J/ApJ/808/13 XO-2S and XO-2N chemical composition (Ramirez+, 2015)
The dissimilar chemical composition of the planet-hosting stars of the
XO-2 binary system.
Ramirez I., Khanal S., Aleo P., Sobotka A., Liu F., Casagrande L.,
Melendez J., Yong D., Lambert D.L., Asplund M.
<Astrophys. J., 808, 13 (2015)>
=2015ApJ...808...13R 2015ApJ...808...13R (SIMBAD/NED BibCode)
ADC_Keywords: Equivalent widths ; Stars, double and multiple ; Spectroscopy
Keywords: planetary systems; stars: abundances; stars: fundamental parameters;
stars: individual: XO-2
Abstract:
Using high-quality spectra of the twin stars in the XO-2 binary
system, we have detected significant differences in the chemical
composition of their photospheres. The differences correlate strongly
with the elements' dust condensation temperature. In XO-2N, volatiles
are enhanced by about 0.015dex and refractories are overabundant by up
to 0.090dex. On average, our error bar in relative abundance is
0.012dex. We present an early metal-depletion scenario in which the
formation of the gas giant planets known to exist around these stars
are responsible for a 0.015 dex offset in the abundances of all
elements while 20M⊕ of non-detected rocky objects that formed
around XO-2S explain the additional refractory-element difference. An
alternative explanation involves the late accretion of at least
20M⊕of planet-like material by XO-2N, allegedly as a result of
the migration of the hot Jupiter detected around that star. Dust
cleansing by a nearby hot star as well as age or Galactic birthplace
effects can be ruled out as valid explanations for this phenomenon.
Description:
Spectroscopic observations of the XO-2 system were carried out with
the HIRES spectrograph on Keck's 10m Telescope on 2015 January 24-25.
We used the kv408 filter, which allows a wavelength coverage from
about 4080 to 8300Å and a spectral resolution R=67000.
We also took a solar spectrum of very high S/N (>700 per pixel) at
R=84000.
Objects:
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RA (ICRS) DE Designation(s)
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07 48 06.47 +50 13 33.0 XO-2N = TYC 3413-5-1
07 48 07.48 +50 13 03.3 XO-2S = TYC 3413-210-1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 49 1598 Line list
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See also:
J/ApJ/801/L10 : XO-2N and XO-2S equivalent widths (Teske+, 2015)
J/A+A/583/A135 : XO-2N and XO-2S spectra (Biazzo+, 2015)
J/A+A/575/A111 : GAPS V: Global analysis of the XO-2 system (Damasso+, 2015)
J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 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/A+A/552/A6 : Abundances of F-G MS stars (Gonzalez Hernandez+, 2013)
J/ApJ/757/161 : Spectroscopy of 56 exoplanet host stars (Torres+, 2012)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJ/732/55 : Abundances of stars with planets (Schuler+, 2011)
J/ApJ/715/1050 : Predicted abundances for extrasolar planets. I. (Bond+, 2010)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/ApJ/709/447 : Chemical composition of OGLE-2007-BLG-514S (Epstein+, 2010)
J/AJ/137/4911 : Six transits of the exoplanet XO-2b (Fernandez+, 2009)
J/A+A/508/L17 : Abundances in solar analogs (Ramirez+, 2009)
J/A+A/465/271 : Oxygen abundances in nearby stars (Ramirez+, 2007)
J/MNRAS/373/13 : Lower main-sequence stars param. (Casagrande+, 2006)
J/ApJ/626/446 : Effective temperature scale of FGK stars (Ramirez+, 2005)
J/A+A/275/101 : Chemical evolution of the galactic disk I. (Edvardsson+ 1993)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1 A1 --- f_lambda [-] -: no equivalent width values
2- 10 F9.4 0.1nm lambda [4218.7/8092.7] Wavelength in Angstroms
12- 16 F5.1 --- Sp [6/106] Numeric species code (1)
18- 23 F6.4 eV ExPot [0/9.2] Excitation Potential
25- 31 F7.4 [-] log(gf) [-6.3/0.6] Log of the oscillator strength
33- 37 F5.1 10-13m XO-2N [6/217]?=0 Equivalent width in XO-2N (2)
39- 43 F5.1 10-13m XO-2S [7/210]?=0 Equivalent width in XO-2S (2)
45- 49 F5.1 10-13m Sun [3/158]?=0 Equivalent width in the Sun (2)
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Note (1): In the format of XX.Y where XX is the atomic number and Y is the
ionization level, e.g. 26.0 => Fe I.
Note (2): In units of milli-Angstroms.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Nov-2015