- ID:
- ivo://CDS.VizieR/J/MNRAS/468/703
- Title:
- Abell 168 ultra-diffuse galaxies distribution
- Short Name:
- J/MNRAS/468/703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Taking advantage of the Sloan Digital Sky Survey Stripe82 data, we have explored the spatial distribution of ultra-diffuse galaxies (UDGs) within an area of 8x8Mpc^2^ centred around the galaxy cluster Abell 168 (z=0.045). This intermediate massive cluster ({sigma}=550km/s) is surrounded by a complex large-scale structure. Our work confirms the presence of UDGs in the cluster and in the large-scale structure that surrounds it, and it is the first detection of UDGs outside clusters. Approximately 50 per cent of the UDGs analysed in the selected area inhabit the cluster region (~11+/-5 per cent in the core and ~39+/-9 per cent in the outskirts), whereas the remaining UDGs are found outside the main cluster structure (~50+/-11 per cent). The colours and the spatial distribution of the UDGs within this large-scale structure are more similar to dwarf galaxies than to L* galaxies, suggesting that most UDGs could be bona fide dwarf galaxies.
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- ID:
- ivo://CDS.VizieR/J/A+A/612/A19
- Title:
- Abell 2052 VLT/MUSE datacubes
- Short Name:
- J/A+A/612/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report observations of the radio galaxy 3C317 (at z=0.0345) located at the center of the Abell cluster A2052, obtained with the VLT/MUSE integral field spectrograph. The Chandra images of this cluster show cavities in the X-ray emitting gas, which were produced by the expansion of the radio lobes inflated by the active galactic nucleus (AGN). Our exquisite MUSE data show with unprecedented detail the complex network of line emitting filaments enshrouding the northern X-ray cavity. We do not detect any emission lines from the southern cavity, with a luminosity asymmetry between the two regions higher than ~75. The emission lines produced by the warm phase of the interstellar medium (WIM) enable us to obtain unique information on the properties of the emitting gas. We find dense gas (up to 270cm^-3^) that makes up part of a global quasi spherical outflow that is driven by the radio source, and obtain a direct estimate of the expansion velocity of the cavities (265km/s). The emission lines diagnostic rules out ionization from the AGN or from star-forming regions, suggesting instead ionization from slow shocks or from cosmic rays. The striking asymmetric line emission observed between the two cavities contrasts with the less pronounced differences between the north and south sides in the hot gas; this represents a significant new ingredient for our understanding of the process of the exchange of energy between the relativistic plasma and the external medium. We conclude that the expanding radio lobes displace the hot tenuous phase of the interstellar medium (ISM), but also impact the colder and denser ISM phases. These results show the effects of the AGN on its host and the importance of radio mode feedback.
- ID:
- ivo://CDS.VizieR/J/ApJ/774/148
- Title:
- Ab initio EOS for hydrogen-helium mixtures
- Short Name:
- J/ApJ/774/148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using density functional molecular dynamics simulations, we determine the equation of state (EOS) for hydrogen-helium mixtures spanning density-temperature conditions typical of giant-planet interiors, ~0.2-9g/cm3 and 1000-80000K for a typical helium mass fraction of 0.245. In addition to computing internal energy and pressure, we determine the entropy using an ab initio thermodynamic integration technique. A comprehensive EOS table with 391 density-temperature points is constructed and the results are presented in the form of a two-dimensional free energy fit for interpolation. Deviations between our ab initio EOS and the semi-analytical EOS model by Saumon and Chabrier (1992PhRvA..46.2084S, 1995ApJS...99..713S) are analyzed in detail, and we use the results for initial revision of the inferred thermal state of giant planets with known values for mass and radius. Changes are most pronounced for planets in the Jupiter mass range and below. We present a revision to the mass-radius relationship that makes the hottest exoplanets increase in radius by ~0.2 Jupiter radii at fixed entropy and for masses greater than ~0.5 Jupiter mass. This change is large enough to have possible implications for some discrepant "inflated giant exoplanets."
- ID:
- ivo://CDS.VizieR/J/ApJ/806/228
- Title:
- Ab initio EOS for water-hydrogen mixtures
- Short Name:
- J/ApJ/806/228
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from ab initio simulations of liquid water-hydrogen mixtures in the range from 2 to 70GPa and from 1000 to 6000K, covering conditions in the interiors of ice giant planets and parts of the outer envelope of gas giant planets. In addition to computing the pressure and the internal energy, we derive the Gibbs free energy by performing a thermodynamic integration. For all conditions under consideration, our simulations predict hydrogen and water to mix in all proportions. The thermodynamic behavior of the mixture can be well described with an ideal mixing approximation. We suggest that a substantial fraction of water and hydrogen in giant planets may occur in homogeneously mixed form rather than in separate layers. The extent of mixing depends on the planet's interior dynamics and its conditions of formation, in particular on how much hydrogen was present when icy planetesimals were delivered. Based on our results, we do not predict water-hydrogen mixtures to phase separate during any stage of the evolution of giant planets. We also show that the hydrogen content of an exoplanet is much higher if the mixed interior is assumed.
- ID:
- ivo://CDS.VizieR/II/85
- Title:
- Absolute Calibration of Stellar Spectrophotometry
- Short Name:
- II/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains the absolute fluxes for 16 stars published in Tables 1 and 2 of Johnson (1980). The absolute calibrations were accomplished by combining the 13-color photometry calibrations of Johnson and Mitchell (1975) with spectra obtained with a Michelson spectrophotometer and covering the wavelength range 4000 to 10300 Angstroms (Johnson 1977). The agreement between the absolute calibration and another recent one based upon data for alpha Lyr and 109 Vir by Tug et al. (1977) is shown (Johnson 1980) to be quite good. The catalog includes star name, cross identifications to the numbering systems of the Bright Star Catalogue and The Henry Draper Catalogue and arrays of fluxes having the same number of elements for each of the 16 stars.
- ID:
- ivo://CDS.VizieR/J/AJ/128/3053
- Title:
- Absolute flux distribution of BD +17 4708
- Short Name:
- J/AJ/128/3053
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Secondary flux standards are established by measuring their brightness relative to primary standard stars. The Hubble Space Telescope (HST) primary standards are the three pure-hydrogen white dwarf (WD) flux standards that determine the sensitivity calibration for the Space Telescope Imaging Spectrograph. STIS observations have defined the flux of the Sloan Digital Sky Survey (SDSS, http://www.sdss.org) standard BD+17 4708 from 0.17 to 1.0{mu}m with an uncertainty of less than 0.5% relative to the HST primary standards, as verified by two independent sets of photometry.
