- ID:
- ivo://CDS.VizieR/J/ApJS/237/18
- Title:
- Cr, Co, and Ni abundances for metal-poor red giants
- Short Name:
- J/ApJS/237/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the abundances of chromium, cobalt, and nickel in 4113 red giants, including 2277 stars in globular clusters (GCs), 1820 stars in the Milky Way's dwarf satellite galaxies, and 16 field stars. We measured the abundances from mostly archival Keck/DEIMOS medium-resolution spectroscopy with a resolving power of R~6500 and a wavelength range of approximately 6500-9000{AA}. The abundances were determined by fitting spectral regions that contain absorption lines of the elements under consideration. We used estimates of temperature, surface gravity, and metallicity that we previously determined from the same spectra. We estimated systematic error by examining the dispersion of abundances within mono- metallic GCs. The median uncertainties for [Cr/Fe], [Co/Fe], and [Ni/Fe] are 0.20, 0.20, and 0.13, respectively. Finally, we validated our estimations of uncertainty through duplicate measurements, and we evaluated the accuracy and precision of our measurements through comparison to high-resolution spectroscopic measurements of the same stars.
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- ID:
- ivo://CDS.VizieR/J/A+A/640/A17
- Title:
- CR Ground Level Enhancements spectra (IGLED)
- Short Name:
- J/A+A/640/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Continuous measurements of ground-based neutron monitors (NMs) form the main data source to study high-energy/high-intensity solar energetic particle (SEP) events, called ground-level enhancements (GLEs). All available data are collected in the International GLE Database (IGLED, http://gle.oulu.fi), which provides formal NM count-rate increases above the constant pre-increase level due to galactic cosmic rays (GCR). This dataset is used to reconstruct energy spectra of GLE events. However, the assumption of the constant GCR background level throughout GLE events is often invalid. Here we made a major revision of the IGLED dataset and provided a dataset of detrended NM count-rate increases accounting for the variable GCR background. The formal GLE count-rate increases were corrected for the variable GCR background which may vary significantly during GLE events. The corresponding integral omnidirectional fluences of SEPs were reconstructed for all GLEs with the sufficient strength from the detrended data using the "effective rigidity" method. The database of detrended NM count-rate has been reset for all GLE events since 1956. The integral omnidirectional fluences have been estimated for all the GLE evens and parameterized for sufficiently strong ones by the modified Ellison-Ramaty spectral shape. The IGLED has been revisited to account for the variable GCR background. Integral omnidirectional fluences reconstructed for most of GLE events, have benn added to IGLED. This forms a basis for more precise studies of parameters of SEP events and, thus, for Solar and space physics.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A95
- Title:
- C-rich giants synthetic spectrophotometry. IV
- Short Name:
- J/A+A/566/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The evolution and spectral properties of stars on the asymptotic giant branch (AGB) are significantly affected by massloss through dusty stellar winds. Dynamic atmosphere and wind models are an essential tool for studying these evolved stars, both individually and as members of stellar populations, to understand their contribution to the integrated light and chemical evolution of galaxies. This paper is part of a series with the purpose of testing state-of-the-art atmosphere and wind models of C-type AGB stars against observations, and making them available to the community for use in various theoretical and observational studies. We have computed low-resolution spectra and photometry (in the wavelength range 0.35-25um) for a grid of 540 dynamic models with stellar parameters typical of solar-metallicity C-rich AGB stars and with a range of pulsation amplitudes. The models cover the dynamic atmosphere and dusty outflow (if present), assuming spherical symmetry, and taking opacities of gas-phase species and dust grains consistently into account. To characterize the time-dependent dynamic and photometric behaviour of the models in a concise way we defined a number of classes for models with and without winds.Results. Comparisons with observed data in general show a quite satisfactory agreement for example regarding mass-loss rates vs. (J-K) colours or K magnitudes vs. (J-K) colours. Some exceptions from the good overall agreement, however, are found and attributed to the range of input parameters (e.g. relatively high carbon excesses) or intrinsic model assumptions (e.g. small particle limit for grain opacities). While current results indicate that some changes in model assumptions and parameter ranges should be made in the future to bring certain synthetic observables into better agreement with observations, it seems unlikely that these pending improvements will significantly affect the mass-loss rates of the models.
