2009A&A...493..601H


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.08CET19:29:09

2009A&A...493..601H - Astronomy and Astrophysics, volume 493, 601-612 (2009/1-2)

Lithium abundances of halo dwarfs based on excitation temperature. I. Local thermodynamic equilibrium.

HOSFORD A., RYAN S.G., GARCIA PEREZ A.E., NORRIS J.E. and OLIVE K.A.

Abstract (from CDS):

The discovery of the Spite plateau in the abundances of 7Li for metal-poor stars led to the determination of an observationally deduced primordial lithium abundance. However, after the success of the Wilkinson Microwave Anisotropy Probe (WMAP) in determining the baryon density, ΩBh2, there was a discrepancy between observationally determined and theoretically determined abundances in the case of 7Li. One of the most important uncertain factors in the calculation of the stellar 7Li abundance is the effective temperature, Teff. We use sixteen metal-poor halo dwarfs to calculate new Teff values using the excitation energy method. With this temperature scale we then calculate new Li abundances for this group of stars in an attempt to resolve the 7Li discrepancy. Using high signal-to-noise (S/N≃100) spectra of 16 metal-poor halo dwarfs, obtained with the UCLES spectrograph on the AAT, measurements of equivalent widths from a set of unblended FeI lines are made. These equivalent widths are then used to calculate new Teff values with the use of the single line radiative transfer program WIDTH6, where we have constrained the gravity using either theoretical isochrones or the Hipparcos parallax, rather than the ionization balance. The lithium abundances of the stars are calculated with these temperatures. The physical parameters are derived for the 16 programme stars, and two standards. These include Teff, logg, [Fe/H], microturbulence and 7Li abundances. A comparison between the temperature scale of this work and those adopted by others has been undertaken. We find good consistency with the temperatures derived from the Hα line by Asplund et al. (2006ApJ...644..229A), but not with the hotter scale of Melendez & Ramirez (2004ApJ...615L..33M). We also present results of the investigation into whether any trends between 7Li and metallicity or temperature are present in these metal-poor stars.

Abstract Copyright:

Journal keyword(s): Galaxy: halo - cosmology: early universe - nuclear reactions, nucleosynthesis, abundances - stars: abundances

VizieR on-line data: <Available at CDS (J/A+A/493/601): stars.dat table.dat>

Simbad objects: 18

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Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 CD-33 1173 Pe* 03 19 35.3161303154 -32 50 43.157841051   11.272 10.902 10.421 10.152 CEMP 48 0
2 BD+03 740 HB* 05 01 16.6227347580 +04 06 37.023779331 9.97 10.17   9.6   sdF0 162 0
3 BD+24 1676 PM* 07 30 41.2663867705 +24 05 10.250742299   11.15   10.4   F 113 0
4 BD+20 2030 SB* 08 16 07.3523078897 +19 41 51.433250340   11.556 11.189 10.909 10.632 sdF0 48 0
5 HD 74000 PM* 08 40 50.8038415228 -16 20 42.513275817 9.84 10.09 9.66     F2 249 0
6 BD+09 2190 PM* 09 29 15.5616421382 +08 38 00.469417390   11.54   10.8   sdA5 121 0
7 HD 84937 PM* 09 48 56.09801 +13 44 39.3237 8.49 8.68 8.32 7.97 7.70 F8Vm-5 734 0
8 BD-13 3442 Pe* 11 46 50.6526364381 -14 06 43.453858029   10.662 10.274     CEMP 95 0
9 Wolf 1492 Pe* 13 40 02.4921790616 -00 02 18.750321114 11.601 11.832 11.451 11.184 10.892 sdF0: 264 0
10 Ross 841 Pe* 14 02 30.0901582051 -05 39 05.181328144   11.508 11.149 10.866 10.576 sdA3 142 0
11 BD+26 2621 PM* 14 54 10.7124388855 +25 33 48.928656234   11.40   10.7   F0 39 0
12 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 871 0
13 CD-71 1234 PM* 16 07 44.6413048424 -71 21 01.362624816   10.81 10.44     ~ 34 0
14 HD 338529 PM* 19 32 31.9104538188 +26 23 26.116678290   9.72   9.2   B5 202 0
15 LP 635-14 PM* 20 26 46.8302131628 -00 37 15.177555985 11.57 11.76 11.33     OB- 39 0
16 LP 815-43 PM* 20 38 13.2997980664 -20 26 10.852305467   11.31 10.72     ~ 68 0
17 CD-35 14849 PM* 21 33 49.75243 -35 26 14.2322   10.95 10.56 10.59   B8 65 0
18 CD-24 17504 Pe* 23 07 20.2536159873 -23 52 35.956455668   12.51 12.18     CEMP-no 83 0

    Equat.    Gal    SGal    Ecl

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2021.03.08-19:29:09

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