A Korea-Japan planet search program: Current status and discovery of a brown dwarf candidate

AbstractSince 2005, we have been carrying out a precise radial velocity survey of about 190 intermediate-mass (1.5-5 M⊙) G and K giants at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea and Okayama Astrophysical Observatory (OAO) in Japan, which aims to reveal statistical properties of planetary systems around intermediate-mass stars. We have finished the first screening of 120 stars so far and have identified 5 candidates with large periodic radial velocity variations. One of the candidates turned out to be orbited by a brown dwarf mass companion with minimum mass of 37.6 MJup and semimajor axis of 1.71 AU. The primary star has a mass of 3.9 M⊙, which ranks among the most massive stars with substellar companions. Our discovery may support the current view obtained from results of planet searches around intermediate-mass stars that massive substellar companions tend to form around massive stars.

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Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/62.4.1063 ◽

2010 ◽

Vol 62 (4) ◽

pp. 1063-1069 ◽

Cited By ~ 34

Author(s):

Bun’ei Sato ◽

Masashi Omiya ◽

Yujuan Liu ◽

Hiroki Harakawa ◽

Hideyuki Izumiura ◽

...

Keyword(s):

Intermediate Mass ◽

Intermediate Mass Stars ◽

Substellar Companions

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The effects of Rotation on Wolf–Rayet Stars and on the Production of Primary Nitrogen by Intermediate Mass Stars

Symposium - International Astronomical Union ◽

10.1017/s007418090019624x ◽

2004 ◽

Vol 215 ◽

pp. 579-588 ◽

Cited By ~ 2

Author(s):

Georges Meynet ◽

Max Pettini

Keyword(s):

Star Formation ◽

Time Delay ◽

Main Sequence ◽

Massive Stars ◽

Sequence Evolution ◽

Stellar Rotation ◽

Intermediate Mass ◽

Intermediate Mass Stars ◽

Solar Metallicity ◽

Effects Of Rotation

We use the rotating stellar models described in the paper by A. Maeder & G. Meynet in this volume to consider the effects of rotation on the evolution of the most massive stars into and during the Wolf–Rayet phase, and on the post-Main Sequence evolution of intermediate mass stars. The two main results of this discussion are the following. First, we show that rotating models are able to account for the observed properties of the Wolf–Rayet stellar populations at solar metallicity. Second, at low metallicities, the inclusion of stellar rotation in the calculation of chemical yields can lead to a longer time delay between the release of oxygen and nitrogen into the interstellar medium following an episode of star formation, since stars of lower masses (compared to non-rotating models) can synthesize primary N. Qualitatively, such an effect may be required to explain the relative abundances of N and O in extragalactic metal–poor environments, particularly at high redshifts.

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The Pan-Pacific Planet Search – VIII. Complete results and the occurrence rate of planets around low-luminosity giants

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3378 ◽

2019 ◽

Vol 491 (4) ◽

pp. 5248-5257 ◽

Cited By ~ 3

Author(s):

Robert A Wittenmyer ◽

R P Butler ◽

Jonathan Horner ◽

Jake Clark ◽

C G Tinney ◽

...

Keyword(s):

Radial Velocity ◽

Main Sequence ◽

Giant Planets ◽

Occurrence Rate ◽

Velocity Measurements ◽

Intermediate Mass ◽

Giant Stars ◽

Intermediate Mass Stars ◽

Final Data ◽

Solar Type

ABSTRACT Our knowledge of the populations and occurrence rates of planets orbiting evolved intermediate-mass stars lags behind that for solar-type stars by at least a decade. Some radial velocity surveys have targeted these low-luminosity giant stars, providing some insights into the properties of their planetary systems. Here, we present the final data release of the Pan-Pacific Planet Search (PPPS), a 5 yr radial velocity survey using the 3.9 m Anglo-Australian Telescope. We present 1293 precise radial velocity measurements for 129 stars, and highlight 6 potential substellar-mass companions, which require additional observations to confirm. Correcting for the substantial incompleteness in the sample, we estimate the occurrence rate of giant planets orbiting low-luminosity giant stars to be approximately 7.8$^{+9.1}_{-3.3}$ per cent. This result is consistent with the frequency of such planets found to orbit main-sequence A-type stars, from which the PPPS stars have evolved.

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Constraining the properties of HD 206893 B

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935044 ◽

2019 ◽

Vol 627 ◽

pp. L9 ◽

Cited By ~ 8

Author(s):

A. Grandjean ◽

A.-M. Lagrange ◽

H. Beust ◽

L. Rodet ◽

J. Milli ◽

...

