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- ID:
- ivo://CDS.VizieR/J/MNRAS/446/4039
- Title:
- Stellar kinematics for NGC 2859 and NGC 4371
- Short Name:
- J/MNRAS/446/4039
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of nine S0-Sb galaxies which have (photometric) bulges consisting of two distinct components. The outer component is a flattened, kinematically cool, disc-like structure: a 'discy pseudo-bulge'. Embedded inside is a rounder, kinematically hot spheroidal structure: a `classical bulge'. This indicates that pseudo-bulges and classical bulges are not mutually exclusive phenomena: some galaxies have both. The discy pseudo-bulges almost always consist of an exponential disc (scalelengths=125-870 pc, mean size ~440 pc) with one or more disc-related subcomponents: nuclear rings, nuclear bars, and/or spiral arms. They constitute 11-59 percent of the galaxy stellar mass (mean PB/T=0.33), with stellar masses ~7x10^9^-9x10^10^ M_{sun}_. The classical-bulge components have Sersic indices of 0.9-2.2, effective radii of 25-430 pc and stellar masses of 5x10^8^-3x10^10^ M_{sun}_; they are usually <10 percent of the galaxy's stellar mass (mean B/T=0.06). The classical bulges do show rotation, but are clearly kinematically hotter than the discy pseudo-bulges. Dynamical modelling of three systems indicates that velocity dispersions are isotropic in the classical bulges and equatorially biased in the discy pseudo-bulges. In the mass-radius and mass-stellar mass density planes, classical-bulge components follow sequences defined by ellipticals and (larger) classical bulges. Discy pseudo-bulges also fall on this sequence; they are more compact than large-scale discs of similar mass. Although some classical bulges are quite compact, they are as a class clearly distinct from nuclear star clusters in both size and mass; in at least two galaxies they coexist with nuclear clusters. Since almost all the galaxies in this study are barred, they probably also host boxy/peanut-shaped bulges (vertically thickened inner parts of bars). NGC 3368 shows isophotal evidence for such a zone just outside its discy pseudo-bulge, making it a clear case of a galaxy with all three types of 'bulge'.
- ID:
- ivo://CDS.VizieR/J/ApJ/596/437
- Title:
- Stellar-mass black holes in the SDSS
- Short Name:
- J/ApJ/596/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We search for nearby, isolated, accreting, "stellar-mass" (3-100M_{sun}_) black holes. Models suggest a synchrotron spectrum in visible wavelengths and some emission in X-ray wavelengths. Of 3.7 million objects in the Sloan Digital Sky Survey Early Data Release, Cat. <J/AJ/123/567>, about 150,000 objects have colors and properties consistent with such a spectrum, and 87 of these objects are X-ray sources from the ROSAT All-Sky Survey (Cat. <IX/10> and <IX/29>). Thirty-two of these have been confirmed not to be black holes using optical spectra. We give the positions and colors of these 55 black hole candidates and quantitatively rank them on their likelihood to be black holes. We discuss uncertainties in the expected number of sources and the contribution of black holes to local dark matter.
- ID:
- ivo://CDS.VizieR/J/ApJ/633/844
- Title:
- Stellar mass in disk-dominated galaxies
- Short Name:
- J/ApJ/633/844
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the correlations among stellar mass (M*), disk scale length (R_d_), and rotation velocity at 2.2 disk scale lengths (V_2.2_) for a sample of 81 disk-dominated galaxies (disk/total>=0.9) selected from the SDSS. We measure V_2.2_ from long-slit H{alpha} rotation curves and infer M* from galaxy i-band luminosities (L_i_) and g-r colors.
- ID:
- ivo://CDS.VizieR/J/ApJ/856/15
- Title:
- Stellar mass-metallicity relation. I.
- Short Name:
- J/ApJ/856/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar mass-stellar metallicity relationship (MZR) in the galaxy cluster Cl0024+1654 at z~0.4 using full-spectrum stellar population synthesis modeling of individual quiescent galaxies. The lower limit of our stellar mass range is M*=10^9.7^M_{sun}_, the lowest galaxy mass at which individual stellar metallicity has been measured beyond the local universe. We report a detection of an evolution of the stellar MZR with observed redshift at 0.037+/-0.007dex per Gyr, consistent with the predictions from hydrodynamical simulations. Additionally, we find that the evolution of the stellar MZR with observed redshift can be explained by an evolution of the stellar MZR with the formation time of galaxies, i.e., when the single stellar population (SSP)-equivalent ages of galaxies are taken into account. This behavior is consistent with stars forming out of gas that also has an MZR with a normalization that decreases with redshift. Lastly, we find that over the observed mass range, the MZR can be described by a linear function with a shallow slope ([Fe/H]{propto}(0.16+/-0.03)logM*). The slope suggests that galaxy feedback, in terms of mass-loading factor, might be mass-independent over the observed mass and redshift range.
- ID:
- ivo://CDS.VizieR/J/ApJ/821/101
- Title:
- Stellar MFP for massive quiescent z<0.7 galaxies
- Short Name:
- J/ApJ/821/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the evolution of the relation between stellar mass surface density, velocity dispersion, and half-light radius --the stellar mass fundamental plane (MFP)-- for quiescent galaxies at z<0.6. We measure the local relation from galaxies in the Sloan Digital Sky Survey and the intermediate redshift relation from ~500 quiescent galaxies with stellar masses 10<~log(M*/M_{sun}_)<~11.5. Nearly half of the quiescent galaxies in our intermediate redshift sample are compact. After accounting for important selection and systematic effects, the velocity dispersion distribution of galaxies at intermediate redshifts is similar to that of galaxies in the local universe. Galaxies at z<0.6 appear to be smaller (<~0.1dex) than galaxies in the local sample. The orientation of the stellar MFP is independent of redshift for massive quiescent galaxies at z<0.6 and the zero-point evolves by ~0.04dex. Compact quiescent galaxies fall on the same relation as the extended objects. We confirm that compact quiescent galaxies are the tail of the size and mass distribution of the normal quiescent galaxy population.
