Precise Radial Velocities of 2046 Nearby FGKM Stars and 131 Standards

We present radial velocities with an accuracy of 0.1 km/s for 2046 stars of spectral type F,G,K, and M, based on 29000 spectra taken with the Keck I telescope. We also present 131 FGKM standard stars, all of which exhibit constant radial velocity for at least 10 years, with an RMS less than 0.03 km/s. All velocities are measured relative to the solar system barycenter. Spectra of the Sun and of asteroids pin the zero-point of our velocities, yielding a velocity accuracy of 0.01 km/s for G2V stars. This velocity zero-point agrees within 0.01 \kms with the zero-points carefully determined by Nidever et al. (2002) and Latham et al. (2002). For reference we compute the differences in velocity zero-points between our velocities and standard stars of the IAU, the Harvard-Smithsonian Center for Astrophysics, and l'Observatoire de Geneve, finding agreement with all of them at the level of 0.1 km/s. But our radial velocities (and those of all other groups) contain no corrections for convective blueshift or gravitational redshifts (except for G2V stars), leaving them vulnerable to systematic errors of 0.2 \kms for K dwarfs and ~0.3 km/s for M dwarfs due to subphotospheric convection, for which we offer velocity corrections. The velocities here thus represent accurately the radial component of each star's velocity vector. The radial velocity standards presented here are designed to be useful as fundamental standards in astronomy. They may be useful for Gaia (Crifo et al. 2010, Gilmore et al. 2012} and for dynamical studies of such systems as long-period binary stars, star clusters, Galactic structure, and nearby galaxies, as will be carried out by SDSS, RAVE, APOGEE, SkyMapper, HERMES, and LSST

M2K: I. A Jovian mass planet around the M3V star HIP79431

Doppler observations from Keck Observatory reveal the presence of a planet with Msini of 2.1 Mjup orbiting the M3V star HIP79431. This is the sixth giant planet to be detected in Doppler surveys of M dwarfs and it is one of the most massive planets discovered around an M dwarf star. The planet has an orbital period of 111.7 days and an orbital eccentricity of 0.29. The host star is metal rich, with an estimated [Fe/H] = +0.4. This is the first planet to emerge from our new survey of 1600 M-to-K dwarf stars.Comment: 5 figure

LHS6343C: A Transiting Field Brown Dwarf Discovered by the Kepler Mission

We report the discovery of a brown dwarf that transits one member of the M+M binary system LHS6343AB every 12.71 days. The transits were discovered using photometric data from the Kelper public data release. The LHS6343 stellar system was previously identified as a single high-proper-motion M dwarf. We use high-contrast imaging to resolve the system into two low-mass stars with masses 0.45 Msun and 0.36 Msun, respectively, and a projected separation of 55 arcsec. High-resolution spectroscopy shows that the more massive component undergoes Doppler variations consistent with Keplerian motion, with a period equal to the transit period and an amplitude consistent with a companion mass of M_C = 62.8 +/- 2.3 Mjup. Based on an analysis of the Kepler light curve we estimate the radius of the companion to be R_C = 0.832 +/- 0.021 Rjup, which is consistent with theoretical predictions of the radius of a > 1 Gyr brown dwarf.Comment: Our previous analysis neglected the dependence of the scaled semimajor axis, a/R, on the transit depth. By not correcting a/R for the third-light contamination, we overestimated the mass of Star A, which led to an overestimate the mass and radius of the LHS6343

Radial Velocities as an Exoplanet Discovery Method

The precise radial velocity technique is a cornerstone of exoplanetary astronomy. Astronomers measure Doppler shifts in the star's spectral features, which track the line-of/sight gravitational accelerations of a star caused by the planets orbiting it. The method has its roots in binary star astronomy, and exoplanet detection represents the low-companion-mass limit of that application. This limit requires control of several effects of much greater magnitude than the signal sought: the motion of the telescope must be subtracted, the instrument must be calibrated, and spurious Doppler shifts "jitter" must be mitigated or corrected. Two primary forms of instrumental calibration are the stable spectrograph and absorption cell methods, the former being the path taken for the next generation of spectrographs. Spurious, apparent Doppler shifts due to non-center-of-mass motion (jitter) can be the result of stellar magnetic activity or photospheric motions and granulation. Several avoidance, mitigation, and correction strategies exist, including careful analysis of line shapes and radial velocity wavelength dependence.Comment: Invited review chapter. 13pp. v2 includes corrections to Eqs 3-6, updated references, and minor edit

Regulation of Arabidopsis TGA transcription factors by cysteine residues : implication for redox control

