12 research outputs found
Evidence for a companion to BM Gem, a silicate carbon star
Balmer and Paschen continuum emission as well as Balmer series lines of P
Cygni-type profile from H_gamma through H_23 are revealed in the violet spectra
of BM Gem, a carbon star associated with an oxygen-rich circumstellar shell
(`silicate carbon star') observed with the high dispersion spectrograph (HDS)
on the Subaru telescope. The blue-shifted 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, which is the highest outflow velocity observed to date in a
carbon star. 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_sun for the ionized gas
can be maintained by a mass accretion rate to a dwarf companion of ~10^-8 M_sun
yr^-1, while ~10^-10 M_sun 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 Bond-Hoyle type accretion process. We
concluded 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. The upper limits for
binary separation are 210 AU and 930 AU for a dwarf and a white dwarf,
respectively. We also note that the observed features of BM Gem mimic those of
Mira (omi Cet), which may suggest actual similarities in their binary
configurations and circumstellar structures.Comment: 11 pages, 2 figures, 1 table, accepted for publication in Ap
AN EXPERIMENTAL STUDY ON EMBEDMENT STRENGTH FOR BOLTED CONNECTIONS LOADED PERPENDICULAR TO THE GRAIN
A STUDY WITH FRACTURE MECHANICS ON EVALUATION OF STRENGTH AND FRACTURE CHRACTERISTICS FOR BOLTED JOINTS WITH JAPANESE LARCH GLULAM TENSILE-LOADED PERPENDICULAR TO THE GRAIN
A STRENGTH CALCULATION METHOD OF SINGLE BOLTED TIMBER JOINT LOADED PARALLEL TO THE GRAIN
EXPERIMENTAL STUDY ON ESTIMATION METHOD OF FRACTURE TOUGHNESS VALUE AT CRACK INITIATION (J<sub>i</sub>) WITH COLORING
A DISCUSSION ABOUT EVALUATION METHOD OF MODE I FRACTURE TOUGHNESS PERFORMANCE WITH WOOD FOR STRUCTURAL GLULAM
Multicomponent Coupling Reaction of Perfluoroarenes with 1,3-Butadiene and Aryl Grignard Reagents Promoted by an Anionic Ni(II) Complex
An anionic Ni complex was isolated
and its structure determined
by X-ray crystallography. With such an anionic complex as a key intermediate,
a regio- and stereoselective multicomponent coupling reaction of perfluoroarenes,
aryl Grignard reagents, and 1,3-butadiene in a 1:1:2 ratio was achieved,
resulting in the formation of 1,6-octadiene derivatives containing
two aryl groups, one from the perfluoroarene and the other from the
aryl Grignard reagent, at the 3- and 8-positions, respectively