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Liang Wang,
Bun'ei Sato,
Gang Zhao,
Yujuan Liu, Kunio Noguchi,
Hiroyasu Ando,
Hideyuki Izumiura,
Eiji Kambe,
Masashi Omiya,
Hiroki Harakawa,
Fan Liu,
Xiaoshu Wu,
Yoichi Takeda,
Michitoshi Yoshida,
Eiichiro Kokubo
[show abstract]
[hide abstract]
ABSTRACT: We report the discovery of a substellar companion around the intermediatemass
giant HD 175679. Precise radial velocity data of the star from Xinglong Station
and Okayama Astrophysical Observatory (OAO) revealed a Keplerian velocity
variation with an orbital period of 1366.8 \pm 5.7 days, a semiamplitude of
380.2 \pm 3.2m s.1, and an eccentricity of 0.378 \pm 0.008. Adopting a stellar
mass of 2.7 \pm 0.3 M\odot, we obtain the minimum mass of the HD 175679 b is
37.3 \pm 2.8 MJ, and the semimajor axis is 3.36 \pm 0.12 AU. This discovery is
the second brown dwarf companion candidate from a joint planet-search program
between China and Japan.
10/2011;
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Bun'ei Sato,
Hiroyasu Ando,
Eiji Kambe,
Yoichi Takeda,
Hideyuki Izumiura,
Seiji Masuda,
Etsuji Watanabe, Kunio Noguchi,
Setsuko Wada,
Norio Okada,
Hisashi Koyano,
Hideo Maehara,
Yuji Norimoto,
Takafumi Okada,
Yasuhiro Shimizu,
Fumihiro Uraguchi,
Kenshi Yanagisawa,
and Michitoshi Yoshida
[show abstract]
[hide abstract]
ABSTRACT: We report the detection of a planetary-mass companion to the G9 III giant star HD 104985 from precise Doppler velocity measurements made using the High Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory. The radial velocity variability of this star is best explained by an orbital motion with a period of 198.2 ± 0.3 days, a velocity semiamplitude of 161 ± 2 m s-1, and an eccentricity of 0.03 ± 0.02. Assuming a stellar mass of 1.6 M☉, we obtained a minimum mass and a semimajor axis of 6.3MJ and 0.78 AU, respectively, for the companion. A probable upper limit to the stellar mass of 3 M☉ yielded m2 sin i = 9.6MJ, which falls in the planetary-mass regime. This is the first discovery of a planetary companion orbiting a G-type giant star.
The Astrophysical Journal 12/2008; 597(2):L157. · 6.02 Impact Factor
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Y.-J. Liu,
Bun'ei Sato,
G. Zhao, Kunio Noguchi,
H. Wang,
Eiji Kambe,
Hiroyasu Ando,
Hideyuki Izumiura,
Y.-Q. Chen,
Norio Okada,
Eri Toyota,
Masashi Omiya,
Seiji Masuda,
Yoichi Takeda,
Daisuke Murata,
Yoichi Itoh,
Michitoshi Yoshida,
Eiichiro Kokubo,
and Shigeru Ida
[show abstract]
[hide abstract]
ABSTRACT: 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) reveal Keplerian velocity variations with an orbital period of 326.03 ± 0.32 days, a semiamplitude of 302.8 ± 2.6 m s−1, and an eccentricity of 0.231 ± 0.005. Adopting a stellar mass of 2.7 ± 0.3 M☉, the minimum mass of the companion is 19.4 ± 1.5 MJ, well above the deuterium-burning limit, and the semimajor axis is 1.29 ± 0.05 AU. This is the first result from a joint planet-search program between China and Japan aimed at revealing the statistics of substellar companions around intermediate-mass giants. 11 Com b emerged from 300 targets of the planet-search program at OAO. The program's current detection rate of brown dwarf candidates seems to be comparable to the rate of such detections around solar-type stars with orbital separations of 3 AU.
