Five New Exoplanets Orbiting Three Metal-Rich, Massive Stars: Two-Planet Systems Including Long-Period Planets, and an Eccentric Planet

• Published in: arXiv.org 2015-03
• Main Authors: Harakawa, Hiroki, Sato, Bun'ei, Omiya, Masashi, Fischer, Debra A, Hori, Yasunori, Ida, Shigeru, Kambe, Eiji, Yoshida, Michitoshi, Izumiura, Hideyuki, Koyano, Hisashi, Nagayama, Shogo, Shimizu, Yasuhiro, Okada, Norio, Okita, Kiichi, Sakamoto, Akihiro, Yamamuro, Tomoyasu
• Format: Article
• Language: English
• Subjects: Circular orbits; Eccentric orbits; Extrasolar planets; Main sequence stars; Massive stars; Orbits; Planet detection; Planetary orbits; Planetary systems; Radial velocity; Saturn; Subgiant stars; Telescopes
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1503.07636

We report detections of new exoplanets from a radial velocity (RV) survey of metal-rich FGK stars by using three telescopes. By optimizing our RV analysis method to long time-baseline observations, we have succeeded in detecting five new Jovian-planets around three metal-rich stars HD 1605, HD 1666, and HD 67087 with the masses of \(1.3 M_{\odot}\), \(1.5 M_{\odot}\), and \(1.4 M_{\odot}\), respectively. A K1 subgiant star HD 1605 hosts two planetary companions with the minimum masses of \( M_p \sin i = 0.96 M_{\mathrm{JUP}}\) and \(3.5 M_{\mathrm{JUP}}\) in circular orbits with the planets' periods \(P = 577.9\) days and \(2111\) days, respectively. HD 1605 shows a significant linear trend in RVs. Such a system consisting of Jovian planets in circular orbits has rarely been found and thus HD 1605 should be an important example of a multi-planetary system that is likely unperturbed by planet-planet interactions. HD 1666 is a F7 main sequence star which hosts an eccentric and massive planet of \( M_p \sin i = 6.4 M_{\mathrm{JUP}}\) in the orbit with \(a_{\rm p} = 0.94\) AU and an eccentricity \(e=0.63\). Such an eccentric and massive planet can be explained as a result of planet-planet interactions among Jovian planets. While we have found the large residuals of \(\mathrm{rms} = 35.6\ \mathrm{m\ s^{-1}}\), the periodogram analysis does not support any additional periodicities. Finally, HD 67087 hosts two planets of \( M_p \sin i = 3.1 M_{\mathrm{JUP}}\) and \(4.9 M_{\mathrm{JUP}}\) in orbits with \(P=352.2\) days and \(2374\) days, and \(e=0.17\) and \(0.76\), respectively. Although the current RVs do not lead to accurate determinations of its orbit and mass, HD 67087 c can be one of the most eccentric planets ever discovered in multiple systems.