- ID:
- ivo://CDS.VizieR/J/A+AS/94/399
- Title:
- Absolute fluxes and distances of PN
- Short Name:
- J/A+AS/94/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete list of averaged recalibrated absolute H{beta} fluxes, global (where possible) relative He II {lambda} 4686 fluxes, 5-GHz radio flux densities, and H{alpha}/H{beta} interstellar extinction constants for 778 Galactic planetary nebulae. The catalog provides much of the fundamental data required to generate Zanstra temperatures. When data with the lowest errors are selected, the optical and radio/optical extinctions show a peculiar correlation, with the radio values slightly high at low extinction and notably low at high extinction. The data are used, along with the best estimates of angular diameters, to calculate Shklovsky distances according to the Daub scheme on the scale used earlier by Cahn and Kaler (1971ApJS...22..319C). Use of this distance scale shows approximate equality of the death rates of optically thick and optically thin planetary nebulae. The method gives the correct distances to the Magellanic Clouds.
- ID:
- ivo://CDS.VizieR/J/MNRAS/365/1357
- Title:
- Absolute magnitude of Globular Cluster
- Short Name:
- J/MNRAS/365/1357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We test whether the peak absolute magnitude MV(TO) of the Globular Cluster Luminosity Function (GCLF) can be used for reliable extragalactic distance determination. Starting with the luminosity function of the Galactic Globular Clusters listed in Harris (Cat. <VII/202>) catalogue, we determine MV(TO) either using current calibrations of the absolute magnitude MV(RR) of RR Lyrae stars as a function of the cluster metal content [Fe/H] and adopting selected cluster samples.
- ID:
- ivo://CDS.VizieR/J/AN/326/321
- Title:
- Absolute magnitudes for late-type dwarfs
- Short Name:
- J/AN/326/321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new formula for absolute magnitude determination for late-type dwarf stars as a function of (g-r) and (r-i) for Sloan photometry (as defined by Abazajian et al., 2003AJ....126.2081A). The absolute magnitudes estimated by this approach are brighter than those estimated by colour-magnitude diagrams, and they reduce the luminosity function rather close to the luminosity function of Hipparcos.
- ID:
- ivo://CDS.VizieR/J/other/NewA/12.446
- Title:
- Absolute magnitudes of cataclysmic variables
- Short Name:
- J/other/NewA/12.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using reliable trigonometric measurements, we find that the absolute magnitude of cataclysmic variables depends on the orbital period and de-reddened (J-H)_0_ and (H-Ks)_0_ colours of 2MASS (Two Micron All Sky Survey) photometric system. The calibration equation covers the ranges 0.032d<P_orb_<=0.454d, -0.08<(J-H)_0_<=1.54, -0.03<(H-Ks)_0_<=0.56 and 2.0<M_J_<11.7; It is based on trigonometric parallaxes with relative errors of ({sigma}{pi}/{pi})<=0.4. By using the period-luminosity-colours (PLCs) relation, we estimated the distances of cataclysmic variables with orbital periods and 2MASS observations and compared them with distances found from other methods. We suggest that the PLCs relation can be a useful statistical tool to estimate the distances of cataclysmic variables.
- ID:
- ivo://CDS.VizieR/J/MNRAS/479/5491
- Title:
- Absolute parameters of 509 main-sequence stars
- Short Name:
- J/MNRAS/479/5491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absolute parameters of 509 main-sequence stars selected from the components of detached eclipsing spectroscopic binaries in the solar neighbourhood are used to study mass-luminosity, mass-radius, and mass-effective temperature relations (MLR, MRR, and MTR). The MLR function is found better if expressed by a six-piece classical MLR (L{prop.to}M^{alpha}^) rather than a fifth or a sixth degree polynomial within the mass range of 0.179<=M/M_{sun}_<=31. The break points separating the mass ranges with classical MLR do not appear to us to be arbitrary. Instead, the data indicate abrupt changes along the mass axis in the mean energy generation per unit of stellar mass. Unlike the MLR function, the MRR and MTR functions cannot be determined over the full range of masses. A single-piece MRR function is calibrated from the radii of stars with M<=1.5M_{sun}_, while a second single-piece MTR function is found for stars with M>1.5M_{sun}_. The missing part of the MRR is computed from the MLR and MTR, while the missing part of the MTR is computed from the MLR and MRR. As a result, we have interrelated the MLR, MRR, and MTR, which are useful in determining the typical absolute physical parameters of main-sequence stars of given masses. These functions are also useful to estimate typical absolute physical parameters from typical T_eff_ values. Thus, we were able to estimate the typical absolute physical parameters of main-sequence stars observed in the Sejong Open cluster Survey, based on that survey's published values for Teff. Since typical absolute physical parameters of main-sequence stars cannot normally be determined in such photometric surveys, the interrelated functions are shown to be useful to compute such missing parameters from similar surveys.
- ID:
- ivo://CDS.VizieR/J/A+A/439/387
- Title:
- Absolute photoionization cross sections
- Short Name:
- J/A+A/439/387
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absolute photoionization cross sections for the ions N2+, N3+, O3+, O4+, F3+ , F4+ and Ne4+ are measured using the merged-beam technique, combining the synchrotron radiation from an undulator at the storage ring ASTRID with ions produced by an ECR ion source. The files contain the experimental absolute cross-section data reported in the paper. Each ascii file has 3 columns: Photon energy (eV), Cross section (Mb) and Statistical uncertainty (Mb). In addition to the latter there is a systematic uncertainty on the cross sections of about 15%. (1Mb=10^-18^cm^2^).
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/4485
- Title:
- Absolute polarimetry observations of 33 pulsars
- Short Name:
- J/MNRAS/453/4485
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absolute polarimetry observations of 33 pulsars were carried out with the Green Bank Telescope in the 1100-1900 MHz band using the Green Bank Ultimate Pulsar Processing Instrument. This group was selected to help complete a larger sample for which accurate proper-motion measurements were available. A combination of profile analysis using the core/double cone model and polarization-angle fitting methods were applied to estimate the "fiducial" longitude of the magnetic axis for each star and refer the linear polarization angle at that point to infinite frequency. As had been found previously, a number of the pulsars are found to have fiducial polarization directions that fall either along or at right angles to their proper-motion directions, whereas upwards of a third of the stars studied show alignments that are neither parallel nor orthogonal.
- ID:
- ivo://CDS.VizieR/J/AJ/124/601
- Title:
- Absolute positions and proper motions in NGC 188
- Short Name:
- J/AJ/124/601
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The field of direct imaging is experiencing a considerable growth in the number of available CCD mosaic imagers, especially on large telescopes. To fully exploit the astrometric potential of these imaging devices, we develop a technique, utilizing an astrometric standard, for precision transformation of pixel coordinates into a global coordinate system. We have constructed a new astrometric standard set of 1863 stars in the field of NGC 188 to derive the CCD chip constants for the NOAO CCD Mosaic Imager. The multiple-epoch data on the Mosaic's metrics indicate that this CCD mosaic device may have experienced a one-time nonelastic expansion. We also present a new determination of the pixel scale and the optical field angle distortion constants for the KPNO Mayall 4 m telescope prime focus field corrector. To establish a reliable history of the CCD mosaic imager metrics for current and potential future astrometric applications, we recommend obtaining astrometric calibrations for CCD mosaic imagers on a regular basis. Apart from mechanical positioning of the CCD mosaic camera on the telescope, noticeable changes in the thermal environment of CCD mosaic chips should also prompt new astrometric calibrations. It is shown that, following all precautions, the NOAO CCD Mosaic Imager can produce excellent astrometric results on the Mayall 4 m telescope.