- ID:
- ivo://CDS.VizieR/J/AJ/152/73
- Title:
- Stellar nuclei and bulges of nearby S0 galaxies
- Short Name:
- J/AJ/152/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I analyze statistics of the stellar population properties for stellar nuclei and bulges of nearby lenticular galaxies in different environments by using panoramic spectral data of the integral-field spectrograph SAURON retrieved from the open archive of the Isaac Newton Group. I also estimate the fraction of nearby lenticular galaxies having inner polar gaseous disks by exploring the volume-limited sample of early-type galaxies of the ATLAS-3D survey. By inspecting the two-dimensional velocity fields of the stellar and gaseous components with the running tilted-ring technique, I have found seven new cases of inner polar disks. Together with those, the frequency of inner polar disks in nearby S0 galaxies reaches 10%, which is much higher than the frequency of large-scale polar rings. Interestingly, the properties of the nuclear stellar populations in the inner polar ring hosts are statistically the same as those in the whole S0 sample, implying similar histories of multiple gas-accretion events from various directions.
- ID:
- ivo://CDS.VizieR/J/A+A/589/A61
- Title:
- Stellar parameters and abundances for M30
- Short Name:
- J/A+A/589/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The prediction of the PLANCK-constrained primordial lithium abundance in the Universe is in discordance with the observed Li abundances in warm Population II dwarf and subgiant stars. Among the physically best motivated ideas, it has been suggested that this discrepancy can be alleviated if the stars observed today had undergone photospheric depletion of lithium. The cause of this depletion is investigated by accurately tracing the behaviour of the lithium abundances as a function of effective temperature. Globular clusters are ideal laboratories for such an abundance analysis as the relative stellar parameters of their stars can be precisely determined. We performed a homogeneous chemical abundance analysis of 144 stars in the metal-poor globular cluster M30, ranging from the cluster turnoff point to the tip of the red giant branch. Non-local thermal equilibrium (NLTE) abundances for Li, Ca, and Fe were derived where possible by fitting spectra obtained with VLT/FLAMES-GIRAFFE using the quantitative-spectroscopy package SME. Stellar parameters were derived by matching isochrones to the observed V vs V-I colour-magnitude diagram. Independent effective temperatures were obtained from automated profile fitting of the Balmer lines and by applying colour-Teff calibrations to the broadband photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A72
- Title:
- Stellar parameters and abundances in NGC 6752
- Short Name:
- J/A+A/567/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abundance trends in heavier elements with evolutionary phase have been shown to exist in the globular cluster NGC 6752. These trends are a result of atomic diffusion and additional (non-convective) mixing. Studying such trends can provide us with important constraints on the extent to which diffusion modifies the internal structure and surface abundances of solar-type, metal-poor stars. Taking advantage of a larger data sample, we investigate the reality and the size of these abundance trends and address questions and potential biases associated with the various stellar populations that make up NGC 6752. We perform an abundance analysis by combining photometric and spectroscopic data of 194 stars located between the turnoff point and the base of the red giant branch. Stellar parameters are derived from uvby Stromgren photometry. Using the quantitative-spectroscopy package SME, stellar surface abundances for light elements such as Li, Na, Mg, Al, and Si as well as heavier elements such as Ca, Ti, and Fe are derived in an automated way by fitting synthetic spectra to individual lines in the stellar spectra, obtained with the VLT/FLAMES-GIRAFFE spectrograph. Based on uvby Stromgren photometry, we are able to separate three stellar populations in NGC 6752 along the evolutionary sequence from the base of the red giant branch down to the turnoff point. We find weak systematic abundance trends with evolutionary phase for Ca, Ti, and Fe which are best explained by stellar-structure models including atomic diffusion with efficient additional mixing. We derive a new value for the initial lithium abundance of NGC 6752 after correcting for the effect of atomic diffusion and additional mixing which falls slightly below the predicted standard BBN value. We find three stellar populations by combining photometric and spectroscopic data of 194 stars in the globular cluster NGC 6752. Abundance trends for groups of elements, differently affected by atomic diffusion and additional mixing, are identified. Although the statistical significance of the individual trends is weak, they all support the notion that atomic diffusion is operational along the evolutionary sequence of NGC 6752.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A141
- Title:
- Stellar parameters for 582 HARPS FGK stars
- Short Name:
- J/A+A/533/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand the formation and evolution of solar-type stars and planets in the solar neighborhood, we need to obtain their stellar parameters with high precision. We present a catalog of precise stellar parameters for low-activity FGK single stars in a volume-limited sample followed by the HARPS spectrograph in the quest to identify extra-solar planets. The spectroscopic analysis was completed assuming LTE with a grid of Kurucz atmosphere models and using the ARES code to perform an automatic measurement of the line equivalent widths. The results are compared with different independent methods and also with other values found in the literature for common stars. Both comparisons are consistent and illustrate the homogeneity of the parameters derived by our team. The derived metallicities of this sample reveal a somewhat different distribution for the present planet hosts, but still indicates the already known higher frequency of planets observed for the more metal-rich stars. We combine the results derived in this sample with the one from the CORALIE survey to present the largest homogeneous spectroscopic study of the metallicity-giant-planet relation using a total of 1830 stars.
