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J/A+A/601/A96       Spectroscopy of globular clusters           (Larsen+, 2017)

Detailed abundances from integrated-light spectroscopy: Milky Way globular clusters. Larsen S.S., Brodie J.P., Strader J. <Astron. Astrophys. 601, A96 (2017)> =2017A&A...601A..96L (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, globular ; Abundances, [Fe/H] ; Spectroscopy Keywords: globular clusters: individual (NGC 104, NGC 362, NGC 6254, NGC 6388, NGC 6752, NGC 7078, NGC 7099) - stars: abundances - techniques: spectroscopic Abstract: We test the performance of our analysis technique for integrated-light spectra by applying it to seven well-studied Galactic GCs that span a wide range of metallicities. Integrated-light spectra were obtained by scanning the slit of the UVES spectrograph on the ESO Very Large Telescope across the half-light diameters of the clusters. We modelled the spectra using resolved Hubble Space Telescope colour-magnitude diagrams (CMDs), as well as theoretical isochrones, in combination with standard stellar atmosphere and spectral synthesis codes. The abundances of Fe, Na, Mg, Ca, Ti, Cr, and Ba were compared with literature data for individual stars in the clusters. The typical differences between iron abundances derived from our integrated-light spectra and those compiled from the literature are less than 0.1 dex. A larger difference is found for one cluster (NGC 6752), and is most likely caused primarily by stochastic fluctuations in the numbers of bright red giants within the scanned area. As expected, the alpha-elements (Ca, Ti) are enhanced by about 0.3 dex compared to the Solar-scaled composition, while the [Cr/Fe] ratios are close to Solar. When using up-to-date line lists, our [Mg/Fe] ratios also agree well with literature data. Our [Na/Fe] ratios are, on average, 0.08-0.14 dex lower than average values quoted in the literature, and our [Ba/Fe] ratios may be overestimated by 0.20-0.35 dex at the lowest metallicities. We find that analyses based on theoretical isochrones give very similar results to those based on resolved CMDs. Overall, the agreement between our integrated-light abundance measurements and the literature data is satisfactory. Refinements of the modelling procedure, such as corrections for stellar evolutionary and non-LTE effects, might further reduce some of the remaining offsets. Description: These tables contain the individual abundance measurements for each cluster for our "standard" (CMD-based) analysis. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file clusters.dat 45 7 List of studied clusters tablea1.dat 34 49 Abundances for NGC 104 tablea2.dat 34 51 Abundances for NGC 362 tablea3.dat 34 51 Abundances for NGC 6254 tablea4.dat 34 49 Abundances for NGC 6388 tablea5.dat 34 50 Abundances for NGC 6752 tablea6.dat 34 50 Abundances for NGC 7078 tablea7.dat 34 51 Abundances for NGC 7099
Byte-by-byte Description of file: clusters.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Cluster Cluster name 11- 12 I2 h RAh Simbad right ascension (J2000.0) 14- 15 I2 min RAm Simbad right ascension (J2000.0) 17- 21 F5.2 s RAs Simbad right ascension (J2000.0) 23 A1 --- DE- Simbad declination sign (J2000.0) 24- 25 I2 deg DEd Simbad declination (J2000.0) 27- 28 I2 arcmin DEm Simbad declination (J2000.0) 30- 33 F4.1 arcsec DEs Simbad declination (J2000.0) 35- 45 A11 --- FileName Name of the table with individual abundances
Byte-by-byte Description of file: tablea?.dat
Bytes Format Units Label Explanations
1- 7 A7 --- Element Element ratio 9- 14 F6.1 0.1nm lambda1 Starting wavelength of spectral window 16- 21 F6.1 0.1nm lambda2 Ending wavelength of spectral window 23- 28 F6.3 --- Abd Abundance (dex) 30- 34 F5.3 --- e_Abd Abundance error (dex)
Acknowledgements: Soeren Larsen, s.larsen(at)
(End) Soeren Larsen [Radboud University], Patricia Vannier [CDS] 24-Feb-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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