- ID:
- ivo://CDS.VizieR/J/other/A+AT/25.185
- Title:
- Absolute proper motions of globular clusters
- Short Name:
- J/other/A+AT/25.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The absolute proper motions for a total of 92 globular clusters of the Milky Way (60% of all clusters included in the catalogue published by Harris, 1996, Cat. VII/195) are inferred from the UCAC2 proper motions of their likely member stars. The median formal error of the cluster proper motions is equal to 0.8marcsec/yr in both right ascension and declination, whereas the proper-motion errors of individual clusters range from 0.2 to 3marcsec/yr. Tests performed demonstrate the overall validity of the cluster motions; the resulting transverse velocities remain, on the average, virtually constant out to a heliocentric distance of 15kpc and the full space velocity of most of the clusters relative to the Galactic centre remains, on the average, unchanged near 190km/s out to a Galactocentric distance of about 20kpc, in agreement with the overall isothermal structure of the Galactic halo.
- ID:
- ivo://CDS.VizieR/J/A+A/388/168
- Title:
- Absolute proper motions of 93 open clusters
- Short Name:
- J/A+A/388/168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determined the mean absolute proper motion of 93 open clusters situated farther than 1 kpc from the Sun. The results are derived from the stellar proper motion data given in the Tycho2 Catalogue (<I/259>). The mean proper motion of the clusters and membership probability of individual stars were obtained from the proper motion data by applying the statistical method proposed by Sanders (1971A&A....14..226S). The measurements made use of a large number of stars, usually several tens, for each cluster. The total number of stars investigated in the fields of the clusters is 4864 of which 2021 were considered members. For 55 clusters, this is the first determination of the proper motion. The distances, ages and kinematics parameters of the clusters can be accessed at http://www.iagusp.usp.br/~wilton
- ID:
- ivo://CDS.VizieR/J/A+A/376/441
- Title:
- Absolute proper motions of 112 open clusters
- Short Name:
- J/A+A/376/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present mean absolute proper motions of 112 open clusters, determined using the data from the Tycho2 Catalogue (Cat. <I/259>). For 28 clusters, this is the first determination of proper motion. The measurements made use of a large number of stars (usually several tens) for each cluster. The total number of stars studied in the fields of the 164 open clusters is 5016, of which 4006 were considered members. The mean proper motions of the clusters and membership probability of individual stars were obtained from the proper motion data by applying the statistical method proposed by Sanders (1971A&A....14..226S).
- ID:
- ivo://CDS.VizieR/I/295
- Title:
- Absolute Proper motions of 59766 stars
- Short Name:
- I/295
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog PUL2 was made by photographic method in Pulkovo in accordance with Deutsch plan (KSZ, Deutch A.N., 1952IAUT....8..789D). Observations were made using Pulkovo Normal astrograph. The first epochs of photographic plates were fulfilled since 1937 till 1965, and the second ones - since 1969 till 1986. PUL2 includes 149 areas uniformly covering the North sky. The mean epoch difference is 24 years. For each area there are three pairs of plates. All plates are taken with one hour and 5 min exposure. On the plates with diffraction grating only bright reference stars were measured. For obtaining relative star proper motions the faint (15.2) reference stars we used. Relative proper motions were obtained using a six constant plate model. For obtaining fictitious proper motions of extragalactic objects (absolutization) about 700 galaxies was used. Random errors of relative star proper motions are of 5.5mas/yr in right ascension and 5.9mas/yr in declination. Errors of fictitious proper motions of galaxies are of 7.9mas/yr (mean absolutization error) for both coordinates by a representation of the Oort-Lindblad model. On the base of comparison of the common stars of PUL2 and Hipparcos catalogues the components of the residual rotation vector of the Hipparcos referently to extragalactic reference frame have been derived as follows: w(x,y,z)=(-0.98,-0.03,-1.66)+/-(0.47,0.38,0.42)mas/yr. Mean random errors of absolute bright star proper motions from comparison of PUL2 and Hipparcos catalogues were estimated as 9mas/yr in both coordinates.
- ID:
- ivo://CDS.VizieR/I/331
- Title:
- Absolute Proper motions Outside the Plane (APOP)
- Short Name:
- I/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of absolute proper motions and updated positions derived from the same Space Telescope Science Institute digitized Schmidt survey plates utilized for the construction of the Guide Star Catalog II. As special attention was devoted to the absolutization process and removal of position, magnitude and color dependent systematic errors through the use of both stars and galaxies, this release is solely based on plate data outside the galactic plane, i.e. |b|>=27{deg}. The resulting global zero point error is less than 0.6 mas/yr, and the precision better than 4.0mas/yr for objects brighter than R_F_=18.5, rising to 9.0mas/yr for objects with magnitude in the range 18.5<R_F_<20.0. The catalog covers 22,525 square degrees and lists 100,774,153 objects to the limiting magnitude of R_F_~20.8. Alignment with the International Celestial Reference System (ICRS) was made using 1288 objects common to the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths. As a result, the coordinate axes realized by our astrometric data are believed to be aligned with the extragalactic radio frame to within +/-0.2mas at the reference epoch J2000.0. This makes our compilation one of the deepest and densest ICRF-registered astrometric catalogs outside the galactic plane. Although the Gaia mission is poised to set the new standard in catalog astronomy and will in many ways supersede this catalog, the methods and procedures reported here will prove useful to remove astrometric magnitude- and color-dependent systematic errors from the next generation of ground-based surveys reaching significantly deeper than the Gaia catalog.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1400
- Title:
- Absolute properties of CM Dra
- Short Name:
- J/ApJ/691/1400
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present a complete reanalysis of the eclipsing systems, CM Dra, composed of two dM4.5 stars. New and existing light curves as well as a radial velocity curve are modeled to measure the physical properties of both components. The masses and radii determined for the components of CM Dra are M1=0.2310+/-0.0009M_{sun}_, M2=0.2141+/-0.0010M_{sun}_, R1=0.2534+/-0.0019R_{sun}_, and R2=0.2396+/-0.0015R_{sun}_. With relative uncertainties well below the 1% level, these values constitute the most accurate properties to date for fully convective stars.
