The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468

Detalhes bibliográficos
Autor(a) principal: Meléndez, Jorge
Data de Publicação: 2017
Outros Autores: Bedell, Megan, Bean, Jacob L., Ramírez, Iván, Asplund, Martin, Dreizler, Stefan, Yan, Hong Liang, Shi, Jianrong, Lind, Karin, Ferraz-Mello, Sylvio, Galarza, Jhon Joel Yana, Santos, Leonardo Augusto Gonçalves dos, Spina, Lorenzo, Maia, Marcelo Tucci, Alves-Brito, Alan, Monroe, TalaWanda Rose, Casagrande, Luca
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Institucional da UFRGS
Texto Completo: http://hdl.handle.net/10183/175250
Resumo: Context. More than two thousand exoplanets have been discovered to date. Of these, only a small fraction have been detected around solar twins, which are key stars because we can obtain accurate elemental abundances especially for them, which is crucial for studying the planet-star chemical connection with the highest precision. Aims. We aim to use solar twins to characterise the relationship between planet architecture and stellar chemical composition. Methods. We obtained high-precision (1 ms1) radial velocities with the HARPS spectrograph on the ESO 3.6 m telescope at La Silla Observatory and determined precise stellar elemental abundances ( 0.01 dex) using spectra obtained with the MIKE spectrograph on the Magellan 6.5 m telescope. Results. Our data indicate the presence of a planet with a minimum mass of 26 4 Earth masses around the solar twin HIP 68468. The planet is more massive than Neptune (17 Earth masses), but unlike the distant Neptune in our solar system (30 AU), HIP 68468c is close-in, with a semi-major axis of 0.66 AU, similar to that of Venus. The data also suggest the presence of a super-Earth with a minimum mass of 2.9 0.8 Earth masses at 0.03 AU; if the planet is confirmed, it will be the fifth least massive radial velocity planet candidate discovery to date and the first super-Earth around a solar twin. Both isochrones (5.9 0.4 Gyr) and the abundance ratio [Y/Mg] (6.4 0.8 Gyr) indicate an age of about 6 billion years. The star is enhanced in refractory elements when compared to the Sun, and the refractory enrichment is even stronger after corrections for Galactic chemical evolution. We determined a nonlocal thermodynamic equilibrium Li abundance of 1.52 0.03 dex, which is four times higher than what would be expected for the age of HIP 68468. The older age is also supported by the low log (R0 HK) (–5.05) and low jitter (<1 ms1). Engulfment of a rocky planet of 6 Earth masses can explain the enhancement in both lithium and the refractory elements. Conclusions. The super-Neptune planet candidate is too massive for in situ formation, and therefore its current location is most likely the result of planet migration that could also have driven other planets towards its host star, enhancing thus the abundance of lithium and refractory elements in HIP 68468. The intriguing evidence of planet accretion warrants further observations to verify the existence of the planets that are indicated by our data and to better constrain the nature of the planetary system around this unique star.
