The merger remnant NGC 1316 (Fornax A) is one of the most important objects regarding the investigation of and thus an important object to study merger-related processes. A recent photometric study used globular clusters in NGC 1316 to constrain its star formation history, but without the knowledge of individual radial velocities. The kinematical properties of the globular cluster system in comparison with the diffuse stellar light might give more insight into the formation of NGC 1316. Of particular interest is the dark matter content. Planetary nebulae in NGC 1316 indicate a massive dark halo, and globular cluster velocities provide independent evidence. We aim at measuring radial velocities of globular clusters in NGC 1316. We use these kinematical data to investigate the global structure of NGC 1316 and to constrain the dark matter content. We perform multiobject spectroscopy with VLT/FORS2 and MXU. Out of 562 slits, we extract radial velocities for 177 globular clusters. Moreover, we measure radial velocities of the integrated galaxy light, using slits with a sufficiently bright sky. To these data, we add 20 cluster velocities from the literature. In an appendix, we identify new morphological features of NGC 1316 and its companion galaxy NGC 1317.
We present low-resolution (R~850) spectra for 67 asymptotic giant branch (AGB), horizontal branch, and red giant branch (RGB) stars in the low-metallicity globular cluster NGC 5466, taken with the VIRUS-P integral-field spectrograph at the 2.7m Harlan J. Smith telescope at McDonald Observatory.
We present results from 1078 high-resolution spectra of 990 stars in the young open cluster NGC 2264, obtained with the Hectochelle multiobject echelle spectrograph on the 6.5m MMT. We confirm 471 stars as members on the basis of their radial velocity and/or H{alpha} emission.
We present precise radial velocities from a survey of 247 stars centered on Selected Area 57 at the North Galactic Pole, complete for late-type stars with V magnitude brighter than 12.0. The radial velocities have a typical precision of 0.2-0.3km/s. New spectral types and distances estimates are presented for 120 of the stars in the sample. We have considered all pairs of stars with angular separations between 1 and 600arcsec, and find 11 candidate pairs with velocity differences less than 1.5km/s. We estimate that 4 or 5 of the 11 candidate pairs are actually bound binaries, but none with separations larger than 0.1pc. The constraints imposed by these results on the actual distribution of wide binaries in the Galaxy should now be reanalyzed. The unusual precision of our velocities led to the discovery of a new cluster associated with the multiple system ADS 8811 ABC.
We have used the two-degree field (2dF) multi-fiber spectrograph of the Anglo-Australian Telescope (AAT) to search for candidate members of the unusual globular cluster omega Centauri at and beyond the cluster tidal radius. Velocities with an accuracy of ~10km/s were obtained for 4105 stars selected to lie in the vicinity of the lower giant branch in the cluster color-magnitude diagram (CMD) and which cover an area on the sky of ~2.4x3.9{deg}^2^ centered on the cluster.
Although 47 Oph has been shown to be a binary with a period of ~27days using both spectroscopic and interferometric techniques, only a preliminary orbit has been obtained in the previous work due to the shortage of high precision measurements. Since 1997, new spectroscopic and interferometric measurements have been obtained with much higher precision by the spectrograph of the 2.16m telescope at Xinglong station and the Navy Precision Optical Interferometer, respectively. Combining all of the measurements, a three-dimensional orbit is obtained with high precision in this work. Thus, the component masses are calculated to be 1.50+/-0.06 and 1.34+/-0.06M_{sun}_, respectively. The orbital parallax is 32.6+/-0.6mas, which is consistent with the Hipparcos parallax. With the known apparent magnitudes and color indices of the components, the derived luminosities are 7.80+/-0.36 and 3.41+/-0.25L_{sun}_. The estimated radii of the components are 2.06+/-0.07 and 1.36+/-0.06R_{sun}_. Finally, the evolutionary status of the components are investigated with the help of a stellar evolution model.
We present the results obtained from a long-term spectroscopic campaign to study the multiplicity of O-type stars in both the young open cluster NGC 2244 and the Mon OB2 association. Our spectroscopic monitoring was performed over several years, allowing us to investigate different timescales. For each star, several spectral diagnostic tools were applied to search for line shifts and profile variations. We also measured the projected rotational velocity and revisited the spectral classification.
We have conducted a radial-velocity survey of bright (V<9), overluminous, F stars within 80pc. Of the total of 118 stars selected, the radial velocities of 77 have been measured with the Cambridge CORAVEL in the present survey.
The detection of reflected light from an exoplanet is a difficult technical challenge at optical wavelengths. Even though this signal is expected to replicate the stellar signal, not only is it several orders of magnitude fainter, but it is also hidden among the stellar noise. We apply a variant of the cross-correlation technique to HARPS observations of 51 Peg to detect the reflected signal from planet 51 Peg b. Our method makes use of the cross-correlation function (CCF) of a binary mask with high-resolution spectra to amplify the minute planetary signal that is present in the spectra by a factor proportional to the number of spectral lines when performing the cross correlation. The resulting cross-correlation functions are then normalized by a stellar template to remove the stellar signal. Carefully selected sections of the resulting normalized CCFs are stacked to increase the planetary signal further. The recovered signal allows probing several of the planetary properties, including its real mass and albedo.
The analysis of CORAVEL radial velocities of 93 stars selected on the basis of their proper motion and Geneva CCD photometric observations for 57 stars have permitted to identify 25 new members in the outer part of the Pleiades. Several spectroscopic binaries have been discovered, but their membership is not clear. Two orbits with short periods have been determined, but both stars are probably non-members. The total number of member stars in the outer part of the Pleiades in the spectral range F5-K0 (0.45<B-V<0.90) is now 81 which is comparable to the number of stars known in Hertzsprung's central area (88 stars) in the same spectral domain. Therefore at least 48% of the F5-K0 main-sequence stars are located in the outer part of the cluster. And the census is probably still incomplete.
