- ID:
- ivo://CDS.VizieR/J/A+AS/136/453
- Title:
- Equivalent widths of spectroscopic binaries
- Short Name:
- J/A+AS/136/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopic observations are presented for 19 single-lined binaries (giants and dwarfs) with orbital elements and mass functions similar to those of barium stars, two radial velocity non-variable barium stars, and two standards. All binary systems contain an unseen low-mass component, presumably, a white dwarf. The equivalent widths and oscillator strengths are given for all measured spectral lines.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/610/A66
- Title:
- Equivalent widths of 7 stars in NGC 6705
- Short Name:
- J/A+A/610/A66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar [{alpha}/Fe] abundance is sometimes used as a proxy for stellar age, following standard chemical evolution models for the Galaxy, as seen by different observational results. In this work we show that the Open Cluster NGC6705/M11 has a significant {alpha}-enhancement [{alpha}/Fe]>0.1dex, despite its young age (~300Myr), challenging the current paradigm.}{We use high resolution (R$>65,000$) high signal-to-noise (~70) spectra of 8 Red Clump stars, acquired within the OCCASO survey. We determine very accurate chemical abundances of several {alpha} elements, using an equivalent width methodology (Si, Ca and Ti), and spectral synthesis fits (Mg and O). We obtain [Si/Fe]=0.13+/-0.05, [Mg/Fe]=0.14+/-0.07, [O/Fe]=0.17+/-0.07, [Ca/Fe]=0.06+/-0.05 and [Ti/Fe]=0.03+/-0.03. Our results place these cluster within the group of young [{alpha}/Fe]-enhanced field stars recently found by several authors in the literature. The ages of our stars have an uncertainty of around 50Myr, much more precise than for field stars. By integrating the cluster's orbit in several non-axisymmetric Galactic potentials, we establish the M11's most likely birth radius to lie between 6.8-7.5kpc from the Galactic center, not far from its current position. With the robust Open Cluster age scale, our results prove that a moderate [{alpha}/Fe]-enhancement is no guarantee for a star to be old, and that not all {alpha}-enhanced stars can be explained with an evolved blue straggler scenario. Based on our orbit calculations, we further argue against a Galactic bar origin of M11.
- ID:
- ivo://CDS.VizieR/J/A+A/360/499
- Title:
- Equivalent widths of 9 stars of M 67
- Short Name:
- J/A+A/360/499
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectra of six core helium-burning `clump' stars and three giants in the open cluster M 67 have been obtained with the SOFIN spectrograph on the Nordic Optical Telescope to investigate abundances of up to 25 chemical elements. Abundances of carbon were studied using the C_2_ Swan (0,1) band head at 5635.5{AA}. The wavelength interval 7980-8130{AA} with strong CN features was analysed in order to determine nitrogen abundances and ^12^C/^13^C isotope ratios. The oxygen abundances were determined from the [O I] line at 6300{AA}. The overall metallicity of the cluster stars was found to be close to solar ([Fe/H]=-0.03+/-0.03). Compared with the Sun and other dwarf stars of the Galactic disk, as well as with dwarf stars of M 67 itself, abundances in the investigated stars suggest that carbon is depleted by about 0.2dex, nitrogen is enhanced by about 0.2dex and oxygen is unaltered. Among other mixing-sensitive chemical elements an overabundance of sodium may be suspected. The mean C/N and ^12^C/^13^C ratios are lowered to the values of 1.7+/-0.2 and 24+/-4 in the giants and to the values of 1.4+/-0.2 and 16+/-4 in the clump stars. These results suggest that extra mixing of CN-cycled material to the stellar surface takes place after the He-core flash. Abundances of heavy chemical elements in all nine stars were found to be almost identical and close to solar.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A53
- Title:
- Equivalent widths of 18 subgiant of {omega} Cen
- Short Name:
- J/A+A/534/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze spectra of 18 stars belonging to the faintest subgiant branch in omega Centauri (the SGB-a), obtained with GIRAFFE@VLT at a resolution of R~=17000 and a S/N ratio between 25 and 50. We measure abundances of Al, Ba, Ca, Fe, Ni, Si, and Ti and we find that these stars have <[Fe/H]>=-0.73+/-0.14dex, similarly to the corresponding red giant branch population (the RGB-a). We also measure <[alpha/Fe]>=+0.40+/-0.16dex, and <[Ba/Fe]>=+0.87+/-0.23dex, in general agreement with past studies. It is very interesting to note that we found a uniform Al abundance, <[Al/Fe]>=+0.32+/-0.14dex, for all the 18 SGB-a stars analysed here, thus supporting past evidence that the usual (anti-)correlations are not present in this population, and suggesting a non globular cluster-like origin of this particular population. In the dwarf galaxy hypothesis for the formation of omega Cen, this population might be the best candidate for the field population of its putative parent galaxy, although some of its properties appear contradictory. It has also been suggested that the most metal-rich population in omega Cen is significantly enriched in helium. If this is true, the traditional abundance analysis techniques, based on model atmospheres with normal helium content, might lead to errors. We have computed helium enhanced atmospheres for three stars in our sample and verified that the abundance errors due to the use of non-enhanced atmospheres are negligible. Additional, indirect support to the enhanced helium content of the SGB-a population comes from our Li upper limits.
