- ID:
- ivo://CDS.VizieR/J/ApJ/527/573
- Title:
- Line Strengths in Elliptical Galaxies
- Short Name:
- J/ApJ/527/573
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have restudied line-strength gradients of 80 elliptical galaxies. Typical metallicity gradients of elliptical galaxies are {delta}[Fe/H]/{delta}log(r){=~}-0.3, which is flatter than the gradients predicted by monolithic collapse simulations. The metallicity gradients do not correlate with any physical properties of galaxies, including central and mean metallicities, central velocity dispersions {sigma}_0_, absolute B magnitudes M_B_, absolute effective radii R_e_, and dynamical masses of galaxies. By using the metallicity gradients, we have calculated mean stellar metallicities for individual ellipticals. Typical mean stellar metallicities are <[Fe/H]> {=~} -0.3 and range from <[Fe/H]>{=~}-0.8 to +0.3, which is contrary to what Gonzalez & Gorgas (1996) claimed; the mean metallicities of ellipticals are not universal. The mean metallicities correlate well with {sigma}_0{sigma}_ and dynamical masses, though relations for M_B_ and R_e_ include significant scatters.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/3130
- Title:
- Lists of arm and interarm supernovae
- Short Name:
- J/MNRAS/459/3130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 215 supernovae (SNe), we analyse their positions relative to the spiral arms of their host galaxies, distinguishing grand-design (GD) spirals from non-GD (NGD) galaxies. We find that: (1) in GD galaxies, an offset exists between the positions of Ia and core-collapse (CC) SNe relative to the peaks of arms, while in NGD galaxies the positions show no such shifts; (2) in GD galaxies, the positions of CC SNe relative to the peaks of arms are correlated with the radial distance from the galaxy nucleus. Inside (outside) the corotation radius, CC SNe are found closer to the inner (outer) edge. No such correlation is observed for SNe in NGD galaxies nor for SNe Ia in either galaxy class; (3) in GD galaxies, SNe Ibc occur closer to the leading edges of the arms than do SNe II, while in NGD galaxies they are more concentrated towards the peaks of arms. In both samples of hosts, the distributions of SNe Ia relative to the arms have broader wings. These observations suggest that shocks in spiral arms of GD galaxies trigger star formation in the leading edges of arms affecting the distributions of CC SNe (known to have short-lived progenitors). The closer locations of SNe Ibc versus SNe II relative to the leading edges of the arms supports the belief that SNe Ibc have more massive progenitors. SNe Ia having less massive and older progenitors, have more time to drift away from the leading edge of the spiral arms.
- ID:
- ivo://CDS.VizieR/J/ApJ/855/115
- Title:
- Lithium abundances of KOIs from CKS spectra
- Short Name:
- J/ApJ/855/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The lithium doublet at 6708{AA} provides an age diagnostic for main sequence FGK dwarfs. We measured the abundance of lithium in 1305 stars with detected transiting planets from the Kepler mission using high-resolution spectroscopy. Our catalog of lithium measurements from this sample has a range of abundance from A(Li)=3.11+/-0.07 to an upper limit of -0.84dex. For a magnitude-limited sample that comprises 960 of the 1305 stars, our Keck-HIRES spectra have a median signal-to-noise ratio of 45 per pixel at ~6700{AA} with spectral resolution {lambda}/{Delta}{lambda}=R=55000. We identify 80 young stars that have A(Li) values greater than the Hyades at their respective effective temperatures; these stars are younger than ~650Myr, the approximate age of the Hyades. We then compare the distribution of A(Li) with planet size, multiplicity, orbital period, and insolation flux. We find larger planets preferentially in younger systems, with an A-D two-sided test p-value=0.002, a>3{sigma} confidence that the older and younger planet samples do not come from the same parent distribution. This is consistent with planet inflation/photoevaporation at early ages. The other planet parameters (Kepler planet multiplicity, orbital period, and insolation flux) are uncorrelated with age.
- ID:
- ivo://CDS.VizieR/J/A+A/326/780
- Title:
- Lithium depletion in CABs
- Short Name:
- J/A+A/326/780
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We included 2 tables containing photometric data, together equivalent width of LiI6708 A, for a sample of dwarf components of Chromospherically Active Binaries (CABs).
- ID:
- ivo://CDS.VizieR/J/AJ/151/136
- Title:
- LITTLE THINGS dwarf irregular galaxies FUV regions
- Short Name:
- J/AJ/151/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine FUV images of the LITTLE THINGS sample of nearby dwarf irregular (dIrr) and Blue Compact Dwarf galaxies to identify distinct young regions in their far outer disks. We use these data, obtained with the Galaxy Evolution Explorer satellite, to determine the furthest radius at which in situ star formation can currently be identified. The FUV knots are found at distances from the center of the galaxies of 1-8 disk scale lengths and have ages of =<20 Myr and masses of 20 M_{sun}_ to 1x10^5^ M_{sun}_. The presence of young clusters and OB associations in the outer disks of dwarf galaxies shows that dIrrs do have star formation taking place there in spite of the extreme nature of the environment. Most regions are found where the H I surface density is ~1 M_{sun}_/pc^2^, though both the H I and dispersed old stars go out much further. This limiting density suggests a cutoff in the ability to form distinct OB associations and perhaps even stars. We compare the star formation rates in the FUV regions to the average rates expected at their radii and beyond from the observed gas, using the conventional correlation for gas-rich regions. The localized rates are typically 10% of the expected average rates for the outer disks. Either star formation in dIrrs at surface densities <1 M_{sun}_/pc^2^ occurs without forming distinct associations, or the Kennicutt-Schmidt relation over-predicts the rate beyond this point. In the latter case, the stellar disks in the far-outer parts of dIrrs result from scattering of stars from the inner disk.
