- ID:
- ivo://CDS.VizieR/J/A+A/619/A2
- Title:
- Velocity curves of 3 open cluster stars
- Short Name:
- J/A+A/619/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this work is to search for planets around intermediate-mass stars in open clusters by using data from an extensive survey with more than 15 years of observations. We obtain high-precision radial velocities (RV) with the HARPS spectrograph for a sample of 142 giant stars in 17 open clusters. We fit Keplerian orbits when a significant periodic signal is detected. We also study the variation of stellar activity indicators and line-profile variations to discard stellar-induced signals. We present the discovery of a periodic RV signal compatible with the presence of a planet candidate in the 1.15Gyr open cluster IC4651 orbiting the 2.06M_{sun}_ star No. 9122. If confirmed, the planet candidate would have a minimum mass of 7.2M_J_ and a period of 747 days. However, we also find that the FWHM of the CCF varies with a period close to the RV, casting doubts on the planetary nature of the signal. We also provide refined parameters for the previously discovered planet around NGC2423 No. 3 but show evidence that the BIS of the CCF is correlated with the RV during some of the observing periods. This fact advises us that this might not be a real planet and that the RV variations could be caused by stellar activity and/or pulsations. Finally, we show that the previously reported signal by a brown dwarf around NGC4349 No. 127 is presumably produced by stellar activity modulation. The long-term monitoring of several red giants in open clusters has allowed us to find periodic RV variations in several stars. However, we also show that the follow-up of this kind of stars should last more than one orbital period to detect long-term signals of stellar origin. This work warns that although it is possible to detect planets around red giants, large-amplitude, long-period RV modulations do exist in such stars that can mimic the presence of an orbiting planetary body. Therefore, we need to better understand how such RV modulations behave as stars evolve along the Red Giant Branch and perform a detailed study of all the possible stellar-induced signals (e.g. spots, pulsations, granulation) to comprehend the origin of RV variations.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/537/A117
- Title:
- Velocity curves of SW CMa and HW CMa
- Short Name:
- J/A+A/537/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate physical properties of eclipsing stars provide important constraints on models of stellar structure and evolution, especially when combined with spectroscopic information on their chemical composition. Empirical calibrations of the data also lead to accurate mass and radius estimates for exoplanet host stars. Finally, accurate data for unusual stellar subtypes, such as Am stars, also help to unravel the cause(s) of their peculiarities. We aim to determine the masses, radii, effective temperatures, detailed chemical composition and rotational speeds for the Am-type eclipsing binaries SWCMa (A4-5m) and HWCMa (A6m) and compare them with similar normal stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/224/453
- Title:
- Velocity data of rich clusters
- Short Name:
- J/MNRAS/224/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present redshifts and stellar velocity dispersions for about 40 galaxies in each of 14 rich clusters from the southern cluster survey of Abell & Corwin (1983, Early Evolution of the Universe and Its Present Structure, p.179, Eds. Abell & Chincarini, Reidel, Dordrecht, Holland). The clusters cover a wide range of richnesses and Abell and Bautz-Morgan types, our aim being to compile a large, homogeneous database for examining and comparing dynamical phenomena and morphological properties. Further papers will present photometry for the clusters and an analysis of the database.
22584. Velocity dispersion in AGN
- ID:
- ivo://CDS.VizieR/J/ApJ/585/647
- Title:
- Velocity dispersion in AGN
- Short Name:
- J/ApJ/585/647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been proposed that the width of the narrow [O III] {lambda}5007 emission line can be used as a surrogate for the stellar velocity dispersion in active galaxies. This proposition is tested using the Sloan Digital Sky Survey (SDSS) Early Data Release (EDR) spectra of 107 low-redshift radio-quiet QSOs and Seyfert 1 galaxies by investigating the correlation between black hole mass, as determined from H{beta} FWHM and optical luminosity, and [O III] FWHM. The correlation is real, but the scatter is large. Without additional information or selection criteria, the [O III] width can predict the black hole mass to a factor of 5.
- ID:
- ivo://CDS.VizieR/J/AJ/126/2268
- Title:
- Velocity dispersions and Mg2 index of galaxies
- Short Name:
- J/AJ/126/2268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present central velocity dispersions and Mg_2_ line indices for an all-sky sample of 1175 elliptical and S0 galaxies, of which 984 had no previous measures. This sample contains the largest set of homogeneous spectroscopic data for a uniform sample of elliptical galaxies in the nearby universe. These galaxies were observed as part of the ENEAR (Redshift-Distance Survey of Nearby Early-Type Galaxies) project, designed to study the peculiar motions and internal properties of the local early-type galaxies. Using 523 repeated observations of 317 galaxies obtained during different runs, the data are brought to a common zero point. These multiple observations, taken during the many runs and different instrumental setups employed for this project, are used to derive statistical corrections to the data and are found to be relatively small, typically <~5% of the velocity dispersion and 0.01mag in the Mg_2_ line strength. Typical errors are about 8% in velocity dispersion and 0.01mag in Mg_2_, in good agreement with values published elsewhere.
