CDROM/AJ/V113/P0279 Proton Capture Chains. II (Kraft+ 1997) ================================================================================ Proton Capture Chains in Globular Cluster Stars. II. Oxygen, Sodium, Magnesium, and Aluminum Abundances in M13 Giants Brighter than the Horizontal Branch Robert P. Kraft, Christopher Sneden, Graeme H. Smith, Matthew D. Shetrone, G. E. Langer, and Catherine A. Pilachowski <1997, AJ, 113, 279> =1997AJ....113..279K ================================================================================ Abstract: Observations of 11 giants in the globular cluster M13 fainter than M_V=-1.7 have been obtained with the High Resolution Echelle Spectrograph on the Keck I Telescope. When combined with similar data for brighter giants obtained with the 3.0-m Shane Telescope's Hamilton Echelle spectrograph, these data allow examination of the detailed abundances of oxygen, sodium, magnesium, and aluminium over a wide range of luminosity on the red giant branch. We find that oxygen depletions, correlated with sodium enhancements, can be found in giants with luminosities down to nearly the level of the horizontal branch at M_V=0.3. Aluminum abundances in M13 giants also span a wide range (~1.4 dex) and are anticorrelated with the observed magnesium abundances. However, field halo giants of comparable metallicity and evolutionary state exhibit (normal) high abundances of O and Mg and low abundances of Na and Al. Stars in M13 with high sodium and aluminum and low oxygen and magnesium abundances are found at all giant branch luminosities, as are stars with more normal light element abundances (as defined by field halo stars of comparable metallicity). The detailed abundance patterns of the light elements oxygen, sodium, magnesium, and aluminum can be explained most easily as a result of deep mixing and proton capture nucleosynthesis. Evidence in support of this explanation is (a) the constancy of the abundances of Al+Mg and C+N+O, (b) the shift in the distribution of sodium abundances toward higher values and of oxygen abundances toward lower values in cluster giants with surface gravities below log g = 1.0. The action of deep mixing, however, is seen not only at the top of the giant branch, but already in some giants even as faint as the level of the horizontal branch. (Copyright) 1996 American Astronomical Society. Description: The tables described here contain equivalent width measurements that were not reported in the printed version of the paper. File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- tablea.dat 82 54 KeckR45 Equivalent Widths for M13 Stars tablea.tex 125 92 AASTeX version of tablea.dat tableb.dat 62 69 HamR50 Equivalent Widths for M13 Stars tableb.tex 93 102 AASTeX version of tableb.dat -------------------------------------------------------------------------------- Byte-by-byte Description of file: tablea.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 7 F7.2 0.1nm Lambda Wavelength of identified line 8- 9 2X --- --- Blank 10-14 A5 --- ID Line identification 15-20 F6.2 --- EP E.P. 21-27 F7.2 --- gf log gf 28-32 I5 --- K228 []? EW for M13 star K-228 33-37 I5 --- K188 []? EW for M13 star K-188 38-42 I5 --- K766 []? EW for M13 star K-766 43-47 I5 --- K168 []? EW for M13 star K-168 48-52 I5 --- K726 []? EW for M13 star K-726 53-57 I5 --- K984 []? EW for M13 star K-984 58-62 I5 --- K955 []? EW for M13 star K-955 63-67 I5 --- K337 []? EW for M13 star K-337 68-72 I5 --- K348 []? EW for M13 star K-348 73-77 I5 --- K1062 []? EW for M13 star K-1062 78-82 I5 --- K469 []? EW for M13 star K-469 -------------------------------------------------------------------------------- Byte-by-byte Description of file: tableb.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 7 F7.2 0.1nm Lambda Wavelength of identified line 8- 9 2X --- --- Blank 10-14 A5 --- ID Line identification 15-20 F6.2 --- EP E.P. 21-27 F7.2 --- gf log gf 28-32 I5 --- L598 []? EW for M13 star L-598 33-37 I5 --- L629 []? EW for M13 star L-629 38-42 I5 --- L194 []? EW for M13 star L-194 43-47 I5 --- L973 []? EW for M13 star L-973 48-52 I5 --- L954 []? EW for M13 star L-954 53-57 I5 --- L835 []? EW for M13 star L-835 58-62 I5 --- L70 []? EW for M13 star L-70 -------------------------------------------------------------------------------- ================================================================================ (End) Lee Brotzman [ADS] 04-Apr-1997