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81.
R. F. Griffin F. C. Fekel M. D. Morton R. E. Fried 《Journal of Astrophysics and Astronomy》1994,15(3):309-319
HD 163621 is a double-lined spectroscopic binary in a circular orbit whose period is 3.3 days. Spectral classification of
the components has proved difficult, but current results of K0 V and late K V are reasonably consistent with our best model
of the system, which has spectral types of G8V and K7V. The object shows photometric variability and chromospheric activity
and is therefore a member of the BY Draconis class of variables. The minimum masses are quite small, 0.10 and 0.07 M⊙ for
the primary and secondary, respectively, suggesting an orbital inclination of about 30°. The system is synchronously rotating.
Its distance is estimated to be 31 pc, which makes it an excellent candidate for a trigonometric parallax determination.
Kitt Peak National Observatory, [U.S.] National Optical Astronomy Observatories, operated by AURA Inc. under contract with
the [U.S.] National Science Foundation. 相似文献
82.
E. Pascale I. P. Waldmann C. J. MacTavish A. Papageorgiou A. Amaral-Rogers R. Varley V. Coudé du Foresto M. J. Griffin M. Ollivier S. Sarkar L. Spencer B. M. Swinyard M. Tessenyi G. Tinetti 《Experimental Astronomy》2015,40(2-3):601-619
EChOSim is the end-to-end time-domain simulator of the Exoplanet Characterisation Observatory (EChO) space mission. EChOSim has been developed to assess the capability of the EChO mission concept to detect and characterise the atmospheres of transiting exoplanets. Here we discuss the details of the EChOSim implementation and describe the models used to represent the instrument and to simulate the detection. Software simulators have assumed a central role in the design of new instrumentation and in assessing the level of systematics affecting the measurements of existing experiments. Thanks to its high modularity, EChOSim can simulate basic aspects of several existing and proposed spectrometers including instruments on the Hubble Space Telescope and Spitzer, ground-based and balloon-borne experiments. A discussion of different uses of EChOSim is given, including examples of simulations performed to assess the EChO mission. 相似文献
83.
Ben B. Balsley Dale A. Lawrence Ronald F. Woodman David C. Fritts 《Boundary-Layer Meteorology》2013,147(1):165-178
We report results of preliminary high-resolution in situ atmospheric measurements through the boundary layer and lower atmosphere over the southern coast of Perú. This region of the coast is of particular interest because it lies adjacent to the northern coastal edge of the sub-tropical south-eastern Pacific, a very large area of ocean having a persistent stratus deck located just below the marine boundary layer (MBL) inversion. Typically, the boundary layer in this region during winter is topped by a quasi-permanent, well-defined, and very large temperature gradient. The data presented herein examine fine-scale details of the coastal atmosphere at a point where the edge of this MBL extends over the coastline as a result of persistent onshore flow. Atmospheric data were gathered using a recently-developed in-house constructed, GPS-controlled, micro-autonomous-vehicle aircraft (the DataHawk). Measured quantities include high-resolution profiles of temperature, wind, and turbulence structure from the surface to 1,300 m. 相似文献
84.
85.
We present near-IR spectra of solid CO2 in H2O and CH3OH, and find they are significantly different from that of pure solid CO2. Peaks not present in either pure H2O or pure CO2 spectra become evident when the two are mixed. First, the putative theoretically forbidden CO2 (2ν3) overtone near 2.134 μm (4685 cm−1), that is absent from our spectrum of pure solid CO2, is prominent in the spectra of H2O/CO2=5 and 25 mixtures. Second, a 2.74-μm (3650 cm−1) dangling OH feature of H2O (and a potentially related peak at 1.89 μm) appear in the spectra of CO2-H2O ice mixtures, but are probably not diagnostic of the presence of CO2. Other CO2 peaks display shifts in position and increased width because of intermolecular interactions with H2O. Warming causes some peak positions and profiles in the spectrum of a H2O/CO2=5 mixture to take on the appearance of pure CO2. Absolute strengths for absorptions of CO2 in solid H2O are estimated. Similar results are observed for CO2 in solid CH3OH. Since the CO2 (2ν3) overtone near 2.134 μm (4685 cm−1) is not present in pure CO2 but prominent in mixtures, it may be a good observational (spectral) indicator of whether solid CO2 is a pure material or intimately mixed with other molecules. These observations may be applicable to Mars polar caps as well as outer Solar System bodies. 相似文献
86.
R. F. Griffin 《Journal of Astrophysics and Astronomy》1982,3(2):101-105
Photoelectric radial-velocity measurements show that HD 120803 is a spectroscopic binary with a rather eccentric orbit and
a period of 700 days. Early DDO photographic observations, published individually here for the first time, fit the orbit well. 相似文献
87.
The rate at which, and the processes by which, a passive tracer is stirred and mixed in a turbulent mesoscale eddy field are examined for environmental parameters characteristic of a homogeneous mid-ocean region. The simulated, time-dependent eddy field is obtained by direct integration of the forced/damped barotropic vorticity equation; the dispersal of a spatially localized, instantaneous release of tracer (a “tracer spot”) within the evolving velocity field is subsequently computed from the advective-diffusive equation. An ensemble of 10 independent releases is used to determin the average spreading properties of the tracer spot.On an f-plane, the ensemble-averaged dispersal is approximately isotropic, and is associated with an effective diffusion rate substantially greater than that supported in the absence of turbulent advection. Quantitatively, the effective ensemble-averaged diffusivity is shown to be 0(UL), where U and L are characteristic velocity and length scales of the turbulent flow. This estimate is consistent with the traditional mixing length hypothesis. With the addition of β, the simulated flow field has substantial zonal anisotropy. Ensemble-averaged dispersal of tracer spots is similarly anisotropic, and the overall rate of tracer dispersal is substantially reduced over its f-plane value.Both with and without β, the initial rate at which maximum tracer concentration and total tracer variance decay are given by the approximate law exp[? αγt] where γ is the RMS rate of strain, and α is approximately constant at a value of 0.5. The heightened rate of variance loss over that associated with pure (subgridscale) diffusion is shown to be accommodated by the rapid transfer of tracer variance from the largest to the shortest scale tracer features, that is, by the rapid sharpening of tracer gradients by turbulent advection. A detailed examination of the dispersal of individual tracer realizations, and the associated question of tracer streakiness, is given in part II of this work (Keffer and Haidvogel, in preparation). 相似文献
88.
R. F. Griffin 《Journal of Astrophysics and Astronomy》1988,9(4):205-211
Photoelectric radial-velocity measurements show that HD 116093 is a double-lined spectroscopic binary in a very eccentric
53-day orbit. Very little else is known about the system, but circumstantial evidence is consistent with the hypothesis that
the components’ types are near to F3 V and F8 V. If that is so, the orbit must be seen very nearly edge-on; a search for eclipses
is warranted and an ephemeris for them is given. 相似文献
89.
R. F. Griffin 《Journal of Astrophysics and Astronomy》1983,4(3):171-173
Photoelectric radial-velocity measurements show that HD 116378 is a spectroscopic binary with a period of 17.76 days. The visual companion star is not physically related to it. 相似文献
90.
R. F. Griffin 《Journal of Astrophysics and Astronomy》1988,9(3):127-136
Photoelectric radial-velocity measurements show that HD 106947 is a double-lined spectroscopic binary. The components have
spectral types of about F6 V and G5 V and are in a 59-day orbit of moderate eccentricity. The system is a member of the Coma
Cluster. 相似文献