Detection of a planetary companion around the giant star γ<sup>1</sup>Leonis

Han, Inwoo; Lee, B. C.; Kim, K. M.; Mkrtichian, D. E.; Hatzes, A. P.; Valyavin, G. G.

doi:10.1051/0004-6361/200912536

Cited by 47 publications

(39 citation statements)

References 30 publications

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“…It is premature to discuss the origin of long-term variations until we have longer time-span observations covering several variability cycles. For completeness, we would like to mention two other exoplanethosting candidate K giant stars from our survey: γ 1 Leo (Han et al 2010) and α Ari (Kim et al 2006;Lee et al 2011). They also exhibit long-term variations of the RV residuals that are superimposed with short-term pulsational variability, which is well established from night-to-night observations.…”

Section: Orbital Fitsupporting

confidence: 60%

“…We have reported two new exoplanets (Han et al 2010;Lee et al 2011) and confirmed an exoplanet ) and an oscillating star (Kim et al 2006).…”

Section: Observations and Analysismentioning

confidence: 55%

“…We solved the matrix equation using singular value decomposition instead of the maximum entropy method adopted by Endl et al (2000). The code has been used in several cases (Kim et al 2006;Han et al 2008Han et al , 2010Lee et al 2008Lee et al , 2011.…”

Section: Observations and Analysismentioning

confidence: 99%

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Detection of an exoplanet around the evolved K giant HD 66141

Lee

Mkrtichian

Han

et al. 2012

A&A

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Aims. We have been carrying out a precise radial velocity (RV) survey for K giants to search for and study the origin of the lowamplitude and long-periodic RV variations. Methods. We present high-resolution RV measurements of the K2 giant HD 66141 from December 2003 to January 2011 using the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at the Bohyunsan Optical Astronomy Observatory (BOAO). Results. We find that the RV measurements for HD 66141 exhibit a periodic variation of 480.5 ± 0.5 days with a semi-amplitude of 146.2 ± 2.7 m s −1 . The Hipparcos photometry and bisector velocity span (BVS) do not show any obvious correlations with RV variations. We find indeed 706.4 ± 35.0 day variations in equivalent width (EW) measurements of H α line and 703.0 ± 39.4 day variations in a space-born measurements 1.25μ flux of HD 66141 measured during the COBE/DIRBE experiment. We reveal that a mean value of long-period variations is about 705 ± 53 days, whose origin is a rotation period of the star and variability that is caused by surface inhomogeneities. For the 480-day periods of RV variations an orbital motion is the most likely explanation. Assuming a stellar mass of 1.1 ± 0.1 M for HD 66141, we obtain a minimum mass for the planetary companion of 6.0 ± 0.3 M Jup with an orbital semi-major axis of 1.2 ± 0.1 AU and an eccentricity of 0.07 ± 0.03.

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Section: Orbital Fitsupporting

confidence: 60%

“…We have reported two new exoplanets (Han et al 2010;Lee et al 2011) and confirmed an exoplanet ) and an oscillating star (Kim et al 2006).…”

Section: Observations and Analysismentioning

confidence: 55%

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Detection of an exoplanet around the evolved K giant HD 66141

Lee

Mkrtichian

Han

et al. 2012

A&A

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“…We suspect that this bias was come from the temporary mis-alignments of the BOES echelle spectrometer. But, we did not find any BVS shift in the K-giant γ 1 Leo for the same observing epoch as where a planetary companion system was detected by using the same echelle spectrometer BOES (Han et al 2010). The RV code RVI2CELL takes any changes into account in the instrumental profile in calculations of RVs, and thus instrumental misalignment is not likely to have affected the RV data.…”

Section: Line Bisector Variationsmentioning

confidence: 52%

A likely exoplanet orbiting the oscillating K-giantαArietis

Lee

Mkrtichian

Han

et al. 2011

A&A

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Aims. To search for extrasolar planets around intermediate-mass stars, we are conducting a precise RV survey around K-giants. Methods. We present high-accuracy RV measurements of α Ari made from November 2003 to February 2010. This star belongs to our sample of 55 K-giants studied for extrasolar planet and pulsation searches using the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) attached to the 1.8-m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea.Results. We find a planetary companion with long-period and low-amplitude radial velocity (RV) variations in oscillating K2 III star α Ari (HD 12929). We do not find the correlation between RV variations and chromospheric activity indicators (Ca II H & K region, Hα line). The bisector analysis also shows that the bisector velocity span (BVS) does not show any obvious correlation with RV variation but has periodic component that may be attributed to the rotation of the star. If the RV variation is indeed caused by a planetary companion, an orbital solution with a period of P = 381 days, a semi-amplitude of K = 41 m s −1 , and an eccentricity of e = 0.25 fits the data best. Assuming a possible stellar mass of M = 1.5 M , we estimate the minimum mass for the planetary companion of m 2 sin i = 1.8 M Jup with an orbital semi-major axis of 1.2 AU. Conclusions. Our finding of a likely exoplanet in α Ari supports searching for extrasolar planets around giant stars with multiperiodic oscillations.

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“…For K-giant stars specifically, only four out of 72 known stars harboring planets are members of stellar multiple systems: 11 Com (Liu et al 2008), γ 1 Leo (Han et al 2010), 91 Aqr (Mitchell et al 2013), and 8 UMi (Lee et al 2015). Finding planets in multiple star systems allows us to learn more about the processes of planetary formation and evolution.…”

Section: Introductionmentioning

confidence: 99%

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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Detection of a planetary companion around the giant star γ¹Leonis

Cited by 47 publications

References 30 publications

Detection of an exoplanet around the evolved K giant HD 66141

Detection of an exoplanet around the evolved K giant HD 66141

A likely exoplanet orbiting the oscillating K-giantαArietis

Precise radial velocities of giant stars

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Detection of a planetary companion around the giant star γ1Leonis

Cited by 47 publications

References 30 publications

Detection of an exoplanet around the evolved K giant HD 66141

Detection of an exoplanet around the evolved K giant HD 66141

A likely exoplanet orbiting the oscillating K-giantαArietis

Precise radial velocities of giant stars

Contact Info

Product

Resources

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Detection of a planetary companion around the giant star γ¹Leonis