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spelling Meléndez, JorgeBedell, MeganBean, Jacob L.Ramírez, IvánAsplund, MartinDreizler, StefanYan, Hong LiangShi, JianrongLind, KarinFerraz-Mello, SylvioGalarza, Jhon Joel YanaSantos, Leonardo Augusto Gonçalves dosSpina, LorenzoMaia, Marcelo TucciAlves-Brito, AlanMonroe, TalaWanda RoseCasagrande, Luca2018-05-01T02:27:00Z20170004-6361http://hdl.handle.net/10183/175250001063657Context. More than two thousand exoplanets have been discovered to date. Of these, only a small fraction have been detected around solar twins, which are key stars because we can obtain accurate elemental abundances especially for them, which is crucial for studying the planet-star chemical connection with the highest precision. Aims. We aim to use solar twins to characterise the relationship between planet architecture and stellar chemical composition. Methods. We obtained high-precision (1 ms1) radial velocities with the HARPS spectrograph on the ESO 3.6 m telescope at La Silla Observatory and determined precise stellar elemental abundances ( 0.01 dex) using spectra obtained with the MIKE spectrograph on the Magellan 6.5 m telescope. Results. Our data indicate the presence of a planet with a minimum mass of 26 4 Earth masses around the solar twin HIP 68468. The planet is more massive than Neptune (17 Earth masses), but unlike the distant Neptune in our solar system (30 AU), HIP 68468c is close-in, with a semi-major axis of 0.66 AU, similar to that of Venus. The data also suggest the presence of a super-Earth with a minimum mass of 2.9 0.8 Earth masses at 0.03 AU; if the planet is confirmed, it will be the fifth least massive radial velocity planet candidate discovery to date and the first super-Earth around a solar twin. Both isochrones (5.9 0.4 Gyr) and the abundance ratio [Y/Mg] (6.4 0.8 Gyr) indicate an age of about 6 billion years. The star is enhanced in refractory elements when compared to the Sun, and the refractory enrichment is even stronger after corrections for Galactic chemical evolution. We determined a nonlocal thermodynamic equilibrium Li abundance of 1.52 0.03 dex, which is four times higher than what would be expected for the age of HIP 68468. The older age is also supported by the low log (R0 HK) (–5.05) and low jitter (<1 ms1). Engulfment of a rocky planet of 6 Earth masses can explain the enhancement in both lithium and the refractory elements. Conclusions. The super-Neptune planet candidate is too massive for in situ formation, and therefore its current location is most likely the result of planet migration that could also have driven other planets towards its host star, enhancing thus the abundance of lithium and refractory elements in HIP 68468. The intriguing evidence of planet accretion warrants further observations to verify the existence of the planets that are indicated by our data and to better constrain the nature of the planetary system around this unique star.application/pdfengAstronomy and astrophysics. Les Ulis. Vol. 597 (Jan. 2017), A34, 12 p.Planetas extrasolaresRotacao estelarComposicao estelarAcreçãoPlanetary systemsPlanets and satellites: detectionTechniques: radial velocitiesStars: abundancesThe solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468Estrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSORIGINAL001063657.pdf001063657.pdfTexto completo (inglês)application/pdf2694975http://www.lume.ufrgs.br/bitstream/10183/175250/1/001063657.pdf502b0de3ddebe5324678d9f46b5dc8d6MD51TEXT001063657.pdf.txt001063657.pdf.txtExtracted Texttext/plain58934http://www.lume.ufrgs.br/bitstream/10183/175250/2/001063657.pdf.txtf360755105cde842ddc73c8cb538c4e5MD52THUMBNAIL001063657.pdf.jpg001063657.pdf.jpgGenerated Thumbnailimage/jpeg1734http://www.lume.ufrgs.br/bitstream/10183/175250/3/001063657.pdf.jpg4a33d2444c881647790701ddc7affd73MD5310183/1752502023-05-14 03:25:09.319327oai:www.lume.ufrgs.br:10183/175250Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2023-05-14T06:25:09Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false
dc.title.pt_BR.fl_str_mv The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
title The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
spellingShingle The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
Meléndez, Jorge
Planetas extrasolares
Rotacao estelar
Composicao estelar
Acreção
Planetary systems
Planets and satellites: detection
Techniques: radial velocities
Stars: abundances
title_short The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
title_full The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
title_fullStr The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
title_full_unstemmed The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
title_sort The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
author Meléndez, Jorge
author_facet Meléndez, Jorge
Bedell, Megan
Bean, Jacob L.
Ramírez, Iván
Asplund, Martin
Dreizler, Stefan
Yan, Hong Liang
Shi, Jianrong
Lind, Karin
Ferraz-Mello, Sylvio
Galarza, Jhon Joel Yana
Santos, Leonardo Augusto Gonçalves dos
Spina, Lorenzo
Maia, Marcelo Tucci
Alves-Brito, Alan
Monroe, TalaWanda Rose
Casagrande, Luca
author_role author
author2 Bedell, Megan
Bean, Jacob L.
