We present template radial velocity curves of ab-type RR Lyrae stars constructed from high-precision measurements of H{alpha}, H{beta}, and H{gamma} lines. Amplitude correlations between the Balmer line velocity curves, Johnson V band, and Sloan Digital Sky Survey (SDSS) g- and r-band light curves are also derived. Compared to previous methods, these templates and derived correlations reduce the uncertainty in measured systemic (center-of-mass) velocities of RR Lyrae stars by up to 15km/s, and will be of particular interest to wide-area spectroscopic surveys such as the SDSS and LAMOST Experiment for Galactic Understanding and Exploration.
We present new radial velocities (RVs), improved pulsation periods, and reference epochs of 11 field RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. This study is based on high-resolution spectra obtained with the echelle spectrograph of the 2.5m du Pont telescope at Las Campanas Observatory. We obtained ~200 spectra per star (i.e., a total of ~2300 spectra), distributed more or less uniformly throughout their pulsation cycles. RV curves and photometric light curves phased to our new ephemerides are presented for all program stars.
We have determined spectroscopic orbits for five single-lined spectroscopic binaries, HD100167, HD135991, HD140667, HD158222, HD217924. Their periods range from 60.6 to 2403days and the eccentricities from 0.20 to 0.84. Our spectral classes for the stars confirm that they are of solar type, F9-G5, and all are dwarfs. Their [Fe/H] abundances, determined spectroscopically, are close to the solar value and on average are 0.12 greater than abundances from a photometric calibration. Four of the five stars are rotating faster than their predicted pseudosynchronous rotational velocities.
Radial velocity measurements, made with a CORAVEL type spectrometer, are presented for 211 F5-M stars down to V~13.1 in eight proper motion fields of the MEGA program, located at high Galactic latitudes. These data, together with previous CORAVEL measurements of 116 stars in three of these fields, will be combined with proper motions, photometric distances and metallicities, and ages to investigate the properties of the Galactic disk in the direction perpendicular to the Galactic plane.
We present new precise HIRES radial velocity (RV) data sets of five nearby stars obtained at Keck Observatory. HD 31253, HD 218566, HD 177830, HD 99492, and HD 74156 are host stars of spectral classes F through K and show RV variations consistent with new or additional planetary companions in Keplerian motion. The orbital parameters of the candidate planets in the five planetary systems span minimum masses of Msini=27.43M_{sun}_ to 8.28M_J_, periods of 17.05-4696.95 days and eccentricities ranging from circular to extremely eccentric (e~0.63). The fifth star, HD 74156, was known to have both a 52 day and a 2500 day planet, and was claimed to also harbor a third planet at 336 days, in apparent support of the "Packed Planetary System" hypothesis. Our greatly expanded data set for HD 74156 provides strong confirmation of both the 52 day and 2500 day planets, but strongly contradicts the existence of a 336 day planet, and offers no significant evidence for any other planets in the system.
We present integral-field spectroscopy of the ionized gas in the central regions of four galaxies with a low surface brightness disk taken with the Visible Multi Object Spectrograph at the Very Large Telescope and aimed at testing the accuracy in the determination of the central logarithmic slope alpha of the mass density radial profile rho(r){prop.to}r^alpha^ in this class of objects. For all the sample galaxies we subtracted the best-fit model of gas in circular motions from the observed velocity field and derived the residuals. Only ESO-LV5340200 is characterized by a regular velocity field. We extracted the velocity curves of this galaxy along several position angles, in order to estimate the uncertainty in deriving the central gradient of the total mass density from long-slit spectroscopy.
We present here the appendix to the paper with the new high precision radial velocities for a sample of Galactic Cepheids. The stars are: SU Cas, EV Sct, del Cep, CV Mon, U Sgr, eta Aql, X Cyg, T Mon, RS Pup, and SV Vul.
We report 490 radial velocities for 16 Galactic Cepheid variables. The typical uncertainty of a single velocity is {+/-}0.40km/s. Comparison with published velocities shows excellent agreement. Two of the Cepheids (Z Lac, S Sge) are known binaries and exhibit orbital velocity changes in our observing interval.
We present radial velocities for 18 Galactic O-type stars. These stars display small radial velocity scatter over timescales of one to two weeks. Some of them are long-period binaries while others are probably single stars. By fitting model spectra to our observed spectra we obtain estimates for effective temperature, log g, rotational velocity, and average radial velocity for each target.
