of the system during primary and secondary eclipses, as well as out of eclipse, based on an empirical metallicity calibration in the H and K near-infrared (NIR) bands. We derive an [Fe/H] = -0.30 ? 0.12 that is consistent across all orbital phases. The determination of [Fe/H] for this system constrains a key dimension of parameter space when attempting to reconcile model isochrone predictions and observations.
17485541
MEASURING STELLAR RADIAL VELOCITIES WITH A DISPERSED FIXED-DELAY INTERFEROMETER
We demonstrate the ability to measure precise stellar barycentric radial velocities with the dispersed fixed-delay interferometer technique using the Exoplanet Tracker (ET), an instrument primarily designed for precision differential Doppler velocity measurements using this technique. Our barycentric radial velocities, derived from observations taken at the KPNO 2.1 m telescope, differ from those of Nidever et al. by 0.047 km s−1 (rms) when simultaneous iodine calibration is used, and by 0.120 km s−1 (rms) without simultaneous iodine calibration. Our results effectively show that a Michelson interferometer coupled to a spectrograph allows precise measurements of barycentric radial velocities even at a modest spectral resolution of R ~ 5100. A multiobject version of the ET instrument capable of observing ~500 stars per night is being used at the Sloan 2.5 m telescope at Apache Point Observatory for the Multiobject APO Radial Velocity Exoplanet Large-area Survey (MARVELS), a wide-field radial velocity survey for extrasolar planets around TYCHO-2 stars in the magnitude range 7.6 < V < 12. In addition to precise differential velocities, this survey will also yield precise barycentric radial velocities for many thousands of stars using the data analysis techniques reported here. Such a large kinematic survey at high velocity precision will be useful in identifying the signature of accretion events in the Milky Way and understanding local stellar kinematics, in addition to discovering exoplanets, brown dwarfs, and spectroscopic binaries.
14122353
Ground-Based Multisite Observations of Two Transits of HD 80606b
We present ground-based optical observations of the 2009 September and 2010 January transits of HD 80606b. Based on three partial light curves of the 2009 September event, we derive a midtransit time of T_c [HJD] = 2455099.196 ± 0.026, which is about 1σ away from the previously predicted time. We observed the 2010 January event from nine different locations, with most phases of the transit being observed by at least three different teams. We determine a midtransit time of Tc [HJD] = 2455210.6502 ± 0.0064, which is within 1.3σ of the time derived from a Spitzer observation of the same event.
119219393
The SDSS-HET Survey of Kepler Eclipsing Binaries: Spectroscopic Dynamical Masses of the Kepler-16 Circumbinary Planet Hosts
We have used high-resolution spectroscopy to observe the Kepler-16 eclipsing binary as a double-lined system and measure precise radial velocities for both stellar components. These velocities yield a dynamical mass ratio of q = 0.2994 {+-} 0.0031. When combined with the inclination, i 90.{sup 0}3401{sup +0.0016}{sub -0.0019}, measured from the Kepler photometric data by Doyle et al. (D11), we derive dynamical masses for the Kepler-16 components of M{sub A} = 0.654 {+-} 0.017 M{sub Sun} and M{sub B} = 0.1959 {+-} 0.0031 M{sub Sun }, a precision of 2.5% and 1.5%, respectively. Our results confirm at the {approx}2% level the mass-ratio derived by D11 with their photometric-dynamical model (PDM), q = 0.2937 {+-} 0.0006. These are among the most precise spectroscopic dynamical masses ever measured for low-mass stars and provide an important direct test of the results from the PDM technique.
15305191
Factorization Approach for Top Mass Reconstruction at High Energies
Using effective theories for jets and heavy quarks it is possible to prove that the double differential top-antitop invariant mass distribution for the process $e^+e^-\to t\bar t$ in the resonance region for c.m. energies $Q$ much larger than the top mass can factorized into perturbatively computable hard coefficients and jet functions and a non-perturbative soft function. For invariant mass prescriptions based on hemispheres defined with respect to the thrust axis the soft function can be extracted from massless jet event shape distributions. This approach allows in principle for top mass determinations without uncertainties from hadronization using the reconstruction method and to quantify the top mass scheme dependence of the measured top quark mass value.
116268330
Rapidity Divergences and Deep Inelastic Scattering in the Endpoint Region
The deep inelastic scattering cross section in the endpoint region, $x \sim 1$, has been subjected to extensive analysis. We revisit this process, and show that in the endpoint individual factors in the factorized hadronic tensor have rapidity divergences. We regulate these divergences using a recently introduced rapidity regulator, and find that each factor requires a different scale to minimize large rapidity logarithms. Interestingly, in this case running in rapidity is non-perturbative. In addition, we give an operator definition of the parton distribution function in the endpoint region, and remark on the issues that should be considered in constructing this function.
119229852
Factorization of e+e- event shape distributions with hadronic final states in soft collinear effective theory
We present a new analysis of two-jet event shape distributions in soft collinear effective theory. Extending previous results, we observe that a large class of such distributions can be expressed in terms of vacuum matrix elements of operators in the effective theory. We match these matrix elements to the full theory in the two-jet limit without assuming factorization of the complete set of hadronic final states into independent sums over partonic collinear and soft states. We also briefly discuss the relationship of this approach to diagrammatic factorization in the full theory.
73671853
Anomalous dimensions of the double parton fragmentation functions
Double parton fragmentation is a process in which a pair of partons produced in the short-distance process hadronize into the final state hadron. This process is important for quarkonium production when the transverse momentum is much greater than the quark mass. Resummation of logarithms of the ratio of these two scales requires the evolution equations for double parton fragmentation functions (DPFF). In this paper we complete the one-loop evaluation of the anomalous dimensions for the DPFF. We also consider possible mixing between the DPFF and single parton power suppressed gluon fragmentation and show that such effects are subleading.
2000018
Systematics of quarkonium production at the LHC and double parton fragmentation
In this paper we discuss the systematics of quarkonium production at the LHC. In particular, we focus on the necessity to sum logs of the form log(Q/p⊥) and log(p⊥/mQ). We show that the former contributions are power suppressed, while the latter, whose contribution in fragmentation is well known, also arise in the short distance (i.e., non-fragmentation) production mechanisms. Though these contributions are suppressed by powers of mQ/p⊥, they can be enhanced by inverse powers of v, the relative velocity between heavy quarks in the quarkonium. In the limit p⊥ ≫ mQ short distance production can be thought of as the fragmentation of a pair of partons (i.e., the heavy quark and anti-quark) into the final state quarkonium. We derive an all order factorization theorem for this process in terms of double parton fragmentation functions (DPFF) and calculate the one-loop anomalous dimension matrix for the DPFF.