- ID:
- ivo://CDS.VizieR/J/A+A/359/18
- Title:
- Line-strength predictions in Elliptical Galaxies
- Short Name:
- J/A+A/359/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table shows the line-strength predictions computed for: CaT, NaI, and MgI in the near infrared and Mgb, Mg2, Fe52, Fe53, NaD and H{beta}, in the blue-visible range, for Single Stellar Population (SSP) of 6 different metallicities, (Z=0.0004, 0.001, 0.004, 0.008, 0.02 and 0.05), and ages from log(age)=6.60 (4Gyr) to log(age)=10.30 (20Gyr), in steps of 0.10dex from 6.60 until 10.00, and 0.02 afterwards. (Therefore there are 50 records for each metallicity except that Z=0.001 has only 47). All indices have been computed taken the model atmospheres from Lejeune et al. (1997, Cat. <J/A+AS/125/229>, 1998, Cat. <J/A+AS/130/65>) and Clegg & Middlemass (1987MNRAS.228..759C) for hot stars (Teff > 50000 K). The used isochrones are from the Padova group (Bressan et al., 1993, Cat. <J/A+AS/100/647>). The total mass of every SSP is 10^9^M_{sun}_ with a Salpeter-type IMF, Phi(m)=m^-{alpha}^, with {alpha}=2.35, from m_low=0.6M_{sun}_ to m_up_=100M_{sun}_. The fitting functions for blue indices are those from Worthey et al. (1994, Cat. <J/ApJS/94/687>).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/364/674
- Title:
- Li-rich giants atomic lines
- Short Name:
- J/A+A/364/674
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A detailed analysis has been carried out for a sample of 16 red giants showing a strong Li I 670.8nm line. Ten of them were detected in a survey by Castilho et al. (1998A&AS..127..139C), and the other 6 stars are Li-rich giants selected from the literature. Element abundances in the sample Li-rich giants are similar to those in normal red giants, differing only by their high Li abundance and infrared excess. This suggests that Li-rich giants may correspond to a phase of stellar evolution of normal red giants, when Li is produced and transported to the atmosphere.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/4368
- Title:
- Lithium abundance of solar-like stars
- Short Name:
- J/MNRAS/451/4368
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the determination of the lithium abundance [A(Li)] of 52 solar-like stars. For 41 objects the A(Li) here presented corresponds to the first measurement. We have measured the equivalent widths of the 6708 {AA} lithium feature in high-resolution spectroscopic images (R~80000), obtained at the Observatorio Astrofisico Guillermo Haro (Sonora, Mexico), as part of the first scientific observations of the revitalized Lunar and Planetary Laboratory (LPL) Echelle Spectrograph, now known as the Cananea High-resolution Spectrograph (CanHiS). Lithium abundances were derived with the Fortran code MOOG, using as fundamental input a set of atmospheric parameters recently obtained by our group. With the help of an additional small sample with previous A(Li) determinations, we demonstrate that our lithium abundances are in agreement, to within uncertainties, with other works. Two target objects stand out from the rest of the sample. The star BD+47 3218 (T_eff_=6050+/-52 K, A(Li)=1.86+/-0.07 dex) lies inside the so-called lithium desert in the A(Li)-T_eff_ plane. The other object, BD+28 4515, has an A(Li)=3.05+/-0.07 dex, which is the highest of our sample and compatible with the expected abundances of relatively young stars.
- ID:
- ivo://CDS.VizieR/J/PASJ/57/45
- Title:
- Lithium abundances of F-K stars
- Short Name:
- J/PASJ/57/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An extensive profile-fitting analysis was performed for the Li(+Fe) 6707-6708{AA} feature of nearby 160 F-K dwarfs/subgiants (including 27 planet-host stars) in the Galactic disk (7000K>~Teff>~5000K, -1<~[Fe/H]<~+0.4), in order to establish the photospheric lithium abundances of these stars. The non-LTE effect (though quantitatively insignificant) was taken into account based on our statistical equilibrium calculations, which were carried out on an adequate grid of models. Our results confirmed most of the interesting observational characteristics revealed by recently published studies, such as the bimodal distribution of the Li abundances for stars at Teff>~6000K, the satisfactory agreement of the upper envelope of the A(Li) vs. [Fe/H] distribution with the theoretical models, the existence of a positive correlation between A(Li) and the stellar mass, and the tendency of lower lithium abundances of planet-host stars (as compared to stars without planets) at the narrow ``transition'' region of 5900K>~Teff>~5800K. The solar Li abundance derived from this analysis is 0.92 (H=12.00), which is by 0.24dex lower than the widely referenced standard value of 1.16.
- 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/505/L13
- Title:
- Lithium in globular NGC 6397
- Short Name:
- J/A+A/505/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most globular clusters are believed to host a single stellar population. They can thus be considered a good place to study the Spite plateau and to search for possible evolutionary modifications of the Li content. We want to determine the Li content of subgiant (SG) and main sequence (MS) stars of the old, metal-poor globular cluster NGC 6397. This work was aimed not only at studying possible Li abundance variations but also to investigate the cosmological Li discrepancy.