Keyword(s):

Radial Velocity ◽

Semimajor Axis ◽

High Contrast ◽

Brown Dwarf ◽

Contrast Imaging ◽

Dynamical Mass ◽

Orbital Parameters ◽

High Contrast Imaging ◽

Very Large Telescope ◽

Astrometric Data

Context. High contrast imaging enables the determination of orbital parameters for substellar companions (planets, brown dwarfs) from the observed relative astrometry and the estimation of model and age-dependent masses from their observed magnitudes or spectra. Combining astrometric positions with radial velocity gives direct constraints on the orbit and on the dynamical masses of companions. A brown dwarf was discovered with the VLT/SPHERE instrument at the Very Large Telescope (VLT) in 2017, which orbits at ∼11 au around HD 206893. Its mass was estimated between 12 and 50 MJ from evolutionary models and its photometry. However, given the significant uncertainty on the age of the system and the peculiar spectrophotometric properties of the companion, this mass is not well constrained. Aims. We aim at constraining the orbit and dynamical mass of HD 206893 B. Methods. We combined radial velocity data obtained with HARPS spectra and astrometric data obtained with the high contrast imaging VLT/SPHERE and VLT/NaCo instruments, with a time baseline less than three years. We then combined those data with astrometry data obtained by HIPPARCOS and Gaia with a time baseline of 24 yr. We used a Markov chain Monte Carlo approach to estimate the orbital parameters and dynamical mass of the brown dwarf from those data. Results. We infer a period between 21 and 33 yr and an inclination in the range 20−41° from pole-on from HD 206893 B relative astrometry. The RV data show a significant RV drift over 1.6 yr. We show that HD 206893 B cannot be the source of this observed RV drift as it would lead to a dynamical mass inconsistent with its photometry and spectra and with HIPPARCOS and Gaia data. An additional inner (semimajor axis in the range 1.4–2.6 au) and massive (∼15 MJ) companion is needed to explain the RV drift, which is compatible with the available astrometric data of the star, as well as with the VLT/SPHERE and VLT/NaCo nondetection.

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Single star evolution I. Massive stars and early evolution of low and intermediate mass stars

Physics Reports ◽

10.1016/0370-1573(84)90142-x ◽

1984 ◽

Vol 105 (6) ◽

pp. 329-406 ◽

Cited By ~ 145

Author(s):

Icko Iben ◽

Alvio Renzini

Keyword(s):

Massive Stars ◽

Early Evolution ◽

Intermediate Mass ◽

Single Star ◽

Intermediate Mass Stars ◽

Star Evolution

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Insights into the planetary dynamics of HD 206893 with ALMA

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2386 ◽

2020 ◽

Vol 498 (1) ◽

pp. 1319-1334

Author(s):

S Marino ◽

A Zurlo ◽

V Faramaz ◽

J Milli ◽

Th Henning ◽

...

Keyword(s):

Radial Velocity ◽

Time Scales ◽

Proper Motion ◽

Semimajor Axis ◽

Brown Dwarf ◽

Secular Resonances ◽

The Third ◽

Planetary Dynamics ◽

Wide Gap ◽

Gap Width

ABSTRACT Radial substructure in the form of rings and gaps has been shown to be ubiquitous among protoplanetary discs. This could be the case in exo-Kuiper belts as well, and evidence for this is emerging. In this paper, we present ALMA observations of the debris/planetesimal disc surrounding HD 206893, a system that also hosts two massive companions at 2 and 11 au. Our observations reveal a disc extending from 30 to 180 au, split by a 27 au wide gap centred at 74 au, and no dust surrounding the reddened brown dwarf (BD) at 11 au. The gap width suggests the presence of a 0.9MJup planet at 74 au, which would be the third companion in this system. Using previous astrometry of the BD, combined with our derived disc orientation as a prior, we were able to better constrain its orbit finding it is likely eccentric ($0.14^{+0.05}_{-0.04}$). For the innermost companion, we used radial velocity, proper motion anomaly, and stability considerations to show its mass and semimajor axis are likely in the ranges 4–100MJup and 1.4–4.5 au. These three companions will interact on secular time-scales and perturb the orbits of planetesimals, stirring the disc and potentially truncating it to its current extent via secular resonances. Finally, the presence of a gap in this system adds to the growing evidence that gaps could be common in wide exo-Kuiper belts. Out of six wide debris discs observed with ALMA with enough resolution, four to five show radial substructure in the form of gaps.

