J/ApJ/831/20 C/O and Mg/Si for solar neighborhood's stars (Brewer+, 2016)
C/O and Mg/Si ratios of stars in the solar neighborhood.
Brewer J.M., Fischer D.A.
<Astrophys. J., 831, 20-20 (2016)>
=2016ApJ...831...20B 2016ApJ...831...20B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, G-type ; Abundances ; Planets
Keywords: stars: abundances; stars: solar-type; stars: statistics
Abstract:
The carbon-to-oxygen ratio in a protoplanetary disk can have a
dramatic influence on the compositions of any terrestrial planets
formed. In regions of high C/O, planets form primarily from
carbonates, and in regions of low C/O, the ratio of magnesium to
silicon determines the types of silicates that dominate the
compositions. We present C/O and Mg/Si ratios for 852 F, G, and K
dwarfs in the solar neighborhood. We find that the frequency of
carbon-rich dwarfs in the solar neighborhood is <0.13% and that 156
known planet hosts in the sample follow a similar distribution as all
of the stars as a whole. The cosmic distribution of Mg/Si for these
same stars is broader than the C/O distribution and peaks near 1.0,
with ∼60% of systems having 1≤Mg/Si<2, leading to rocky planet
compositions similar to the Earth. This leaves 40% of systems that can
have planets that are silicate-rich and that may have very different
compositions than our own.
Description:
The catalog of Brewer+ (2016, J/ApJS/225/32) has abundances of 15
elements, including C, O, Mg, and Si, for more than 1600 F, G, and K
stars. The stars were all observed using the HIRES instrument on the
Keck telescope with the same instrumental setup. Most of the stars
were observed as part of the California Planet Search (CPS) program
and have a typical S/N≫100.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 847 Stellar C/O and Mg/Si ratios (corrected version
from the author)
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See also:
J/ApJS/225/32 : Extended abundance analysis of cool stars (Brewer+, 2016)
J/A+A/584/A72 : A rocky planet at 6.5pc from the Sun (Motalebi+ 2015)
J/A+A/568/A25 : C and O abundances in stellar populations (Nissen+, 2014)
J/ApJ/778/132 : C and O abundances in 55 Cnc (Teske+, 2013)
J/ApJ/735/41 : Carbon and oxygen abundances in FGK stars (Petigura+, 2011)
J/ApJ/725/2349 : C/O vs Mg/Si of planetary systems (Delgado Mena+, 2010)
J/ApJ/715/1050 : Predicted abundances for extrasolar planets. I. (Bond+, 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- SPOCS [2/3247] SPOCS ID
6- 17 A12 --- Name Star name (1)
19- 24 F6.2 mag Vmag [0/13.7]? V band magnitude from SIMBAD (1)
26- 31 F6.3 [-] [C/H] [-1.2/0.7] Derived [C/H] abundance (1)
33- 38 F6.3 [-] [O/H] [-0.4/0.7] Derived [O/H] abundance (1)
40- 45 F6.3 [-] [Mg/H] [-0.8/0.6] Derived [Mg/H] abundance (1)
47- 52 F6.3 [-] [Si/H] [-0.7/0.6] Derived [Si/H] abundance (1)
54- 57 F4.2 --- C/O [0.04/0.7] Abundance number ratio, NC/NO (2)
59- 62 F4.2 --- Mg/Si [0.4/1.4] Abundance number ratio, NMg/NSi (2)
64 I1 --- Np [1/5]? Number of known planets
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Note (1): As listed or derived in Brewer+ (2016, J/ApJS/225/32).
Note (2): Based on the uncertainties provided in Brewer+ (2016, J/ApJS/225/32),
the uncertainties in the C/O values are ±10% and the uncertainties
in the Mg/Si values are ±3.3%.
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History:
From electronic version of the journal
07-Apr-2017: table 1 corrected version sent from the author
(see also erratum published in 2017,ApJ,840,121)
Acknowledgements:
John M. Brewer [yale.edu].
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Jan-2017