75 research outputs found
A Planetary Companion to the Intermediate-Mass Giant HD 100655
A precise radial velocity survey conducted by a Korean-Japanese planet search
program revealed a planetary companion around the intermediate-mass clump giant
HD 100655. The radial velocity of the star exhibits a periodic Keplerian
variation with a period, semi-amplitude and eccentricity of 157.57 d, 35.2 m
s^-1 and 0.085, respectively. Adopting an estimated stellar mass of 2.4 M_Sun,
we confirmed the presence of a planetary companion with a semi-major axis of
0.76 AU and a minimum mass of 1.7 M_Jup. The planet is the lowest-mass planet
yet discovered around clump giants with masses greater than 1.9 M_Sun.Comment: 17 pages, 8 figures, accepted for publication in PAS
Korean-Japanese Planet Search Program: Substellar Companions around Intermediate-Mass Giants
A Korean-Japanese planet search program has been carried out using the 1.8m
telescope at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea, and the
1.88m telescope at Okayama Astrophysical Observatory (OAO) in Japan to search
for planets around intermediate-mass giant stars. The program aims to show the
properties of planetary systems around such stars by precise Doppler survey of
about 190 G or K type giants together with collaborative surveys of the
East-Asian Planet Search Network. So far, we detected two substellar companions
around massive intermediate-mass giants in the Korean-Japanese planet search
program. One is a brown dwarf-mass companion with 37.6
orbiting a giant HD 119445 with 3.9 , which is the most massive
brown dwarf companion among those found around intermediate-mass giants. The
other is a planetary companion with 1.8 orbiting a giant star
with 2.4 , which is the lowest-mass planetary companion among those
detected around giant stars with 1.9 . Plotting these systems on
companion mass vs. stellar mass diagram, there seem to exist two unpopulated
regions of substellar companions around giants with 1.5--3 and
planetary companions orbiting giants with 2.4--4 . The existence of
these possible unpopulated regions supports a current characteristic view that
more massive substellar companions tend to exist around more massive stars.Comment: 8 pages, 3 figures, Part of PlanetsbeyondMS/2010 proceedings
http://arxiv.org/html/1011.660
Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314
We report the detections of two substellar companions orbiting around evolved
intermediate-mass stars from precise Doppler measurements at Subaru Telescope
and Okayama Astrophysical Observatory. HD 145457 is a K0 giant with a mass of
1.9 M_sun and has a planet of minimum mass m_2sini=2.9 M_J orbiting with period
of P=176 d and eccentricity of e=0.11. HD 180314 is also a K0 giant with 2.6
M_sun and hosts a substellar companion of m_2sin i=22 M_J, which falls in
brown-dwarf mass regime, in an orbit with P=396 d and e=0.26. HD 145457 b is
one of the innermost planets and HD 180314 b is the seventh candidate of
brown-dwarf-mass companion found around intermediate-mass evolved stars.Comment: 16 pages, 4 figures, accepted for publication in PAS
Planetary Companions to Evolved Intermediate-Mass Stars: 14 Andromedae, 81 Ceti, 6 Lyncis, and HD 167042
We report on the detection of four extrasolar planets orbiting evolved
intermediate-mass stars from a precise Doppler survey of G and K giants at
Okayama Astrophysical Observatory. All of the host stars are considered to be
formerly early F-type or A-type dwarfs when they were on the main sequence. 14
And (K0 III) is a clump giant with a mass of 2.2 M_solar and has a planet of
minimum mass m_2sin i=4.8 M_Jup in a nearly circular orbit with a 186 day
period. This is one of the innermost planets around evolved intermediate-mass
stars and such planets have only been discovered in clump giants. 81 Cet (G5
III) is a clump giant with 2.4 M_solar hosting a planet of m_2sin i=5.3 M_Jup
in a 953 day orbit with an eccentricity of e=0.21. 6 Lyn (K0 IV) is a less
evolved subgiant with 1.7 M_solar and has a planet of m_2sin i=2.4 M_Jup in a
899 day orbit with e=0.13. HD 167042 (K1 IV) is also a less evolved star with
1.5 M_solar hosting a planet of m_2sin i=1.6 M_Jup in a 418 day orbit with
e=0.10. This planet was independently announced by Johnson et al. (2008, ApJ,
675, 784). All of the host stars have solar or sub-solar metallicity, which
supports the lack of metal-rich tendency in planet-harboring giants in contrast
to the case of dwarfs.Comment: 23 pages, 6 figures, accepted for publication in PAS
A Substellar Companion to the Intermediate-Mass Giant 11 Com
We report the detection of a substellar companion orbiting the
intermediate-mass giant star 11 Com (G8 III). Precise Doppler measurements of
the star from Xinglong station and Okayama Astrophysical Observatory (OAO)
revealed Keplerian velocity variations with an orbital period of 326.03 +/-
0.32 days, a semiamplitude of 302.8 +/- 2.6 m/s, and an eccentricity of 0.231
+/- 0.005. Adopting a stellar mass of 2.7 +/- 0.3 M_solar, the minimum mass of
