J/MNRAS/487/2474 GALAH unresolved triple Sun-like star (Cotar+, 2019)
The GALAH survey: unresolved triple Sun-like stars discovered by the Gaia
mission.
Cotar K., Zwitter T., Traven G., Kos J., Asplund M., Bland-Hawthorn J.,
Buder S., DOrazi V., De Silva G.M., Lin J., Martell S.L., Sharma S.,
Simpson J.D, Zucker D.B, Horner J., Lewis G.F, Nordlander T., Ting Y.-S.,
Wittenmyer R.A., GALAH collaboration
<Mon. Not. R. Astron. Soc. 487, 2474 (2019)>
=2019MNRAS.487.2474C 2019MNRAS.487.2474C (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, G-type ; Stars, double and multiple
Keywords: methods: data analysis - binaries: general - stars: solar-type -
Galaxy: stellar content
Abstract:
The latest Gaia data release enables us to accurately identify stars
that are more luminous than would be expected on the basis of their
spectral type and distance. During an investigation of the 329 best
solar twin candidates uncovered among the spectra acquired by the
GALAH survey, we identified 64 such overluminous stars. In order to
investigate their exact composition, we developed a data-driven
methodology that can generate a synthetic photometric signature and
spectrum of a single star. By combining multiple such synthetic stars
into an unresolved binary or triple system and comparing the results
to the actual photometric and spectroscopic observations, we uncovered
6 definitive triple stellar system candidate and an additional 14
potential candidates whose combined spectrum mimics the solar
spectrum. Considering the volume correction factor for a
magnitude-limited survey, the fraction of probable unresolved triple
stars with long orbital periods is 2 per cent. Possible orbital
configurations of the candidates were investigated using the selection
and observational limits. To validate the discovered multiplicity
fraction, the same procedure was used to evaluate the multiplicity
fraction of other stellar types.
Description:
We provide a list of 329 Sun-like stars that were analysed for their
possible multiplicity based on their absolute magnitude and distance
derived from Gaia DR2 data. The GALAH proprietary spectra are used to
confirm their similarity with solar spectrum and to determine [Fe/H]
of the determined systems. We uncovered 20 candidates for unresolved
triple stellar systems that have to analysed with other approaches to
confirm their multiple nature.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 469 329 Catalogue of analysed objects
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See also:
http://galah-survey.org/ : GALAH home page
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR2 ?=- Gaia DR2 identifier, source_id (source_id)
21- 35 I15 --- GALAH GALAH unique per observation id (sobject_id)
37- 56 F20.16 deg RAdeg Right ascension from Gaia DR2 (ICRS)
at epoch 2015.5 (ra)
58- 79 F22.18 deg DEdeg Declination from Gaia DR2 (ICRS)
at epoch 2015.5 (dec)
81- 99 F19.16 --- RUWE Value of renormalized astrometric chi2 (ruwe)
101-121 F21.16 --- msimp Photometric chi2 for original parameters
(msimp)
123-144 F22.13 --- msimf Spectroscopic chi2 for original parameters
(msimf)
146-163 F18.13 K s1Teff1 Teff1 in a fitted single system (s1_teff1)
165-187 F23.20 [-] s1[Fe/H] Abundance of [Fe/H] in a fitted single system
(s1_feh)
189-209 F21.16 --- s1simp ? Photometric chi2 of a fitted single system
(s1simp)
211-232 F22.13 --- s1simf ? Spectroscopic chi2 of a fitted single system
(s1simf)
234-251 F18.13 K s2Teff1 Teff1 in a fitted binary system (s2_teff1)
253-270 F18.13 K s2Teff2 Teff2 in a fitted binary system (s2_teff2)
272-293 F22.19 [-] s2[Fe/H] Abundance of [Fe/H] in a fitted binary system
(s2_feh)
295-316 F22.16 --- s2simp ? Photometric chi2 of a fitted binary system
(s2simp)
318-339 F22.13 --- s2simf ? Spectroscopic chi2 of a fitted binary system
(s2simf)
341-358 F18.13 K s3Teff1 ? Teff1 in a fitted triple system (s3_teff1)
360-377 F18.13 K s3Teff2 ? Teff2 in a fitted triple system (s3_teff2)
379-396 F18.13 K s3Teff3 ? Teff3 in a fitted triple system (s3_teff3)
398-418 F21.18 [-] s3[Fe/H] ? Abundance of [Fe/H] in a fitted
triple system (s3_feh)
420-440 F21.16 --- s3simp ? Photometric chi2 of a fitted triple system
(s3simp)
442-460 F19.13 --- s3simf ? Spectroscopic chi2 of a fitted triple system
(s3simf)
462 I1 --- Nstarsp [1/3] Best-fitting photometric configuration
(nstarsp) (1)
464 I1 --- Nstarsf [1/3] Best-fitting spectroscopic configuration
(nstarsf) (1)
466-467 A2 --- Class [123> i] Final configuration classification
(class) (1)
469 I1 --- Flag [0/7] Result quality flags (flag) (2)
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Note (1): configuration code as follows:
1 = single
2 = binary
3 = triple
>1 = one or more stars
>2 = two or more stars
i = inconclusive
Note (2): Quality flags as follows:
0 = None of the flags was raised
1 = High astrometric uncertainty (RUWE>1.4)
2 = Deviating photometric fit (sXsimp>msimp)
4 = Deviating spectroscopic fit (sXsims > msims)
5 = High astrometric uncertainty (RUWE>1.4) and
deviating spectroscopic fit (sXsims > msims)
6 = High astrometric uncertainty (RUWE>1.4) and
deviating spectroscopic fit (sXsims>msims)
7 = High astrometric uncertainty (RUWE>1.4) and
deviating photometric fit (sXsimp>msimp) and
deviating spectroscopic fit (sXsims>msims)
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Acknowledgements:
Klemen Cotar, klemen.cotar(at)fmf.uni-lj.si
References:
(End) Patricia Vannier [CDS] 21-Jun-2019