- ID:
- ivo://CDS.VizieR/J/PAZh/39/58
- Title:
- Equivalent widths of thick-disk red giants
- Short Name:
- J/PAZh/39/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The atmospheric parameters and elemental abundances for ten thick-disk red giants have been determined from high-resolution spectra by the method of model stellar atmospheres. The results of a comparative analysis of the [Na/Fe] abundances in the atmospheres of the investigated stars and thindisk red giants are presented. Sodium in the atmospheres of thick-disk red giants is shown to have no overabundances typical of thin-disk red giants.
- ID:
- ivo://CDS.VizieR/J/A+A/440/1153
- Title:
- Equivalent widths of 7 thin-disk stars
- Short Name:
- J/A+A/440/1153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In Papers I (del Peloso et al. 2005, Cat. <J/A+A/434/275>) and II (2005A&A...434..301D) we performed the first determination of the age of the Galactic thin disk from Th/Eu nucleocosmochronology. The present work aimed at reducing the age uncertainty by expanding the stellar sample with the inclusion of seven new objects. The Th and Eu abundances used in the dating procedure were obtained through spectral synthesis, and to perform the synthesis it was necessary to know the atmospheric parameters and chemical abundances of contaminating elements.
- ID:
- ivo://CDS.VizieR/J/A+A/417/269
- Title:
- Equivalent widths of two post-AGB stars
- Short Name:
- J/A+A/417/269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In an effort to extend the still limited sample of s-process enriched post-AGB stars, high-resolution, high signal-to-noise VLT+UVES spectra of the optical counterparts of the infrared sources IRAS 06530-0213 and IRAS 08143-4406 were analysed.
- ID:
- ivo://CDS.VizieR/J/A+A/421/59
- Title:
- Equivalent widths of VMF73 and VMF74 galaxies
- Short Name:
- J/A+A/421/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic analysis of two galaxy clusters out to ~4Mpc at z~0.2. The two clusters VMF73 and VMF74 identified by Vikhlinin et al. (1998, Cat. <J/ApJ/502/558>) were observed with MOSCA at the Calar Alto 3.5m telescope. Both clusters lie in the ROSAT PSPC field R285 and were selected from the X-ray Dark Cluster Survey (Gilbank et al., 2004MNRAS.348..551G) that provides optical V- and I-band data. VMF73 and VMF74 are located at respective redshifts of z=0.25 and z=0.18 with velocity dispersions of 671km/s and 442km/s, respectively. The spectroscopic observations reach out to ~2.5 virial radii. Line strength measurements of the emission lines H_alpha and [OII]3727 are used to assess the star formation activity of cluster galaxies which show radial and density dependences. The mean and median of both line strength distributions as well as the fraction of star forming galaxies increase with increasing clustercentric distance and decreasing local galaxy density. Except for two galaxies with strong H_alpha and [OII] emission, all of the cluster galaxies are normal star forming or passive galaxies. Our results are consistent with other studies that show the truncation in star formation occurs far from the cluster centre.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/19
- Title:
- Equivalent widths of WASP-94A and WASP-94B
- Short Name:
- J/ApJ/819/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary stars provide an ideal laboratory for investigating the potential effects of planet formation on stellar composition. Assuming that the stars formed in the same environment/from the same material, any compositional anomalies between binary components might indicate differences in how material was sequestered in planets, or accreted by the star in the process of planet formation. We present here a study of the elemental abundance differences between WASP-94A and B, a pair of stars that each host a hot Jupiter exoplanet. The two stars are very similar in spectral type (F8 and F9), and their ~2700AU separation suggests that their protoplanetary disks were likely not influenced by stellar interactions, but WASP-94Ab's orbit --misaligned with the host star spin axis and likely retrograde-- points toward a dynamically active formation mechanism, perhaps different from that of WASP-94Bb, which is not misaligned and has a nearly circular orbit. Based on our high-quality spectra and strictly relative abundance analysis, we detect a depletion of volatiles (~-0.02dex, on average) and enhancement of refractories (~0.01dex) in WASP-94A relative to B (standard errors are ~0.005dex). This is different from every other published case of binary host star abundances, in which either no significant abundance differences are reported or there is some degree of enhancement in all elements, including volatiles. Several scenarios that may explain the abundance trend are discussed, but none can be definitively accepted or rejected. Additional high-contrast imaging observations to search for companions that may be dynamically affecting the system, as well as a larger sample of binary host star studies, are needed to better understand the curious abundance trends we observe in WASP-94A and B.
- ID:
- ivo://CDS.VizieR/J/A+A/420/683
- Title:
- Equivalent widths of 23 wide binaries
- Short Name:
- J/A+A/420/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present iron abundance analysis for 23 wide binaries with main sequence components in the temperature range 4900-6300K, taken from the sample of the pairs currently included in the radial velocity planet search on going at the Telescopio Nazionale Galileo (TNG) using the high resolution spectrograph SARG. The use of a line-by-line differential analysis technique between the components of each pair allows us to reach errors of about 0.02dex in the iron content difference. Most of the pairs have abundance differences lower than 0.02dex and there are no pairs with differences larger than 0.07dex. The four cases of differences larger than 0.02dex may be spurious because of the larger error bars affecting pairs with large temperature difference, cold stars and rotating stars.