126 research outputs found
A Search for Interstellar CHD
We report on a search for Interstellar CH2D+. Four transitions occur in
easily accessible portions of the spectrum; we report on emission at the
frequencies of these transitions toward high column density star-forming
regions. While the observations can be interpreted as being consistent with a
detection of the molecule, further observations will be needed to secure that
identification. The CH2D+ rotational spectrum has not been measured to high
accuracy. Lines are weak, as the dipole moment induced by the inclusion of
deuterium in the molecule is small. Astronomical detection is favored by
observations toward strongly deuterium-fractionated sources. However, enhanced
deuteration is expected to be most significant at low temperatures. The
sparseness of the available spectrum and the low excitation in regions of high
fractionation make secure identification of CH2D+ difficult. Nonetheless, owing
to the importance of CH3+ to interstellar chemistry, and the lack of rotational
transitions of that molecule owing to its planar symmetric structure, a measure
of its abundance would provide key data to astrochemical models.Comment: 2 pages, 1 figure, submitted to IAU Symposium 251, Organic Matte
The Atacama Large Millimeter Array (ALMA)
The Atacama Large Millimeter Array, or ALMA, is an international telescope
project which will be built over the coming decade in Northern Chile. With over
7000 m^2 of collecting area comprised of 64 12m antennas arrayed over baselines
up to 14 km in extent, ALMA will provide images of unprecedented clarity and
detail. One revolutionary feature of ALMA will be its ability to combine
interferometric and single telescope data, providing complete flux recovery.
ALMA will cover a spectral wavelength range from 7mm to 0.3 mm or shorter
wavelengths, providing astronomy with its first detailed look at the structures
which emit millimeter and submillimeter photons, the most abundant photons in
the Universe
A Proper Motion Study of the Haro 6-10 Outflow: Evidence for a Subarcsecond Binary
We present single-dish and VLBI observations of an outburst of water maser
emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus
molecular cloud and contains a visible T Tauri star with an infrared companion
1.3" north. Using the Very Long Baseline Array, we obtained five observations
spanning 3 months and derived absolute positions for 20 distinct maser spots.
Three of the masers can be traced over 3 or more epochs, enabling us to extract
absolute proper motions and tangential velocities. We deduce that the masers
represent one side of a bipolar outflow that lies nearly in the plane of the
sky with an opening angle of ~45\deg. They are located within 50 mas of the
southern component of the binary, the visible T Tauri star Haro 6-10S. The mean
position angle on the sky of the maser proper motions (~220\deg) suggests they
are related to the previously observed giant Herbig-Haro (HH) flow which
includes HH410, HH411, HH412, and HH184A-E. A previously observed HH jet and
extended radio continuum emission (mean position angle of ~190\deg) must also
originate in the vicinity of Haro6-10S and represent a second, distinct outflow
in this region. We propose that a yet unobserved companion within 150 mas of
Haro6-10S is responsible for the giant HH/maser outflow while the visible star
is associated with the HH jet. Despite the presence of H_2 emission in the
spectrum of the northern component of the binary, Haro6-10N, none of
outflows/jets can be tied directly to this young stellar object
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