Precise radial velocities of giant stars

Trifonov, T.; Reffert, S.; Zechmeister, M.; Reiners, A.; Quirrenbach, A.

doi:10.1051/0004-6361/201526196

Cited by 18 publications

(17 citation statements)

References 37 publications

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“…The RV semi-amplitude of K opt = 136.9 +3.8 −4.6 m s −1 from the optical RVs is within 2.25σ from the IR value. If we calculate κ = K IR /K opt , as in Trifonov et al (2015), then we obtain a value of κ = 1.50 ± 0.22, but we note that the calculated error might be underestimated as the error on the fitting of the stellar component is not taken into account. This result shows that the near-IR signal is not flat or of a smaller amplitude than the optical one, which we would expect for a spot or pulsations; the amplitude of pulsations decreases with increasing wavelength in pulsating giant stars (Huber et al 2003;Percy et al 2008).…”

Section: Infrared Radial Velocitiesmentioning

confidence: 87%

“…In 2012 and 2013, Trifonov et al (2015) obtained infrared RVs of HD 59686 A using the CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES; Käufl et al 2004) at the Very Large Telescope (VLT), in Chile. Their CRIRES spectra have a resolution of R ∼ 100 000 and cover the wavelength range 1.57-1.61 µm.…”

Section: Infrared Radial Velocitiesmentioning

confidence: 99%

“…An additional test can be made by fitting only the CRIRES data to derive the RV semi-amplitude, K IR . Following Trifonov et al (2015), we first subtracted the signal of the stellar companion from the CRIRES data. As the presence of HD 59686 B is clearly detected in the system, it is fair to assume that the RV signal due to this star is consistent in the optical and infrared data sets.…”

Section: Infrared Radial Velocitiesmentioning

confidence: 99%

“…Their CRIRES spectra have a resolution of R ∼ 100 000 and cover the wavelength range 1.57-1.61 µm. Details of the CRIRES observations and the reduction process, including the measured RVs for HD 59686 A, can be found in Trifonov et al (2015).…”

Section: Infrared Radial Velocitiesmentioning

confidence: 99%

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Precise radial velocities of giant stars

Ortiz

Reffert

Trifonov

et al. 2016

A&A

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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 m p sin i = 6.92 +0.18 −0.24 M Jup orbiting at a p = 1.0860 +0.0006 −0.0007 au from the giant star HD 59686 A. In addition to the planetary signal, we discovered an eccentric (e B = 0.729 +0.004 −0.003 ) binary companion with a mass of m B sin i = 0.5296 +0.0011 −0.0008 M orbiting at a close separation from the giant primary with a semi-major axis of a B = 13.56 +0.18 −0.14 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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Section: Infrared Radial Velocitiesmentioning

confidence: 87%

Section: Infrared Radial Velocitiesmentioning

confidence: 99%

Section: Infrared Radial Velocitiesmentioning

confidence: 99%

Section: Infrared Radial Velocitiesmentioning

confidence: 99%

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Precise radial velocities of giant stars

Ortiz

Reffert

Trifonov

et al. 2016

A&A

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“…Old main-sequence systems (e.g. Campante et al 2015), dust and planets around giant branch stars (Bonsor et al 2014;Trifonov et al 2015;Lillo-Box, Barrado & Correia 2016;Wittenmyer et al 2016), and polluted white dwarfs at a variety of cooling ages (Koester, Gänsicke & Farihi 2014;Hollands et al, in preparation) all provide necessary constraints. Main-sequence planetary studies have now begun to utilize white dwarf atmosphere chemical signatures in their planetary formation models (Carter-Bond et al 2012;Morlok et al 2014;Bergin et al 2015;Ramírez et al 2015;Mordasini et al 2016;Spina, Meléndez & Ramírez 2016), and future missions such as PLATO will further enable comparisons with well-constrained stellar ages (Veras et al 2015b).…”

Section: P O Rta N C E O F D E T E R M I N I N G Fat Ementioning

confidence: 99%

The unstable fate of the planet orbiting the A star in the HD 131399 triple stellar system

Veras

Mustill

Gänsicke

2016

Mon. Not. R. Astron. Soc.

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Validated planet candidates need not lie on long-term stable orbits, and instability triggered by post-main-sequence stellar evolution can generate architectures which transport rocky material to white dwarfs, hence polluting them. The giant planet HD 131399Ab orbits its parent A star at a projected separation of about 50-100 au. The host star, HD 131399A, is part of a hierarchical triple with HD 131399BC being a close binary separated by a few hundred au from the A star. Here, we determine the fate of this system, and find the following: (i) Stability along the main sequence is achieved only for a favourable choice of parameters within the errors. (ii) Even for this choice, in almost every instance, the planet is ejected during the transition between the giant branch and white dwarf phases of HD 131399A. This result provides an example of both how the free-floating planet population may be enhanced by similar systems and how instability can manifest in the polluted white dwarf progenitor population.

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Precise radial velocities of giant stars

Quirrenbach

Trifonov

Lee

et al. 2019

A&A

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We present radial-velocity (RV) measurements for the K giant ν Oph (= HIP 88048, HD 163917, HR 6698), which reveal two brown dwarf companions with a period ratio close to 6:1. For our orbital analysis we use 150 precise RV measurements taken at the Lick Observatory between 2000 and 2011, and we combine them with RV data for this star available in the literature. Using a stellar mass of M = 2.7M⊙ for ν Oph and applying a self-consistent N-body model we estimate the minimum dynamical companion masses to be m1 sin i ≈ 22.2 MJup and m2 sin i ≈ 24.7 MJup, with orbital periods P1 ≈ 530 d and P2 ≈ 3185 d. We study a large set of potential orbital configurations for this system, employing a bootstrap analysis and a systematic χν2 grid-search coupled with our dynamical fitting model, and we examine their long-term stability. We find that the system is indeed locked in a 6:1 mean motion resonance (MMR), with Δω and all six resonance angles θ1–θ6 librating around 0°. We also test a large set of coplanar inclined configurations, and we find that the system will remain in a stable resonance for most of these configurations. The ν Oph system is important for probing planetary formation and evolution scenarios. It seems very likely that the two brown dwarf companions of ν Oph formed like planets in a circumstellar disk around the star and have been trapped in an MMR by smooth migration capture.

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Precise radial velocities of giant stars

Cited by 18 publications

References 37 publications

Precise radial velocities of giant stars

Precise radial velocities of giant stars

The unstable fate of the planet orbiting the A star in the HD 131399 triple stellar system

Precise radial velocities of giant stars

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