20 research outputs found
The intriguing giant bow shocks near HH 131
Using the High Dispersion Spectrograph at the Subaru Telescope, echelle
spectra of two giant arcs, i.e. nebulosities Cw and L associated with HH 131 in
Orion are presented. Typical emission lines of Herbig-Haro objects have been
detected towards Cw. With the 2.16 m telescope of National Astronomical
Observatories, spectra of Nebu. C, L and K are obtained, which also show strong
[SII]6717/6731, H and [NII]6583 emission lines. Position-velocity
distributions of Cw and L are analyzed. The fastest radial velocity of Cw is
V_r ~ -18.0 km/s. When the flow at L goes to the south, it slows down. The
fastest radial velocity of L has been observed of -45.0 km/s and the slowest
value is about -18.3 km/s. The similarity of the velocities and their
positional connection indicate that Cw and L are physically associated. The
entire flow tends to become less excited and less ionized when going further to
the south (i.e., from Nebu. K, L to C). The electron densities of all the
observed nebulosities are low (n_e ~ 10^2 cm^-3). Double kinematic signatures
have been found in Cw from its [NII]6583 profiles while the observed H
profiles of Cw are almost symmetric. Bow shock models appear to agree with the
observed position-velocity diagrams of the [NII spectra better than H
spectra. With the suggestion that these arcs are HH shocks possibly ejected out
of the Orion A molecular cloud by an uncertain source, their spectra show low
to intermediate excitation from their diagnostic line ratios.Comment: 27 pages, 10 figures, accepted for publiscation in A
"Dark" GRB 080325 in a Dusty Massive Galaxy at z ~ 2
We present optical and near infrared observations of GRB 080325 classified as
a "Dark GRB". Near-infrared observations with Subaru/MOIRCS provided a clear
detection of afterglow in Ks band, although no optical counterpart was
reported. The flux ratio of rest-wavelength optical to X-ray bands of the
afterglow indicates that the dust extinction along the line of sight to the
afterglow is Av = 2.7 - 10 mag. This large extinction is probably the major
reason for optical faintness of GRB 080325. The J - Ks color of the host
galaxy, (J - Ks = 1.3 in AB magnitude), is significantly redder than those for
typical GRB hosts previously identified. In addition to J and Ks bands, optical
images in B, Rc, i', and z' bands with Subaru/Suprime-Cam were obtained at
about one year after the burst, and a photometric redshift of the host is
estimated to be z_{photo} = 1.9. The host luminosity is comparable to L^{*} at
z \sim 2 in contrast to the sub-L^{*} property of typical GRB hosts at lower
redshifts. The best-fit stellar population synthesis model for the host shows
that a large dust extinction (Av = 0.8 mag) attributes to the red nature of the
host and that the host galaxy is massive (M_{*} = 7.0 \times 10^{10} Msun)
which is one of the most massive GRB hosts previously identified. By assuming
that the mass-metallicity relation for star-forming galaxies at z \sim 2 is
applicable for the GRB host, this large stellar mass suggests the high
metallicity environment around GRB 080325, consistent with inferred large
extinction.Comment: 22 pages, 10 figures, accepted for publication in The Astrophysical
Journa
Phase I clinical study of a novel lipophilic platinum complex (SM-11355) in patients with hepatocellular carcinoma refractory to cisplatin/lipiodol
On The Spectrum and Spectropolarimetry of Type Ic Hypernova SN 2003dh/GRB 030329
Spectroscopic and spectropolarimetric observations of SN 2003dh/GRB 030329
obtained in 2003 May using the Subaru 8.2 m telescope are presented. The
properties of the SN are investigated through a comparison with spectra of the
Type Ic hypernovae SNe 1997ef and 1998bw. (Hypernovae being a tentatively
defined class of SNe with very broad absorption features: these features
suggest a large velocity of the ejected material and possibly a large explosion
kinetic energy.) Comparison with spectra of other hypernovae shows that the
spectrum of SN 2003dh obtained on 2003 May 8 and 9, i.e., 34-35 rest-frame days
after the GRB (for z=0.1685), are similar to those of SN 1997ef obtained ~34-42
days after the fiducial time of explosion of that SN. The match with SN 1998bw
spectra is not as good (at rest 7300-8000 A, but again spectra obtained ~33-43
days after GRB 980425 are preferred. This indicates that the SN may have
intermediate properties between SNe 1997ef and 1998bw. Based on the analogy
with the other hypernovae, the time of explosion of SN 2003dh is then
constrained to be between -8 and +2 days of the GRB. The Si and O P-Cygni lines
of SN 2003dh seem comparable to those of SN 1997ef, which suggests that the
ejected mass in SN 2003dh may match that in SN 1997ef. Polarization was
marginally detected at optical wavelengths. This is consistent with
measurements of the late afterglow, implying that it mostly originated in the
interstellar medium of the host galaxy.Comment: 7 pages, 4 figures, uses emulateapj5.sty, accepted for puclication in
ApJ
A Rapidly Declining Transient Discovered with the Subaru/Hyper Suprime-Cam
We perform a high-cadence transient survey with the Subaru Hyper Suprime-Cam (HSC), which we call the Subaru HSC survey Optimized for Optical Transients (SHOOT). We conduct HSC imaging observations with time intervals of about one hour on two successive nights, and spectroscopic and photometric follow-up observations. A rapidly declining blue transient SHOOT14di at z = 0.4229 is found in observations on two successive nights using an image-subtraction technique. The rate of brightness change is +1.28(-0.20)(+0.40) mag day(-1) (+1.83(-0.39)(+0.57) day(-1)) in the observer (rest) frame and the rest-frame color between 3400 and 4400 angstrom is M-3400 (angstrom)-M-4400 (angstrom) = -0.4. The nature of the object is investigated by comparing its peak luminosity, decline rate, and color with those of transients and variables previously observed, and with those of theoretical models. None of the transients or variables share the same properties as SHOOT14di. Comparisons with theoretical models demonstrate that, while the emission from the cooling envelope of a SN IIb shows a slower decline rate than SHOOT14di, and the explosion of a red supergiant star with a dense circumstellar wind shows a redder color than SHOOT14di, the shock breakout at the stellar surface of the explosion of a 25M(circle dot) red supergiant star with a small explosion energy of <= 0.4 x 10(51) erg reproduces the multicolor light curve of SHOOT14di. This discovery shows that a high-cadence, multicolor optical transient survey at intervals of about one hour, and continuous and immediate follow-up observations, is important for studies of normal core-collapse supernovae at high redshifts
Subaru Deep Survey I. Near-Infrared Observations
Deep near-infrared images of a blank 2'x2' 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 automated detection procedure
are 385 in the J band and 350 in K'. Based on photometric measurements of these
sources, we present number count vs. magnitude relations, color vs. magnitude
diagrams, size vs. color relationships, etc. The slope of the galaxy number
count plotted against the AB magnitude scale is about 0.23 in the 22 to 26 AB
magnitude range of both bands. The spatial number density of galaxies as well
as the slopes in the faint-end region given by the Subaru Deep Field (SDF)
survey is consistent with those given by HST-NICMOS surveys as expressed on the
AB magnitude diagram. Several sources having very large J-K' color are found
including a few K' objects without detection at J. In addition, a number of
faint Galactic stars are also detected, most of which are assigned to
M-subdwarfs, together with a few brown dwarf candidates.Comment: 11 pages, 14 figures, to appear in Publ.Astr.Soc.Japan. The full ps
file can be retrieved at
ftp://ftp-cr.scphys.kyoto-u.ac.jp/pub/crmember/maihara/sdf/sdf.ps.g