- ID:
- ivo://CDS.VizieR/J/A+A/421/763
- Title:
- Liverpool-Edinburgh High Proper Motion Catalogue
- Short Name:
- J/A+A/421/763
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a machine selected catalogue of 11289 objects with proper motions exceeding 0.18arcsec/yr and an R-band faint magnitude limit of 19.5mag. The catalogue was produced using SuperCOSMOS digitized R-Band ESO and UK Schmidt Plates in 287 Schmidt fields covering almost 7000 square degrees (~17% of the whole sky) at the South Galactic Cap. The catalogue includes UK Schmidt BJ and I magnitudes for all of the stars as well as 2MASS magnitudes for 10447 of the catalogue stars. We also show that the NLTT is ~95% complete for DE>-32.5{deg}.
- ID:
- ivo://CDS.VizieR/J/A+A/397/575
- Title:
- Liverpool-Edinburgh high proper motion survey
- Short Name:
- J/A+A/397/575
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 6206 stars which have proper motions exceeding 0.18 arcsec/yr with an R-band faint magnitude limit of 19.5mag. This catalogue has been produced using SuperCOSMOS digitized R-Band ESO and UK Schmidt Plates in 131 Schmidt fields covering more than 3,000 square degrees (>7.5% of the whole sky) at the South Galactic Cap. The survey is >90% complete within the nominal limits of the Luyten Two Tenths Catalogue of m_R_<18.5mag and 0.2<{mu}<2.5arcsec/yr, and is >80% complete for m_R_<19.5mag and {mu}<2.5arcsec/yr.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1233
- Title:
- LkH{alpha} 101 and the young cluster in NGC 1579
- Short Name:
- J/AJ/128/1233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The central region of the dark cloud L1482 is illuminated by LkH{alpha} 101, a heavily reddened (A_V_~10mag) high-luminosity (>=8x10^3^L_Sun_) star having an unusual emission-line spectrum plus a featureless continuum. About 35 much fainter (mostly between R=16 and >21) H{alpha} emitters have been found in the cloud. Their color-magnitude distribution suggests a median age of about 0.5Myr, with considerable dispersion. There are also at least five bright B-type stars in the cloud, presumably of about the same age; none show the peculiarities expected of HAeBe stars. Dereddened, their apparent V magnitudes lead to a distance of about 700pc. Radio observations suggest that the optical object LkH{alpha} 101 is in fact a hot star surrounded by a small H II region, both inside an optically thick dust shell.
- ID:
- ivo://CDS.VizieR/J/AJ/158/104
- Title:
- LL Com BVR bands photometry & times of light minimum
- Short Name:
- J/AJ/158/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Despite the discovery of LL Com, a Lyrae-type eclipsing binary system, approximately 60 yr ago, little has been found concerning its detailed photometry and orbital-period change until now. In this paper, we present the first multi-band charge-coupled-device photometric light curves, from which a significant luminosity reduction around the primary eclipse is revealed. Based on LAMOST data, we first determined LL Com's spectrum as F1V and then analyzed the light curves with the 2015 version of the Wilson-Devinney code. The fact that LL Com is a near-contact binary system with a semi-detached configuration, where the secondary component only fills its Roche lobe and the primary component fills more than 95% of its Roche lobe, is suggested through the photometric solution. In addition, according to archival photometry and previously published times of minima, a secular period increase at a rate of P=2.62x10^-7^ day/yr was found, which implies a continuous mass transfer from the secondary to the primary. Utilizing the photometric solution and the simulations of single-particle trajectories, we propose the existence of a cool spot on the surface of the primary component. This cool spot can be naturally produced by the impacts that occur during mass flow, and it also successfully interprets the luminosity reduction in the light curves. Finally, with the combination of thermal relaxation oscillation theory and the Roche-Lobe model, we conclude that LL Com is transitioning from the semi-detached to the detached phase.
1950. LMC bar star clusters
- ID:
- ivo://CDS.VizieR/J/A+A/606/A21
- Title:
- LMC bar star clusters
- Short Name:
- J/A+A/606/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results on star clusters located in the South-Eastern half of the Large Magellanic (LMC) bar fromWashington CT1 photometry. Using appropriate kernel density estimators we detected 73 star cluster candidates, three of which do not show any detectable trace of star cluster sequences in their colour-magnitude diagrams (CMDs).We did not detect other 38 previously catalogued clusters, which could not be recognized when visually inspecting the C and T1 images either; the distribution of stars in their respective fields do not resemble that of an stellar aggregate. They represent ~33 per cent of all catalogued objects located within the analysed LMC bar field. From matching theoretical isochrones to the cluster CMDs cleaned from field star contamination, we derived ages in the range 7.2<log(t[yr^-1^])<10.1. As far as we are aware, this is the first time homogeneous age estimates based on resolved stellar photometry are obtained for most of the studied clusters. We built the cluster frequency (CF) for the surveyed area, and found that the major star cluster formation activity has taken place during the period log(t[yr^-1^])~8.0-9.0. Since ~100Myr ago, clusters have been formed during few bursting formation episodes. When comparing the observed CF to that recovered from the star formation rate we found noticeable differences, which suggests that field star and star cluster formation histories could have been significantly different.