- ID:
- ivo://CDS.VizieR/J/AJ/138/1622
- Title:
- Absolute properties of LV Her
- Short Name:
- J/AJ/138/1622
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report extensive spectroscopic and differential V-band photometric observations of the 18.4 day detached double-lined eclipsing binary LV Her (F9V), which has the highest eccentricity (e~0.613) among the systems with well-measured properties. We determine the absolute masses and radii of the components to be M1=1.193+/-0.010M_{sun}_, M2=1.1698+/-0.0081M_{sun}_, R1=1.358+/-0.012R_{sun}_, and R2=1.313+/-0.011R_{sun}_, with fractional errors of 0.9% or better. The effective temperatures are 6060+/-150K and 6030+/-150K, respectively, and the overall metallicity is estimated to be [m/H]=+0.08+/-0.21. A comparison with current stellar evolution models for this composition indicates an excellent fit for an age between 3.8 and 4.2Gyr, with both stars being near the middle of their main-sequence lifetimes. Full integration of the equations for tidal evolution is consistent with the high eccentricity, and suggests that the stars' spin axes are aligned with the orbital axis, and that their rotations should be pseudo-synchronized. The latter prediction is not quite in agreement with the measured projected rotational velocities.
- ID:
- ivo://CDS.VizieR/J/A+A/636/A36
- Title:
- Absolute radial velocities of CARMENES M dwarfs
- Short Name:
- J/A+A/636/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For years, the standard procedure to measure radial velocities (RVs) of spectral observations consisted in cross-correlating the spectra with a binary mask, that is, a simple stellar template that contains information on the position and strength of stellar absorption lines. The cross-correlation function (CCF) profiles also provide several indicators of stellar activity. We present a methodology to first build weighted binary masks and, second, to compute the CCF of spectral observations with these masks from which we derive radial velocities and activity indicators. These methods are implemented in a python code that is publicly available. To build the masks, we selected a large number of sharp absorption lines based on the profile of the minima present in high signal-to-noise ratio (S/N) spectrum templates built from observations of reference stars. We computed the CCFs of observed spectra and derived RVs and the following three standard activity indicators: full-width-at-half-maximum as well as contrast and bisector inverse slope. We applied our methodology to CARMENES high-resolution spectra and obtain RV and activity indicator time series of more than 300 M dwarf stars observed for the main CARMENES survey. Compared with the standard CARMENES template matching pipeline, in general we obtain more precise RVs in the cases where the template used in the standard pipeline did not have enough S/N. We also show the behaviour of the three activity indicators for the active star YZ CMi and estimate the absolute RV of the M dwarfs analysed using the CCF RVs.
- ID:
- ivo://CDS.VizieR/J/AJ/155/213
- Title:
- Absolute reflectance & new calibration site of the Moon
- Short Name:
- J/AJ/155/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- How bright the Moon is forms a simple but fundamental and important question. Although numerous efforts have been made to answer this question such as use of sophisticated electro-optical measurements and suggestions for calibration sites, the answer is still debated. An in situ measurement with a calibration panel on the surface of the Moon is crucial for obtaining the accurate absolute reflectance and resolving the debate. China's Chang'E-3 (CE-3) "Yutu" rover accomplished this type of measurement using the Visible-Near Infrared Spectrometer (VNIS). The measurements of the VNIS, which were at large emission and phase angles, complement existing measurements for the range of photometric geometry. The in situ reflectance shows that the CE-3 landing site is very dark with an average reflectance of 3.86% in the visible bands. The results are compared with recent mission instruments: the Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC), the Spectral Profiler (SP) on board the SELENE, the Moon Mineralogy Mapper (M^3^) on board the Chandrayaan-1, and the Chang'E-1 Interference Imaging Spectrometer (IIM). The differences in the measurements of these instruments are very large and indicate inherent differences in their absolute calibration. The M^3^ and IIM measurements are smaller than LROC WAC and SP, and the VNIS measurement falls between these two pairs. When using the Moon as a radiance source for the on-orbit calibration of spacecraft instruments, one should be cautious about the data. We propose that the CE-3 landing site, a young and homogeneous surface, should serve as the new calibration site.
- ID:
- ivo://CDS.VizieR/J/A+A/607/A72
- Title:
- Absolute Refletivity of Jupiter and Saturn
- Short Name:
- J/A+A/607/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide measurements of the absolute reflectivity of Jupiter and Saturn along their central meridians in filters covering a wide range of visible and near-infrared wavelengths (from 0.38 to 1.7um) that are not often presented in the literature. We also give measurements of the geometric albedo of both planets and discuss the limb-darkening behavior and temporal variability of their reflectivity values for a period of four years (2012-2016). This work is based on observations with the PlanetCam-UPV/EHU instrument at the 1.23m and 2.2m telescopes in Calar Alto Observatory (Spain). The instrument simultaneously observes in two channels: visible (VIS; 0.38-1.0um) and short-wave infrared (SWIR; 1.0-1.7um). We obtained high-resolution observations via the lucky-imaging method. We show that our calibration is consistent with previous independent determinations of reflectivity values of these planets and, for future reference, provide new data extended in the wavelength range and in the time. Our results have an uncertainty in absolute calibration of 10-20%. We show that under the hypothesis of constant geometric albedo, we are able to detect absolute reflectivity changes related to planetary temporal evolution of about 5-10%.
- ID:
- ivo://CDS.VizieR/J/ApJ/425/418
- Title:
- Absolute R mag of brightest cluster galaxies
- Short Name:
- J/ApJ/425/418
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured the velocity of the Local Group with respect to an inertial frame defined by the 119 Abell and Abell, Corwin, & Olowin (ACO, Cat. <VII/110A>) clusters contained within 15000km/s. The observations consist of a full-sky peculiar velocity survey with an effective depth ranging from 8000 to 11000km/s, depending on how the observations are weighted with redshift. This is the deepest peculiar velocity survey yet conducted. Clusters are selected by heliocentric redshift, and the sample is volume-limited. We use the Hoessel (1980ApJ...241..493H) relationship between the metric luminosities of the brightest clusters galaxies (BCGs) and the slope of their brightness profiles as the distance indicator. The Cousins R-band luminosity within a metric radius of 10h^-1^kpc yields a typical distance error of 16% for a single BCG.
- ID:
- ivo://CDS.VizieR/J/AJ/135/2245
- Title:
- Absolute spectrum of the Sun and Vega for 0.2-30um
- Short Name:
- J/AJ/135/2245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine an absolute calibration for the Multiband Imaging Photometer for Spitzer 24um band and recommend adjustments to the published calibrations for Two Micron All Sky Survey (2MASS), Infrared Array Camera (IRAC), and IRAS photometry to put them on the same scale. We show that consistent results are obtained by basing the calibration on either an average A0V star spectral energy distribution (SED), or by using the absolutely calibrated SED of the Sun in comparison with solar-type stellar photometry (the solar analog method).
- ID:
- ivo://CDS.VizieR/J/ApJ/721/1608
- Title:
- Absolute UV magnitudes of type Ia SNe
- Short Name:
- J/ApJ/721/1608
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the absolute magnitudes and light-curve shapes of 14 nearby (redshift z=0.004-0.027) Type Ia supernovae (SNe Ia) observed in the ultraviolet (UV) with the Swift Ultraviolet/Optical Telescope. Colors and absolute magnitudes are calculated using both a standard Milky Way extinction law and one for the Large Magellanic Cloud that has been modified by circumstellar scattering. We find very different behavior in the near-UV filters (uvw1_rc_ covering ~2600-3300{AA} after removing optical light, and u~3000-4000{AA}) compared to a mid-UV filter (uvm2~2000-2400{AA}).