- ID:
- ivo://CDS.VizieR/J/A+AS/113/151
- Title:
- Velocity dispersions for elliptical galaxies
- Short Name:
- J/A+AS/113/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measurements of central velocity dispersions and heliocentric radial velocities are presented for 94 field galaxies. Among these, 5 new radial velocities and 80 new central velocity dispersions are obtained. Reduction was performed independently by cross-correlation, Fourier-quotient and Fourier-correlation-quotient methods.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/29
- Title:
- Velocity dispersions in active galaxies
- Short Name:
- J/ApJS/201/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive spatially resolved stellar kinematics for a sample of 84 out of 104 observed local (0.02<z<0.09) galaxies hosting type-1 active galactic nuclei (AGNs), based on long-slit spectra obtained at the 10m W. M. Keck-1 Telescope. In addition to providing central stellar velocity dispersions, we measure major axis rotation curves and velocity dispersion profiles using three separate wavelength regions, including the prominent Ca H&K, MgIb, and CaII NIR stellar features. In this paper, we compare kinematic measurements of stellar velocity dispersion obtained for different apertures, wavelength regions, and signal-to-noise ratios, and provide recipes to cross-calibrate the measurements reducing systematic effects to the level of a few percent. We also provide simple recipes based on readily observable quantities such as global colors and Ca H&K equivalent width that will allow observers of high-redshift AGN hosts to increase the probability of obtaining reliable stellar kinematic measurements from unresolved spectra in the region surrounding the Ca H&K lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/724/714
- Title:
- Velocity dispersions of MS1054-03 & Coma galaxies
- Short Name:
- J/ApJ/724/714
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured velocity dispersions ({sigma}) for a sample of 36 galaxies with J<21.2 or M_r_<-20.6mag in MS 1054-03, a massive cluster of galaxies at z=0.83. Our data are of uniformly high quality down to our selection limit, our 16h exposures typically yielding errors of only {delta}({sigma})~10% for L* and fainter galaxies. By combining our measurements with data from the literature, we have 53 cluster galaxies with measured dispersions, and HST/ACS-derived sizes, colors and surface brightness. This sample is complete for the typical L^*^ galaxy at z~1, unlike most previous z~1 cluster samples which are complete only for the massive cluster members (>10^11^M_{sun}_). We find no evidence for a change in the tilt of the fundamental plane (FP).
- ID:
- ivo://CDS.VizieR/J/AJ/146/150
- Title:
- Velocity dispersions of 12 nearby galaxies
- Short Name:
- J/AJ/146/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive study of the velocity dispersion of the atomic (HI) and molecular (H_2_) gas components in the disks (R{<~}R_25_) of a sample of 12 nearby spiral galaxies with moderate inclinations. Our analysis is based on sensitive high-resolution data from the THINGS (atomic gas) and HERACLES (molecular gas) surveys. To obtain reliable measurements of the velocity dispersion, we stack regions several kiloparsecs in size, after accounting for intrinsic velocity shifts due to galactic rotation and large-scale motions. We stack using various parameters: the galactocentric distance, star formation rate surface density, HI surface density, H_2_ surface density, and total gas surface density. We fit single Gaussian components to the stacked spectra and measure median velocity dispersions for HI of 11.9+/-3.1km/s and for CO of 12.0+/-3.9km/s. The CO velocity dispersions are thus, surprisingly, very similar to the corresponding ones of HI, with an average ratio of {sigma}_HI_/{sigma}_CO_=1.0+/-0.2 irrespective of the stacking parameter. The measured CO velocity dispersions are significantly higher (factor of ~2) than the traditional picture of a cold molecular gas disk associated with star formation. The high dispersion implies an additional thick molecular gas disk (possibly as thick as the HI disk). Our finding is in agreement with recent sensitive measurements in individual edge-on and face-on galaxies and points toward the general existence of a thick disk of molecular gas, in addition to the well-known thin disk in nearby spiral galaxies.
- ID:
- ivo://CDS.VizieR/J/other/NewA/27.41
- Title:
- Velocity distributions in galaxy clusters
- Short Name:
- J/other/NewA/27.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study 416 galaxy systems with more than 7 members selected from the 2MASS catalog. We applied five well known normality tests to the velocity distributions of these systems to distinguish Gaussian and non-Gaussian clusters. Using controlled samples, we estimated type I and II errors for each test. We verified that individual tests minimize the chances of classifying a Gaussian system as non-Gaussian, while the Fisher's meta-analysis method, a procedure to combine p-values from several statistical tests, minimizes the chances of classifying a non-Gaussian system as Gaussian. Taking the positive elements of each method and also including a modality analysis of the velocity distribution, we defined objective criteria to split up the sample into Gaussian and non-Gaussian clusters. Our analysis indicates that 50-58% of groups have Gaussian distribution, a lower fraction than that we found using individual normality tests, 71-87%. We also found that some properties of galaxy clusters are significantly different between Gaussian and non-Gaussian systems. For instance, non-Gaussian clusters have larger radii and contain more galaxies than Gaussian clusters. Finally, we discussed the importance of choosing the adequate methodology to classify galaxy systems from their velocity distributions and also the dependence of the results on the criteria used to identify clusters in galaxy surveys.