- ID:
- ivo://CDS.VizieR/J/A+A/324/1059
- Title:
- C-rich stars IR and UBVRI photometry
- Short Name:
- J/A+A/324/1059
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A study of circumstellar dust shells (CDS) around carbon stars is presented. This study is based on the analysis of the 1-100{mu}m broad-band spectra of 23 objects which have been monitored in the 1-20{mu}m region over several years at ESO. The sources in the sample range from Irr/SR variables and optical Miras to Extreme Carbon Stars which have only been discovered recently in infrared surveys. A modelling accounting for the photometric variations with phase (with up to 9 spectra per object) has been developed. All the CDSs in the sample can be modelled successfully in spherical geometry with a dust opacity law {prop.to}{lambda}^-1.3^ and a dust formation temperature ~950K. The modelling favors the case of an acceleration of dust, from the site of formation and on a distance of ~10^15^cm, over the case of a uniform expansion. Mass loss rates in the range 0.1-50x10^-6^M_{sun}_/yr are derived. The estimates based on this modelling are consistent with those derived from the CO emission line measurements. In view of the incoming near-infrared surveys (DENIS and 2MASS), an analysis of the location of carbon-rich sources in color diagrams is presented. It is shown that the near-infrared colors are well correlated with the mass loss rate. This property can be used to get an estimate, within a factor 3, of this rate for carbon stars without a priori on the distance.
- ID:
- ivo://CDS.VizieR/J/ApJ/658/345
- Title:
- CRIc photometry of Magellanic Bridge Fields
- Short Name:
- J/ApJ/658/345
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on observations of the stellar populations in 12 fields spanning the region between the Magellanic Clouds, made with the Mosaic II camera on the 4m telescope at the Cerro-Tololo Inter-American Observatory. The two main goals of the observations are to characterize the young stellar population (which presumably formed in situ in the Bridge and therefore represents the nearest stellar population formed from tidal debris), and to search for an older stellar component (which would have been stripped from either Cloud as stars, by the same tidal forces that formed the gaseous Bridge). We determine the star formation history of the young inter-Cloud population, which provides a constraint on the timing of the gravitational interaction that formed the Bridge. We do not detect an older stellar population belonging to the Bridge in any of our fields, implying that the material that was stripped from the Clouds to form the Magellanic Bridge was very nearly a pure gas.
- ID:
- ivo://CDS.VizieR/J/A+A/539/A109
- Title:
- CRIRES-POP: high resolution IR spectra library
- Short Name:
- J/A+A/539/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New instrumental capabilities and the wealth of astrophysical information extractable from the near-infrared wavelength region have led to a growing interest in the field of high resolution spectroscopy at 1-5m. We aim to provide a library of observed high-resolution and high signal-to-noise-ratio near-infrared spectra of stars of various types throughout the Hertzsprung-Russell diagram. This is needed for the exploration of spectral features in this wavelength range and for comparison of reference targets with observations and models.
- ID:
- ivo://CDS.VizieR/J/ApJ/667/1267
- Title:
- CrI transition probabilities
- Short Name:
- J/ApJ/667/1267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Branching fraction measurements from Fourier transform spectra in conjunction with published radiative lifetimes are used to determine transition probabilities for 263 lines of neutral chromium.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A192
- Title:
- C3R2-KMOS zsp & galaxy physical properties
- Short Name:
- J/A+A/642/A192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Complete Calibration of the Colour-Redshift Relation survey (C3R2) is a spectroscopic effort involving ESO and Keck facilities designed specifically to empirically calibrate the galaxy colour-redshift relation - P(zjC) to the Euclid depth (i_AB_=24.5) and is intimately linked to the success of upcoming Stage IV dark energy missions based on weak lensing cosmology. The aim is to build a spectroscopic calibration sample that is as representative as possible of the galaxies of the Euclid weak lensing sample. In order to minimise the number of spectroscopic observations necessary to fill the gaps in current knowledge of the P(zjC), self-organising map (SOM) representations of the galaxy colour space have been constructed. Here we present the first results of an ESO@VLT Large Programme approved in the context of C3R2, which makes use of the two VLT optical and near-infrared multi-object spectrographs, FORS2 and KMOS. This data release paper focuses on high-quality spectroscopic redshifts of high-redshift galaxies observed with the KMOS spectrograph in the near-infrared H- and K-bands. A total of 424 highly-reliable