The Arabidopsis TGA family of basic leucine zipper transcription factors regulate the expression of pathogenesis-related genes and are required for resistance to disease. Members of the family possess diverse properties in respect to their ability to transactivate and interact with NPR1, the central regulator of systemic acquired resistance in Arabidopsis. Two TGA factors, TGA1 and TGA2, have 83 % amino acid similarity but possess differing properties. TGA1 does not interact with NPR1 but is able to transactivate, while TGA2 interacts with NPR1 but is unable to transactivate. This study uses these two TGA factors to identify amino acids that are responsible for their function. Four cysteines residues within TGA1 were targeted for study by site-directed mutagenesis and the resulting mutants were tested for interaction with NPR1 in yeast. The construct containing a mutation of cysteine 260 (Cys-260) interacted well with NPR1, while those with mutations at Cys-172 or Cys-266 interacted poorly. The Cys-260 mutant also displayed the greatest decrease in transactivation potential in yeast, while mutation of Cys-172 or Cys-266 resulted in smaller decreases. Mutation of Cys-287 had no effect on NPR1 interaction or transactivation. Combining various point mutations in a single protein did not increase NPR1 interaction or transactivation levels, indicating that Cys-260 is crucial for regulating TGA1 properties. Cysteines possess the unique ability of forming reversible disulfide bonds which have been shown to regulate several mammalian cellular processes. The observation that mutation of a single TGA1 cysteine (Cys-260) greatly alters the protein’s properties provides a convincing argument that oxidoreduction of this residue is important for its regulation, possibly through the formation of a disulfide bond with either Cys-172 or Cys-266. To test whether other members of the TGA family could be regulated by oxidoreduction, several TGA2 constructs were created that introduced Cys at positions corresponding to those found in TGA1. When tested in yeast none were able to transactivate but continued to interact with NPR1

M2K: I. A Jupiter-Mass Planet Orbiting the M3V Star HIP 79431

Doppler observations from Keck Observatory reveal the presence of a planet with M sin i of 2.1 M_(Jup) orbiting the M3V star HIP 79431. This is the sixth giant planet to be detected in Doppler surveys of M dwarfs and it is one of the most massive planets discovered around an M dwarf star. The planet has an orbital period of 111.7 days and an orbital eccentricity of 0.29. The host star is metal rich, with an estimated [Fe/H] = +0.4. This is the first planet to emerge from our new survey of 1600 M-to-K dwarf stars

Ruprecht 147: The oldest nearby open cluster as a new benchmark for stellar astrophysics

Ruprecht 147 is a hitherto unappreciated open cluster that holds great promise as a standard in fundamental stellar astrophysics. We have conducted a radial velocity survey of astrometric candidates with Lick, Palomar, and MMT observatories and have identified over 100 members, including 5 blue stragglers, 11 red giants, and 5 double-lined spectroscopic binaries (SB2s). We estimate the cluster metallicity from spectroscopic analysis, using Spectroscopy Made Easy (SME), and find it to be [M/H] = +0.07 \pm 0.03. We have obtained deep CFHT/MegaCam g'r'i' photometry and fit Padova isochrones to the (g' - i') and 2MASS (J - K) CMDs using the \tau^2 maximum-likelihood procedure of Naylor (2009), and an alternative method using 2D cross-correlations developed in this work. We find best fits for isochrones at age t = 2.5 \pm 0.25 Gyr, m - M = 7.35 \pm 0.1, and A_V = 0.25 \pm 0.05, with additional uncertainty from the unresolved binary population and possibility of differential extinction across this large cluster. The inferred age is heavily dependent by our choice of stellar evolution model: fitting Dartmouth and PARSEC models yield age parameters of 3 Gyr and 3.25 Gyr respectively. At approximately 300 pc and 3 Gyr, Ruprecht 147 is by far the oldest nearby star cluster.Comment: 31 pages, 21 figures, 6 tables. Comments welcom

Software framework for geophysical data processing, visualization and code development

IGeoS is an integrated open-source software framework for geophysical data processing under development at the UofS seismology group. Unlike other systems, this processing monitor supports structured multicomponent seismic data streams, multidimensional data traces, and employs a unique backpropagation execution logic. This results in an unusual flexibility of processing, allowing the system to handle nearly any geophysical data. In this project, a modern and feature-rich Graphical User Interface (GUI) was developed for the system, allowing editing and submission of processing flows and interaction with running jobs. Multiple jobs can be executed in a distributed multi-processor networks and controlled from the same GUI. Jobs, in their turn, can also be parallelized to take advantage of parallel processing environments such as local area networks and Beowulf clusters. A 3D/2D interactive display server was created and integrated with the IGeoS geophysical data processing framework. With introduction of this major component, the IGeoS system becomes conceptually complete and potentially bridges the gap between the traditional processing and interpretation software. Finally, in a specialized application, network acquisition and relay components were written allowing IGeoS to be used for real-time applications. The completion of this functionality makes the processing and display capabilities of IGeoS available to multiple streams of seismic data from potentially remote sites. Seismic data can be acquired, transferred to the central server, processed, archived, and events picked and placed in database completely automatically