420 research outputs found
LSS 1135: an O-Type Spectroscopic Binary in the galactic OB association Bochum 7
From radial velocities derived from optical spectroscopic observations
performed at CTIO, Chile, and CASLEO, Argentina, we have discovered that LSS
1135 is a single--lined O-type binary system with an orbital period of 2.7532
days. We present an analysis of the orbital elements of this system based on
radial velocities of the He absorption lines. We classify the spectrum of LSS
1135 as O6.5V((f)). We also present spectral classifications and radial
velocities for other seven OB stars in the region of Bochum 7, an OB
association to which LSS 1135 belongs. Our data indicate a distance of 5.0 kpc
for this star group.Comment: 5 pages, 4 figures, many tables, uses aa.cls version 4.05. Accepted
for publication in A&
Infrared Observations of The Millisecond Pulsar Binary J1023+0038: Evidence for Short-Term Nature of Its Interacting Phase in 2000--2001
We report our multi-band infrared (IR) imaging of the transitional
millisecond pulsar system J1023+0038, a rare pulsar binary known to have an
accretion disk in 2000--2001. The observations were carried out with
ground-based and space telescopes from near-IR to far-IR wavelengths. We
detected the source in near-IR JH bands and Spitzer 3.6 and 4.5 m mid-IR
channels. Combined with the previously-reported optical spectrum of the source,
the IR emission is found to arise from the companion star, with no excess
emission detected in the wavelength range. Because our near-IR fluxes are
nearly equal to those obtained by the 2MASS all-sky survey in 2000 Feb., the
result indicates that the binary did not contain the accretion disk at the
time, whose existence would have raised the near-IR fluxes to 2-times larger
values. Our observations have thus established the short-term nature of the
interacting phase seen in 2000--2001: the accretion disk at most existed for
2.5 yrs. The binary was not detected by the WISE all-sky survey carried out in
2010 at its 12 and 22 m bands and our Herschel far-IR imaging at 70 and
160 m. Depending on the assumed properties of the dust, the resulting flux
upper limits provide a constraint of <3x10^{22}--3x10^{25} g on the mass of the
dust grains that possibly exist as the remnant of the previously-seen accretion
disk.Comment: 7 page, 1 figure, 2 tables, accepted for publication in Ap
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