A radial velocity (RV) survey for intermediate-mass giants has been operated for over a decade at Okayama Astrophysical Observatory (OAO). The OAO survey has revealed that some giants show long-term linear RV accelerations (RV trends), indicating the presence of outer companions. Direct imaging observations can help clarify what objects generate these RV trends. We present the results of high-contrast imaging observations of six intermediate-mass giants with long-term RV trends using the Subaru Telescope and HiCIAO camera. We detected co-moving companions to Hya , HD 5608 B (0.10 ± 0.01 ), and HD 109272 B (0.28 ± 0.06 ). For the remaining targets( Dra, 18 Del, and HD 14067) we exclude companions more massive than 30-60 at projected separations of 1-7. We examine whether these directly imaged companions or unidentified long-period companions can account for the RV trends observed around the six giants. We find that the Kozai mechanism can explain the high eccentricity of the inner planets Dra b, HD 5608 b, and HD 14067 b.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7402361 | PMC |
| http://dx.doi.org/10.3847/0004-637X/825/2/127 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Simulations predict intermediate-mass black hole formation in globular clusters.
Science
June 2024
Department of Planetology, Kobe University, Kobe, Hyogo 657-8501, Japan.
The formation process of intermediate-mass black holes (IMBHs), defined as those between 100 and 10 solar masses (), is debated. One potential origin is the growth of less-massive black holes merging with stars and compact objects within globular clusters (GCs). However, previous simulations have indicated that this process only produces IMBHs under 500 before gravitational wave recoil ejects them from the GC.
View Article and Find Full Text PDFMagnetic fields of 30 to 100 kG in the cores of red giant stars.
Nature
October 2022
IRAP, Université de Toulouse, CNRS, CNES, UPS, Toulouse, France.
A red giant star is an evolved low- or intermediate-mass star that has exhausted its central hydrogen content, leaving a helium core and a hydrogen-burning shell. Oscillations of stars can be observed as periodic dimmings and brightenings in the optical light curves. In red giant stars, non-radial acoustic waves couple to gravity waves and give rise to mixed modes, which behave as pressure modes in the envelope and gravity modes in the core.
View Article and Find Full Text PDF(Sub)stellar companions shape the winds of evolved stars.
Science
September 2020
Department of Physics and Astronomy, University College London, London WC1E 6BT, UK.
Binary interactions dominate the evolution of massive stars, but their role is less clear for low- and intermediate-mass stars. The evolution of a spherical wind from an asymptotic giant branch (AGB) star into a nonspherical planetary nebula (PN) could be due to binary interactions. We observed a sample of AGB stars with the Atacama Large Millimeter/submillimeter Array (ALMA) and found that their winds exhibit distinct nonspherical geometries with morphological similarities to planetary nebulae (PNe).
View Article and Find Full Text PDFVery regular high-frequency pulsation modes in young intermediate-mass stars.
Nature
May 2020
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Asteroseismology probes the internal structures of stars by using their natural pulsation frequencies. It relies on identifying sequences of pulsation modes that can be compared with theoretical models, which has been done successfully for many classes of pulsators, including low-mass solar-type stars, red giants, high-mass stars and white dwarfs. However, a large group of pulsating stars of intermediate mass-the so-called δ Scuti stars-have rich pulsation spectra for which systematic mode identification has not hitherto been possible.
View Article and Find Full Text PDFFission of Relativistic Nuclei with Fragment Excitation and Reorientation.
Phys Rev Lett
April 2020
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay 91405, France.
Experimental studies of fission induced in relativistic nuclear collisions show a systematic enhancement of the excitation energy of the primary fragments by a factor of ∼2, before their decay by fission and other secondary fragments. Although it is widely accepted that by doubling the energies of the single-particle states may yield a better agreement with fission data, it does not prove fully successful, since it is not able to explain yields for light and intermediate mass fragments. State-of-the-art calculations are successful to describe the overall shape of the mass distribution of fragments, but fail within a factor of 2-10 for a large number of individual yields.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!