J/ApJ/803/90 τ Cet chemical composition (Pagano+, 2015)
The chemical composition of τ Ceti and possible effects on
terrestrial planets.
Pagano M., Truitt A., Young P.A., Shim S.-H.
<Astrophys. J., 803, 90 (2015)>
=2015ApJ...803...90P 2015ApJ...803...90P
ADC_Keywords: Stars, double and multiple ; Planets ; Equivalent widths
Keywords: astrobiology; planets and satellites: composition;
planets and satellites: interiors; stars: abundances;
stars: individual: * sig Cet
Abstract:
τ Ceti (HD10700), a G8 dwarf with mass 0.78M☉, is a close
(3.65pc) Sun-like star where five possibly terrestrial planet
candidates (minimum masses of 2, 3.1, 3.5, 4.3, and 6.7M⊕)
have recently been discovered. We report abundances of 23 elements
using spectra from the MIKE spectrograph on Magellan. We find
[Fe/H]=-0.49 and Teff=5387K. Using stellar models with the
abundances determined here, we calculate the position of the classical
habitable zone (HZ) with time. At the current best fit age,
7.63-1.5+0.87Gyr, up to two planets (e and f) may be in the HZ,
depending on atmospheric properties. The Mg/Si ratio of the star is
found to be 1.78, which is much greater than for Earth (∼1.2). With a
system that has such an excess of Mg/Si ratio it is possible that the
mineralogical make-up of planets around τ Ceti could be
significantly different from that of Earth, with possible
oversaturation of MgO, resulting in an increase in the content of
olivine and ferropericlase compared with Earth. The increase in MgO
would have a drastic impact on the rheology of the mantles of the
planets around τ Ceti.
Description:
The spectrum for τ Ceti was taken by Paul Butler from the Carnegie
Institute of Washington as part of the Magellan Planet Search Program,
using the MIKE echelle spectrograph on the 6.5m Magellan II telescope.
The spectrum has R∼50000 in the range 4700-7100Å.
Objects:
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RA (ICRS) DE Designation(s)
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01 44 04.08 -15 56 14.9 tau Ceti = HD 10700
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 39 188 Complete line list
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See also:
J/A+A/576/A89 : Oxygen abundances from HARPS (Bertran de Lis+, 2015)
J/AJ/148/54 : The Hypatia Catalog ((Hinkel+, 2014)
J/ApJ/770/90 : Candidate planets in the habitable zones (Gaidos, 2013)
J/ApJ/767/95 : Improved parameters of smallest KIC stars (Dressing+, 2013)
J/A+A/551/A79 : RV periodic variations in τ Ceti (Tuomi+, 2013)
J/A+A/547/A36 : Chemical abundances of 87 KOIs (Adibekyan++, 2012)
J/ApJS/199/8 : Interstellar column density compilation (Gudennavar+, 2012)
J/MNRAS/414/1227 : Mg/Fe ratio of MILES stars (Milone+, 2011)
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 exoplanets. I. (Bond+, 2010)
J/A+A/497/563 : Chemical abundances of 451 stars (Neves+, 2009)
J/PASJ/59/335 : Properties of 160 F-K disk dwarfs/subgiants (Takeda+, 2007)
J/MNRAS/370/163 : Abundance distribution of stars with planets (Bond+, 2006)
J/A+A/449/723 : Atmospheres of stars with planets (Gilli+, 2006)
J/ApJS/159/141 : Spectroscopic properties of cool stars. I. (Valenti+, 2005)
J/A+A/398/363 : Statistical properties of exoplanets II (Santos+, 2003)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 0.1nm lambda [4773/6858] Wavelength; Angstroms
9- 13 A5 --- El Element identifier
15- 19 F5.2 eV ExPot [0/10.8] Lower excitation potential
21- 25 F5.2 [-] log(gf) [-9.8/0.6] Oscillator strength
27- 32 F6.2 10-13m EWsun [4/133] Solar equivalent width (mÅ)
34- 39 F6.2 10-13m EW [1.5/114.6] τ Ceti equivalent width (mÅ)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 04-Aug-2015