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SMBH Luminosity in the Starburst Environment

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310006666 ◽

2009 ◽

Vol 5 (S267) ◽

pp. 336-336

Author(s):

Sergiy Silich ◽

Guillermo Tenorio-Tagle ◽

Filiberto Hueyotl-Zahuantitla ◽

Jan Palouš ◽

Richard Wünsch

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Accretion Rate ◽

Massive Stars ◽

Mass Loss Rate ◽

Intermediate Mass ◽

Star Forming ◽

Intermediate Mass Stars

We claim that in the starburst environment there is no accretion of the ISM onto the BH and thus, in such cases, the BH luminosity is regulated by the mass-loss rate from massive stars in the star forming region. We calculate the accretion rate and show that it is usually small during the superwind stage and grows at the post-starburst stage, when the matter reinserted by intermediate–mass stars remains gravitationally bound and fuels the central BH.

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The Onset of Planet Formation in Brown Dwarf Disks

Science ◽

10.1126/science.1118042 ◽

2005 ◽

Vol 310 (5749) ◽

pp. 834-836 ◽

Cited By ~ 140

Author(s):

Dániel Apai ◽

Ilaria Pascucci ◽

Jeroen Bouwman ◽

Antonella Natta ◽

Thomas Henning ◽

...

Keyword(s):

Infrared Spectra ◽

Planet Formation ◽

Protoplanetary Disks ◽

Brown Dwarfs ◽

Circumstellar Disks ◽

Dust Grains ◽

Brown Dwarf ◽

Intermediate Mass ◽

Intermediate Mass Stars ◽

Robust Process

The onset of planet formation in protoplanetary disks is marked by the growth and crystallization of sub–micrometer-sized dust grains accompanied by dust settling toward the disk mid-plane. Here, we present infrared spectra of disks around brown dwarfs and brown dwarf candidates. We show that all three processes occur in such cool disks in a way similar or identical to that in disks around low- and intermediate-mass stars. These results indicate that the onset of planet formation extends to disks around brown dwarfs, suggesting that planet formation is a robust process occurring in most young circumstellar disks.

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The Pennsylvania-Toruń search for planets around evolved stars with HET

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311020734 ◽

2010 ◽

Vol 6 (S276) ◽

pp. 445-447

Author(s):

Andrzej Niedzielski ◽

Alex Wolszczan ◽

Grzegorz Nowak ◽

Paweł Zieliński ◽

Monika Adamów ◽

...

Keyword(s):

Main Sequence ◽

Convincing Evidence ◽

Current Status ◽

Brown Dwarf ◽

Solar Mass ◽

Rotation Rates ◽

Evolved Stars ◽

Intermediate Mass Stars ◽

Red Dwarfs ◽

Formation And Evolution

AbstractSearches for planets around giants represent an essential complement to ’traditional’ surveys, because they furnish information about properties of planetary systems around stars that are the descendants of the A-F main sequence (MS) stars with masses as high as ~5 M⊙. As the stars evolve off the MS, their effective temperatures and rotation rates decrease to the point that their radial velocity variations can be measured with a few ms−1 precision. This offers an excellent opportunity to improve our understanding of the population of planets around stars that are significantly more massive than the Sun, without which it would be difficult to produce abroad, integrated picture of planet formation and evolution. Since 2001, about 30 such objects have been identified, including our five published HET detections (Niedzielski et al. 2007; Niedzielski et al. 2009a; Niedzielski et al. 2009b). Our work has produced the tightest orbit of a planet orbiting a K-giant identified so far (0.6 AU), and the first convincing evidence for a multiplanet system around such as star (Niedzielski et al. 2009a). Our most recent discoveries (Niedzielski et al. 2009b) have identified new multiplanet systems, including a very intriguing one of two brown dwarf-mass bodies orbiting a 2.8M⊙, K2 giant. This particular detection challenges the standard interpretation of the so-called brown dwarf desert known to exist in the case of solar-mass stars. Along with discoveries supplied by other groups, our work has substantially added to the emerging evidence that stellar mass positively correlates with masses of substellar companions, all the way from red dwarfs to intermediate-mass stars. We present current status and forthcoming results from the Pennsylvania-Toruń Search for Planets performed with the Hobby-Eberly Telescope (HET) since 2004.

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