The Astrophysical Journal 12/2008; 672(1):553. · 6.02 Impact Factor
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Hideyuki Izumiura, Kunio Noguchi,
Wako Aoki,
Satoshi Honda,
Hiroyasu Ando,
Masahide Takada-Hidai,
Eiji Kambe,
Satoshi Kawanomoto,
Kozo Sadakane,
Bun'ei Sato,
Akito Tajitsu,
Wataru Tanaka,
Ki'ichi Okita,
Etsuji Watanabe,
and Michitoshi Yoshida
[show abstract]
[hide abstract]
ABSTRACT: Balmer and Paschen continuum emission, as well as Balmer series lines of P Cygni-type profile from Hγ through H23, are revealed in the violet spectra of BM Gem, a carbon star associated with an oxygen-rich circumstellar shell ("silicate carbon star"). The blueshifted absorption in the Balmer lines indicates the presence of an outflow, the line-of-sight velocity of which is at least 400 km s−1. The Balmer lines show a significant change in profile over a period of 75 days. We argue that the observed unusual features in BM Gem are strong evidence for the presence of a companion, which should form an accretion disk that gives rise to both an ionized gas region and a high-velocity variable outflow. The estimated luminosity of ~0.2 (0.03-0.6) L☉ for the ionized gas can be maintained by a mass accretion rate for a dwarf companion of ~10−8 M☉ yr−1, while ~10−10 M☉ yr−1 is sufficient for accretion to a white dwarf companion. These accretion rates are feasible for some detached binary configurations on the basis of the Bondi-Hoyle-type accretion process. Therefore, we conclude that the carbon star BM Gem is in a detached binary system with a companion of low mass and low luminosity. However, we are unable to determine whether this companion object is a dwarf or a white dwarf, although the gas outflow velocity of 400 km s−1, as well as the nondetection in the X-ray survey, favor its identity as a dwarf star. The upper limits for binary separation are 210 and 930 AU for a dwarf and a white dwarf, respectively, in the case of circular orbit. We also note that the observed features of BM Gem mimic those of Mira (o Cet), which may suggest actual similarities in their binary configurations and circumstellar structures.
The Astrophysical Journal 12/2008; 682(1):499. · 6.02 Impact Factor
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Kunio Noguchi,
Wako Aoki,
Satoshi Kawanomoto,
Hiroyasu Ando,
Satoshi Honda,
Hideyuki Izumiura,
Eiji Kambe,
Kiichi Okita,
Kozo Sadakane,
Bun'ei Sato,
Akito Tajitsu,
Tasahide Takada-Hidai,
Wataru Tanaka,
Etsuji Watanabe,
Michitoshi Yoshida
[show abstract]
[hide abstract]
ABSTRACT: We present the design and performance of the High Dispersion
Spectrograph (HDS) of the Subaru Telescope. HDS is an echelle
spectrograph located at the Nasmyth focus of the telescope. The
collimated beam size is 272mm, and the echelle is 300mm by 840mm in
total size (31.6 gr mm-1, R = 2.8). HDS has two
cross-dispersing gratings with 400 gr mm-1 and 250 gr
mm-1, which are optimized for the blue and red wavelength
regions, respectively. The camera is of the catadioptric type system,
consisting of three corrector lenses and a mirror. Two EEV-CCD's with
4100 × 2048 pixels and a pixel size of 13.5 μm are used as the
detector. A standard configuration with a 0".4 slit gives a spectral
resolution of R = 90000, and a narrower slit width enables higher
resolution of up to R = ˜ 160000. The spectrograph has
sensitivities from 3000Å to 1μm, and one exposure covers a
range of 1500-2500Å, depending on the wavelength region. The
throughput of the telescope and the spectrograph, including the
efficiency of the detector, is about 13% in 5000-6000Å and about
8% at 4000Å. The stability of the spectrograph and scattered light
level are also reported.
Publications- Astronomical Society of Japan 11/2002; 54:855-864. · 2.44 Impact Factor
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Eiji Kambe,
Bun'ei Sato,
Yoichi Takeda,
Hiroyasu Ando, Kunio Noguchi,
Wako Aoki,
Hideyuki Izumiura,
Setsuko Wada,
Seiji Masuda,
Norio Okada,
Yasuhiro Shimizu,
Etsuji Watanabe,
Michitoshi Yoshida,
Satoshi Honda,
Satoshi Kawanomoto
[show abstract]
[hide abstract]
ABSTRACT: We have developed iodine (I2) cells for the High Dispersion
Spectrograph (HDS) on the Subaru telescope and for the HIgh Dispersion
Echelle Spectrograph (HIDES) on the Okayama 1.88m reflector. The cell is
put into a compact vacuum vessel, which fits into a small space behind
the entrance slit of the HDS. The cell assembly is designed to minimize
heat losses from the cell, which is heated during observations, to keep
I2 vapor from condensation. The amount of I2 in
the cell is determined to be best suited for radial-velocity
measurements of solar-type stars. We also report on some performances of
the HDS and HIDES as well as their instrumental profiles based on tests
of our I2 cells. Lastly, we discuss future improvements of
our instruments and data-analysis softwares for I2
observations, and also describe the scientific goals of our project.