- ID:
- ivo://CDS.VizieR/J/A+A/541/A150
- Title:
- Lithium in M67 and Hyades
- Short Name:
- J/A+A/541/A150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Lithium abundances in open clusters are a very effective probe of mixing processes, and their study can help to understand the large depletion of lithium in the Sun. Due to its age and metallicity, the open cluster M67 is especially interesting on this regard. Many studies on lithium abundances in M67 have already been performed, but a homogeneous global analysis of lithium in stars from subsolar up to the most massive members, was never accomplished for a large sample based on high-quality spectra. We tested our non-standard models, which were calibrated using the Sun with observational data. We collected literature data to follow, for the first time in a homogeneous way, NLTE lithium abundances of all observed single stars in M67 more massive than about 0.9 solar masses.
528. Lithium in Praesepe
- ID:
- ivo://CDS.VizieR/J/AJ/106/1080
- Title:
- Lithium in Praesepe
- Short Name:
- J/AJ/106/1080
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Echelle observations are presented of lithium in 63 F and G dwarfs of the Praesepe cluster. For stars earlier than about G0V, Praesepe follows the same trends seen in the Hyades, which has approximately the same age and composition. Stars in Praesepe later than about G5V have more Li than their Hyades counterparts, possibly because Praesepe is slightly younger than the Hyades or has slightly lower metallicity. Significant differences in the abundance of Li are seen among stars of the same color, and, as in the Hyades, there is a tendency for the deviant stars to be binaries to the extent that duplicity in Praesepe is known. There are also stars with much less Li than most cluster members yet which appear to be true members of Praesepe. The close binary KW 181 has a normal Li abundance, despite the fact that similar close binaries in the Hyades are Li rich.
- ID:
- ivo://CDS.VizieR/J/ApJ/689/1295
- Title:
- Lithium test implications for brown dwarfs
- Short Name:
- J/ApJ/689/1295
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a large sample of optical spectra of late-type dwarfs, we identify a subset of late-M through L field dwarfs that, because of the presence of low-gravity features in their spectra, are believed to be unusually young. From a combined sample of 303 field L dwarfs, we find observationally that 7.6+/-1.6% are younger than 100Myr. This percentage is in agreement with theoretical predictions once observing biases are taken into account. We find that these young L dwarfs tend to fall in the southern hemisphere (DEC<0{deg}) and may be previously unrecognized, low-mass members of nearby, young associations like Tucana-Horologium, TW Hydrae, {beta} Pictoris, and AB Doradus. We use a homogeneously observed sample of ~150 optical spectra to examine lithium strength as a function of L/T spectral type and further corroborate the trends noted by Kirkpatrick and coworkers. We use our low-gravity spectra to investigate lithium strength as a function of age. The data weakly suggest that for early- to mid-L dwarfs the line strength reaches a maximum for a fewx100Myr, whereas for much older (few Gyr) and much younger (<100Myr) L dwarfs the line is weaker or undetectable.
- ID:
- ivo://CDS.VizieR/J/A+A/509/A61
- Title:
- Long slit spectroscopy in M31
- Short Name:
- J/A+A/509/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new optical long-slit data along six position angles of the bulge region of M31. We derive accurate stellar and gas kinematics reaching 5-arcmin from the center, where the disk light contribution is always less than 30%, and out to 8-arcmin along the major axis, where the disk provides 55% of the total light. We show that the velocity dispersions of McElroy (1983ApJ...270..485M) are severely underestimated (by up to 50km/s). As a consequence, previous dynamical models have underestimated the stellar mass of M31's bulge by a factor of 2. As a further consequence, the light-weighted velocity dispersion of the galaxy grows to 166km/s and to 170km/s if rotation is also taken into account, thus reducing the discrepancy between the predicted and measured mass of the black hole at the center of M31 from a factor of 3 to a factor of 2. The kinematic position angle varies with distance, pointing to triaxiality, but a quantitative conclusion can be reached only after simultaneous proper dynamical modeling of the bulge and disk components is performed. We detect gas counter-rotation near the bulge minor axis. We measure eight emission-corrected Lick indices. They are approximately constant on circles. Using simple stellar population models we derive the age, metallicity and {alpha}-element overabundance profiles. Except for the region in the inner arcsecs of the galaxy, the bulge of M31 is uniformly old (>=12Gyr, with many best-fit ages at the model grid limit of 15Gyr), slightly {alpha}-elements overabundant ([{alpha}/Fe]~0.2) and of solar metallicity, in agreement with studies of the resolved stellar components. The predicted u-g, g-r and r-i Sloan color profiles match the dust-corrected observations reasonably well, within the known limitations of current simple stellar population models. The stellar populations have approximately radially constant mass-to-light ratios (M/L_R~4-4.5M_{sun}_/L_{sun}_ for a Kroupa IMF), which is in agreement with the stellar dynamical estimates based on our new velocity dispersions. In the inner arcsecs the luminosity-weighted age drops to 4-8Gyr, while the metallicity increases to above three times the solar value. Starting from 6-arcmin from the center along the major axis, the mean age drops to >=8Gyr with slight supersolar metallicity (~+0.1dex) and {alpha}-element overabundance (~+0.2dex) for a mass-to-light ratio M/L_R<=3M_{sun}_/L_{sun}_. Diagnostic diagrams based on the [OIII]/H{beta} and [NI]H{beta} emission line equivalent widths (EWs) ratios indicate that the gas is ionized by shocks outside 10-arcsec, but an AGN-like ionizing source could be present near the center. We speculate that a gas-rich minor merger happened some 100Myr ago, causing the observed minor axis gas counter-rotation, the recent star formation event and possibly some nuclear activity.
