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Type Ia supernovae are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions about supernovae are how the explosion actually proceeds and whether accretion(More)
Infrared absorption lines of H + 3 , including the metastable R(3,3) l line, have been observed toward eight bright infrared sources associated with hot and massive stars located in and between the Galactic Center Cluster and the Quintuplet Cluster 30 pc to the east. The absorption lines with high velocity dispersion arise in the Galaxy's Central Molecular(More)
Using an absorption line from the metastable (J ; K) ¼ (3; 3) level of H þ 3 together with other lines of H þ 3 and CO observed along several sight lines, we have discovered a vast amount of high-temperature (T $ 250 K) and low-density (n $ 100 cm À3) gas with a large velocity dispersion in the central molecular zone (CMZ) of the Galaxy, i.e., within 200 pc(More)
We present high-resolution (R = 20000) spectroscopy of H + 3 absorption toward the luminous Galactic center sources GCS 3-2 and GC IRS 3. With the efficient wavelength coverage afforded by Subaru IRCS, six absorption lines of H + 3 have been detected in each source from 3.5 to 4.0 µm, three of which are new. In particular the 3.543 µm absorption line of the(More)
We present a follow-up observation on Geballe and Oka (2010, ApJ, 709, L70), who found high column densities of H + 3 100 pc apart from the Galactic center on the lines of sight to 2MASS J174321732951430 (J1743) and 2MASS J174708982829561 (J1747). The wavelength coverages on these sightlines have been extended in order to observe two key transitions of H +(More)
This paper describes a Cooled Infrared Spectrograph and Camera for OHS (CISCO), mounted on the Nasmyth focus of the Subaru telescope. It is primarily designed as a back-end camera of the OH-Airglow Suppressor (OHS), and is also used as an independent, general-purpose near-infrared camera/spectrograph. CISCO is based on a single 1024×1024 format HgCdTe(More)
HiCIAO is a high contrast instrument which works with a 188 element adaptive optics system (AO188) for the Subaru Telescope. The instrument is specifically designed for extrasolar planet search and studies of proto-planetary or debris disks. A coronagraph technique and some differential observing modes implemented in HiCIAO extract faint objects from the(More)
Observational and theoretical evidence suggests that high-energy Galactic cosmic rays are primarily accelerated by supernova remnants. If also true for low-energy cosmic rays, the ionization rate near a supernova remnant should be higher than in the general Galactic interstellar medium (ISM). We have searched for H + 3 absorption features in six sight lines(More)
Deep near-infrared images of a blank 2 × 2 section of sky near the Galactic north pole taken by Subaru Telescope are presented. The total integration times of the J and K bands are 12.1 hours and 9.7 hours, resulting in 5-sigma limiting magnitudes of 25.1 and 23.5 mag, respectively. The numbers of sources within these limiting magnitudes found with an(More)
Cassiopeia A is the youngest supernova remnant known in the Milky Way and a unique laboratory for supernova physics. We present an optical spectrum of the Cassiopeia A supernova near maximum brightness, obtained from observations of a scattered light echo more than three centuries after the direct light of the explosion swept past Earth. The spectrum shows(More)