- ID:
- ivo://CDS.VizieR/J/A+A/517/A60
- Title:
- Absorption coefficient of polystyrene
- Short Name:
- J/A+A/517/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The surfaces of airless bodies in the Solar System are continuously altered by the bombardment of micrometeoroids and irradiation by solar wind, flares, and cosmic particles. Major effects of this process - space weathering - are darkening and "reddening" of the spectra of surface materials, as well as a "degrading" of absorption features. We studied the changes induced by energetic ion irradiation in the ultraviolet-visual-near-infrared (UV-Vis-NIR) (0.2-0.98um) reflectance spectra of targets selected to mimic the surfaces of airless bodies in the inner Solar System. Our chosen targets are olivine pellets, pure or covered by an organic polymer (polystyrene), which is transparent before irradiation. Polystyrene is used as a template for organic matter of low volatility that can be present on asteroidal surfaces. Moreover we measured the changes induced by ion irradiation in the absorption coefficient of the polymer. The purpose was to have a tool to better compare laboratory with observed spectra and distinguish between planetary objects with pure silicate surfaces and those whose surface is covered by organic matter exposed to cosmic ion bombardment.
- ID:
- ivo://CDS.VizieR/J/AJ/161/285
- Title:
- Absorption & emission lines and RVel for vA 351
- Short Name:
- J/AJ/161/285
- Date:
- 08 Mar 2022
- Publisher:
- CDS
- Description:
- We extend results first announced by Franz et al., that identified vA351=H346 in the Hyades as a multiple star system containing a white dwarf. With Hubble Space Telescope Fine Guidance Sensor fringe tracking and scanning, and more recent speckle observations, all spanning 20.7years, we establish a parallax, relative orbit, and mass fraction for two components, with a period, P=2.70yr and total mass 2.1M{sun}. With ground-based radial velocities from the McDonald Observatory Otto Struve 2.1m Telescope Sandiford Spectrograph, and Center for Astrophysics Digital Speedometers, spanning 37 years, we find that component B consists of BC, two M-dwarf stars orbiting with a very short period (P_BC_=0.749days), having a mass ratio M_C_/M_B_=0.95. We confirm that the total mass of the system can only be reconciled with the distance and component photometry by including a fainter, higher-mass component. The quadruple system consists of three M dwarfs (A, B, C) and one white dwarf (D). We determine individual M-dwarf masses M_A_=0.53{+/-}0.10M{sun}, M_B_=0.43{+/-}0.04M{sun}, and M_C_=0.41{+/-}0.04M{sun}. The white dwarf mass, 0.54{+/-}0.04M{sun}, comes from cooling models, an assumed Hyades age of 670Myr, and consistency with all previous and derived astrometric, photometric, and radial velocity results. Velocities from H{alpha} and HeI emission lines confirm the BC period derived from absorption lines, with similar (HeI) and higher (H{alpha}) velocity amplitudes. We ascribe the larger H{alpha} amplitude to emission from a region each component shadows from the other, depending on the line of sight.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/11
- Title:
- Absorption features in SDSS. I. MgII abs. doublets
- Short Name:
- J/ApJS/235/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for MgII{lambda}{lambda}2796,2803 narrow absorption doublets in the spectra data around MgII{lambda}2798 emission lines. We obtain 17316 MgII doublets, within the redshift range of 0.3299<=z_abs_<=2.5663. We find that a velocity offset of {upsilon}_r_<6000km/s is a safe boundary to constrain the vast majority of associated Mg ii systems, although we find some doublets at {upsilon}_r_>6000km/s. If associated Mg ii absorbers are defined by {upsilon}_r_<6000km/s, ~33.3% of the absorbers are supposed to be contaminants of intervening systems. Removing the 33.3% contaminants, ~4.5% of the quasars present at least one associated MgII system with W_r_^{lambda}2796^>=0.2{AA}. The fraction of associated MgII systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The {upsilon}_r_ distribution of the outflow MgII absorbers is peaked at 1023km/s, which is smaller than the corresponding value of the outflow CIV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by {upsilon}_r_{>}-3000km/s differs from that of absorbers constrained by {upsilon}_r_>2000km/s. Absorbers limited by {upsilon}_r_>2000km/s and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger {upsilon}_r_. The distributions of equivalent widths, and the ratio of W_r_^{lambda}2796^/W_r_^{lambda}2803^, are the same for associated and intervening systems, and independent of quasar luminosity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/445/2061
- Title:
- Absorption in multiphase circumgalactic medium
- Short Name:
- J/MNRAS/445/2061
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents an absorption-line study of the multiphase circumgalactic medium (CGM) based on observations of Ly{alpha}, CII, CIV, SiII, SiIII, and SiIV absorption transitions in the vicinities of 195 galaxies at redshift z<0.176. The galaxy sample is established based on a cross-comparison between public galaxy and quasi-stellar object (QSO) survey data and is characterized by a median redshift of <z>=0.041, a median projected distance of <d>=362kpc to the sightline of the background QSO, and a median stellar mass of log(M_star_/M_{sun}_)=9.7+/-1.1. Comparing the absorber features identified in the QSO spectra with known galaxy properties has led to strong constraints for the CGM absorption properties at z<~0.176. First, abundant hydrogen gas is observed out to d~500kpc, well beyond the dark matter halo radius R_h_ of individual galaxies, with a mean covering fraction of ~60 percent. In contrast, no heavy elements are detected at d>~0.7R_h_ from either low-mass dwarfs or high-mass galaxies. The lack of detected heavy elements in low- and high-ionization states suggests that either there exists a chemical enrichment edge at d~0.7R_h_ or gaseous clumps giving rise to the observed absorption lines cannot survive at these large distances. Considering all galaxies at d>R_h_ leads to a strict upper limit for the covering fraction of heavy elements of ~3% (at a 95% confidence level) over d=(1-9)R_h_. At d<R_h_, differential covering fraction between low- and high-ionization gas is observed, suggesting that the CGM becomes progressively more ionized from d<0.3R_h_ to larger distances. Comparing CGM absorption observations at low and high redshifts shows that at a fixed fraction of R_h_ the CGM exhibits stronger mean absorption at z=2.2 than at z~0, and that the distinction is most pronounced in low-ionization species traced by CII and SiII absorption lines. We discuss possible pseudo-evolution of the CGM as a result of misrepresentation of halo radius, and present a brief discussion on the implications of these findings.