redshifts are measured in the 1.3<=z<=2.5 range, with total success rates of 60.7% in the H-band and 32.8% in the K-band. The newly determined redshifts fill 55% of high (mainly regions with no spectroscopic measurements) and 35% of lower (regions with low-resolution/low-quality spectroscopic measurements) priority empty SOMgrid cells.We measured H fluxes in a 1.2" radius aperture from the spectra of the spectroscopically confirmed galaxies and converted them into star formation rates. In addition, we performed an SED fitting analysis on the same sample in order to derive stellar masses, E(B-V), total magnitudes, and SFRs. We combine the results obtained from the spectra with those derived via SED fitting, and we show that the spectroscopic failures come from either weakly star-forming galaxies (at z<1.7, i.e. in the H-band) or low S/N spectra (in the K-band) of z>2 galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A67
- Title:
- CRL618, MWC922 and M2-9 RRL spectra
- Short Name:
- J/A+A/603/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results from a pilot search for radio recombination line (RRL) emission at millimeter wavelengths in a small sample of pre-planetary nebulae (pPNe) and young PNe (yPNe) with emerging central ionized regions. Observations of the H30{alpha}, H31{alpha}, H39{alpha}, H41{alpha}, H48{beta}, H49{beta}, H51{beta}, and H55{gamma} lines at ~1 and ~3mm have been performed with the IRAM 30m radio telescope. These lines are excellent probes of the dense inner (<~150 au) and heavily obscured regions of these objects, where the yet unknown agents for PN-shaping originate. We detected mm-RRLs in three objects: CRL 618, MWC922, and M2-9. For CRL 618, the only pPN with previous published detections of H41{alpha}, H35{alpha}, and H30{alpha} emission, we find significant changes in the line profiles indicating that current observations are probing regions of the ionized wind with larger expansion velocities and mass-loss rate than ~29 years ago. In the case of MWC922, we observe a drastic transition from single-peaked profiles at 3mm (H39{alpha} and H41{alpha}) to double-peaked profiles at 1mm (H31{alpha} and H30{alpha}), which is consistent with maser amplification of the highest frequency lines; the observed line profiles are compatible with rotation and expansion of the ionized gas, probably arranged in a disk+wind system around a ~5-10M_{sun}_ central mass. In M2-9, the mm-RRL emission appears to be tracing a recent mass outburst by one of the stars of the central binary system. We present the results from non-LTE line and continuum radiative transfer models, which enables us to constrain the structure, kinematics, and physical conditions (electron temperature and density) of the ionized cores of our sample. We find temperatures Te~6000-17000K, mean densities ne~10^5^-10^8^cm^-3^, radial density gradients ne{prop.to}r^-alpha_n_^ whit alpha_n_~2-3.5, and motions of velocities of ~10-30km/s in the ionized wind regions traced by these mm-wavelength observations. We deduce mass-loss rates of dM_pAGB_/dt~=10^-6^-10^-7^M_{sun}_/yr, which are significantly higher than the values adopted by stellar evolution models currently in use and would result in a transition from the asymptotic giant branch to the PN phase faster than hitherto assumed.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/5
- Title:
- Crosscorrelation function (CCF) studies in GX 17+2
- Short Name:
- J/ApJS/244/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Neutron star Z-type sources provide a unique platform in order to understand the structure of accretion disk-corona geometry emitting close to the Eddington luminosity. Using RXTE and Nuclear Spectroscopic Telescope Array Mission (NuSTAR) satellite data, we performed crosscorrelation function (CCF) studies in GX 17+2 in order to constrain the size of the corona responsible for hard X-rays. From the RXTE data, we found that during horizontal and normal branches, the CCFs show anticorrelated hard (16-30keV) and soft (2-5keV) X-ray delays of the order of a few tens to hundred seconds with a mean correlation coefficient of 0.42+/-0.11. Few observations shows correlated lags and, on one occasion, coincident with radio emission. We also report an anticorrelated hard X-ray delay of 113+/-51s using the NuSTAR data of GX 17+2. Based on RXTE data, we find that soft and hard X-ray fluxes are varying, indicating the changes in the disk-corona structure during delays. We bridle the size of the corona using relativistic precession, transition layer models, and boundary layer models. Assuming the delays to be a readjustment timescale of the disk-corona structure, the height of the corona was estimated to be ~17-100km. Assuming that the inner region of the truncated disk is occupied by the corona, we constrain the coronal readjustment velocities (v_corona_={beta}v_disk_, where v_disk_ is the radial velocity component of the disk) of the order of {beta}=0.06-0.12. This study indicates that the observed delays are primarily dependent on the varying coronal readjustment velocities.