Precise radial velocities of giant stars: IX. HD 59686 Ab: A massive circumstellar planet orbiting a giant star in a ~ 13.6 au eccentric binary system

Mauricio Ortiz, Sabine Reffert, Trifon Trifonov, Andreas Quirrenbach, David S. Mitchell, Grzegorz Nowak, Esther Buenzli, Neil Zimmerman, Mickaël Bonnefoy, Andy Skemer, Denis Defrère, Man Hoi Lee, Debra A. Fischer, Philip M Hinz

Research output: Contribution to journalArticle

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Abstract

Context. For over 12 yr, we have carried out a precise radial velocity (RV) survey of a sample of 373 G-and K-giant stars using the Hamilton Échelle Spectrograph at the Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims. We aim at detecting and characterizing substellar and stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods. We obtained high-precision RV measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. To distinguish between RV variations that are due to non-radial pulsation or stellar spots, we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to characterize the system in more detail, we obtained high-resolution images with LMIRCam at the Large Binocular Telescope. Results. We report the probable discovery of a giant planet with a mass of mp sin i = 6.92-0.24+0.18 MJup orbiting at ap = 1.0860-0.0007+0.0006 au from the giant star HD 59686 A. In addition to the planetary signal, we discovered an eccentric (eB = 0.729-0.003+0.004) binary companion with a mass of mB sin i = 0.5296-0.0008+0.0011 M orbiting at a close separation from the giant primary with a semi-major axis of aB = 13.56-0.14+0.18 au. Conclusions. The existence of the planet HD 59686 Ab in a tight eccentric binary system severely challenges standard giant planet formation theories and requires substantial improvements to such theories in tight binaries. Otherwise, alternative planet formation scenarios such as second-generation planets or dynamical interactions in an early phase of the system's lifetime need to be seriously considered to better understand the origin of this enigmatic planet.

Original languageEnglish (US)
Article numberA55
JournalAstronomy and Astrophysics
Volume595
DOIs
StatePublished - Nov 1 2016

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giant stars
eccentrics
radial velocity
planets
planet
spectrographs
telescopes
K stars
hot isostatic pressing
planetary systems
image resolution
velocity measurement
observatories
observatory
stars
life (durability)
high resolution

Keywords

  • Planetary systems
  • Planets and satellites: detection
  • Planets and satellites: formation
  • Planets and satellites: fundamental parameters
  • Planets and satellites: gaseous planets
  • Planets and satellites: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Precise radial velocities of giant stars : IX. HD 59686 Ab: A massive circumstellar planet orbiting a giant star in a ~ 13.6 au eccentric binary system. / Ortiz, Mauricio; Reffert, Sabine; Trifonov, Trifon; Quirrenbach, Andreas; Mitchell, David S.; Nowak, Grzegorz; Buenzli, Esther; Zimmerman, Neil; Bonnefoy, Mickaël; Skemer, Andy; Defrère, Denis; Lee, Man Hoi; Fischer, Debra A.; Hinz, Philip M.

In: Astronomy and Astrophysics, Vol. 595, A55, 01.11.2016.

Research output: Contribution to journalArticle

Ortiz, M, Reffert, S, Trifonov, T, Quirrenbach, A, Mitchell, DS, Nowak, G, Buenzli, E, Zimmerman, N, Bonnefoy, M, Skemer, A, Defrère, D, Lee, MH, Fischer, DA & Hinz, PM 2016, 'Precise radial velocities of giant stars: IX. HD 59686 Ab: A massive circumstellar planet orbiting a giant star in a ~ 13.6 au eccentric binary system', Astronomy and Astrophysics, vol. 595, A55. https://doi.org/10.1051/0004-6361/201628791
Ortiz, Mauricio ; Reffert, Sabine ; Trifonov, Trifon ; Quirrenbach, Andreas ; Mitchell, David S. ; Nowak, Grzegorz ; Buenzli, Esther ; Zimmerman, Neil ; Bonnefoy, Mickaël ; Skemer, Andy ; Defrère, Denis ; Lee, Man Hoi ; Fischer, Debra A. ; Hinz, Philip M. / Precise radial velocities of giant stars : IX. HD 59686 Ab: A massive circumstellar planet orbiting a giant star in a ~ 13.6 au eccentric binary system. In: Astronomy and Astrophysics. 2016 ; Vol. 595.
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abstract = "Context. For over 12 yr, we have carried out a precise radial velocity (RV) survey of a sample of 373 G-and K-giant stars using the Hamilton {\'E}chelle Spectrograph at the Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims. We aim at detecting and characterizing substellar and stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods. We obtained high-precision RV measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. To distinguish between RV variations that are due to non-radial pulsation or stellar spots, we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to characterize the system in more detail, we obtained high-resolution images with LMIRCam at the Large Binocular Telescope. Results. We report the probable discovery of a giant planet with a mass of mp sin i = 6.92-0.24+0.18 MJup orbiting at ap = 1.0860-0.0007+0.0006 au from the giant star HD 59686 A. In addition to the planetary signal, we discovered an eccentric (eB = 0.729-0.003+0.004) binary companion with a mass of mB sin i = 0.5296-0.0008+0.0011 M⊙ orbiting at a close separation from the giant primary with a semi-major axis of aB = 13.56-0.14+0.18 au. Conclusions. The existence of the planet HD 59686 Ab in a tight eccentric binary system severely challenges standard giant planet formation theories and requires substantial improvements to such theories in tight binaries. Otherwise, alternative planet formation scenarios such as second-generation planets or dynamical interactions in an early phase of the system's lifetime need to be seriously considered to better understand the origin of this enigmatic planet.",
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T2 - IX. HD 59686 Ab: A massive circumstellar planet orbiting a giant star in a ~ 13.6 au eccentric binary system