- ID:
- ivo://CDS.VizieR/J/ApJS/239/19
- Title:
- Absorption lines in 21 Lyn A-type star
- Short Name:
- J/ApJS/239/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of absorption lines in the z', Y, and J bands that we identified in 21 Lyn, a slowly rotating A0.5V star. We detected 155 absorption features in the high-resolution (0.90-1.35um, R=28000) spectrum obtained with the WINERED spectrograph after the telluric absorption was carefully removed using a spectrum of a B-type star as a telluric standard. With a visual comparison with synthetic spectra, we compiled a catalog of 219 atomic lines for the 155 features, some of which are composed of multiple fine structure lines. The high-quality WINERED spectrum enabled us to detect a large number of weak lines down to ~1% in depth, which are identified for an A-type star for the first time. The catalog includes the lines of H, C, N, O, Mg, Al, Si, S, Ca, Fe, and Sr. These new lines are expected to be useful for spectral classification and chemical abundance analyses, while the line catalog is useful for observers who plan to use A-type stars as telluric standards because it is necessary to distinguish between stellar lines and telluric absorption lines in high-resolution spectra. ASCII versions of the spectra are available in the online version of the journal.
- ID:
- ivo://CDS.VizieR/J/A+A/318/347
- Title:
- Absorption lines in QSO 0000-2619
- Short Name:
- J/A+A/318/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We give the list of absorption lines in the high resolution (FWHM=13 km/s) spectrum of the z=4.12 QSO 0000-2619. The first table contains the lines of the Lyman-alpha forest, while in the second table the lines of the metal systems are listed.
- ID:
- ivo://CDS.VizieR/J/MNRAS/386/715
- Title:
- Absorption-line strengths in Coma galaxies
- Short Name:
- J/MNRAS/386/715
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present stellar population parameters of 12 elliptical and S0 galaxies in the Coma cluster around and including the cD galaxy NGC 4874, based on spectra obtained using the Low Resolution Imaging Spectrograph on the Keck II Telescope. Our data are among the most precise and accurate absorption-line strengths yet obtained for cluster galaxies, allowing us to examine in detail the zero-point and scatter in the stellar population properties of Coma cluster early-type galaxies (ETGs).
- ID:
- ivo://CDS.VizieR/J/A+A/412/707
- Title:
- Absorption-line systems in QSO spectra - CoALS
- Short Name:
- J/A+A/412/707
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absorption lines and absorption-line systems (ALSs) observed in the spectra of QSOs contain fundamental information on distribution of matter between the observer and the QSO, and on physical processes in the Universe in different epochs of the cosmological evolution. The presented catalog contains a compilation of basic information on absorption-line systems (ALSs) in QSO spectra. The data are taken from publications available to the authors up to January 2002. The catalog includes, in particular, all the data of the catalogs by Junkkarinen et al. (1991ApJS...77..203J) and York et al. (1991MNRAS.250...24Y ). The catalog consists of table1.dat, table2.txt and the list of references in refs.dat file. The present catalog is also available at the site of the Dept. of Theor. Astrophys. of the Ioffe Physical Technical Institute: <www.ioffe.ru/astro/QC>
- ID:
- ivo://CDS.VizieR/J/ApJ/799/115
- Title:
- Absorption spectrum of SO up to 2.5THz
- Short Name:
- J/ApJ/799/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to obtain accurate terahertz center frequencies for SO and its isotopologues, we have studied the absorption spectrum of SO, ^34^SO, and ^33^SO up to 2.5THz using continuous-wave terahertz photomixing based on a frequency comb providing an accuracy down to 10kHz. Sulfur monoxide was produced in a radio frequency discharge of air in a cell containing pure sulfur. Together with the strong absorption signal of the main isotopologue, transitions of ^34^SO (^34^S: 4.21%) and ^33^SO (^33^S: 0.75%) were observed in natural abundance. The newly observed transitions constitute an extension of the observed rotational quantum numbers of the molecule toward higher N values, allowing an improvement of the molecular parameters for the three species. An isotopically invariant fit has been performed based on pure rotational and ro-vibrational transitions of all SO isotopologues, enabling their accurate line position prediction at higher frequencies. Thanks to this new set of parameters, it is now possible to predict with very high accuracy the frequencies of the ro-vibrational lines. This should enable the research of SO in the mid-IR using ground-based IR telescopes, space-based telescope archives (Infrared Space Observatory, Spitzer), and future space missions such as the James Webb Space Telescope. This set of parameters is particularly well adapted for the detection of SO lines in O-rich evolved stars or in molecular clouds in absorption against bright IR sources.
- ID:
- ivo://CDS.VizieR/J/A+AS/127/217
- Title:
- Absorption spectrum of the QSO PKS2126-158
- Short Name:
- J/A+AS/127/217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectra of the z_em_=3.268 quasar PKS 2126-158 have been obtained in the wavelength range 430-662nm with a resolution R=27000 and an average signal to noise ratio s/n=25 per resolution element. 12 metal absorption systems have been identified, two of which were previously unknown. All the lines shortward of the Lyman{alpha} emission not identified as due to metals have been fitted as Lyman{alpha} and Lyman{beta}. We reported statistical analysis of this sample of lines. In particular, the two-point correlation function for metal systems has been computed.
- ID:
- ivo://CDS.VizieR/J/A+A/294/377
- Title:
- Absorption systems of HS 1700+6416
- Short Name:
- J/A+A/294/377
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ultraviolet observations of the high-redshift quasat HS 1700+6416 were obtained with the Faint Object Spectrograph (FOS) onboard the Hubble Space Telescope (HST) in the range 115-328nm, on 1991-12-13/14 and 1992-02-13/14 at a resolution R=1300. The identification of the numerous absoprtion lines provides evidence for 15 heavy-element absorption systems, among them 7 Lyman Limit systems (LLS).
- ID:
- ivo://CDS.VizieR/J/ApJS/155/351
- Title:
- Absorption toward PG 1116+215
- Short Name:
- J/ApJS/155/351
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the intergalactic absorption toward QSO PG 1116+215 in the 900-3000{AA} spectral region.
- ID:
- ivo://CDS.VizieR/J/ApJ/845/85
- Title:
- Absorption velocities for 21 super-luminous SNe Ic
- Short Name:
- J/ApJ/845/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Super-luminous supernovae (SLSNe) are tremendously luminous explosions whose power sources and progenitors are highly debated. Broad-lined SNe Ic (SNe Ic-bl) are the only type of SNe that are connected with long-duration gamma-ray bursts (GRBs). Studying the spectral similarity and difference between the populations of hydrogen-poor SLSNe (SLSNe Ic) and of hydrogen-poor stripped-envelope core-collapse SNe, in particular SNe Ic and SNe Ic-bl, can provide crucial observations to test predictions of theories based on various power source models and progenitor models. In this paper, we collected all of the published optical spectra of 32 SLSNe Ic, 21 SNe Ic-bl, as well as 17 SNe Ic, quantified their spectral features, constructed average spectra, and compared them in a systematic way using new tools we have developed. We find that SLSNe Ic and SNe Ic-bl, including those connected with GRBs, have comparable widths for their spectral features and average absorption velocities at all phases. Thus, our findings strengthen the connection between SLSNe Ic and GRBs. In particular, SLSNe Ic have average FeII{lambda}5169 absorption velocities of -15000+/-2600km/s at 10 days after peak, which are higher than those of SNe Ic by ~7000km/s on average. SLSNe Ic also have significantly broader FeII{lambda}5169 lines than SNe Ic. Moreover, we find that such high absorption and width velocities of SLSNe Ic may be hard to explain with the interaction model, and none of the 13 SLSNe Ic with measured absorption velocities spanning over 10 days has a convincing flat velocity evolution, which is inconsistent with the magnetar model in one dimension. Lastly, we compare SN 2011kl, the first SN connected with an ultra-long GRB, with the mean spectrum of SLSNe Ic and of SNe Ic-bl.
