Planetary Companions to Three Evolved Intermediate-Mass Stars: HD 2952, HD 120084, and omega Serpentis

Abstract

We report the detections of planetary companions orbiting around three evolved intermediate-mass stars from precise radial velocity measurements at Okayama Astrophysical Observatory. HD 2952 (K0III, 2.5 M_sun) and omega Ser (G8III, 2.2 M_sun) host a relatively low mass planet with minimum mass of m_2sin i=1.6 M_J and 1.7 M_J in nearly circular orbits with period of P=312 and 277 d, respectively. HD 120084 (G7 III, 2.4 M_sun) hosts an eccentric planet with m_2sin i=4.5 M_J in an orbit with P=2082 d and eccentricity of e=0.66. The planet has one of the largest eccentricities among those ever discovered around evolved intermediate-mass stars, almost all of which have eccentricity smaller than 0.4. We also show that radial velocity variations of stellar oscillations for G giants can be averaged out below a level of a few m/s at least in timescale of a week by high cadence observations, which enables us to detect a super-Earth and a Neptune-mass planet in short-period orbits even around such giant stars.

15 pages, 11 figures, accepted for publication in PASJ, stellar name corrected (not omicron Ser but omega Ser)

References in corpus (10)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Origins of Eccentric Extrasolar Planets: Testing the Planet-Planet Scattering Model
• Planets around evolved intermediate-mass stars. I. Two substellar companions in the open clusters NGC 2423 and NGC 4349
• Direct Imaging Discovery of a `Super-Jupiter' Around the late B-Type Star Kappa And
• Confirmation of the Planet Hypothesis for the Long-period Radial Velocity Variations of Beta Geminorum
• On the Semimajor Axis Distribution of Extrasolar Gas Giant Planets: Why Hot Jupiters Are Rare Around High-Mass Stars
• A Substellar Companion to the Intermediate-Mass Giant 11 Com
• A Planet in a 0.6-AU Orbit Around the K0 Giant HD 102272
• A Double Planetary System around the Evolved Intermediate-Mass Star HD 4732
• A planetary companion around the K giant eps Corona Borealis

Cited by in corpus (21)

• 3-D selection of 167 sub-stellar companions to nearby stars
• A-type Stars, the Destroyers of Worlds: The lives and deaths of Jupiters in evolving stellar binaries
• S-Type and P-Type Habitability in Stellar Binary Systems: A Comprehensive Approach. I. Method and Applications
• Characterization of the gaseous companion κ Andromedae b: New Keck and LBTI high-contrast observations
• Five New Exoplanets Orbiting Three Metal-Rich, Massive Stars: Two-Planet Systems Including Long-Period Planets, and an Eccentric Planet
• SWEET-Cat update and FASMA. A new minimization procedure for stellar parameters using high-quality spectra
• The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements
• Kepler-432 b: a massive warm Jupiter in a 52-day eccentric orbit transiting a giant star
• 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
• HIDES spectroscopy of bright detached eclipsing binaries from the $Kepler$ field - I. Single-lined objects
• Planets around the evolved stars 24 Booties and $\gamma$ Libra: A 30d-period planet and a double giant-planet system in possible 7:3 MMR
• Chemical Composition Of Bright Stars In The Northern Hemisphere: Star-Planet Connection
• A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration
• Precise radial velocities of giant stars VIII. Testing for the presence of planets with CRIRES Infrared Radial Velocities
• Unseen companions of V Hya inferred from periodic ejections
• Puzzling out the coexistence of terrestrial planets and giant exoplanets. The 2/1 resonant periodic orbits
• Regular Radial Velocity Variations in Nine G- and K-type Giant Stars: Eight Planets and One Planet Candidate
• High-Contrast Imaging of Intermediate-Mass Giants with Long-Term Radial Velocity Trends
• A Search for Exoplanets around Northern Circumpolar Stars. IV. Six Planet Candidates to the K Giants, HD 44385, HD 97619, HD 106574, HD 118904, HD 164428, and HD 202432
• Revealing the Fate of Exoplanet Systems: Asteroseismic Identification of Host Star in the Red Clump or Red Giant Branch
• A Trio of Giant Planets Orbiting Evolved Star HD 184010