Publications- Astronomical Society of Japan 11/2002; 54:865-871. · 2.44 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We present [O/Fe] and other α-elements/Fe ratios in a sample of 24
mildly metal-poor stars. The sample stars are thought to be brighter
than 9.0 magnitude and have available uvby photometric data. Also, based
on the typical LTE abundance analysis, we find that [Si/Fe] and [Ca/Fe]
are correlated with each other. Combining the kinematic data and the
metallicity, we can classify the sample stars into three groups. An
abundance analysis shows some evidence that these groups are chemically
discrete from each other. Further, the general trend of a decreasing
overabundance of the α elements with increasing metallicity has
been confirmed.
Publications- Astronomical Society of Japan 01/2002; 54:103-111. · 2.44 Impact Factor
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Norio Kaifu,
Tomonori Usuda,
Saeko S. Hayashi,
Yoichi Itoh,
Masayuki Akiyama,
Takuya Yamashita,
Yasushi Nakajima,
Motohide Tamura,
Shuichiro Inutsuka,
Masahiko Hayashi, [......],
Yasuo Torii,
Koichi Waseda,
Junichi Watanabe,
Masaru Watanabe,
Masafumi Yagi,
Yasumasa Yamashita,
Naoki Yasuda,
Michitoshi Yoshida,
Shigeomi Yoshida,
Masami Yutani
[show abstract]
[hide abstract]
ABSTRACT: This paper describes the first light and subsequent test observations
with the 8.2 m aperture Subaru Telescope constructed at the summit of
Mauna Kea. Following the engineering first light, which started 1998
December, the astronomical first light and test observations were
carried out in 1999 January with 4 testing instruments under seeing
conditions of 0.''2-0.''5 for near-infrared and 0.''3-0.6 for optical
wavelengths. The actively supported primary mirror was shown to achieve
an overall imaging performance of 0.''1 (FWHM) or better in the absence
of any atmospheric disturbance. The pointing accuracy of the telescope
is about 1'' rms, and a closed-loop tracking accuracy of <~ 0.''07
rms has been achieved. Infrared images of the Orion Nebula covering
{5'}times {5'}, obtained with J, K', and H_2 v=1-0 S(1) filters, have
revealed much finer and fainter details of the BN/KL region, the bright
bar, and other conspicuous features compared with previous observations.
K' band photometry of 516 point sources yielded a luminosity function
with a peak at K' ~ 12 mag with a long tail in K' ~ 13 mag down to K' ~
17 mag, suggesting a fairly large number of young brown dwarfs existing
in the Trapezium cluster. Several new features around the Orion BN/KL
region are also reported.
Publications- Astronomical Society of Japan 01/2000; 52:1. · 2.44 Impact Factor
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Masanori Iye,
Fumihide Iwamuro,
Toshinori Maihara,
Satoshi Miyazaki,
Sadanori Okamura,
Kazuhiro Shimasaku,
Chris Simpson,
Masayuki Akiyama,
Hiroyasu Ando,
Tetsuo Aoki, [......],
Tomonori Usuda,
Junichi Watanabe,
Masaru Watanabe,
Masafumi Yagi,
Takuya Yamashita,
Yasumasa Yamashita,
Naoki Yasuda,
Michitoshi Yoshida,
Shigeomi Yoshida,
Masami Yutani
[show abstract]
[hide abstract]
ABSTRACT: We report on the results of optical and near-infrared photometry of the
cluster of galaxies A 851 (=CL 0939+4713) carried out as one of the
first-light observations of the 8.2 m Subaru telescope on Mauna Kea.
Images as sharp as 0.''3 FWHM in K' and 0.''45 in R were obtained in
these observations. The 3 sigma limiting magnitudes for points sources
in 0.''3 seeing with a 0.''6 software aperture were shown to go down to
R=28.1, J=25.1, and K'=24.0, respectively, for about 1 hour integration.
