- ID:
- ivo://CDS.VizieR/J/MNRAS/473/4731
- Title:
- Barred galaxies structural decomposition
- Short Name:
- J/MNRAS/473/4731
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of two-component (disc+bar) and three-component (disc+bar+bulge) multiwavelength 2D photometric decompositions of barred galaxies in five Sloan Digital Sky Survey (SDSS) bands (ugriz). This sample of ~3500 nearby (z<0.06) galaxies with strong bars selected from the Galaxy Zoo citizen science project is the largest sample of barred galaxies to be studied using photometric decompositions that include a bar component. With detailed structural analysis, we obtain physical quantities such as the bar- and bulge-to-total luminosity ratios, effective radii, Sersic indices and colours of the individual components. We observe a clear difference in the colours of the components, the discs being bluer than the bars and bulges. An overwhelming fraction of bulge components have Sersic indices consistent with being pseudo-bulges. By comparing the barred galaxies with a mass-matched and volume-limited sample of unbarred galaxies, we examine the connection between the presence of a large-scale galactic bar and the properties of discs and bulges. We find that the discs of unbarred galaxies are significantly bluer compared to the discs of barred galaxies, while there is no significant difference in the colours of the bulges. We find possible evidence of secular evolution via bars that leads to the build-up of pseudo-bulges and to the quenching of star formation in the discs. We identify a subsample of unbarred galaxies with an inner lens/oval and find that their properties are similar to barred galaxies, consistent with an evolutionary scenario in which bars dissolve into lenses. This scenario deserves further investigation through both theoretical and observational work.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/439/1749
- Title:
- Barred S0 galaxies in the Coma cluster
- Short Name:
- J/MNRAS/439/1749
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study uses r-band images from the Eighth Data Release of the Sloan Digital Sky Survey (SDSS DR8) to study bars in lenticular (S0) galaxies in one of the nearest rich cluster environments, the Coma cluster. We develop techniques for bar detection and assess their success when applied to SDSS image data. To detect and characterize bars, we perform 2D bulge+disc+bar light decompositions of galaxy images with galfit. Using a sample of artificial galaxy images, we determine the faintest magnitude at which bars can be successfully measured at the depth and resolution of SDSS. We perform detailed decompositions of 83 S0 galaxies in Coma, 64 from a central sample, and 19 from a cluster outskirt sample. For the central sample, the S0 bar fraction is 72^+5^_-6_%. This value is significantly higher than that obtained using an ellipse-fitting method for bar detection, 48^+6^_-6_%. At a fixed luminosity, barred S0s are redder in g-r colour than unbarred S0s by 0.02mag. The frequency and strength of bars increase towards fainter luminosities. Neither central metallicity nor stellar age distributions differ significantly between barred and unbarred S0s. There is an increase in the bar fraction towards the cluster core, but this is at a low significance level. Bars have at most a weak correlation with cluster-centric radius.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A88
- Title:
- Barred & unbarred galaxies N, O abundance ratio
- Short Name:
- J/A+A/584/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Bar-induced gas inflows towards galaxy centres are recognised as a key agent for the secular evolution of galaxies. One immediate consequence of this inflow is the accumulation of gas in the centre of galaxies where it can form stars and alter the chemical and physical properties. Our aim is to study whether the properties of the ionised gas in the central parts of barred galaxies are altered by the presence of a bar and whether the change in central properties is related to bar and/or parent galaxy properties. We use a sample of nearby face-on disc galaxies with available SDSS spectra, morphological decomposition, and information on the stellar population of their bulges, to measure the internal Balmer extinction from the H{alpha} to H{beta} line ratio, star formation rate, and relevant line ratios to diagnose chemical abundances and gas density.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A17
- Title:
- Barycentric radial velocities of Gl 586A
- Short Name:
- J/A+A/559/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The visual A component of the Gliese 586AB system is a double-lined spectroscopic binary consisting of two cool stars with the exceptional orbital eccentricity of 0.976. Such an extremely eccentric system may be important for our understanding of low-mass binary formation. Precise stellar masses, ages, orbital elements, and rotational periods are a prerequisite for comparing stellar observations to angular-momentum evolution models.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A34
- Title:
- Baryon Acoustic Oscillations in LRGs
- Short Name:
- J/A+A/542/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Baryon Acoustic Oscillations (BAO) have been previously detected using correlation functions and power spectra of the galaxy distribution. In this work, we present a new method for the detection of the real-space structures associated with this feature. These baryon acoustic structures are spherical shells with a relatively small density contrast, surrounding high density central regions. We design a specific wavelet adapted to the search for shells, and exploit the physics of the process by making use of two different mass tracers, introducing a specific statistic to detect the BAO features. We apply our method to the detection of BAO in a galaxy sample drawn from the Sloan Digital Sky Survey (SDSS). We use the 'Main' catalogue to trace the shells, and the Luminous Red Galaxies (LRG) as tracers of the high density central regions.
- ID:
- ivo://CDS.VizieR/J/A+A/361/429
- Title:
- Baryon content of groups and clusters
- Short Name:
- J/A+A/361/429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analyzed the properties of a sample of 33 groups and clusters of galaxies for which both optical and X-ray data were available in the literature. This sample was built to examine the baryon content and to check for trends over a decade in temperature down to 1keV. We examine the relative contribution of galaxies and ICM to baryons in clusters through the gas-to-stellar mass ratio (M_gas_/M_*_). We find that the typical stellar contribution to the baryonic mass is between 5 and 20%, at the virial radius. The ratio (M_gas_/M_*_) is found to be roughly independent of temperature. Therefore, we do not confirm the trend of increasing gas-to-stellar mass ratio with increasing temperature as previously claimed.
