We consider the relationship between two flare-associated waves, a chromospheric Moreton wave and a coronal EIT wave, based on an analysis of an X-class flare event in AR 8100 on 1997 November 4. A Moreton wave was observed in $\mathrm{H}\alpha$, $\mathrm{H}\alpha {+} 0.8\,$$Å$, and $\mathrm{H}\alpha-0.8\,$$Å$ with the Flare-Monitoring Telescope (FMT) at the Hida Observatory. An EIT wave was observed in EUV with the Extreme ultraviolet Imaging Telescope (EIT) on board SOHO. The propagation speeds of the Moreton wave and the EIT wave were approximately $715 \,\mathrm{km} \,\mathrm{s}^{-1}$ and $202 \,\mathrm{km} \,\mathrm{s}^{-1}$, respectively. The times of visibility for the Moreton wave did not overlap those of the EIT wave, but the continuation of the former is indicated by a filament oscillation. Data on the speed and location clearly show that the Moreton wave differed physically from the EIT wave in this case. The Moreton wave preceded the EIT wave, which is inconsistent with an identification of the EIT wave with a fast-mode MHD shock.
Fibre Multi-Object Spectrograph (FMOS) is the first near-infrared instrument with a wide field of view capable of acquiring spectra simultaneously from up to 400 objects. It has been developed as a common-use instrument for the F$/$2 prime-focus of the Subaru Telescope. The field coverage of 30$^\prime$ diameter is achieved using a new 3-element corrector optimized in the near-infrared (0.9–1.8$\ \mu$m) wavelength range. Due to limited space at the prime-focus, we have had to develop a novel fibre positioner, called “Echidna”, together with two OH-airglow suppressed spectrographs. FMOS consists of three subsystems: the prime focus unit for IR, the fibre positioning system/connector units, and the two spectrographs. After full systems integration, FMOS was installed on the telescope in late 2007. Many aspects of the performance were checked through various test and engineering observations. In this paper, we present the optical and mechanical components of FMOS, and show the results of our on-sky engineering observations to date.
Near-infrared spectra of 15 high-redshift radio galaxies (HzRGs) located at 2 < z < 2.6 were obtained by the OH Airglow Suppressor spectrograph mounted on the Subaru telescope. The UV-optical line ratio diagnostic diagrams indicate that half of the observed HzRGs have extended emission-line regions with low metal abundance, photoionized by a flat-continuum active galactic nucleus such as a quasar. We also found two probable correlations between radio and rest-optical parameters: (1) HzRGs with massive hosts tend to have a redder rest-optical continuum, and (2) HzRGs with smaller radio sizes also show a redder optical continuum. On the basis of the correlations, the nature of HzRGs at 2 < z < 2.6 is discussed.
We have carried out near-infrared JHK spectroscopy of the gravitationally lensed submillimeter galaxy SMM J14011+0252 at z ¼ 2:565, using the OH-airglow suppressor and the Cooled Infrared Camera and Spectrograph for OHS on the Subaru Telescope. This object consists of two optical components, J1 and J2, which are lensed by the cluster Abell 1835. J1 suffers additional strong lensing by a foreground galaxy at z ¼ 0:25 in the cluster. The restframe optical H, H, and [O ii] k3727 lines are detected in both J1 and J2, and [N ii] kk6548, 6583 lines are also detected in J1. A diagnosis of emission-line ratios shows that the excitation source of J1 is stellar in origin, consistent with previous X-ray observations. The continua of J1 and J2 show breaks at rest-frame 4000 8, indicating a relatively young age. Combined with optical photometry, we have carried out model-spectrum fitting of J2 and find that it is a very young ($50 Myr) galaxy of rather small mass ($10 8 M ) that suffers some amount of dust extinction. A new gravitational lensing model is constructed to assess both the magnification factor and contamination from the lensing galaxy of the component J1, using a Hubble Space Telescope F702W image. We have found that J1 suffers strong lensing with magnification of $30, and its stellar mass is estimated to be P10 9 M . These results suggest that SMM J14011+0252 is a major merger system at high redshift that undergoes intense star formation but is not a formation site of a giant elliptical galaxy. Still having plenty of gas, it will transform most of the gas into stars and will evolve into a galaxy of P10 10 M . Therefore, this system is possibly an ancestor of a present-day, less massive galaxy such as a midsized elliptical galaxy or a spiral galaxy.
The Fibre Multi-Object Spectrograph (FMOS) is a second-generation common-use instrument of the Subaru telescope. Under an international collaboration scheme of Japan, UK, and Australia, a realistic design of FMOS has been already in completion, and the fabrications of hardware components have been in progress. We present the overall design details together with the special features of FMOS subsystems, such as the prime focus corrector, the prime focus mechanical unit including fibre positioners, and the near-infrared spectrograph, etc.
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