- ID:
- ivo://CDS.VizieR/J/MNRAS/421/3189
- Title:
- CaII and H{alpha} data for dK5/dM4 stars
- Short Name:
- J/MNRAS/421/3189
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use 665 high-resolution spectra for 60 different dM4 stars and 1088 high-resolution spectra for 97 different dK5 stars from the European Southern Observatory (ESO) and Observatoire de Haute Provence (OHP) data bases. We present 179 new measurements of the CaII resonance lines and 615 new measurements of the H{alpha} line for dM4 stars. We also present 701 new measurements of the CaII resonance lines and 1088 new measurements of the H{alpha} line for dK5 stars. We also compiled other measurements available in the literature.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/1591
- Title:
- CaII equivalent widths of dM1 stars
- Short Name:
- J/MNRAS/426/1591
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 187 high-resolution spectra for 62 different M1 dwarfs from observations obtained with the FIbre-fed Echelle Spectrograph (FIES) on the Nordic Optical Telescope (NOT) and from observations with the Fibre-fed Extended Range Echelle Spectrograph (FEROS) from the European Southern Observatory (ESO) data base. We also compiled other measurements available in the literature.
- ID:
- ivo://CDS.VizieR/J/AJ/139/1168
- Title:
- CaII spectroscopy of SMC fields stars
- Short Name:
- J/AJ/139/1168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained metallicities of ~360 red giant stars distributed in 15 Small Magellanic Cloud (SMC) fields from near-infrared spectra covering the CaII triplet lines using the VLT + FORS2.
- ID:
- ivo://CDS.VizieR/J/AJ/149/154
- Title:
- CaII spectroscopy of SMC red giants. III.
- Short Name:
- J/AJ/149/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained spectra of red giants in 15 Small Magellanic Cloud (SMC) clusters in the region of the CaII lines with FORS2 on the Very Large Telescope. We determined the mean metallicity and radial velocity with mean errors of 0.05dex and 2.6km/s, respectively, from a mean of 6.5 members per cluster. One cluster (B113) was too young for a reliable metallicity determination and was excluded from the sample. We combined the sample studied here with 15 clusters previously studied by us using the same technique, and with 7 clusters whose metallicities determined by other authors are on a scale similar to ours. This compilation of 36 clusters is the largest SMC cluster sample currently available with accurate and homogeneously determined metallicities. We found a high probability that the metallicity distribution is bimodal, with potential peaks at -1.1 and -0.8dex. Our data show no strong evidence of a metallicity gradient in the SMC clusters, somewhat at odds with recent evidence from CaII triplet spectra of a large sample of field stars. This may be revealing possible differences in the chemical history of clusters and field stars. Our clusters show a significant dispersion of metallicities, whatever age is considered, which could be reflecting the lack of a unique age-metallicity relation in this galaxy. None of the chemical evolution models currently available in the literature satisfactorily represents the global chemical enrichment processes of SMC clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/152/58
- Title:
- CaII spectroscopy of SMC red giants. IV.
- Short Name:
- J/AJ/152/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper represents a major step forward in the systematic and homogeneous study of Small Magellanic Cloud (SMC) star clusters and field stars carried out by applying the calcium triplet technique. We present in this work the radial velocity and metallicity of approximately 400 red giant stars in 15 SMC fields, with typical errors of about 7km/s and 0.16dex, respectively. We added to this information our previously determined metallicity values for 29 clusters and approximately 350 field stars using the identical techniques. Using this enlarged sample, we analyze the metallicity distribution and gradient in this galaxy. We also compare the chemical properties of the clusters and of their surrounding fields. We find a number of surprising results. While the clusters, taken as a whole, show no strong evidence for a metallicity gradient (MG), the field stars exhibit a clear negative gradient in the inner region of the SMC, consistent with the recent results of Dobbie et al. For distances to the center of the galaxy less than 4{deg}, field stars show a considerably smaller metallicity dispersion than that of the clusters. However, in the external SMC regions, clusters and field stars exhibit similar metallicity dispersions. Moreover, in the inner region of the SMC, clusters appear to be concentrated in two groups: one more metal-poor and another more metal-rich than field stars. Individually considered, neither cluster group presents an MG. Most surprisingly, the MG for both stellar populations (clusters and field stars) appears to reverse sign in the outer regions of the SMC. The difference between the cluster metallicity and the mean metallicity of the surrounding field stars turns out to be a strong function of the cluster metallicity. These results could be indicating different chemical evolution histories for these two SMC stellar populations. They could also indicate variations in the chemical behavior of the SMC in its internal and external regions.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A76
- Title:
- CaII triplet equivalent widths in 30 globulars
- Short Name:
- J/A+A/563/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- When they are established with sufficient precision, the ages, metallicities and kinematics of Galactic globular clusters (GGCs) can shed much light on the dynamical and chemical evolution of the Galactic halo and bulge. While the most fundamental way of determining GC abundances is by mean high-resolution spectroscopy, in practice this method is limited to only the brighter stars in the nearest and less reddened objects. This restriction has, over the years, led to the development of a large number of techniques that measure the overall abundance indirectly from parameters that correlate with overall metallicity. One of the most efficient methods is measuring of the equivalent width (EW) of the calcium II triplet (CaT) at {lambda}~~8500{AA} in red giants, which are corrected for the luminosity and temperature effects using the V magnitude differences from the horizontal branch (HB). We establish a similar method in the near-infrared (NIR), by combining the power of the differential magnitudes technique with the advantages of NIR photometry to minimize differential reddening effects. We used the Ks magnitude difference between the star and the reddest part of the HB (RHB) or of the red clump (RC) to generate reduced equivalent widths (rEW) from the previously presented datasets. Then we calibrated these rEW against three previously reported different metallicity scales; one of which we corrected using high-resolution spectroscopic metallicities.
