J/ApJ/801/L10 XO-2N and XO-2S equivalent widths (Teske+, 2015)
Abundance differences between exoplanet binary host stars XO-2N and XO-2S -
Dependence on stellar parameters.
Teske J.K., Ghezzi L., Cunha K., Smith V.V., Schuler S.C., Bergemann M.
<Astrophys. J., 801, L10 (2015)>
=2015ApJ...801L..10T 2015ApJ...801L..10T
ADC_Keywords: Stars, double and multiple ; Equivalent widths
Keywords: planets and satellites: formation; stars: atmospheres ;
planets and satellites: individual: XO-2; stars: abundances
Abstract:
The chemical composition of exoplanet host stars is an important
factor in understanding the formation and characteristics of their
orbiting planets. The best example of this to date is the
planet-metallicity correlation. Other proposed correlations are thus
far less robust, in part due to uncertainty in the chemical history of
stars pre- and post-planet formation. Binary host stars of similar
type present an opportunity to isolate the effects of planets on host
star abundances. Here we present a differential elemental abundance
analysis of the XO-2 stellar binary, in which both G9 stars host giant
planets, one of which is transiting. Building on our previous work, we
report 16 elemental abundances and compare the Δ(XO-2N-XO-2S)
values to elemental condensation temperatures. The Δ(N-S) values
and slopes with condensation temperature resulting from four different
pairs of stellar parameters are compared to explore the effects of
changing the relative temperature and gravity of the stars. We find
that most of the abundance differences between the stars depend on the
chosen stellar parameters, but that Fe, Si, and potentially Ni are
consistently enhanced in XO-2N regardless of the chosen stellar
parameters. This study emphasizes the power of binary host star
abundance analysis for probing the effects of giant planet formation,
but also illustrates the potentially large uncertainties in abundance
differences and slopes induced by changes in stellar temperature and
gravity.
Description:
The observations and data reduction for XO-2N and -2S are detailed in
Teske et al. (2013, J/ApJ/768/L12). The R∼60000, signal-to-noise ratio
(S/N) ∼170-230 data were acquired in February 2012 with the High
Dispersion Spectrograph at the 8.2m Subaru Telescope.
Objects:
----------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------
07 48 07.48 +50 13 03.3 XO-2S = TYC 3413-210-1
07 48 06.47 +50 13 33.0 XO-2N = TYC 3413-5-1
----------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 8 Derived stellar parameters and Δ(N-S)
abundances
table2.dat 56 342 Lines and equivalent widths measured
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See also:
V/136 : Teff and metallicities for Tycho-2 stars (Ammons+, 2006)
J/A+A/575/A111 : GAPS V: Global analysis of the XO-2 system (Damasso+, 2015)
J/A+A/564/A133 : Gaia FGK benchmark stars: metallicity (Jofre+, 2014)
J/A+A/561/A7 : Abundances for stars with planets (Ramirez+, 2014)
J/A+A/558/A106 : Chemical abundances for 83 transit hosts (Mortier+, 2013)
J/ApJ/770/36 : APOSTLE transits of XO-2 system (Kundurthy+, 2013)
J/ApJ/768/L12 : Abundances in host stars XO-2S and XO-2N (Teske+, 2013)
J/ApJ/757/161 : Spectroscopy of 56 exoplanet host stars (Torres+, 2012)
J/ApJ/732/55 : Abundances of stars with planets (Schuler+, 2011)
J/ApJ/720/1290 : Abundances of stars hosting planets (Ghezzi+, 2010)
J/AJ/137/4911 : Six transits of the exoplanet XO-2b (Fernandez+, 2009)