the companion is 19.4 +/- 1.5 M_Jup, well above the deuterium burning limit,
and the semimajor axis is 1.29 +/- 0.05 AU. This is the first result from the
joint planet search program between China and Japan aiming at revealing
statistics of substellar companions around intermediate-mass giants. 11 Com b
emerged from 300 targets of the planet search program at OAO. The current
detection rate of a brown dwarf candidate seems to be comparable to that around
solar-type stars within orbital separations of 3 AU.Comment: 19 pages, 4 figures, accepted by Ap
A Massive Substellar Companion to the Massive Giant HD 119445
We detected a brown dwarf-mass companion around the intermediate-mass giant
star HD 119445 (G6III) using the Doppler technique. This discovery is the first
result from a Korean-Japanese planet search program based on precise radial
velocity measurements. The radial velocity of this star exhibits a periodic
Keplerian variation with a period, semi-amplitude and eccentricity of 410.2
days, 413.5 m/s and 0.082, respectively. Adopting a stellar mass of 3.9
M_solar, we were able to confirm the presence of a massive substellar companion
with a semimajor axis of 1.71 AU and a minimum mass of 37.6 M_Jup, which falls
in the middle of the brown dwarf-mass region. This substellar companion is the
most massive ever discovered within 3 AU of a central intermediate-mass star.
The host star also ranks among the most massive stars with substellar
companions ever detected by the Doppler technique. This result supports the
current view of substellar systems that more massive substellar companions tend
to exist around more massive stars, and may further constrain substellar system
formation mechanisms.Comment: 17 pages, 5 figures, PASJ accepte
Diagnosis of Myocardial Viability by Fluorodeoxyglucose Distribution at the Border Zone of a Low Uptake Region
Purpose: In cardiac 2-[F-18]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) examination, interpretation of myocardial viability in the low uptake region (LUR) has been difficult without additional perfusion imaging. We evaluated distribution patterns of FDG at the border zone of the LUR in the cardiac FDG-PET and established a novel parameter for diagnosing myocardial viability and for discriminating the LUR of normal variants. Materials and Methods: Cardiac FDG-PET was performed in patients with a myocardial ischemic event (n = 22) and in healthy volunteers (n = 22). Whether the myocardium was not a viable myocardium (not-VM) or an ischemic but viable myocardium (isch-VM) was defined by an echocardiogram under a low dose of dobutamine infusion as the gold standard. FDG images were displayed as gray scaled-bull’s eye mappings. FDG-plot profiles for LUR ( = true ischemic region in the patients or normal variant region in healthy subjects) were calculated. Maximal values of FDG change at the LUR border zone (a steepness index; Smax scale/pixel) were compared among not-VM, isch-VM, and normal myocardium. Results: Smax was significantly higher for n-VM compared to those with isch-VM or normal myocardium (ANOVA). A cut-off value of 0.30 in Smax demonstrated 100 % sensitivity and 83 % specificity for diagnosing n-VM and isch-VM. Smax less than 0.23 discriminated LUR in normal myocardium from the LUR in patients with both n-VM and isch-VM with a 94 % sensitivity and a 93 % specificity. Conclusion: Smax of the LUR in cardiac FDG-PET is a simple and useful parameter to diagnose n-VM and isch
Genome-Wide Association Study of Schizophrenia in Japanese Population
Schizophrenia is a devastating neuropsychiatric disorder with genetically complex traits. Genetic variants should explain a considerable portion of the risk for schizophrenia, and genome-wide association study (GWAS) is a potentially powerful tool for identifying the risk variants that underlie the disease. Here, we report the results of a three-stage analysis of three independent cohorts consisting of a total of 2,535 samples from Japanese and Chinese populations for searching schizophrenia susceptibility genes using a GWAS approach. Firstly, we examined 115,770 single nucleotide polymorphisms (SNPs) in 120 patient-parents trio samples from Japanese schizophrenia pedigrees. In stage II, we evaluated 1,632 SNPs (1,159 SNPs of p<0.01 and 473 SNPs of p<0.05 that located in previously reported linkage regions). The second sample consisted of 1,012 case-control samples of Japanese origin. The most significant p value was obtained for the SNP in the ELAVL2 [(embryonic lethal, abnormal vision, Drosophila)-like 2] gene located on 9p21.3 (p = 0.00087). In stage III, we scrutinized the ELAVL2 gene by genotyping gene-centric tagSNPs in the third sample set of 293 family samples (1,163 individuals) of Chinese descent and the SNP in the gene showed a nominal association with schizophrenia in Chinese population (p = 0.026). The current data in Asian population would be helpful for deciphering ethnic diversity of schizophrenia etiology
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