J/MNRAS/376/361 Abundances of 5 Ap/Bp stars of NGC 6475 (Folsom+, 2007)
Rotation and chemical abundances of Ap/Bp stars in the open cluster NGC 6475.
Folsom C.P., Wade G.A., Bagnulo S., Landstreet J.D.
<Mon. Not. R. Astron. Soc., 376, 361-370 (2007)>
=2007MNRAS.376..361F 2007MNRAS.376..361F
ADC_Keywords: Clusters, open ; Stars, peculiar ; Abundances
Keywords: open clusters and associations: individual: NGC 6475 -
stars: abundances - stars: chemically peculiar -
stars: fundamental parameters - rotation
Abstract:
The connection between age, rotation and chemical abundance of
magnetic Ap stars is poorly understood. Using open clusters, we are
able to study samples of stars that are both coeval and
co-environmental. By determining rotation and chemical abundance for
Ap star members of clusters with various ages, the variations of these
properties as a function of age and environment can be derived. All
four probable Ap star members of the open cluster NGC 6475, as well as
one normal late B star, were studied using detailed spectrum synthesis
of high-resolution UVES-POP spectra. Probable cluster membership was
confirmed for all five stars; however, chemical abundance anomalies
only appear to be present in spectra of three. Projected rotational
velocity and chemical abundances for 21 elements ranging from C to Eu
are presented for the five stars. In the three peculiar stars, we find
overabundances of Si, Cr, Mn, Fe and rare earths, such as Nd,
characteristic of Ap stars. The set of chemically peculiar stars show
fairly homogeneous abundance tables, however, notable differences
exist for a few elements. There also exist appreciable differences in
the vsini and main-sequence evolutionary stage of the chemically
peculiar stars. This may hint at the underlying processes giving rise
to the observed abundance anomalies. With this first detailed study of
chemical abundances of a complete sample of magnetic Ap/Bp stars in an
open cluster, we have initiated an exploration of the environmental
and evolutionary influence on chemical peculiarity.
Description:
These tables provide the fundamental atomic line data used for
spectrum synthesis of the 5 stars investigated in NGC 6475. Each table
contains the dat a for one star, originally extracted from the VALD
database.
Objects:
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RA (2000) DE Designation(s) (files)
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17 53 16 -34 37.3 HD 162576 = V* V958 Sco (table3.dat)
17 53 58 -34 49.9 HD 162725 = V* V951 Sco (table4.dat)
17 51 53 -34 46.9 HD 162305 = CD-34 12154 (table5.dat)
17 52 10 -34 53.7 HD 320764 = CD-34 12161 (table6.dat)
17 54 27 -34 28.0 HD 162817 = CD-34 12244 (table7.dat)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 31 1310 List of atomic line data used for HD 162576
table4.dat 31 1238 List of atomic line data used for HD 162725
table5.dat 31 683 List of atomic line data used for HD 162305
table6.dat 31 1798 List of atomic line data used for HD 320764
table7.dat 31 616 List of atomic line data used for HD 162817
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Byte-by-byte Description of file: table[34567].dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- El Element
4 I1 --- State Ionization State (1=neutral)
7- 15 F9.4 0.1nm lambda Wavelength
18- 23 F6.3 --- log(gf) Oscillator Strength
26- 31 F6.3 eV Elow Lower Level Energy
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Acknowledgements:
Colin Folsom, cpf(at)arm.ca.uk
(End) Patricia Vannier [CDS] 17-Sep-2007