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AU - Reffert, Sabine

AU - Trifonov, Trifon

AU - Quirrenbach, Andreas

AU - Mitchell, David S.

AU - Nowak, Grzegorz

AU - Buenzli, Esther

AU - Zimmerman, Neil

AU - Bonnefoy, Mickaël

AU - Skemer, Andy

AU - Defrère, Denis

AU - Lee, Man Hoi

AU - Fischer, Debra A.

AU - Hinz, Philip M

PY - 2016/11/1

Y1 - 2016/11/1

N2 - Context. For over 12 yr, we have carried out a precise radial velocity (RV) survey of a sample of 373 G-and K-giant stars using the Hamilton Échelle Spectrograph at the Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims. We aim at detecting and characterizing substellar and stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods. We obtained high-precision RV measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. To distinguish between RV variations that are due to non-radial pulsation or stellar spots, we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to characterize the system in more detail, we obtained high-resolution images with LMIRCam at the Large Binocular Telescope. Results. We report the probable discovery of a giant planet with a mass of mp sin i = 6.92-0.24+0.18 MJup orbiting at ap = 1.0860-0.0007+0.0006 au from the giant star HD 59686 A. In addition to the planetary signal, we discovered an eccentric (eB = 0.729-0.003+0.004) binary companion with a mass of mB sin i = 0.5296-0.0008+0.0011 M⊙ orbiting at a close separation from the giant primary with a semi-major axis of aB = 13.56-0.14+0.18 au. Conclusions. The existence of the planet HD 59686 Ab in a tight eccentric binary system severely challenges standard giant planet formation theories and requires substantial improvements to such theories in tight binaries. Otherwise, alternative planet formation scenarios such as second-generation planets or dynamical interactions in an early phase of the system's lifetime need to be seriously considered to better understand the origin of this enigmatic planet.

AB - Context. For over 12 yr, we have carried out a precise radial velocity (RV) survey of a sample of 373 G-and K-giant stars using the Hamilton Échelle Spectrograph at the Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims. We aim at detecting and characterizing substellar and stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods. We obtained high-precision RV measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. To distinguish between RV variations that are due to non-radial pulsation or stellar spots, we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to characterize the system in more detail, we obtained high-resolution images with LMIRCam at the Large Binocular Telescope. Results. We report the probable discovery of a giant planet with a mass of mp sin i = 6.92-0.24+0.18 MJup orbiting at ap = 1.0860-0.0007+0.0006 au from the giant star HD 59686 A. In addition to the planetary signal, we discovered an eccentric (eB = 0.729-0.003+0.004) binary companion with a mass of mB sin i = 0.5296-0.0008+0.0011 M⊙ orbiting at a close separation from the giant primary with a semi-major axis of aB = 13.56-0.14+0.18 au. Conclusions. The existence of the planet HD 59686 Ab in a tight eccentric binary system severely challenges standard giant planet formation theories and requires substantial improvements to such theories in tight binaries. Otherwise, alternative planet formation scenarios such as second-generation planets or dynamical interactions in an early phase of the system's lifetime need to be seriously considered to better understand the origin of this enigmatic planet.

KW - Planetary systems

KW - Planets and satellites: detection

KW - Planets and satellites: formation

KW - Planets and satellites: fundamental parameters

KW - Planets and satellites: gaseous planets

KW - Planets and satellites: general

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