Ramírez, Iván
Asplund, Martin
Dreizler, Stefan
Yan, Hong Liang
Shi, Jianrong
Lind, Karin
Ferraz-Mello, Sylvio
Galarza, Jhon Joel Yana
Santos, Leonardo Augusto Gonçalves dos
Spina, Lorenzo
Maia, Marcelo Tucci
Alves-Brito, Alan
Monroe, TalaWanda Rose
Casagrande, Luca
author2_role author
author
author
author
author
author
author
author
author
author
author
author
author
author
author
author
dc.contributor.author.fl_str_mv Meléndez, Jorge
Bedell, Megan
Bean, Jacob L.
Ramírez, Iván
Asplund, Martin
Dreizler, Stefan
Yan, Hong Liang
Shi, Jianrong
Lind, Karin
Ferraz-Mello, Sylvio
Galarza, Jhon Joel Yana
Santos, Leonardo Augusto Gonçalves dos
Spina, Lorenzo
Maia, Marcelo Tucci
Alves-Brito, Alan
Monroe, TalaWanda Rose
Casagrande, Luca
dc.subject.por.fl_str_mv Planetas extrasolares
Rotacao estelar
Composicao estelar
Acreção
topic Planetas extrasolares
Rotacao estelar
Composicao estelar
Acreção
Planetary systems
Planets and satellites: detection
Techniques: radial velocities
Stars: abundances
dc.subject.eng.fl_str_mv Planetary systems
Planets and satellites: detection
Techniques: radial velocities
Stars: abundances
description Context. More than two thousand exoplanets have been discovered to date. Of these, only a small fraction have been detected around solar twins, which are key stars because we can obtain accurate elemental abundances especially for them, which is crucial for studying the planet-star chemical connection with the highest precision. Aims. We aim to use solar twins to characterise the relationship between planet architecture and stellar chemical composition. Methods. We obtained high-precision (1 ms1) radial velocities with the HARPS spectrograph on the ESO 3.6 m telescope at La Silla Observatory and determined precise stellar elemental abundances ( 0.01 dex) using spectra obtained with the MIKE spectrograph on the Magellan 6.5 m telescope. Results. Our data indicate the presence of a planet with a minimum mass of 26 4 Earth masses around the solar twin HIP 68468. The planet is more massive than Neptune (17 Earth masses), but unlike the distant Neptune in our solar system (30 AU), HIP 68468c is close-in, with a semi-major axis of 0.66 AU, similar to that of Venus. The data also suggest the presence of a super-Earth with a minimum mass of 2.9 0.8 Earth masses at 0.03 AU; if the planet is confirmed, it will be the fifth least massive radial velocity planet candidate discovery to date and the first super-Earth around a solar twin. Both isochrones (5.9 0.4 Gyr) and the abundance ratio [Y/Mg] (6.4 0.8 Gyr) indicate an age of about 6 billion years. The star is enhanced in refractory elements when compared to the Sun, and the refractory enrichment is even stronger after corrections for Galactic chemical evolution. We determined a nonlocal thermodynamic equilibrium Li abundance of 1.52 0.03 dex, which is four times higher than what would be expected for the age of HIP 68468. The older age is also supported by the low log (R0 HK) (–5.05) and low jitter (<1 ms1). Engulfment of a rocky planet of 6 Earth masses can explain the enhancement in both lithium and the refractory elements. Conclusions. The super-Neptune planet candidate is too massive for in situ formation, and therefore its current location is most likely the result of planet migration that could also have driven other planets towards its host star, enhancing thus the abundance of lithium and refractory elements in HIP 68468. The intriguing evidence of planet accretion warrants further observations to verify the existence of the planets that are indicated by our data and to better constrain the nature of the planetary system around this unique star.
publishDate 2017
dc.date.issued.fl_str_mv 2017
dc.date.accessioned.fl_str_mv 2018-05-01T02:27:00Z
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dc.relation.ispartof.pt_BR.fl_str_mv Astronomy and astrophysics. Les Ulis. Vol. 597 (Jan. 2017), A34, 12 p.
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