Subaru photometry of the galaxies in this cluster has shown in its
color-magnitude diagrams a well-defined sequence of the early-type
galaxy population that is consistent with the track predicted for a
single-burst passive-evolution model of galaxies at z = 0.4. We
attempted a morphological classification of galaxies in the Subaru
R-band image using the C_in method, and found that discrimination
between ellipticals and spirals can be achieved fairly consistently with
the types assigned by MORPHs on the HST F702W image down to R<23. A
weak lensing analysis made on the Subaru R-band image yielded a
reconstructed surface mass-density distribution that shows a significant
maximum corresponding to the peak of the smoothed luminosity
distribution of cluster galaxies. We found no significant excess of
faint and/or small galaxies in the putative cluster area around the z=2
quasar and no difference in the colors for galaxies in this area from
those in the main cluster either. Two extremely red objects (ERO) with
R-K>6 are newly identified in the field. The colors of the reddest,
disk-shaped galaxy R1 are found compatible with those of an unreddened
E/S0 galaxy at z = 1.6.
Publications- Astronomical Society of Japan 01/2000; 52:9. · 2.44 Impact Factor
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Masanori Iye,
Hiroyasu Ando,
Nobunari Kashikawa,
Satoshi Miyazaki,
Tetsuo Nishimura, Kunio Noguchi,
Masashi Otsubo,
Toshiyuki Sasaki,
Kazuhiro Sekiguchi,
Masaki Sekiguchi,
Hideki Takami,
Naruhisa Takato,
Wataru Tanaka,
Sadanori Okamura,
Hiroshi Akahori,
Masaharu Muramatsu
[show abstract]
[hide abstract]
ABSTRACT: The overall updated plan for constructing 7 scientific instruments and 3 baseline programs for the 8 m Subaru telescope is shown. Somewhat detailed descriptions are given further for projects to develop large format CCDs, faint object camera and spectrograph (FOCAS), high dispersion spectrograph (HDS), Subaru prime focus camera (Suprime-Cam), and Cassegrain adaptive optics system (AO).© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
03/1997;
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Yoichi Takeda,
Mudumba Parthasarathy,
Wako Aoki,
Yoshifusa Ita,
Yoshikazu Nakada,
Hideyuki Izumiura, Kunio Noguchi,
Masahide Takada-Hidai,
Ei Sato,
Akito Tajitsu,
Satoshi Honda,
Satoshi Kawanomoto,
Hiroyasu Ando,
Hiroshi Karoji
[show abstract]
[hide abstract]
ABSTRACT: We report on the detection of two Zn I lines at 4722.1 A and 4810.5 A in the high-quality spectrum of the very metal-poor post-AGB star HR 4049, which was obtained with the High Dispersion Spectrograph attached to the Subaru Telescope. The strengths of these lines indicate an appreciable underabundance of Zn by ∼ −1.3dex relative to the Sun. The fact that this volatile element, similarly to others belonging to the same group (e.g., C, N, O, S), does not conform to the extreme depletion (> 4dex) of refractory metals (e.g., Fe), strongly suggests that grain formation has something to do with the origin of the chemical peculiarity. This (not extremely but significantly) subsolar value of [Zn/H] is quantitatively discussed in connection with those of other volatile species, especially with respect to S. We also detected a new Fe II line at 5159.0 A along with the already known Fe II 4923.9 A line; based on these two lines the Fe abundance of HR 4049 is determined to be ∼ 2.8 ([Fe/H] ∼ −4.7).
Publications- Astronomical Society of Japan 04/2005; 54:765-773. · 2.44 Impact Factor
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Masanori Iye,
Hiroshi Karoji,
Hiroyasu Ando,
Norio Kaifu,
Keiichi Kodaira,
Kentaro Aoki,
Wako Aoki,
Yoshihiro Chikada,
Yoshiyuki Doi,
Noboru Ebizuka, [......],
Tomonori Usuda,
Mark Weber,
Tom Winegar,
Masafumi Yagi,
Toru Yamada,
Takuya Yamashita,
Yasumasa Yamashita,
Naoki Yasuda,
Michitoshi Yoshida,
Masami Yutani
[show abstract]
[hide abstract]
ABSTRACT: An overview of the current status of the 8.2m Subaru Telescope constructed and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of Japan is presented. The basic design concept and the verified performance of the telescope system are described. Also given are the status of the instrument package offered to the astronomical community, the status of operation, and some of the future plans. The status of the telescope reported in a number of SPIE papers as of the summer of 2002 are incorporated with some updates included as of 2004 February. However, readers are encouraged to check the most updated status of the telescope through the home page, http://subarutelescope.org/index.html, and/or the direct contact with the observatory staff.
Publications of the Astronomical Society of Japan, v.56, 381-397 (2004).