- ID:
- ivo://CDS.VizieR/J/MNRAS/445/1584
- Title:
- AB-type RR Lyrae stars from ASAS and WASP
- Short Name:
- J/MNRAS/445/1584
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this article, we present results based on high-density, high-precision Wide-Angle Search for Planets (WASP) light curves supplemented with lower-precision photometry from the All-Sky Automated Survey (ASAS) for 268 RR Lyrae stars (176 regular, 92 Blazhko). Light curves were Fourier-decomposed and coefficients from WASP were transformed to the ASAS standard using 24 common stars. Coefficients were then compared with similar data from Galactic globular clusters, the Galactic bulge and the Large and Small Magellanic Clouds (LMC and SMC). Using Fourier coefficients, we also calculated physical parameters via standard equations from the literature. We confirmed the results of previous authors, including lower amplitudes and longer rise times for Blazhko stars. It was found that in the R_31_ versus R_21_ plot the location of a star depends mainly on its metallicity and that Blazhko stars prefer a different location from modulation-free stars. Field and globular cluster RR Lyrae variables have a different {phi}21 and {phi}31 from stars in the LMC, SMC and Galactic bulge. Although there are some weak indications that Blazhko stars could tend towards a slightly lower metallicity and shorter periods, no convincing proof was found. The most interesting highlight is the identification of a very recently proposed new group of metal-rich RR Lyrae type stars. These low-luminosity, metal-strong variables, comprising both Blazhko and regular stars, have shorter periods and about 180K higher temperature at constant (B-V)_0_ than the rest of the stars in the sample.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A83
- Title:
- Abunbances of 9 red giants of Pal 14
- Short Name:
- J/A+A/537/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundances of 25 elements, which include {alpha}-, iron peak-, and neutron-capture elements, in the outer halo globular cluster Palomar 14 have been determined for the nine red giants observed with the FLAMES/UVES spectrograph. The abundance pattern of Pal 14 is similar to the inner halo GCs, halo field stars, and GCs of recognized extragalactic origin, but differs from what is customarily found in dSphs field stars. The abundance properties of Pal 14 as well as those of the other outer halo GCs are thus compatible with an accretion origin from dSphs. The neutron-capture elements show an r-process signature.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A25
- Title:
- Abundance-age relations with open clusters
- Short Name:
- J/A+A/652/A25
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Precise chemical abundances coupled with reliable ages are key ingredients to understand the chemical history of our Galaxy. Open Clusters (OCs) are useful for this purpose because they provide ages with good precision. The aim of this work is to investigate the relations of different chemical abundance ratios vs age traced by red clump (RC) stars in OCs. We analyze a large sample of "NGoodstars" reliable members in "NClusters" OCs with available high-resolution spectroscopy. We applied a differential line-by-line analysis to provide a comprehensive chemical study of "NElements" chemical species. This sample is among the largest samples of OCs homogeneously characterized in terms of atmospheric parameters, detailed chemistry, and ages. In our metallicity range (-0.2<[M/H]<+0.2) we find that while most Fe-peak and {alpha} elements have flat dependence with age, the s-process elements show decreasing trends with increasing age with a remarkable knee at 1Gyr. For Ba, Ce, Y, Mo and Zr we find a plateau at young ages (<1Gyr). We investigate the relations of all possible combinations among the computed chemical species with age. We find 19 combinations with significant slopes, including [Y/Mg] and [Y/Al]. The ratio [Ba/{alpha}] is the one with the most significant correlations found. We find that the [Y/Mg] relation found in the literature using Solar twins is compatible with the one found here in the Solar neighbourhood. The age-abundance relations show larger scatter for clusters at large distances (d>1kpc) than for the Solar neighbourhood, particularly in the outer disk. We conclude that these relations need to be understood also in terms of the complexity of the chemical space introduced by the Galactic dynamics, on top of pure nucleosynthetic arguments, especially out of the local bubble.
- ID:
- ivo://CDS.VizieR/J/ApJ/479/427
- Title:
- Abundance Analyses of RV Tauri Variables
- Short Name:
- J/ApJ/479/427
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Analyses of the photospheric compositions of the four field RV Tauri stars, EP Lyr, DY Ori, AR Pup, and R Sge, indicate that to varying degrees they have experienced fractionation processes that have preferentially depleted their atmospheres of elements with high condensation temperatures. The depletion, as indicated by, for instance, [S/Fe], is greatest for DY Ori, [S/Fe]=2.5, and least for R Sge, [S/Fe]=0.9. The initial composition, presumably indicated by the sulfur abundance, was nearly solar for AR Pup, R Sge, and DY Ori, while it was about 0.6--- less than solar for EP Lyr. This implies that the RV Tauri stars as a group may not be as metal-poor as previously thought---they are instead ``metal-depleted''. The field RV Tauri's are not halo stars, but probably belong to the thick disk. This brings to seven the number of type II Cepheids that show such a trend; the other three are IW Car and V1 in omega Cen, RV Tauri stars, and ST Pup, a W Virginis star. The 12C/13C ratios for EP Lyr and DY Ori are 9+/-1 and 6+/-3, respectively, indicating that CN-cycled material has been mixed with their surface layers. This is consistent with the general consensus that RV Tau stars are in a post-AGB evolutionary stage. There is also evidence that EP Lyr has a stellar mass companion, but additional observations are required to calculate an orbit; hence, EP Lyr could be a link to the group of metal-depleted, high-latitude A-F supergiants, all of which are binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/847/127
- Title:
- Abundance analyses of V652 Her and HD 144941
- Short Name:
- J/ApJ/847/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical high-resolution spectra of V652 Her and HD 144941, the two extreme helium stars with exceptionally low C/He ratios, have been subjected to a non-LTE abundance analysis using the tools TLUSTY and SYNSPEC. Defining atmospheric parameters were obtained from a grid of non-LTE atmospheres and a variety of spectroscopic indicators including HeI and HeII line profiles, and the ionization equilibrium of ion pairs such as CII/CIII and NII/NIII. The various indicators provide a consistent set of atmospheric parameters: Teff=25000+/-300K, logg=3.10+/-0.12(cgs), and {xi}=13+/-2km/s are provided for V652 Her, and Teff=22000+/-600K, logg=3.45+/-0.15(cgs), and {xi}=10km/s are provided for HD 144941. In contrast to the non-LTE analyses, the LTE analyses-LTE atmospheres and an LTE line analysis-with the available indicators do not provide a consistent set of atmospheric parameters. The principal non-LTE effect on the elemental abundances is on the neon abundance. It is generally considered that these extreme helium stars with their very low C/He ratio result from the merger of two helium white dwarfs. Indeed, the derived composition of V652 Her is in excellent agreement with predictions by Zhang & Jeffery (2012MNRAS.419..452Z), who model the slow merger of helium white dwarfs; a slow merger results in the merged star having the composition of the accreted white dwarf. In the case of HD 144941, which appears to have evolved from metal-poor stars, a slow merger is incompatible with the observed composition but variations of the merger rate may account for the observed composition. More detailed theoretical studies of the merger of a pair of helium white dwarfs are to be encouraged.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A112