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/199
- Title:
- CaII triplet in red giant spectra
- Short Name:
- J/MNRAS/455/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measurements are presented and analysed of the strength of the CaII triplet lines in red giants in Galactic globular and open clusters, and in a sample of red giants in the LMC disc that have significantly different [Ca/Fe] abundance ratios to the Galactic objects. The Galactic objects are used to generate a calibration between CaII triplet line strength and [Fe/H], which is then used to estimate [Fe/H]CaT for the LMC stars. The values are then compared with the [Fe/H]spec determinations from high-dispersion spectroscopy. After allowance for a small systematic offset, the two abundance determinations are in excellent agreement. Further, as found in earlier studies, the difference is only a very weak function of the [Ca/Fe] ratio. For example, changing [Ca/Fe] from +0.3 to -0.2 causes the CaII-based abundance to underestimate [Fe/H]spec by only ~0.15dex, assuming a Galactic calibration. Consequently, the CaII triplet approach to metallicity determinations can be used without significant bias to study stellar systems that have substantially different chemical evolution histories.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/1013
- Title:
- CaII triplet in Sextans dSph galaxy
- Short Name:
- J/MNRAS/411/1013
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Very Large Telescope (VLT)/Fibre Large Array Multi Element Spectrograph (FLAMES) intermediate-resolution (R~6500) spectra of individual red giant branch stars in the near-infrared Ca ii triplet (CaT) region to investigate the wide-area metallicity properties and internal kinematics of the Sextans dwarf spheroidal galaxy (dSph). Our final sample consists of 174 probable members of Sextans with accurate line-of-sight velocities (+/-2km/s) and CaT [Fe/H] measurements (+/-0.2dex).
119. CALYMHA survey. I.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/1242
- Title:
- CALYMHA survey. I.
- Short Name:
- J/MNRAS/466/1242
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the CAlibrating LYMan-{alpha} with H{alpha} (CALYMHA) pilot survey and new results on Lyman {alpha} (Ly{alpha}) selected galaxies at z~2. We use a custom-built Ly{alpha} narrow-band filter at the Isaac Newton Telescope, designed to provide a matched volume coverage to the z=2.23H{alpha} HiZELS survey. Here, we present the first results for the COSMOS and UDS fields. Our survey currently reaches a 3{sigma} line flux limit of ~4x10^-17^erg/s/cm^2^, and a Ly{alpha} luminosity limit of ~10^42.3^erg/s. We find 188 Ly{alpha} emitters over 7.3x10^5^Mpc^3^, but also find significant numbers of other line-emitting sources corresponding to HeII, CIII] and CIV emission lines. These sources are important contaminants, and we carefully remove them, unlike most previous studies. We find that the Ly{alpha} luminosity function at z=2.23 is very well described by a Schechter function up to L_Ly{alpha}_~=10^43^erg/s^ with L*=10^42.59(10^42.75^-10^42.01^)erg/s, {phi}*=10^-3.09^(10^-3.43^-10^2.95)Mpc^-3^ and {alpha}=-1.75+/-0.25. Above L_Ly{alpha}_~=10^43^erg/s, the Ly{alpha} luminosity function becomes power-law like, driven by X-ray AGN. We find that Ly{alpha}-selected emitters have a high escape fraction of 37+/-7 per cent, anticorrelated with Ly{alpha} luminosity and correlated with Ly{alpha} equivalent width. Ly{alpha} emitters have ubiquitous large (~=40kpc) Ly{alpha} haloes, ~2 times larger than their H{alpha} extents. By directly comparing our Ly{alpha} and H{alpha} luminosity functions, we find that the global/overall escape fraction of Ly{alpha} photons (within a 13kpc radius) from the full population of star-forming galaxies is 5.1+/-0.2 per cent at the peak of the star formation history. An extra 3.3+/-0.3 per cent of Ly{alpha} photons likely still escape, but at larger radii.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/3622
- Title:
- Candidate Be stars in the Magellanic Clouds
- Short Name:
- J/MNRAS/421/3622
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mennickent et al. (2002A&A...393..887M) and Sabogal et al. (2005, Cat. J/MNRAS/361/1055) identified a large number of classical Be (CBe) candidates (~3500) in the Large and Small Magellanic Clouds (LMC and SMC) based on their photometric variability using the OGLE II data base (Udalski et al., 1998, Cat. J/AcA/48/147; 2000, Cat. J/AcA/50/307). They classified these stars into four different groups based on the appearance of their variability. In order to refine and understand the nature of this large number of stars, we studied the infrared properties of the sample and the spectroscopic properties of a subsample. We cross-correlated the optical sample with the IRSF-MCPS catalogue to obtain the J, H, Ks magnitudes of all the four types of stars (~2500) in the LMC and SMC. Spectra of 120 stars belonging to the types 1, 2 and 3 were analysed to study their spectral properties.
