A Double Planetary System Around the Evolved Intermediate-Mass Star Hd 4732

Sato, Bun’ei; Omiya, Masashi; Wittenmyer, Robert A.; Harakawa, Hiroki; Nagasawa, Makiko; Izumiura, Hideyuki; Kambe, Eiji; Takeda, Yoichi; Yoshida, Michitoshi; Itoh, Yoichi; Ando, Hiroyasu; Kokubo, Eiichiro; Ida, Shigeru

doi:10.1088/0004-637x/762/1/9

Cited by 60 publications

(24 citation statements)

References 45 publications

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“…TYC 1422-614-1 belongs to the very small sample 4 of known multiple planetary systems around giants (i.e., stars with log g < 3.5). Multiple systems around giants include BD+20 2457 b, c (Niedzielski et al 2009b), 24 Sex b,c andHD 200694 b, c (Johnson et al 2011b), HD 4732 b, c (Sato et al 2013), Kepler 391 b, c (Rowe et al 2014), and Kepler 56 b, c, d (Huber et al 2013). They represent ≈16% of all the planets orbiting giant stars (including TYC 1422-614-1).…”

Section: Discussionmentioning

confidence: 99%

Tracking Advanced Planetary Systems (TAPAS) with HARPS-N

Niedzielski

Villaver

Wolszczan

et al. 2014

A&A

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Context. Stars that have evolved off the main sequence are crucial for expanding the frontiers of knowledge on exoplanets toward higher stellar masses and for constraining star-planet interaction mechanisms. These stars have an intrinsic activity, however, which complicates the interpretation of precise radial velocity (RV) measurements, and therefore they are often avoided in planet searches. Over the past ten years, we have monitored about 1000 evolved stars for RV variations in search for low-mass companions under the Penn State -Toruń Centre for Astronomy Planet Search program with the Hobby-Eberly Telescope. Selected prospective candidates that required higher RV precision measurements have been followed with HARPS-N at the 3.6 m Telescopio Nazionale Galileo. Aims. We aim to detect planetary systems around evolved stars, to be able to build sound statistics on the frequency and intrinsic nature of these systems, and to deliver in-depth studies of selected planetary systems with evidence of star-planet interaction processes. Methods. We obtained 69 epochs of precise RV measurements for TYC 1422-614-1 collected over 3651 days with the Hobby-Eberly Telescope, and 17 epochs of ultra-precise HARPS-N data collected over 408 days. We complemented these RV data with photometric time-series from the All Sky Automatic Survey archive. Results. We report the discovery of a multiple planetary system around the evolved K2 giant star TYC 1422-614-1. The system orbiting the 1.15 M star is composed of a planet with mass m sin i = 2.5 M J in a 0.69 AU orbit, and a planet or brown dwarf with m sin i = 10 M J in an orbit of 1.37 AU. The multiple planetary system orbiting TYC 1422-614-1 is the first finding of the TAPAS project, a HARPS-N monitoring of evolved planetary systems identified with the Hobby-Eberly Telescope.

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Section: Discussionmentioning

confidence: 99%

Tracking Advanced Planetary Systems (TAPAS) with HARPS-N

Niedzielski

Villaver

Wolszczan

et al. 2014

A&A

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“…Eight of the 15 systems with a secure planet in our Lick sample have been published already: ι Dra b (Frink et al 2002), Pollux b Hatzes et al 2006), ε Tau b (Sato et al 2007), 11 Com b (Liu et al 2008), ν Oph b and c (Quirrenbach et al 2011;Sato et al 2013), τ Gem b and 91 Aqr b (Mitchell et al 2013), and η Cet b and c (Trifonov et al 2014); we will publish the remaining ones in the near future.…”