- Title:
- Abundance analysis of ALW Carina 8
- Short Name:
- J/A+A/606/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Carbon-enhanced metal-poor (CEMP) stars bear important imprints of the early chemical enrichment of any stellar system. While these stars are known to exist in copious amounts in the Milky Way halo, detailed chemical abundance data from the faint dwarf spheroidal (dSph) satellites are still sparse, although the relative fraction of these stars increases with decreasing metallicity. Here, we report the abundance analysis of a metal-poor ([Fe/H]=-2.5dex), carbon-rich ([C/Fe]=1.4dex) star, ALW-8, in the Carina dSph using high-resolution spectroscopy obtained with the ESO/UVES instrument. Its spectrum does not indicate any over-enhancements of neutron capture elements. Thus classified as a CEMP-no star, this is the first detection of this kind of star in Carina. Another of our sample stars, ALW-1, is shown to be a CEMP-s star, but its immediate binarity prompted us to discard it from a detailed analysis. The majority of the 18 chemical elements we measured are typical of Carina's field star population and also agree with CEMP stars in other dSph galaxies. Similar to the only known CEMP-no star in the Sculptor dSph and the weak-r-process star HD 122563, the lack of any strong barium-enhancement is accompanied by a moderate overabundance in yttrium, indicating a weak r-process activity. The overall abundance pattern confirms that, also in Carina, the formation site for CEMP-no stars has been affected by both faint supernovae and by standard core collapse supernovae. Whichever process was responsible for the heavy element production in ALW-8 must be a ubiquitous source to pollute the CEMP-no stars, acting independently of the environment such as in the Galactic halo or in dSphs.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A86
- Title:
- Abundance analysis of HD 140283
- Short Name:
- J/A+A/584/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 140283 is a reference subgiant that is metal poor and confirmed to be a very old star. The abundances of this type of old star can constrain the nature and nucleosynthesis processes that occurred in its (even older) progenitors. The present study may shed light on nucleosynthesis processes yielding heavy elements early in the Galaxy. A detailed abundance analysis of a high-quality spectrum is carried out, with the intent of providing a reference on stellar lines and abundances of a very old, metal-poor subgiant.
- ID:
- ivo://CDS.VizieR/J/ApJ/865/129
- Title:
- Abundance analysis of HD 222925
- Short Name:
- J/ApJ/865/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed abundance analysis of the bright (V=9.02), metal-poor ([Fe/H]=-1.47+/-0.08) field red horizontal-branch star HD222925, which was observed as part of an ongoing survey by the R-Process Alliance. We calculate stellar parameters and derive abundances for 46 elements based on 901 lines examined in a high-resolution optical spectrum obtained using the Magellan Inamori Kyocera Echelle spectrograph. We detect 28 elements with 38<=Z<=90; their abundance pattern is a close match to the solar r-process component. The distinguishing characteristic of HD222925 is an extreme enhancement of r-process elements ([Eu/Fe]=+1.33+/-0.08, [Ba/Eu]=-0.78+/-0.10) in a moderately metal-poor star, so the abundance of r-process elements is the highest ([Eu/H]=-0.14+/-0.09) in any known r-process-enhanced star. The abundance ratios among lighter (Z<=30) elements are typical for metal-poor stars, indicating that production of these elements was dominated by normal Type II supernovae, with no discernible contributions from Type Ia supernovae or asymptotic giant branch stars. The chemical and kinematic properties of HD 222925 suggest it formed in a low-mass dwarf galaxy, which was enriched by a high-yield r-process event before being disrupted by interaction with the Milky Way.
- ID:
- ivo://CDS.VizieR/J/MNRAS/369/1677
- Title:
- Abundance analysis of LSS 3378
- Short Name:
- J/MNRAS/369/1677
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abundance analysis of the cool extreme helium (EHe) star LSS 3378 is presented. The abundance analysis is done using local thermodynamic equilibrium (LTE) line formation and LTE model atmospheres constructed for EHe stars.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A178
- Title:
- Abundance analysis of 4 red giants in NGC 6558
- Short Name:
- J/A+A/619/A178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 6558 is a bulge globular cluster with a blue horizontal branch (BHB), combined with a metallicity of [Fe/H]~-1.0. It is similar to HP 1 and NGC 6522, which could be among the oldest objects in the Galaxy. Element abundances in these clusters could reveal the nature of the first supernovae. We aim to carry out detailed spectroscopic analysis for four red giants of NGC 6558, in order to derive the abundances of the light elements C, N, O, Na, Al, the {alpha}-elements Mg, Si, Ca, Ti, and the heavy elements Y, Ba, and Eu. High-resolution spectra of four stars with FLAMES-UVES@VLT UT2-Kueyen were analysed. Spectroscopic parameter-derivation was based on excitation and ionization equilibrium of FeI and FeII. This analysis results in a metallicity of [Fe/H]=-1.17+/-0.10 for NGC 6558. We find the expected {alpha}-element enhancements in O and Mg with [O/Fe]=+0.40, [Mg/Fe]=+0.33, and low enhancements in Si and Ca. Ti has a moderate enhancement of [Ti/Fe]=+0.22. The r-element Eu appears very enhanced with a mean value of [Eu/Fe]=+0.63. The first peak s-elements Y and Sr are also enhanced, these results have however to be treated with caution, given the uncertainties in the continuum definition; the use of neutral species (Sr I, YI), instead of the dominant ionized species is another source of uncertainty. Ba appears to have a solar abundance ratio relative to Fe. NGC 6558 shows an abundance pattern that could be typical of the oldest inner bulge globular clusters, together with the pattern in the similar clusters NGC 6522 and HP 1. They show low abundances of the odd-Z elements Na and Al, and of the explosive nucleosynthesis {alpha}-elements Si, Ca, and Ti. The hydrostatic burning {alpha}-elements O and Mg are normally enhanced as expected in old stars enriched with yields from core-collapse supernovae, and the iron-peak elements Mn, Cu, Zn show low abundances, which is expected forMn and Cu, but not for Zn. Finally, the cluster trio NGC 6558, NGC 6522 and HP 1 have relatively high abundances of first-peak heavy elements, variable second-peak element Ba, and the r-element Eu is enhanced. The latter is particularly high in NGC 6558.