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J/MNRAS/459/610     47 Tuc sub-giant branch chemical abundances  (Marino+, 2016)

Chemical abundances in the multiple sub-giant branch of 47 Tucanae: insights on its faint sub-giant branch component. Marino A.F., Milone A.P., Casagrande L., Collet R., Dotter A., Johnson C.I., Lind K., Bedin L.R., Jerjen H., Aparicio A., Sbordone L. <Mon. Not. R. Astron. Soc., 459, 610-623 (2016)> =2016MNRAS.459..610M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Photometry, UBV ; Abundances Keywords: techniques: photometric - techniques: spectroscopic - stars: Population II - globular clusters: general - globular clusters: individual: NGC104 (47 Tucanae) Abstract: The globular cluster 47 Tuc exhibits a complex sub-giant branch (SGB) with a faint-SGB comprising only about the 10 per cent of the cluster mass and a bright-SGB hosting at least two distinct populations. We present a spectroscopic analysis of 62 SGB stars including 21 faint-SGB stars. We thus provide the first chemical analysis of the intriguing faint-SGB population and compare its abundances with those of the dominant populations. We have inferred abundances of Fe, representative light elements C, N, Na, and Al, α elements Mg and Si for individual stars. Oxygen has been obtained by co-adding spectra of stars on different sequences. In addition, we have analysed 12 stars along the two main RGBs of 47 Tuc. Our principal results are (i) star-to-star variations in C/N/Na among RGB and bright-SGB stars; (ii) substantial N and Na enhancements for the minor population corresponding to the faint-SGB; (iii) no high enrichment in C+N+O for faint-SGB stars. Specifically, the C+N+O of the faint-SGB is a factor of 1.1 higher than the bright-SGB, which, considering random (±1.3) plus systematic errors (±0.3), means that their C+N+O is consistent within observational uncertainties. However, a small C+N+O enrichment for the faint-SGB, similar to what predicted on theoretical ground, cannot be excluded. The N and Na enrichment of the faint-SGB qualitatively agrees with this population possibly being He-enhanced, as suggested by theory. The iron abundance of the bright and faint-SGB is the same to a level of ∼0.10dex, and no other significant difference for the analysed elements has been detected. Description: The photometric data set used in our study of 47 Tuc consists of HST photometry for the innermost ∼3x3arcmin and ground-based photometry for the outer cluster region. Specifically, we have used the catalogues published by Milone et al. (2012ApJ...744...58M) that include photometry in the F336W (30s+1160s images from GO 11729, PI. Holtzmann), F395N bands (90s+2x1120s images from GO 11729, PI. Holtzmann) from the Ultraviolet and Visual Channel of the Advanced Camera for Surveys 3 (UVIS/WFC3) and in the F435W (9x105 s images from GO 9281, PI. Grindlay), F606W (3s+4x50s images from GO 10775, PI. Sarajedini), and F814W (3s+4x50s images from GO 10775, PI. Sarajedini) band from the Wide Field Channel of the Advanced Camera for Surveys (WFC/ACS) on board of HST. Moreover, we have used ground-based photometry in the U, B, V, and I filters from the archive maintained by Peter Stetson. The photometric catalogue has been obtained by Stetson (2000PASP..112..925S) from 856 CCD images, including 480 images taken with the Wide-Field Imager of the ESO/MPI 2.2 m telescope, and 200 with the 1.5 m telescope at Cerro Tololo Inter-American Observatory. The remaining 176 images come from various other telescopes. All the images were reduced using the method described by Stetson (2005PASP..117..563S) and are calibrated on the Landolt (1992AJ....104..340L, Cat. II/183) photometric system. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 59 75 Coordinates, basic photometric data and radial velocities for the stars in the field of view of 47 Tucanae table2.dat 78 74 Adopted atmospheric parameters and inferred chemical abundances of 47 Tucanae
See also: J/ApJS/85/293 : HST Observations of core of 47 Tuc (de Marchi+ 1993) J/A+A/372/85 : Detected sources at 12µm in 47 Tuc (Ramdani+, 2001) J/other/Sci/292.2290 : Chandra compact binaries in 47 Tuc (Grindlay+, 2001) J/ApJ/559/1060 : Variables in 47 Tuc (Albrow+, 2001) J/AJ/125/197 : CN abundances of the 47 Tuc main sequence (Harbeck+, 2003) J/AJ/127/1588 : 47 Tuc main-sequence star abundances (Briley+, 2004) J/ApJ/625/796 : X-ray sources in the globular cluster 47 Tuc (Heinke+, 2005) J/AJ/135/1551 : Abundances of stars in 47 Tuc (Koch+, 2008) J/A+A/537/A2 : 8.6um imaging of 47 Tuc (Momany+, 2012) J/AJ/143/50 : White dwarfs in 47 Tuc (NGC 104) with HST (Woodley+, 2012) J/A+A/549/A41 : Horizontal branch stars in 47 Tuc and M5 (Gratton+, 2013) J/A+A/550/A34 : Abundances of red giants in M4 and 47 Tuc (Carretta+, 2013) J/A+A/565/A121 : Abundances of 47 Tuc turn-off stars (Dobrovolskas+, 2014) J/A+A/572/A108 : 47 Tuc red giants chemical composition (Thygesen+, 2014) J/ApJ/780/94 : Abundances of red giants in 47 Tuc (Cordero+, 2014) J/ApJ/797/124 : AGB and RGB stars in 47 Tuc (Lapenna+, 2014) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 12 A12 --- Name Name (N104a-NNNNNN) 16- 17 I2 h RAh Right ascension (J2000) 19- 20 I2 min RAm Right ascension (J2000) 22- 26 F5.2 s RAs Right ascension (J2000) 28 A1 --- DE- Declination sign (J2000) 29- 30 I2 deg DEd Declination (J2000) 32- 33 I2 arcmin DEm Declination (J2000) 35- 38 F4.1 arcsec DEs Declination (J2000) 40- 45 F6.3 mag Bmag Landolt B magnitude corrected for differential reddening 47- 52 F6.3 mag Vmag Landolt V magnitude corrected for differential reddening 54- 59 F6.2 km/s RV Radial velocity
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 12 A12 --- Name Name 16- 19 I4 K Teff Effective temperature (adopted parameter) 21- 24 F4.2 [cm/s2] logg Surface gravity (adopted parameter) 26- 29 F4.2 km/s xit Microturbulent velocity (adopted parameter) 31- 35 F5.2 [-] [Fe/H] Metallicity (adopted parameter) 37- 41 F5.2 [-] [C/Fe] ?=- [C/Fe] abundance 43- 46 F4.2 [-] [N/Fe] ?=- [N/Fe] abundance 48- 51 F4.2 [-] [Na/Fe]LTE ?=- LTE [Na/Fe] abundance 53- 57 F5.2 [-] [Na/Fe]NLTE ?=- NLTE [Na/Fe] abundance 59- 62 F4.2 [-] [Mg/Fe] ?=- [Mg/Fe] abundance 64- 67 F4.2 [-] [Al/Fe] ?=- [Al/Fe] abundance 69- 72 F4.2 [-] [Si/Fe] ?=- [Si/Fe] abundance 74- 78 F5.2 [-] [Ni/Fe] ?=- [Ni/Fe] abundance
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Jun-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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