18 Sco

A solar twin rich in refractory and neutron-capture elements. Implications for chemical tagging

Jorge Meléndez, Iván Ramírez, Amanda I. Karakas, David Yong, Talawanda R. Monroe, Megan Bedell, Maria Bergemann, Martin Asplund, Marcelo Tucci Maia, Jacob Bean, José Dias Do Nascimento, Michael Bazot, Alan Alves-Brito, Fabrício C. Freitas, Matthieu Castro

Research output: Contribution to journalArticle

Abstract

We study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R ∼ 110,000), high signal-to-noise ratio (800-1,000) Very Large Telescope UVES spectra, which allow us to achieve a precision of about 0.005 dex in differential abundances. The effective temperature and surface gravity of 18 Sco are T eff = 5823 ± 6 K and log g = 4.45 ± 0.02 dex, i.e., 18 Sco is 46 ± 6 K hotter than the Sun and log g is 0.01 ± 0.02 dex higher. Its metallicity is [Fe/H] = 0.054 ± 0.005 dex, and its microturbulence velocity is +0.02 ± 0.01 km s-1 higher than solar. Our precise stellar parameters and differential isochrone analysis show that 18 Sco has a mass of 1.04 ± 0.02 M and that it is ∼1.6 Gyr younger than the Sun. We use precise High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities to search for planets, but none are detected. The chemical abundance pattern of 18 Sco displays a clear trend with condensation temperature, thus showing higher abundances of refractories in 18 Sco than in the Sun. Intriguingly, there are enhancements in the neutron-capture elements relative to the Sun. Despite the small element-to-element abundance differences among nearby n-capture elements (∼0.02 dex), we successfully reproduce the r-process pattern in the Solar System. This is independent evidence for the universality of the r process. Our results have important implications for chemical tagging in our Galaxy and nucleosynthesis in general.

Original languageEnglish (US)
Article number14
JournalAstrophysical Journal
Volume791
Issue number1
DOIs
StatePublished - Aug 10 2014

Fingerprint

tagging
refractories
marking
neutrons
radial velocity
planets
planet
nuclear fusion
solar system
signal-to-noise ratio
metallicity
condensation
chemical composition
sun
signal to noise ratios
temperature
telescopes
gravity
gravitation
galaxies

Keywords

  • abundances
  • abundances - stars
  • AGB and post-AGB - stars
  • fundamental parameters - Sun
  • stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Meléndez, J., Ramírez, I., Karakas, A. I., Yong, D., Monroe, T. R., Bedell, M., ... Castro, M. (2014). 18 Sco: A solar twin rich in refractory and neutron-capture elements. Implications for chemical tagging. Astrophysical Journal, 791(1), [14]. https://doi.org/10.1088/0004-637X/791/1/14

18 Sco : A solar twin rich in refractory and neutron-capture elements. Implications for chemical tagging. / Meléndez, Jorge; Ramírez, Iván; Karakas, Amanda I.; Yong, David; Monroe, Talawanda R.; Bedell, Megan; Bergemann, Maria; Asplund, Martin; Tucci Maia, Marcelo; Bean, Jacob; Do Nascimento, José Dias; Bazot, Michael; Alves-Brito, Alan; Freitas, Fabrício C.; Castro, Matthieu.

In: Astrophysical Journal, Vol. 791, No. 1, 14, 10.08.2014.

Research output: Contribution to journalArticle

Meléndez, J, Ramírez, I, Karakas, AI, Yong, D, Monroe, TR, Bedell, M, Bergemann, M, Asplund, M, Tucci Maia, M, Bean, J, Do Nascimento, JD, Bazot, M, Alves-Brito, A, Freitas, FC & Castro, M 2014, '18 Sco: A solar twin rich in refractory and neutron-capture elements. Implications for chemical tagging', Astrophysical Journal, vol. 791, no. 1, 14. https://doi.org/10.1088/0004-637X/791/1/14
Meléndez, Jorge ; Ramírez, Iván ; Karakas, Amanda I. ; Yong, David ; Monroe, Talawanda R. ; Bedell, Megan ; Bergemann, Maria ; Asplund, Martin ; Tucci Maia, Marcelo ; Bean, Jacob ; Do Nascimento, José Dias ; Bazot, Michael ; Alves-Brito, Alan ; Freitas, Fabrício C. ; Castro, Matthieu. / 18 Sco : A solar twin rich in refractory and neutron-capture elements. Implications for chemical tagging. In: Astrophysical Journal. 2014 ; Vol. 791, No. 1.
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abstract = "We study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R ∼ 110,000), high signal-to-noise ratio (800-1,000) Very Large Telescope UVES spectra, which allow us to achieve a precision of about 0.005 dex in differential abundances. The effective temperature and surface gravity of 18 Sco are T eff = 5823 ± 6 K and log g = 4.45 ± 0.02 dex, i.e., 18 Sco is 46 ± 6 K hotter than the Sun and log g is 0.01 ± 0.02 dex higher. Its metallicity is [Fe/H] = 0.054 ± 0.005 dex, and its microturbulence velocity is +0.02 ± 0.01 km s-1 higher than solar. Our precise stellar parameters and differential isochrone analysis show that 18 Sco has a mass of 1.04 ± 0.02 M ⊙ and that it is ∼1.6 Gyr younger than the Sun. We use precise High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities to search for planets, but none are detected. The chemical abundance pattern of 18 Sco displays a clear trend with condensation temperature, thus showing higher abundances of refractories in 18 Sco than in the Sun. Intriguingly, there are enhancements in the neutron-capture elements relative to the Sun. Despite the small element-to-element abundance differences among nearby n-capture elements (∼0.02 dex), we successfully reproduce the r-process pattern in the Solar System. This is independent evidence for the universality of the r process. Our results have important implications for chemical tagging in our Galaxy and nucleosynthesis in general.",
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AU - Karakas, Amanda I.

AU - Yong, David

AU - Monroe, Talawanda R.

AU - Bedell, Megan

AU - Bergemann, Maria

AU - Asplund, Martin

AU - Tucci Maia, Marcelo

AU - Bean, Jacob

AU - Do Nascimento, José Dias

AU - Bazot, Michael

AU - Alves-Brito, Alan

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