559 research outputs found
VERTICAL DISTRIBUTION OF NOCTURNAL NET RADIATION IN THE LOWEST FEW HUNDRED METERS OF THE ATMOSPHERE*
Winter thermoregulation of free-ranging Ethiopian hedgehogs (Paraechinus aethiopicus) in Qatar
Biologists focus on thermoregulation of desert mammals in terms of how they minimise heat gain during hotter months, and put less effort on how they maximise heat gain during cooler months. Heat gain may contribute to energy savings of desert mammals during cooler period when the ambient temperature in desert is substantially lower than their body temperatures. We investigated the thermoregulation in free-ranging Ethiopian hedgehogs, Paraechinus aethiopicus, during winter using radio-telemetry in Qatar. Temperatures detected by the tag attached to hedgehogs were significantly higher than ambient temperatures throughout the day, and the difference was more extreme during the mid-day. We also observed several hedgehogs basking with their radio-tags exposed to direct sunlight. It is possible that basking is beneficial for the hedgehog's winter thermoregulation in the desert where plenty of solar radiation is available.qscienc
ASTE Observations of Warm Gas in Low-mass Protostellar Envelopes: Different Kinematics between Submillimeter and Millimeter Lines
With the ASTE telescope, we have made observations of three low-mass
protostellar envelopes around L483, B335, and L723 in the submillimeter CS
(=7--6) and HCN (=4--3) lines. We detected both the CS and HCN lines
toward all the targets, and the typical CS intensity ( 1.0 K in T)
is twice higher than that of the HCN line. Mapping observations of L483 in
these lines have shown that the submillimeter emissions in the low-mass
protostellar envelope are resolved, exhibit a western extension from the
central protostar, and that the deconvolved size is 5500 AU
3700 AU (P.A. = 78) in the HCN emission. The extent of the
submillimeter emissions in L483 implies the presence of higher-temperature
( 40 K) gas at 4000 AU away from the central protostar, which suggests
that we need to take 2-dimensional radiative transfer models with a flattened
disklike envelope and bipolar cavity into account to explain the temperature
structure inside the low-mass protostellar envelope. The position-velocity
diagrams of these submillimeter lines in L483 and B335 exhibit different
velocity gradients from those found in the previous millimeter observations. In
particular, along the axis of the associated molecular outflow the sense of the
velocity gradient traced by the submillimeter lines is opposite to that of the
millimeter observations or the associated molecular outflow, both in L483 and
B335. We suggest that expanding gas motions at the surface of the flattened
disklike envelope around the protostar, which is irradiated from the central
star directly, are the origin of the observed submillimeter velocity structure.Comment: 20 pages, 11 figure
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