J/A+A/487/373 : Spectroscopic parameters of 451 HARPS-GTO stars (Sousa+, 2008)
J/A+A/469/783 : Code for automatic determination of EW (ARES) (Sousa+, 2007)
J/A+A/454/581 : Iron abundances of 33 wide binaries (Desidera+, 2006)
J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)
J/A+A/420/683 : Equivalent widths of 23 wide binaries (Desidera+, 2004)
J/A+A/415/1153 : [Fe/H] for 98 extra-solar planet-host stars (Santos+, 2004)
J/A+A/377/123 : Equivalent widths of 6 binaries (Gratton+, 2001)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
------------------------------------------------------------------------------
1- 4 A4 --- Param "Orig" or "Alt" set
6- 11 A6 --- --- [Params]
13 I1 --- Set ? Set number for "Alt" params (1)
15- 19 A5 --- Name Star name (XO-2N or XO-2S)
21- 24 I4 K Teff [5343/5547] Effective temperature
26- 27 I2 K e_Teff [32/78] Teff uncertainty
29- 32 F4.2 [cm/s2] logg [4.2/4.5] Log of surface gravity
34- 37 F4.2 [cm/s2] e_logg [0.08/0.3] logg uncertainty
39- 42 F4.2 km/s xi [1/1.4] Microturbulent velocity ξ
44- 47 F4.2 km/s e_xi [0.05/0.2] xi uncertainty
49- 52 F4.2 [-] [Fe/H] [0.2/0.5] Metallicity
54- 57 F4.2 [-] e_[Fe/H] [0.04/0.2] [Fe/H] uncertainty
59- 60 I2 --- N1 [23/72] Number of FeI lines measured
62- 65 A4 --- --- [Fe I]
67- 68 I2 --- N2 [8/10] Number of FeII lines measured
70- 74 A5 --- --- [Fe II]
76- 78 A3 --- Sol? [yes no] Relative to solar?
80- 83 A4 --- IRAF? [IRAF ARES] IRAF/ARES reduction
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Note (1): Alternative Parameter as follows:
1 = We repeated our analysis relative to solar, using by-hand IRAF
measurements of the lines in Ghezzi et al. (2010, J/ApJ/720/1290).
2 = We adopted the full analysis approach of Ghezzi et al. (2010,
J/ApJ/720/1290) and derived parameters based on absolute abundances, not
relative to solar. The Ghezzi et al. (2010, J/ApJ/720/1290) line list,
with lab-measured gf-values, was compiled specifically for an absolute
analysis.
3 = We used ODFNEW models with a different and longer line list of 72/67 FeI
and 9/8 FeII lines for N/S, compiled from Sousa et al. (2008,
J/A+A/487/373). The equivalent widths were measured with ARES
(Sousa et al. 2007, J/A+A/469/783); lines >0.30dex from the average in
the Sun were removed and an interative 2σ clipping was applied to
the stars during the parameter determination.
See section 2.2 for full details.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Ion Ion designation
7- 13 F7.2 0.1nm lambda [4465.8/7114.6] Wavelength, in Angstroms
15- 18 F4.2 eV ExPot [0/8] Excitation potential
20- 24 F5.2 [-] log(gf) [-9.8/0.6] Log of oscillator strength
26- 30 F5.1 10-13m EW0 [4/123]? Solar equivalent width (mÅ)
32- 36 F5.1 10-13m EW2S [11/170]? XO-2S equivalent width (mÅ)
38- 38 A1 --- f_EW2S [a-d] Flag on XO-2S (1)
(for TiI only)
40- 43 F4.2 [-] dA2S [0.03/0.1]? NLTE abundance correction for XO-2S
45- 49 F5.1 10-13m EW2N [8.2/176.3]? XO-2N equivalent width (mÅ)
51- 51 A1 --- f_EW2N [b-d] Flag on XO2N (1)
(for TiI only)
53- 56 F4.2 [-] dA2N [0.02/0.1]? NLTE abundance correction for XO-2N
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Note (1): Flag as follows:
a = abundance derived through synthesis;
b = outlier, removed from final abundance;
c = measured for alt param sets 1, 2, 3 (see section 2.2 and table1);
d = measured for alt param set 4
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 21-Jul-2015