- ID:
- ivo://CDS.VizieR/J/A+A/555/A66
- Title:
- Baryons from groups and clusters of galaxies
- Short Name:
- J/A+A/555/A66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on XMM-Newton, Chandra, and SDSS data, we investigate the baryon distribution in groups and clusters and its use as a cosmological constraint. For this, we considered a sample of 123 systems with temperatures kT_500_=1.0-9.0keV, total masses in the mass range M_500_=(~10^13^-4x10^15^)h_70_^-1^M_{sun}_, and redshifts 0.02<z<1.3. The gas masses and total masses are derived from X-ray data under the assumption of hydrostatic equilibrium and spherical symmetry. The stellar masses are based on SDSS-DR8 optical photometric data. For the 37 systems out of 123 that had both optical and X-ray data available, we investigated the gas, stellar, and total baryon mass fractions inside r2500 and r500 and the differential gas mass fraction within the spherical annulus between r2500 and r500, as a function of total mass. For the other objects, we investigated the gas mass fraction only.
- ID:
- ivo://CDS.VizieR/J/ApJ/791/128
- Title:
- Basic galaxy data for spiral-rich group members
- Short Name:
- J/ApJ/791/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, the COS Science Team has conducted a high signal-to-noise survey of 14 bright QSOs. In a previous paper (Savage et al., 2014ApJS..212....8S), these far-UV spectra were used to discover 14 "warm" (T >= 10^5^ K) absorbers using a combination of broad Ly{alpha} and broad O VI absorptions. A reanalysis of a few of this new class of absorbers using slightly relaxed fitting criteria finds as many as 20 warm absorbers could be present in this sample. A shallow, wide spectroscopic galaxy redshift survey has been conducted around these sight lines to investigate the warm absorber environment, which is found to be spiral-rich groups or cluster outskirts with radial velocity dispersions {sigma}=250-750 km/s. While 2{sigma} evidence is presented favoring the hypothesis that these absorptions are associated with the galaxy groups and not with the individual, nearest galaxies, this evidence has considerable systematic uncertainties and is based on a small sample size so it is not entirely conclusive. If the associations are with galaxy groups, the observed frequency of warm absorbers (idN/dz = 3.5-5 per unit redshift) requires them to be very extended as an ensemble on the sky (~1 Mpc in radius at high covering factor). Most likely these warm absorbers are interface gas clouds whose presence implies the existence of a hotter (T ~ 10^6.5^ K), diffuse, and probably very massive (>10^11^ M_{sun}_) intra-group medium which has yet to be detected directly.
- ID:
- ivo://CDS.VizieR/J/AJ/121/2159
- Title:
- Basic parameters for 372 A, F & G stars
- Short Name:
- J/AJ/121/2159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Paper I (Cat. <J/AJ/121/2148>) of this series presented precise MK spectral types for 372 late A-, F-, and early G-type stars with the aim of understanding the nature of luminosity classification on the MK spectral classification system for this range of spectral types. In this paper, a multidimensional downhill simplex technique is introduced to determine the basic parameters of the program stars from fits of synthetic spectra and fluxes with observed spectra and fluxes from Strvmgren uvby photometry. This exercise yields useful calibrations of the MK spectral classification system but, most importantly, gives insight into the physical nature of luminosity classification on the MK spectral classification system. In particular, we find that in this range of spectral types, microturbulence appears to be at least as important as gravity in determining the MK luminosity type.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/1577
- Title:
- Basic properties of Kepler and CoRoT targets
- Short Name:
- J/MNRAS/462/1577
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- So-called scaling relations based on oscillation frequencies have the potential to reveal the mass and radius of solar-like oscillating stars. In the derivation of these relations, it is assumed that the first adiabatic exponent at the surface ({Gamma}_1s_) of such stars is constant. However, by constructing interior models for the mass range 0.8-1.6M_{sun}_, we show that {Gamma}_1s_ is not constant at stellar surfaces for the effective temperature range with which we deal. Furthermore, the well-known relation between large separation and mean density also depends on {Gamma}_1s_. Such knowledge is the basis for our aim of modifying the scaling relations. There are significant differences between masses and radii found from modified and conventional scaling relations. However, a comparison of predictions of these relations with the non-asteroseismic observations of Procyon A reveals that new scaling relations are effective in determining the mass and radius of stars. In the present study, solar-like oscillation frequencies of 89 target stars (mostly Kepler and CoRoT) were analysed. As well as two new reference frequencies ({nu}_min1_ and {nu}_min2_) found in the spacing of solar-like oscillation frequencies of stellar interior models, we also take into account {nu}_min0_. In addition to the frequency of maximum amplitude, these frequencies have a very strong diagnostic potential in the determination of fundamental properties. The present study applies the derived relations from the models to the solar-like oscillating stars, and computes their effective temperatures using purely asteroseismic methods. There are in general very close agreements between effective temperatures from asteroseismic and non-asteroseismic (spectral and photometric) methods. For the Sun and Procyon A, for example, the agreement is almost total.