Section: Substellar Companion Statisticsmentioning

confidence: 99%

Precise radial velocities of giant stars

Reffert

Bergmann

Quirrenbach

et al. 2015

A&A

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265

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Context.We have obtained precise radial velocities for a sample of 373 G and K type giants at Lick Observatory regularly over more than 12 years. Planets have been identified around 15 of these giant stars, and an additional 20 giant stars host planet candidates. Aims. We are interested in the occurrence rate of substellar companions around giant stars as a function of stellar mass and metallicity. We probe the stellar mass range from approximately 1 to beyond 3 M , which is not being explored by main-sequence samples. Methods. We fit the giant planet occurrence rate as a function of stellar mass and metallicity with a Gaussian and an exponential distribution, respectively. Results. We find strong evidence for a planet-metallicity correlation among the secure planet hosts of our giant star sample, in agreement with the one for main-sequence stars. However, the planet-metallicity correlation is absent for our sample of planet candidates, raising the suspicion that a good fraction of them might indeed not be planets despite clear periodicities in the radial velocities. Consistent with the literature results for subgiants, the giant planet occurrence rate increases in the stellar mass interval from 1 to 1.9 M . However, there is a maximum at a stellar mass of 1.9 +0.1 −0.5 M , and the occurrence rate drops rapidly for masses larger than 2.5-3.0 M . We do not find any planets around stars more massive than 2.7 M , although there are 113 stars with masses between 2.7 and 5 M in our sample (corresponding to a giant planet occurrence rate smaller than 1.6% at 68.3% confidence in that stellar mass bin). We also show that this result is not a selection effect related to the planet detectability being a function of the stellar mass. Conclusions. We conclude that giant planet formation or inward migration is suppressed around higher mass stars, possibly because of faster disk depletion coupled with a longer migration timescale.

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“…We obtained the following orbital parameter for HIP 67851 c: P = 2131.8 ± 88.3 d, m c sin i = 6.0 ± 0.8 M J , and e = 0.17 ± 0.06. Apart from HIP 67851, there are eight giant stars (log g < ∼ 3.6) that are known to host multiplanet systems 3 : namely, 24 Sextantis and HD 200964 (Johnson et al 2011), HD 4732 (Sato et al 2013 (Huber et al 2013), Kepler 432 (Ciceri et al 2015;Ortiz et al 2015;Quinn et al 2015), Kepler 391 (Rowe et al 2014), η Ceti (Trifonov et al 2014), and TYC 1422-614-1 (Niedzielski et al 2015. Interestingly, η Ceti is the only one that is located in the clump region, although according to Trifonov et al (2014) it is most likely a RGB star instead of a HB star.…”

Section: Summary and Discussionmentioning

confidence: 99%

Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP 67851c

Jones

Jenkins

Rojo

et al. 2015

A&A

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Context. Precision radial velocities are required to discover and characterize exoplanets. Optical spectra that exhibit many hundreds of absorption lines can allow the m s −1 precision levels required for this work. After the main-sequence, intermediate-mass stars expand and rotate more slowly than their progenitors, thus, thousands of spectral lines appear in the optical region, permitting the search for Doppler signals in these types of stars. Aims. In 2009, we began the EXPRESS program, aimed at detecting substellar objects around evolved stars, and studying the effects of the mass and evolution of the host star on their orbital and physical properties. Methods. We obtained precision radial velocity measurements for the giant stars HIP 65891 and HIP 107773, from CHIRON and FEROS spectra. Also, we obtained new radial velocity epochs for the star HIP 67851, which is known to host a planetary system. Additionally, HIP 67851 is one of five giant stars that are known to host a planetary system having a close-in planet (a < 0.7 AU). Based on the evolutionary states of those five stars, we conclude that close-in planets do exist in multiple systems around subgiants and slightly evolved giants stars, but most likely they are subsequently destroyed by the stellar envelope during the ascent of the red giant branch phase.

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A Double Planetary System Around the Evolved Intermediate-Mass Star Hd 4732

Cited by 60 publications

References 45 publications

Tracking Advanced Planetary Systems (TAPAS) with HARPS-N

Tracking Advanced Planetary Systems (TAPAS) with HARPS-N

Precise radial velocities of giant stars

Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP 67851c

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